Nucleic Acids - DNA, RNA -Genetics

Gene transfer techniques

2010-04-06T04:24:00.000-07:00

Gene transfer techniques Success of gene therapy lies in efficient gene transfer into the cell. The gene (cDNA) is generally cloned into a vector to be able to deposit the foreign gene into the target cell. Selection of the right vector is crucial to gene ther-apy. An ideal vector should be able to protect and deliver DNA easily across the cell membrane into the nucleus, should have the ability to regulate expression of the gene of interest and minimize toxicity by targeting gene delivery to specific cells. It should be easy and inexpensive to produce in large quantities. Once the therapeutic gene is cloned into a vector with appropriate regulatory sequences (promoter/enhancer), it is introduced into the target cells. The genes can be delivered either ex vivo –where cells from a selected tissue of the patient are removed, exposed to the gene-transfer vector, selected forthe transgene using markers, and then the genetically cor-rected cells are reintroduced into the patient’s body; or in vivo where the vector DNA is injected directly into the body, generally into the tissue to be treated. Physical and chemical methods of gene transfer Various methods have evolved in the past few years to transfer genes to the target cells. Physical methods such as (a) microinjection of DNA into the cells or (b) electroporation, although very efficient, have their drawbacks in delivering genes in vivo. Also they are expensive as they involve use of specialized instruments. Chemical methods such as (a) calcium phosphate precipitation, where DNA in trapped in a fine precipitate which is endocytosed by the cell, or (b) DNA bound to the positively charged molecules such as DEAE-dextran or polybrene which then bind to the negatively charged cell membrane, are commonly used in the laboratories. DNA encapsulated in synthetic cationic lipid vesicles which fuse with the cell membrane and release DNA into the cell are being used in a number of gene therapy trials 2. Cationic liposome-mediated gene transfer is a safe and effective means of delivering genes directly into tumours. This approach prevents undesirable side effects.

Gene Therapy for Cancer

2010-04-06T04:21:00.000-07:00

Gene therapy, the latest development in the field of medicine, is based on manipulating, or changing the genetic material to treat and prevent the appearance of certain diseases that are difficult to heal with normal treatment. Gene therapy involves the introduction of genes, the biological unit of heredity, in cells or tissues of people who suffer from diseases like cancer. Gene therapy is done for the first time on September 14, 1990 by a group of physicians, consisting of W. French Anderson, MD and his colleagues Michael R. Blaese, MD, Bouza C. Institute and Kenneth Culver, MD, U. S. National Health. Performed in a four-year-old child suffering from "severe immunodeficiency combined, a rare genetic disease. Gene therapy can be classified into two main types of germ-line gene therapy and somatic gene therapy. Germline gene therapy involves the introduction of functional genes in the germ or reproductive cells (sperm and eggs) from the body, while in the case of somatic gene therapy, therapeutic genes are introduced into somatic cells. Gene therapy consists primarily in changing the genetic material (DNA and genes), and plays a key role in determining individual traits and characteristics. It has added a new dimension to cancer treatment, which is caused by mutation or DNA damage that leads to uncontrolled growth of abnormal cells. Most research was conducted and some are still underway to discover the potential of gene therapy in the treatment of breast, lung, prostate, bone, and leukemia. Different approaches for gene therapy to treat cancer, mainly concentrated or destroy or prevent growth of cancer cells or improve the ability of normal cells to fight cancer cells. If cancer is caused due to missing or changed genes, then gene therapy is the replacement of these genes with healthy ones. In addition, gene therapy can be done to stimulate the immune system to attack cancer cells. Through this technology, genes can be inserted into the patient's body, which, to instruct the cancer cells to produce certain proteins to inhibit stimulated Oncogenes cause cancer or tumor suppressor genes. Several other studies also underway to introduce genes into cancer cells, which can help make cancer cells more sensitive to various cancer treatments, including chemotherapy and radiotherapy. In addition, investigations are also underway to reduce the side effects of anticancer drugs to different cells increased resistance to flow. However, gene therapy, genes are introduced directly into the patient's body, but the virus used for this purpose. The virus is generally used for this therapy are retrovirus, adenovirus, herpes virus, lentivirus and poxviruses. Sometimes, liposomes (a small vesicle in a cell to shops and transport of substances in a cell) is also used as carriers in gene therapy. The virus can be used for both ex vivo and in vivo gene therapy. Ex vivo gene therapy involves the collection of blood or less bone marrow cells of the patient. Then the virus to insert genes into cells are needed in a laboratory, then injected into the patient's body. Furthermore, in vivo gene therapy involves the direct introduction of viruses or liposomes containing the desired gene in the patient's body. However, gene therapy is not without its drawbacks. One of the potential risks associated with gene therapy on the possibility of infection of healthy cells caused by the virus used to deliver the gene. Moreover, if genetic material is accidentally introduced into germ cells, then changes induced by it, will become the next generation. Again, this is very important to insert the desired gene in the right place, which can lead to failure and cause genetic mutations and cancer. More research is needed to eliminate the shortcomings of gene therapy, so you can truly revolutionize the treatment of life-threatening diseases like cancer.

Gene doping

2010-03-02T07:03:00.001-08:00

Gene doping is defined by the World Anti-Doping Agency as "the non-therapeutic use of cells, genes, genetic elements, or of the modulation of gene expression, having the capacity to improve athletic performance". A complex ethical and philosophical issue is what defines "gene doping", especially in the context of bioethical debates about human enhancement. An example of gene doping could involve the recreational use of gene therapies intended to treat muscle-wasting disorders. Many of these chemicals may be indistinguishable from their natural counterparts. In such cases, nothing unusual would enter the bloodstream so officials would detect nothing in a blood or urine test.

Genome mapping

2010-03-02T07:02:00.001-08:00

Genome mapping is the creation of a genetic map assigning DNA fragments to chromosomes. When a genome is first investigated, this map is nonexistent. The map improves with the scientific progress and is perfect when the genomic DNA sequencing of the species has been completed. During this process, and for the investigation of differences in strain, the fragments are identified by small tags. These may be genetic markers (PCR products) or the unique sequence-dependent pattern of DNA-cutting enzymes. The ordering is derived from genetic observations (recombinant frequency) for these markers or in the second case from a computational integration of the fingerprinting data. The term "mapping" is used in two different but related contexts. Two different ways of mapping are distinguished. Genetic mapping uses classical genetic techniques (e.g. pedigree analysis or breeding experiments) to determine sequence features within a genome. Using modern molecular biology techniques for the same purpose is usually referred to as physical mapping.

Types of Gene Therapy

2010-03-02T06:58:00.000-08:00

Virtually all cells in the human body contain genes, making them potential targets for gene therapy. However, these cells can be divided into two major categories: somatic cells (most cells of the body) or cells of the germline (eggs or sperm). In theory it is possible to transform either somatic cells or germ cells. Gene therapy using germ line cells results in permanent changes that are passed down to subsequent generations. If done early in embryologic development, such as during preimplantation diagnosis and in vitro fertilization, the gene transfer could also occur in all cells of the developing embryo. The appeal of germ line gene therapy is its potential for offering a permanent therapeutic effect for all who inherit the target gene. Successful germ line therapies introduce the possibility of eliminating some diseases from a particular family, and ultimately from the population, forever. However, this also raises controversy. Some people view this type of therapy as unnatural, and liken it to "playing God." Others have concerns about the technical aspects. They worry that the genetic change propagated by germ line gene therapy may actually be deleterious and harmful, with the potential for unforeseen negative effects on future generations. Somatic cells are nonreproductive. Somatic cell therapy is viewed as a more conservative, safer approach because it affects only the targeted cells in the patient, and is not passed on to future generations. In other words, the therapeutic effect ends with the individual who receives the therapy. However, this type of therapy presents unique problems of its own. Often the effects of somatic cell therapy are short-lived. Because the cells of most tissues ultimately die and are replaced by new cells, repeated treatments over the course of the individual's life span are required to maintain the therapeutic effect. Transporting the gene to the target cells or tissue is also problematic. Regardless of these difficulties, however, somatic cell gene therapy is appropriate and acceptable for many disorders, including cystic fibrosis, muscular dystrophy, cancer, and certain infectious diseases. Clinicians can even perform this therapy in utero, potentially correcting or treating a life-threatening disorder that may significantly impair a baby's health or development if not treated before birth.

Types of Gene Therapy

2010-02-06T17:50:00.001-08:00

Gene therapy is the insertion of genes into an individual's cells and tissues to treat a disease, and hereditary diseases in which a defective mutant allele is replaced with a functional one. Although the technology is still in its infancy, it has been used with some success. Antisense therapy is not strictly a form of gene therapy, but is a genetically-mediated therapy and is often considered together with other methods. How does gene therapy work? In most gene therapy studies, a "normal" gene is inserted into the genome to replace an "abnormal," disease-causing gene. A carrier molecule called a vector must be used to deliver the therapeutic gene to the patient's target cells. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Viruses have evolved a way of encapsulating and delivering their genes to human cells in a pathogenic manner. Scientists have tried to take advantage of this capability and manipulate the virus genome to remove disease-causing genes and insert therapeutic genes. Target cells such as the patient's liver or lung cells are infected with the viral vector. The vector then unloads its genetic material containing the therapeutic human gene into the target cell. The generation of a functional protein product from the therapeutic gene restores the target cell to a normal state. How is gene therapy being studied in the treatment of cancer? Researchers are studying several ways to treat cancer using gene therapy. Some approaches target healthy cells to enhance their ability to fight cancer. Other approaches target cancer cells, to destroy them or prevent their growth. Some gene therapy techniques under study are described below. In one approach, researchers replace missing or altered genes with healthy genes. The types of gene therapy described thus far all have one factor in common: that is, that the tissues being treated are somatic (somatic cells include all the cells of the body, excluding sperm cells and egg cells). In contrast to this is the replacement of defective genes in the germline cells (which contribute to the genetic heritage of the offspring). Gene therapy in germline cells has the potential to affect not only the individual being treated, but also his or her children as well. Germline therapy would change the genetic pool of the entire human species, and future generations would have to live with that change. Gene Therapy: requirements The gene must be identified and cloned. This has been done for the ADA gene.It must be inserted in cells that can take up long-term residence in the patient. So far, this means removing the patient's own cells, treating them in tissue culture, and then returning them to the patient. It must be inserted in the DNA so that it will be expressed adequately; that is, transcribed and translated with sufficient efficiency that worthwhile amounts of the enzyme are produced. All these requirements seem to have been met for SCID therapy using a retrovirus as the gene vector. Retroviruses have several advantages for introducing genes into human cells. Their envelope protein enables the virus to infect human cells. RNA copies of the human ADA gene can be incorporated into the retroviral genome using a packaging cell.

Gene Therapy

2010-02-06T17:47:00.000-08:00

What is Gene Therapy? Gene therapy is substituting defective genes in a cell with the correct ones. Genes are the basis of heredity. The are made of triplets of nitrogenous bases that code for amino acids. The amino acids make up proteins that play important role in the way our body functions. Hence, defective genes result in malfunctioning metabolic pathways that manifest as diseases, the causes of which are embedded deep within our genetic makeup. Hence, till date there is no cure for genetic disorders. Treatment is only symptomatic. No wonder there is so much frenzy in the scientific community about the therapeutic effects of gene therapy. Read more on what is human gene therapy. Gene Therapy Treatment Gene therapy can be broadly classified into two types. One is the somatic cell gene therapy and the other is the reproductive cell or germline gene therapy. In somatic cell gene therapy, the somatic cells are targeted for gene replacement, whereas in the reproductive cell gene therapy, the defective gene lies in the reproductive cells that are replaced by the correct gene. The alterations made in the genetic makeup of the somatic cells is corrective only for the patient. This change is not inherited by the treated person's offspring. However, in case of germline gene therapy, the changes are passed on to the descendants of the treated individual. Hence, this line of treatment has the potential of altering the human gene pool for good. Read more on understanding genes. How is Gene Therapy Done? Gene therapy depends upon vectors, that is carriers of the normal genes that transfer them to the cells that have the defective gene. One of the most popular vectors are virus, most popularly retroviruses that have the capability of injecting their genetic material into the host cells. This viral genetic material is armed with the correct gene and once it integrates with the host genome, all the cells resulting from cell division of the host cell will contain the copy of the correct gene in place of the defective one. Liposomes, adeno-viruses and using naked DNA are some other options for vectors that are being investigated to replace defective genes in organisms.

TYPES OF GENE THERAPY: -

2010-01-01T06:09:00.000-08:00

Gene therapy may be classified into two types 1) Germ line gene therapy 2) Somatic cell gene therapy a) Incase of germ line gene therapy germ cells that is sperms or eggs are modified by the introduction of functional genes, which are ordinarily integrated into their genomes. Therefore the change due to therapy is heritable and passed onto the later generations. This approach, heretically, is highly effective in counteracting the genetic disorders. However this option is not consider, at least for the present for application in human beings for a variety of technical and ethical reasons. b) In the case of somatic cell gene therapy the gene is introduced only in somatic cells, especially of those tissues in which expression of the concerned gene is critical for health. Expression of the introduced gene relieves symptoms of the disorder, but this effect is not heritable, as it does not involve the germ line. It is the only feasible option, and clinical trials have already started mostly for the treatment of cancer and blood disorders. GENERAL GENE THERAPY STRATEGIES 1) Gene augmentation therapy (GAT): - It is done by simple addition of functional alleles has been used to treat several inherited disorders caused by genetic deficiency of a gene product. It is also involved in transfer to cells of genes encoding toxic compounds (suicide genes) or prodrugs (reagents which confer sensitivity to subsequent treatment with a drug). It has been particularly applied to autosomal recessive disorders where even modest expression levels of an introduced gene may make a substantial difference. 2) Targeted killing of specific cells: - Artificial cell killing and immune system assisted cell killing have been popular in the treatment of cancers. It can be done by two ways. a) Direct cell killing: - it is possible if the inserted genes are expressed to produce a lethal toxin (suicide genes), or a gene encoding a prodrug is inserted, conferring susceptibility to killing by a subsequently administered drug. Alternatively selectively lytic viruses can be used. b) Indirect cell killing: - It uses immunostimulatory genes to provoke or enhance an immune response against the target cell. 3) Targeted mutation correction: - The repair of a genetic defect to restore a functional allele, is the exception, technical difficulties have meant that it is not sufficiently reliable to warrant clinical trails. 4) Targeted inhibition of gene expression: - It is suitable for treating infectious diseases and some cancers. If disease cells display a novel gene product or inappropriate expression of a gene a variety of different systems can be used specifically to block the expression of a single gene at the DNA, RNA or Protein levels.

Gene Therapy

2010-01-01T06:08:00.000-08:00

The term gene therapy can be defined as introduction of a normal functional gene into cells, which contain the defective allele of concerned gene with the objective of correcting a genetic disorder or an acquired disorder. The first approach in gene therapy is: - a) Identification of the gene that plays the key role in the development of a genetic disorder. b) Determination of the role of its product in health and disease. c) Isolation and cloning of the gene. d) Development of an approach for gene therapy. The genetic material may be transferred directly into cells within a patient, which is referred as in vivo gene therapy or else cells may be removed from the patient and the genetic material inserted into them, which is referred as invitro gene therapy. Apart from the two methods mentioned above there is one more method that is ex-vivo gene therapy in which genetic material is inserted into the cells just prior to transplanting the modified cells back into the patient. Major disease classes under gene therapy include: - a) Infectious diseases: - infection by a virus or bacterial pathogen b) Cancers: - uncontrolled and enormous cell division and cell proliferation as a result of activation of an oncogene or inactivation of a tumors suppressor gene or an apoptosis gene. c) Inherited disorders: - genetic deficiency of an individual gene product or genetically determined in appropriate expression of a gene. d) Immune system disorders: - includes allergies, inflammation and also autoimmune diseases in which immune system cells appropriately destroy body cells.

Cell division

2010-01-01T05:13:00.000-08:00

Cell division is the process by which a parent cell divides into two or more daughter cells. Cell division is usually a small segment of a larger cell cycle. This type of cell division in eukaryotes is known as mitosis, and leaves the daughter cell capable of dividing again. The corresponding sort of cell division in prokaryotes is known as binary fission. In another type of cell division present only in eukaryotes, called meiosis, a cell is permanently transformed into a gamete and cannot divide again until fertilization. For simple unicellular organisms such as the amoeba, one cell division is equivalent to reproduction-- an entire new organism is created. On a larger scale, mitotic cell division can create progeny from multicellular organisms, such as plants that grow from cuttings. Cell division also enables asexually reproducing organisms to develop from the one-celled zygote, which itself was produced by cell division from gametes. And after growth, cell division allows for continual construction and repair of the organism. A human being's body experiences about 10,000 trillion cell divisions in a lifetime. The primary concern of cell division is the maintenance of the original cell's genome. Before division can occur, the genomic information which is stored in chromosomes must be replicated, and the duplicated genome separated cleanly between cells. A great deal of cellular infrastructure is involved in keeping genomic information consistent between "generations".

Cell biology

2010-01-01T05:08:00.000-08:00

Cell biology (formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells – their physiological properties, their structure, the organelles they contain, interactions with their environment, their life cycle, division and death. This is done both on a microscopic and molecular level. Cell biology research encompasses both the great diversity of single-celled organisms like bacteria and protozoa, as well as the many specialized cells in multicellular organisms like humans. Knowing the components of cells and how cells work is fundamental to all biological sciences. Appreciating the similarities and differences between cell types is particularly important to the fields of cell and molecular biology as well as to biomedical fields such as cancer research and developmental biology. These fundamental similarities and differences provide a unifying theme, sometimes allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. Hence, research in cell biology is closely related to genetics, biochemistry, molecular biology, Immunology, and developmental biology.

Happy New Year 2010

2010-01-01T00:01:00.000-08:00

Wish You All Happy New Year. Please Welcome the new year 2010 
We are post about the Nucleic Acids - DNA, RNA -Genetics .all sources are taken from the internet we didn’t create anything or discover thing.Just we collect for you all. Thanks For visiting our blog www.biomolecules-world.blogspot.com/.Thanks for  supporting us. Please support us for this coming year also.
DNA,GENE,DNA VS RNA,Bio Molecules,DNA Testing centers,DNA Implementation,RNA Implementation,Genetic testing,DNA sequencing

2009-12-01T16:31:00.001-08:00

This is a versatile RNA molecule. In his famous book, RNA acts as an intermediary, such as genetic information from DNA to protein synthesis machinery. RNA also plays a more active role, performing many functions of a catalyst and recognition usually reserved for proteins. Indeed, the majority of RNA in cells found in the ribosomes - protein synthesis, our cars - and transfer RNA molecules are used to add each new amino acids to the growing protein. In addition, many small RNA molecules involved in regulation, treatment and disposal of the continuous traffic of messenger RNA. RNA polymerase from a great responsibility to create all these different RNA molecules. RNA plant RNA polymerase is a large factory with many moving parts. Shown here since the entry 1i6h AP, is that the yeast cells. It consists of a dozen different proteins. Together, they form a team that surrounds the DNA strands, relaxes and builds a string of RNA from information contained in DNA. After starting enzyme, the rise of faith in DNA copy of RNA polymerase RNA chains of thousands of nucleotides long. Accuracy As expected, RNA polymerase must be an exact copy of genetic information. To improve accuracy, correctness is a simple step to facilitate the RNA chain. Active site has been created to be able to remove nucleotides and add them to the chain growth. The enzyme normally float around nucleotide mismatch to add more if necessary as time for enzyme to remove them. This process is somewhat useless if necessary nucleotides were also dropped from time to time, but this is a small price to pay for the creation of better RNA transcripts. In general, RNA polymerase makes a mistake while adding 10,000 nucleotides, or about once in RNA chain is created.

DNA topoisomerase:

2009-12-01T16:27:00.000-08:00

DNA topoisomerase DNA supercoiling changes. Reduction of DNA-DNA topoisomerase. Type of DNA topoisomerase I drop a hair and DNA topoisomerase II-type knife with two teeth. DNA Topoisomerase regulates DNA supercoiling. Help topoisomerase DNA transcription and replication of DNA. And DNA topoisomerase I and DNA topoisomerase II, a DNA topoisomerase DNA topoisomerase III and IV. DNA topoisomerase: DNA topoisomerase is an enzyme that changes the supercoiling of double DNA. DNA topoisomerase acts for a short cut one or both strands of DNA. DNA topoisomerase type I series of cuts and the level of DNA topoisomerase II knife with two strands of DNA. Coil leave DNA topoisomerase and extends the DNA molecule. DNA topoisomerase helps regulate DNA supercoiling. DNA topoisomerase using DNA replication and transcription. Just as DNA topoisomerase I and DNA topoisomerase II, a DNA topoisomerase DNA topoisomerase III and IV. DNA topoisomerase III may regulate recombination. DNA topoisomerase IV regulates the separation of newly replicated chromosomes.

Helicases

2009-12-01T16:24:00.000-08:00

Helicases are a class of enzymes vital to all living organisms. They are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separating two annealed nucleic acid strands (i.e. DNA, RNA, or RNA-DNA hybrid) using energy derived from ATP hydrolysis. Many cellular processes (DNA replication, transcription, translation, recombination, DNA repair, ribosome biogenesis) involve the separation of nucleic acid strands. Helicases are often utilized to separate strands of a DNA double helix or a self-annealed RNA molecule using the energy from ATP hydrolysis, a process characterized by the breaking of hydrogen bonds between annealed nucleotide bases. They move incrementally along one nucleic acid strand of the duplex with a directionality and processivity specific to each particular enzyme. There are many helicases (14 confirmed in E. coli, 24 in human cells) resulting from the great variety of processes in which strand separation must be catalyzed. Helicases adopt different structures and oligomerization states. Whereas DnaB-like helicases unwind DNA as donut shaped hexamers, other enzymes have been shown to be active as monomers or dimers. Studies have shown that helicases may act passively, waiting for uncatalyzed unwinding to take place and then translocating between displaced strands, or can play an active role in catalyzing strand separation using the energy generated in ATP hydrolysis. In the latter case, the helicase acts comparably to an active motor, unwinding and translocating along its substrate as a direct result ATPase activity.. Helicases may process much faster in vivo than in vitro due to the presence of accessory proteins that aid in the destabilization of the fork junction. Defects in the gene that codes helicase cause Werner syndrome, a disorder characterized by the appearance of premature aging.

DNA polymerase

2009-12-01T16:23:00.001-08:00

A DNA polymerase is an enzyme that catalyzes the polymerization of deoxyribonucleotides into a DNA strand. DNA polymerases are best-known for their role in DNA replication, in which the polymerase "reads" an intact DNA strand as a template and uses it to synthesize the new strand. The newly-polymerized molecule is complementary to the template strand and identical to the template's original partner strand. DNA polymerases use a magnesium ion for catalytic activity. DNA polymerase can add free nucleotides to only the 3’ end of the newly-forming strand. This results in elongation of the new strand in a 5'-3' direction. No known DNA polymerase is able to begin a new chain (de novo). DNA polymerase can add a nucleotide onto only a preexisting 3'-OH group, and, therefore, needs a primer at which it can add the first nucleotide. Primers consist of RNA and DNA bases with the first two bases always being RNA, and are synthesized by another enzyme called primase. An enzyme known as a helicase is required to unwind DNA from a double-strand structure to a single-strand structure to facilitate replication of each strand consistent with the semiconservative model of DNA replication. Error correction is a property of some, but not all, DNA polymerases. This process corrects mistakes in newly-synthesized DNA. When an incorrect base pair is recognized, DNA polymerase reverses its direction by one base pair of DNA. The 3'->5' exonuclease activity of the enzyme allows the incorrect base pair to be excised Following base excision, the polymerase can re-insert the correct base and replication can continue.

Benefits of Genetic genealogy

2009-11-03T08:44:00.001-08:00

Genetic genealogy gives the Genealogists, which are to examine or be supplemented means, their results of genealogy with the information, which is caught up over DNA examination. Positive test matches with another individual can: * you put to positions for further descent research at the disposal * assistance place ererbtes native country * firmly discover you living relatives * validate you existing research * confirm you or refuse you assumed connections between families * examine you or disprove you concerning theories sex

Types of Genetic testing

2009-11-03T08:39:00.000-08:00

• Newborn Screening: Newborn screening immediately after birth using genetic disorders that can be treated early in life are identified. Regular testing of children for some genetic disorders and the most widely used is Geprüftmillionen children every year in the United States are examined. Coll kid on the states considered Phenylketonuria (a genetic disorder that causes mental illness, if treatment) and congenital hypothyroidism (thyroid gland disorder of). • Clinical trials: Clinical trials to determine the status of a specific genetic or chromosome, or hit out is used. In many cases, for genetic diagnosis were confirmed when a certain situation suggested the test was based on physical changes and symptoms. One person at any time during the clinical trials done 'can be, S life, but all the genes or genetic conditions is not available for all. Clinical trial results of a one-man, S. affect health care and disease management can choose. • carrier testing: carrier testing people, a copy of a gene mutation which, if used to identify existing lift, two copies of a genetic disorder caused. Examination of such individuals a genetic disorder that people in ethnic groups have offered to family history and increased risk of specific genetic conditions. If both parents are tested, "made a pair is available, the risk of a child with a genetic condition S test report. • Prenatal testing: one for pre-natal testing "to detect changes in the use of embryos, genes or chromosomes before birth is s. Examination of such a genetic or chromosomal disorder, with an increased risk of having a baby has offered to couples. In some cases, a prenatal test 'two, S-uncertainty may reduce or help them decide whether pregnancy terminates. Identify all possible inherited disorders and birth can not fault. • Preimplantation genetic diagnosis: Genetic testing that the human embryo, before implantation as part of the processes are performing in vitro fertilization. • East and presymptomatic testing: pre-determined, changes in gene identification and evaluation of presymptomatic forms often used in later life disorders that appear after birth are associated with. These tests are the people, a genetic disorder, with one family member can help, but whatever time you test a feature of the disorder is. Pre-determined test changes, a growing 'human, such as some types of cancer as a genetic basis, the possibility of developing disorders with S can be identified. Example, one person BRCA1, 65% cumulative risk of breast cancer have a change. Can determine whether a Presymptomatic testing person (an iron overload disorder) as developed hemochromatosis is a genetic disorder, no signs or symptoms first appear. Previous results and a specific disorder, presymptomatic testing and treatment in developing decision support available information about an individual's risks can provide. • Judicial Review: Forensic testing uses DNA sequence identity of any person for the purposes authorized. Unlike the test described above, the use of judicial review that gene mutations are associated with illness is not identified. Testing of such crime or accident victims, to identify or exclude a biological relationship between people Verbrechenverdächtigen or installation means (eg, parenthood) can cross.

Genetic testing

2009-11-03T08:34:00.000-08:00

Point 1 Genetic testing permits Genetic diagnosis of diseases and vulnerability to a "child, S (genetic father) or a person's sex may determine paternity can be used. Normally, each person has two copies of a gene is one that her mother, one inherited from his father but will be taken. Human genome includes around 20,000 for the trust - is 25,000 genes. Point 2 Individual gene and gene genetic diseases, genetic disorders that are associated with increasing risk of developing type variation for the possible presence of biochemical tests in the direction of a further level of chromosomes, including genetic testing than to study. Genetic testing identifies changes in chromosomes, genes or proteins. Generally, changes in testing that are associated with inherited disorders is found. Point 3 A genetic test results confirm a suspected genetic condition or can cross out or to determine a "person of science or beyond is likely to help developing a genetic disorder. Coll several hundred genetic tests are common, and more are being developed.

DNA profiling

2009-11-03T08:12:00.000-08:00

DNA profiling (also called DNA testing, DNA that writes, or genetic fingerprint) with a legitimate use by scientists based on their respective DNA profiles have the technology to identify individuals. The number of DNA profiles, statistics indicate that a 'person's DNA makeup, whatever' person can be used as a symbol S. S is a set of DNA not like the framework should consider the entire genome. Although 99.9% of human DNA sequences are the same in every person, one person with one difference from DNA is quite different. DNA Framework ( "repeat") uses repeated sequences that are highly variable, together called variable number repeats (VNTR). Very between Places of human VNTRs are closely related but independent variables that people have very VNTRs are unlikely. The lawsuit starts with a champion d' a individual' ; DNA S . The method more desirable than collected of the champion of reference is l' ; j' employ plugs oral, like this reduces the possibility of contamination. When this n' (for example parce qu' is not available; a mandate can be necessary and not realizable) other methods can need d' to be employed to collect a champion d' heart, salted it, seed, or l' ; other liquidates or woven j' adapt personal articles (for example toothbrush, razor, of l' etc) or of the stored champions (woven of banking type of biopsy or for example of sperm). Champions obtained of the parents d' heart (biological relative) can provide un' ; indication d' a individual' ; profile of S, as they could the human remainders that précédentement erano shaped.

DNA sequencing and genomics

2009-10-03T09:34:00.000-07:00

One of the most fundamental technologies developed to study genetics, DNA sequencing allows researchers to determine the sequence of nucleotides in DNA fragments. Developed in 1977 by Frederick Sanger and coworkers, chain-termination sequencing is now routinely used to sequence DNA fragments. With this technology, researchers have been able to study the molecular sequences associated with many human diseases. As sequencing has become less expensive, researchers have sequenced the genomes of many organisms, using computational tools to stitch together the sequences of many different fragments (a process called genome assembly). These technologies were used to sequence the human genome, leading to the completion of the Human Genome Project in 2003. New high-throughput sequencing technologies are dramatically lowering the cost of DNA sequencing, with many researchers hoping to bring the cost of resequencing a human genome down to a thousand dollars. The large amount of sequence data available has created the field of genomics, research that uses computational tools to search for and analyze patterns in the full genomes of organisms. Genomics can also be considered a subfield of bioinformatics, which uses computational approaches to analyze large sets of biological data.

Molecular models of DNA

2009-10-03T09:32:00.000-07:00

Molecular models of DNA structures are representations of the molecular geometry and topology of Deoxyribonucleic acid (DNA) molecules using one of several means, such as: closely packed spheres (CPK models) made of plastic, metal wires for 'skeletal models', graphic computations and animations by computers, artistic rendering, and so on, with the aim of simplifying and presenting the essential, physical and chemical, properties of DNA molecular structures either in vivo or in vitro. Computer molecular models also allow animations and molecular dynamics simulations that are very important for understanding how DNA functions in vivo. Thus, an old standing dynamic problem is how DNA "self-replication" takes place in living cells that should involve transient uncoiling of supercoiled DNA fibers. Although DNA consists of relatively rigid, very large elongated biopolymer molecules called "fibers" or chains (that are made of repeating nucleotide units of four basic types, attached to deoxyribose and phosphate groups), its molecular structure in vivo undergoes dynamic configuration changes that involve dynamically attached water molecules and ions. Supercoiling, packing with histones in chromosome structures, and other such supramolecular aspects also involve in vivo DNA topology which is even more complex than DNA molecular geometry, thus turning molecular modeling of DNA into an especially challenging problem for both molecular biologists and biotechnologists. Like other large molecules and biopolymers, DNA often exists in multiple stable geometries (that is, it exhibits conformational isomerism) and configurational, quantum states which are close to each other in energy on the potential energy surface of the DNA molecule. Such geometries can also be computed, at least in principle, by employing ab initio quantum chemistry methods that have high accuracy for small molecules. Such quantum geometries define an important class of ab initio molecular models of DNA whose exploration has barely started.

DNA structure

2009-09-20T20:28:00.000-07:00

DNA structure shows a variety of forms, both double-stranded and single-stranded. The mechanical properties of DNA, which are directly related to its structure, are a significant problem for cells. Every process which binds or reads DNA is able to use or modify the mechanical properties of DNA for purposes of recognition, packaging and modification. The extreme length (a chromosome may contain a 10 cm long DNA strand), relative rigidity and helical structure of DNA has led to the evolution of histones and of enzymes such as topoisomerases and helicases to manage a cell's DNA. The properties of DNA are closely related to its molecular structure and sequence, particularly the weakness of the hydrogen bonds and electronic interactions that hold strands of DNA together compared to the strength of the bonds within each strand.

Dna Structure

Experimental techniques which can directly measure the mechanical properties of DNA are relatively new, and high-resolution visualization in solution is often difficult. Nevertheless, scientists have uncovered large amount of data on the mechanical properties of this polymer, and the implications of DNA's mechanical properties on cellular processes is a topic of active current research. The DNA found in many cells can be macroscopic in length - a few centimetres long for each human chromosome. Consequently, cells must compact or "package" DNA to carry it within them. In eukaryotes this is carried by spool-like proteins known as histones, around which DNA winds. It is the further compaction of this DNA-protein complex which produces the well known mitotic eukaryotic chromosomes.

DNA Double Helix

2009-09-01T07:25:00.000-07:00

DNA is a normally double stranded macromolecule. Two polynucleotide chains, held together by weak thermodynamic forces, form a DNA molecule. Features of the DNA Double Helix * Two DNA strands form a helical spiral, winding around a helix axis in a right-handed spiral * The two polynucleotide chains run in opposite directions * The sugar-phosphate backbones of the two DNA strands wind around the helix axis like the railing of a sprial staircase * The bases of the individual nucleotides are on the inside of the helix, stacked on top of each other like the steps of a spiral staircase. DNA Helix Axis The helix axis is most apparent from a view directly down the axis. The sugar-phosphate backbone is on the outside of the helix where the polar phosphate groups (red and yellow atoms) can interact with the polar environment. The nitrogen (blue atoms) containing bases are inside, stacking perpendicular to the helix axis.

Components of DNA

2009-09-01T07:16:00.000-07:00

DNA is a polymer. The monomer units of DNA are nucleotides, and the polymer is known as a "polynucleotide." Each nucleotide consists of a 5-carbon sugar (deoxyribose), a nitrogen containing base attached to the sugar, and a phosphate group. There are four different types of nucleotides found in DNA, differing only in the nitrogenous base. The four nucleotides are given one letter abbreviations as shorthand for the four bases. • A is for adenine • G is for guanine • C is for cytosine • T is for thymine DNA Backbone The DNA backbone is a polymer with an alternating sugar-phosphate sequence. The deoxyribose sugars are joined at both the 3'-hydroxyl and 5'-hydroxyl groups to phosphate groups in ester links, also known as "phosphodiester" bonds. DNA Double Helix DNA is a normally double stranded macromolecule. Two polynucleotide chains, held together by weak thermodynamic forces, form a DNA molecule. Features of the DNA Double Helix • Two DNA strands form a helical spiral, winding around a helix axis in a right-handed spiral • The two polynucleotide chains run in opposite directions • The sugar-phosphate backbones of the two DNA strands wind around the helix axis like the railing of a sprial staircase • The bases of the individual nucleotides are on the inside of the helix, stacked on top of each other like the steps of a spiral staircase.

Privacy Policy

2009-08-20T20:15:00.000-07:00

Privacy Policy for http://biomolecules-world.blogspot.com/ If you require any more information or have any questions about our privacy policy, please feel free to contact us by email at veni.krishna0@gmail.com. At http://biomolecules-world.blogspot.com/, the privacy of our visitors is of extreme importance to us. This privacy policy document outlines the types of personal information is received and collected by http://biomolecules-world.blogspot.com/ and how it is used. Log Files : Like many other Web sites, http://biomolecules-world.blogspot.com/ makes use of log files. The information inside the log files includes internet protocol ( IP ) addresses, type of browser, Internet Service Provider ( ISP ), date/time stamp, referring/exit pages, and number of clicks to analyze trends, administer the site, track user’s movement around the site, and gather demographic information. IP addresses, and other such information are not linked to any information that is personally identifiable. Cookies and Web Beacons: http://biomolecules-world.blogspot.com/ does use cookies to store information about visitors preferences, record user-specific information on which pages the user access or visit, customize Web page content based on visitors browser type or other information that the visitor sends via their browser. Some of our advertising partners may use cookies and web beacons on our site. Our advertising partners include Google Adsense, . These third-party ad servers or ad networks use technology to the advertisements and links that appear on http://biomolecules-world.blogspot.com/ send directly to your browsers. They automatically receive your IP address when this occurs. Other technologies ( such as cookies, JavaScript, or Web Beacons ) may also be used by the third-party ad networks to measure the effectiveness of their advertisements and / or to personalize the advertising content that you see. http://biomolecules-world.blogspot.com/ has no access to or control over these cookies that are used by third-party advertisers. You should consult the respective privacy policies of these third-party ad servers for more detailed information on their practices as well as for instructions about how to opt-out of certain practices. http://biomolecules-world.blogspot.com/’s privacy policy does not apply to, and we cannot control the activities of, such other advertisers or web sites. If you wish to disable cookies, you may do so through your individual browser options. More detailed information about cookie management with specific web browsers can be found at the browsers’ respective websites. Update : We use third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. Yours Sincerely veni.krishna0@gmail.com

Human genetics

2009-08-09T05:07:00.000-07:00

Human genetics describes the study of inheritance as it occurs in human beings. Human genetics encompasses a variety of overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics, and genetic counseling. Study of human genetics can be useful as it can answer questions about human nature, understand the diseases and development of effective disease treatment, and understand genetics of human life. This article describes only basic features of human genetics; for the genetics of disorders please see: Medical genetics. A genetic disorder is an illness caused by abnormalities in genes or chromosomes. While some diseases, such as cancer, are due in part to a genetic disorders, they can also be caused by environmental factors. Most disorders are quite rare and affect one person in every several thousands or millions. Some types of recessive gene disorders confer an advantage in the heterozygous state in certain environments.[1] A haploid cell has only one set of chromosomes. A diploid cell has two sets of chromosomes. In human, the somatic cells are diploid, and the gametes are haploid.

Human genetics

2009-08-09T05:06:00.000-07:00

Human genetics describes the study of inheritance as it occurs in human beings. Human genetics encompasses a variety of overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics, and genetic counseling. Study of human genetics can be useful as it can answer questions about human nature, understand the diseases and development of effective disease treatment, and understand genetics of human life. This article describes only basic features of human genetics; for the genetics of disorders please see: Medical genetics. Genomics Genomics refers to the field of genetics concerned with structural and functional studies of the genome. A genome is all the DNA contained within an organism or a cell including nuclear and mitochondrial DNA. The human genome is the total collection of genes in a human being contained in the human chromosome, composed of over three billion nucleotides. In April 2003, the Human Genome Project was able to sequence all the DNA in the human genome, to discover the human genome was composed around 20,000 protein coding genes.

Chromosome

2009-08-09T05:05:00.001-07:00

A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. The word chromosome comes from the Greek χρῶμα (chroma, color) and σῶμα (soma, body) due to their property of being very strongly stained by particular dyes. Chromosomes vary widely between different organisms. The DNA molecule may be circular or linear, and can be composed of 10,000 to 1,000,000,000nucleotides in a long chain. Typically eukaryotic cells (cells with nuclei) have large linear chromosomes and prokaryotic cells (cells without defined nuclei) have smaller circular chromosomes, although there are many exceptions to this rule. Furthermore, cells may contain more than one type of chromosome; for example, mitochondria in most eukaryotes and chloroplasts in plants have their own small chromosomes. In eukaryotes, nuclear chromosomes are packaged by proteins into a condensed structure called chromatin. This allows the very long DNA molecules to fit into the cell nucleus. The structure of chromosomes and chromatin varies through the cell cycle. Chromosomes are the essential unit for cellular division and must be replicated, divided, and passed successfully to their daughter cells so as to ensure the genetic diversity and survival of their progeny. Chromosomes may exist as either duplicated or unduplicated—unduplicated chromosomes are single linear strands, whereas duplicated chromosomes (copied during synthesis phase) contain two copies joined by a centromere. Compaction of the duplicated chromosomes during mitosis and meiosis results in the classic four-arm structure (pictured to the right). Chromosomal recombination plays a vital role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe and die, or it may aberrantly evade apoptosis leading to the progression of cancer. However, in practice "chromosome" is a rather loosely defined term. In prokaryotes, a small circular DNA molecule may be called either a plasmid or a small chromosome. These small circular genomes are also found in mitochondria and chloroplasts, reflecting their bacterial origins. The simplest chromosomes are found in viruses: these DNA or RNA molecules are short linear or circular chromosomes that often lack any structural proteins.

Genes and human characteristics

2009-08-08T05:10:00.000-07:00

Genes are a fundamental unit of inheritance. Genes can be defined as a sequence of DNA in the genome that is required for production of a functional product. Genes have both minor and major effects on human characteristics. Human genes have become prominent in the nature versus nurture debate. Genes and behavior Genes have a strong influence on human behavior. IQ is largely heritable. However, this has been questioned. The stance that humans inherit substantial behavioral characteristics is called psychological nativism, compared to the stance that human behavior and culture are virtually entirely constructed (tabula rasa). In the early 20th century, eugenics was policy in parts of the United States and Europe. The goal was to reduce or eliminate traits that were considered undesirable. One form of eugenics was compulsory sterilization of people deemed mentally unfit. Hitler's eugenics programs turned social consciousness against the practice, and psychological nativism became associated with racism and sexism. Genes and gender The biggest genetic difference among healthy humans is in gender Scientists debate the extent to which genes and culture affect gender roles. The case of David Reimer was once a case in point for the tabula rasa camp, though recently that same case has become evidence for a strong genetic component to gender identity. Evolutionary psychology Evolutionary psychology explains many human behaviors as more or less moderated by genes that evolved in the hunter-gatherer stage of human cultural development Genetic disorders Main article: Genetic disorder Humans have several genetic diseases, often caused by recessive genes. A few examples of human genetic diseases are: Turner Syndrome, Huntington's disease, cancer, autism, and sickle cell anemia. For a more comprehensive list see List of genetic disorders. Genetic disorders happen everywhere and are very common in some places. • Cri du Chat syndrome – A disorder caused from a deletion on the short arm of chromosome 5. This deletion results in a phenotype of mental retardation, behavioral problems, and a cat like call. About one in every 50,000 births will have the syndrome. • Huntington's disease – A neurological disorder caused by a trinucleotide repeat sequence. Huntingtons is an autosomal dominant trait. Most individuals with the disease will first display the phenotype around 40 years of age. The symptoms are jerky uncontrollable movements, mental retardation, and behavioral problems. • Turner syndrome – A condition that effects females caused by a 45, XO genotype instead of the normal XX genotype. These individuals have only one X chromosome. These individuals are phenotypically female, but will be sterile due to undeveloped ovaries. • Klinefelter syndrome – A disorder in males caused by the presence of an extra X chromosome. These individuals have a genotype of 47, XXY instead of the normal XY genotype. The symptoms for this syndrome are enlarged breasts, small testes, and sterility.

Genetic erosion

2009-07-19T09:56:00.000-07:00

Genetic erosion is a process whereby an already limited gene pool of an endangered species of plant or animal diminishes even more when individuals from the surviving population die off without getting a chance to meet and breed with others in their endangered low population. Genetic erosion occurs because each individual organism has many unique genes which get lost when it dies without getting a chance to breed. Low genetic diversity in a population of wild animals and plants leads to a further diminishing gene pool, inbreeding and a weakening immune system and fast tracks that species towards eventual extinction. All the world's endangered species are plagued by varying degrees of genetic erosion and most need a human assisted breeding program to keep their population viable and to keep them from going extinct in the long run. The more critically endangered the species is (the smaller the population is), the more magnified the effect of genetic erosion gets when each surviving individual of the species is lost without getting a chance to breed. Genetic erosion gets compounded and accelerated by habitat fragmentation, today most endangered species live in smaller and smaller chunks of fragmented habitat interspersed with human settlements and farmland making it impossible for them to naturally meet and breed with others of their kind, many die off without getting a chance to breed and pass on their genes in the living population. The gene pool of a species or a population is the complete set of unique alleles that would be found by inspecting the genetic material of every living member of that species or population. A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection. Meanwhile, low genetic diversity (see inbreeding and population bottlenecks) can cause reduced biological fitness and an increased chance of extinction.

Privacy Policy

2009-07-19T09:39:00.000-07:00

If you require any more information or have any questions about our privacy policy, please feel free to contact us by email at veni.krishna0@gmail.com

At http://biomolecules-world.blogspot.com/, the privacy of our visitors is of extreme importance to us. This privacy policy document outlines the types of personal information is received and collected by http://biomolecules-world.blogspot.com/ and how it is used.

Log Files : Like many other Web sites, http://biomolecules-world.blogspot.com/ makes use of log files. The information inside the log files includes internet protocol ( IP ) addresses, type of browser, Internet Service Provider ( ISP ), date/time stamp, referring/exit pages, and number of clicks to analyze trends, administer the site, track user’s movement around the site, and gather demographic information. IP addresses, and other such information are not linked to any information that is personally identifiable.

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These third-party ad servers or ad networks use technology to the advertisements and links that appear on http://biomolecules-world.blogspot.com/ send directly to your browsers. They automatically receive your IP address when this occurs. Other technologies ( such as cookies, JavaScript, or Web Beacons ) may also be used by the third-party ad networks to measure the effectiveness of their advertisements and / or to personalize the advertising content that you see.

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Genetic engineering and research

2009-07-11T02:03:00.001-07:00

• Loss of function experiments, such as in a gene knockout experiment, in which an organism is engineered to lack the activity of one or more genes. This allows the experimenter to analyze the defects caused by this mutation, and can be considerably useful in unearthing the function of a gene. It is used especially frequently in developmental biology. A knockout experiment involves the creation and manipulation of a DNA construct in vitro, which, in a simple knockout, consists of a copy of the desired gene, which has been slightly altered such as to cripple its function. The construct is then taken up by embryonic stem cells, wherein the engineered copy of the gene replaces the organism's own gene. These stem cells are injected into blastocysts, which are implanted into surrogate mothers. Another method, useful in organisms such as Drosophila (fruitfly), is to induce mutations in a large population and then screen the progeny for the desired mutation. A similar process can be used in both plants and prokaryotes. • Gain of function experiments, the logical counterpart of knockouts. These are sometimes performed in conjunction with knockout experiments to more finely establish the function of the desired gene. The process is much the same as that in knockout engineering, except that the construct is designed to increase the function of the gene, usually by providing extra copies of the gene or inducing synthesis of the protein more frequently. • Tracking experiments, which seek to gain information about the localization and interaction of the desired protein. One way to do this is to replace the wild-type gene with a 'fusion' gene, which is a juxtaposition of the wild-type gene with a reporting element such as Green Fluorescent Protein (GFP) that will allow easy visualization of the products of the genetic modification. While this is a useful technique, the manipulation can destroy the function of the gene, creating secondary effects and possibly calling into question the results of the experiment. More sophisticated techniques are now in development that can track protein products without mitigating their function, such as the addition of small sequences that will serve as binding motifs to monoclonal antibodies. • Expression studies aim to discover where and when specific proteins are produced. In these experiments, the DNA sequence before the DNA that codes for a protein, known as a gene's promoter, is reintroduced into an organism with the protein coding region replaced by a reporter gene such as GFP or an enzyme that catalyzes the production of a dye. Thus the time and place where a particular protein is produced can be observed. Expression studies can be taken a step further by altering the promoter to find which pieces are crucial for the proper expression of the gene and are actually bound by transcription factor proteins; this process is known as promoter bashing.

Genetics

2009-07-11T01:55:00.000-07:00

Genetics a discipline of biology, is the science of heredity and variation in living organisms. The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the process of inheritance, only began with the work of Gregor Mendel in the mid-nineteenth century. Although he did not know the physical basis for heredity, Mendel observed that organisms inherit traits via discrete units of inheritance, which are now called genes. Genes correspond to regions within DNA, a molecule composed of a chain of four different types of nucleotides—the sequence of these nucleotides is the genetic information organisms inherit. DNA naturally occurs in a double stranded form, with nucleotides on each strand complementary to each other. Each strand can act as a template for creating a new partner strand—this is the physical method for making copies of genes that can be inherited. The sequence of nucleotides in a gene is translated by cells to produce a chain of amino acids, creating proteins—the order of amino acids in a protein corresponds to the order of nucleotides in the gene. This relationship between nucleotide sequence and amino acid sequence is known as the genetic code. The amino acids in a protein determine how it folds into a three-dimensional shape; this structure is, in turn, responsible for the protein's function. Proteins carry out almost all the functions needed for cells to live. A change to the DNA in a gene can change a protein's amino acids, changing its shape and function: this can have a dramatic effect in the cell and on the organism as a whole. Although genetics plays a large role in the appearance and behavior of organisms, it is the combination of genetics with what an organism experiences that determines the ultimate outcome. For example, while genes play a role in determining an organism's size, the nutrition and other conditions it experiences after inception also have a large effect.

Genetic engineering

2009-07-10T02:06:00.000-07:00

There are a number of ways through which genetic engineering is accomplished. Essentially, the process has five main steps

1. Isolation of the genes of interest

2. Insertion of the genes into a transfer vector

3. Transfer of the vector to the organism to be modified

4. Transformation of the cells of the organism

5. Selection of the genetically modified organism (GMO) from those that have not been successfully modified

Isolation is achieved by identifying the gene of interest that the scientist wishes to insert into the organism, usually using existing knowledge of the various functions of genes. DNA information can be obtained from cDNA or gDNA libraries, and amplified using PCR techniques. If necessary, i.e. for insertion of eukaryotic genomic DNA into prokaryotes, further modification may be carried out such as removal of introns or ligating prokaryotic promoters.

Insertion of a gene into a vector such as a plasmid can be done once the gene of interest is isolated. Other vectors can also be used, such as viral vectors, bacterial conjugation, liposomes, or even direct insertion using a gene gun. Restriction enzymes and ligases are of great use in this crucial step if it is being inserted into prokaryotic or viral vectors. Daniel Nathans and Hamilton Smith received the 1978 Nobel Prize in Physiology or Medicine for their isolation of restriction endonucleases.

Once the vector is obtained, it can be used to transform the target organism. Depending on the vector used, it can be complex or simple. For example, using raw DNA with gene guns is a fairly straightforward process but with low success rates, where the DNA is coated with molecules such as gold and fired directly into a cell. Other more complex methods, such as bacterial transformation or using viruses as vectors have higher success rates.

After transformation, the GMO can be selected from those that have failed to take up the vector in various ways. One method is screening with DNA probes that can stick to the gene of interest that was supposed to have been transplanted. Another is to package genes conferring resistance to certain chemicals such as antibiotics or herbicides into the vector. This chemical is then applied ensuring that only those cells that have taken up the vector will survive.

Lung cancer

2009-07-03T09:45:00.000-07:00

Lung cancer is a disease of uncontrolled cell growth in tissues of the lung. This growth may lead to metastasis, which is the invasion of adjacent tissue and infiltration beyond the lungs. The vast majority of primary lung cancers are carcinomas of the lung, derived from epithelial cells. Lung cancer, the most common cause of cancer-related death in men and the second most common in women is responsible for 1.3 million deaths worldwide annually. The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss.

The main types of lung cancer are small cell lung carcinoma and non-small cell lung carcinoma. This distinction is important, because the treatment varies; non-small cell lung carcinoma (NSCLC) is sometimes treated with surgery, while small cell lung carcinoma (SCLC) usually responds better to chemotherapy and radiation. The most common cause of lung cancer is long-term exposure to tobacco smokeThe occurrence of lung cancer in nonsmokers, who account for as many as 15% of cases , is often attributed to a combination of genetic factors, radon gas, asbestos, and air pollution,including secondhand smoke.

Lung cancer may be seen on chest radiograph and computed tomography (CT scan). The diagnosis is confirmed with a biopsy. This is usually performed via bronchoscopy or CT-guided biopsy. Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Possible treatments include surgery, chemotherapy, and radiotherapy. With treatment, the five-year survival rate is 14%.

How Is Malignant Mesothelioma Diagnosed? Part -2

2009-07-03T09:37:00.000-07:00

Positron emission tomography (PET) scan For a PET scan, you receive an injection of glucose (a form of sugar) that contains a radioactive atom. The amount of radioactivity used is very low. Cancer cells in the body are growing quickly, so they absorb large amounts of the radioactive sugar. A special camera can then be used to create a picture of areas of radioactivity in the body. The picture is not finely detailed like a CT or MRI scan, but it can provide helpful information about your whole body. A PET scan can help give the doctor a better idea of whether a thickening of the pleura or peritoneum seen on another imaging test is more likely cancer or merely scar tissue. If you have been diagnosed with cancer, your doctor may use this test to see if the cancer has spread to lymph nodes or other parts of the body. A PET scan can also be useful if your doctor thinks the cancer may have spread but doesn't know where. Some newer machines are able to perform both a PET and CT scan at the same time (PET/CT scan). This allows the doctor to compare areas of higher radioactivity on the PET scan with the more detailed appearance of that area on the CT. Magnetic resonance imaging (MRI) scan Like CT scans, MRI scans provide detailed images of soft tissues in the body. But MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed and then released in a pattern formed by the type of body tissue and by certain diseases. A computer translates the pattern into very detailed images of parts of the body. A contrast material called gadolinium is often injected into a vein before the scan to better see details. MRI scans can sometimes help determine the exact location and extent of a tumor since they provide detailed images of soft tissues. For mesotheliomas, they may be useful in looking at the diaphragm (the thin band of muscle below the lungs that is responsible for breathing), a possible site of cancer spread. MRI scans may be a little more uncomfortable than CT scans. They take longer -- often up to an hour. You may be placed inside a large cylindrical tube, which is confining and can upset people with a fear of enclosed spaces. Newer, more open MRI machines can help with this if needed. The MRI machine makes buzzing and clicking noises that you may find disturbing. Some places will provide earplugs to help block this out. Blood tests Blood levels of certain substances are often elevated in people with mesothelioma: • osteopontin • soluble mesothelin-related peptides (SMRPs), detected with the MesoMark® test Blood tests for these substances are not used to diagnose the disease, but elevated levels may make the diagnosis more likely. Thus far, these blood tests have proven more useful in people who have already been diagnosed to follow their progress during and after treatment. If mesothelioma is diagnosed, other blood tests will be done to check the blood cell counts and levels of certain chemicals in the blood. These tests can give the doctor an idea of how extensive the disease may be, as well as how well organs such as the liver and kidneys are functioning. Tests of fluid and tissue samples A person's symptoms and the results of exams, imaging tests, and/or blood tests may strongly suggest that mesothelioma is present, but the actual diagnosis is made by removing cells from an abnormal area and looking at them under a microscope. This is known as a biopsy. It may be done in different ways, depending on the situation. Thoracentesis, paracentesis, and pericardiocentesis If you have a buildup of fluid in the body that may be related to mesothelioma, a sample of this fluid can be removed by inserting a long, hollow needle through the skin and into the fluid and removing it. Numbing medicine is used on the skin before the needle is inserted. This may be done in a doctor's office or in the hospital. This procedure has different names depending on where the fluid is: • Thoracentesis removes fluid from the chest cavity. • Paracentesis removes fluid from the abdomen. • Pericardiocentesis removes fluid from the sac around the heart. The fluid is then tested to see its chemical makeup and is looked at under a microscope to see if there are cancer cells in the fluid. If cancer cells are present, special tests can determine if the cancer is a mesothelioma, a lung cancer, or another type of cancer. Not finding any cancer cells in the fluid does not necessarily mean there is no cancer, as not all fluid may contain cancer cells. In many cases, doctors need to get an actual sample of the pleural or peritoneal tissue to determine if mesothelioma is present. Needle biopsies Suspected tumors in the chest are sometimes sampled by needle biopsy. A long, hollow needle is passed through the skin in the chest between the ribs and into the pleura. Imaging tests such as CT scans are used to guide the needle into the tumor so that a small sample can be removed to be looked at under the microscope. This procedure is also done without a surgical incision or overnight hospital stay. In some cases, the sample removed may not be big enough to make an accurate diagnosis, and a more invasive biopsy method may be needed. A possible complication of this approach is the buildup of air between the lung and the chest wall, which is known as a pneumothorax. In some cases this can lead to the collapse of part of a lung, causing shortness of breath. If this happens, it can be treated by temporarily placing a suction tube through the skin and into the chest, which will re-expand the lung. Thoracoscopy, laparoscopy, and mediastinoscopy In most cases, a tissue sample of a pleural or pericardial tumor can be obtained using a technique called thoracoscopy. Most often this is done in the operating room while you are under general anesthesia (in a deep sleep). The doctor inserts a thin, lighted tube with a small video camera on the end (a thoracoscope) through a small cut made in the chest wall to view the space between the lungs and the chest wall. (Sometimes more than one cut is made.) Using this, the doctor can see potential areas of cancer and remove small pieces of tissue to look at under the microscope. Thoracoscopy can also be used to sample lymph nodes and fluid and assess whether a tumor is growing into nearby tissues or organs. Similarly, laparoscopy can be used to see and obtain a biopsy of a peritoneal tumor. In this procedure, a flexible tube containing a small video camera is inserted into the abdominal cavity through small cuts on the front of the abdomen. If imaging tests such as a CT scan suggest that the cancer may have spread to the lymph nodes between the lungs, the doctor may do a procedure called a mediastinoscopy. This is also done in an operating room while you are under general anesthesia (in a deep sleep). A small cut is made in the front of the neck above the breastbone (sternum) and a thin, hollow, lighted tube is inserted behind the sternum. Special instruments can be passed through this tube to take tissue samples from the lymph nodes along the windpipe and the major bronchial tube areas. Cancers in the lung often spread to lymph nodes, but mesotheliomas do this less often. Tests on lymph nodes can give the doctor information on whether a cancer is still localized or if it has started to spread, and can help distinguish lung cancer from mesothelioma. Surgical biopsy In some cases, more invasive procedures may be needed to get a large enough tissue sample to make a diagnosis. Surgery, either a thoracotomy (which opens the chest cavity) or a laparotomy (which opens the abdominal cavity), allows the surgeon to remove a larger sample of tumor or, sometimes, to remove the entire tumor. Bronchoscopic biopsy If you might have pleural mesothelioma, the doctor may also do a bronchoscopy. The doctor passes a long, thin, flexible, fiber-optic tube called a bronchoscope down the throat to look at the lining of the lung's main airways. You will be sedated for this. If a tumor is found, the doctor can take a small sample of the tumor through the tube. Testing the samples in the lab No matter which approach used to obtain them, biopsy and fluid specimens are sent to the pathology lab. There, a doctor will look at them under a microscope and do other tests to determine if cancer is present (and if so, what type of cancer it is). It is often hard to diagnose mesothelioma by looking at the cells from the fluid around the lungs, abdomen, or heart. It is even hard to diagnose mesothelioma with tissue from small needle biopsies. Under the microscope, mesothelioma can look like several other types of cancer. For example, pleural mesothelioma may resemble some types of lung cancer, and peritoneal mesothelioma may look like some cancers of the ovaries. For this reason, special lab tests are often done to help distinguish mesothelioma from some other cancers. These tests often use special techniques to recognize certain markers (types of chemicals) contained in mesothelioma cells. • Immunohistochemistry tests look for different proteins on the surface of the cells. It can be used to tell if the cancer is a mesothelioma or a lung cancer, which can appear to start in the lining of the chest cavity. • DNA microarray analysis is a newer test that actually looks at patterns of genes in the cancers. Mesotheliomas have different gene patterns than other cancers. • Electron microscopy can sometimes help diagnose mesothelioma. The electron microscope can magnify samples more than 100 times greater than the light microscope that is generally used in cancer diagnosis. This more powerful microscope makes it possible to see the small parts of the cancer cells that distinguish mesothelioma from other types of cancer. If mesothelioma is diagnosed, the doctor will also determine what type of mesothelioma it is, based on the patterns of cells seen in the microscope. Mesotheliomas are classified as either epithelioid, sarcomatoid, or mixed/biphasic. Pulmonary function tests Pulmonary function tests (PFTs) may be done after a mesothelioma diagnosis to see how well your lungs are working. This is especially important if surgery is an option in treating the cancer. Because surgical removal of part or all of lung results in lower lung capacity, it's important to know how well the lungs are working beforehand. These tests can give the surgeon an idea of whether surgery may be an option, and if so, how much lung can safely be removed. There are a few different types of PFTs, but they all basically involve having you breathe in and out through a tube that is connected to different machines.

How Is Malignant Mesothelioma Diagnosed? -Part 1

2009-07-03T09:35:00.000-07:00

Mesothelioma is most often diagnosed after a patient goes to a doctor because of symptoms. If there is a reason to suspect you may have mesothelioma, your doctor will use one or more tests to find out if the disease is present. Symptoms might suggest that a person may have mesothelioma, but tests are needed to confirm the diagnosis.

Signs and symptoms of mesothelioma

Early symptoms of mesotheliomas are not specific to the disease, and people often ignore them or mistake them for common, minor ailments. Most people with mesothelioma have symptoms for a few months before they are diagnosed, although in some people this is longer.

Symptoms of pleural mesothelioma (mesothelioma of the chest) can include:

• pain in the lower back or at the side of the chest

• shortness of breath

• cough

• fever

• sweating

• fatigue

• weight loss

• trouble swallowing

• hoarseness

• swelling of the face and arms

• muscle weakness

Symptoms of peritoneal mesothelioma can include:

• abdominal (belly) pain

• swelling or fluid in the abdomen

• weight loss

• nausea and vomiting

The symptoms and signs above may be caused by mesothelioma, but they may also be caused by other conditions. Still, if you have any of these problems (especially if have been exposed to asbestos), it's important to see your doctor right away so the cause can be found and treated, if needed.

Medical history and physical exam

If you have any signs or symptoms that suggest you might have mesothelioma, your doctor will want to take a complete medical history to check for symptoms and possible risk factors, especially asbestos exposure. You will also be asked about your general health.

A physical exam can provide information about possible signs of mesothelioma and other health problems. Patients with pleural mesotheliomas often have fluid in their chest cavity (pleural effusion) caused by the cancer. Fluid can build up in the abdominal cavity (ascites) in cases of peritoneal mesothelioma, or in the pericardium (pericardial effusion) in cases of pericardial mesothelioma. Rarely, mesothelioma can develop in the groin and look like a hernia. All of these might be found during a physical exam.

If symptoms and/or the results of the physical exam suggest a mesothelioma might be present, more involved tests will likely be done. These might include imaging tests, blood tests, and other procedures.

Imaging tests

Imaging tests use x-rays, radioactive particles, or magnetic fields to create pictures of the inside of your body. Imaging tests may be done for a number of reasons, including to help find a suspicious area that might be cancerous, to learn how far cancer may have spread, and to help determine if treatment has been effective.

Chest x-ray

This is often the first test done if someone has symptoms such as a constant cough or shortness of breath. It may show an abnormal thickening of the pleura, calcium deposits on the pleura, fluid in the space between the lungs and the chest wall, or changes in the lungs themselves as a result of asbestos exposure. These findings may also suggest a mesothelioma.

Computed tomography (CT) scan

The CT scan is an x-ray procedure that produces detailed cross-sectional images of your body. Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around you while you are lying on a narrow platform. A computer then combines these into images of slices of the part of your body that is being studied.

CT scans are often used to help assess the likelihood that mesothelioma is present and help determine the exact location of the cancer. They can also help stage the cancer (determine the extent of its spread). For example, they can show if the cancer has spread to the liver or other organs. This can help to determine if surgery might be a treatment option. Finally, CT scans can be used to determine if treatment such as chemotherapy has been helpful in shrinking or slowing the growth of the cancer.

Prior to the scan, you may be asked to drink a contrast solution and/or get an intravenous (IV) injection of a contrast dye that helps better outline abnormal areas in the body. You may need an IV line through which the contrast dye is injected. The injection can cause some flushing (redness and warm feeling). Some people are allergic and get hives or, rarely, more serious reactions like trouble breathing and low blood pressure. Be sure to tell the doctor if you have ever had a reaction to any contrast material used for x-rays.

You need to lie still on a table while the scan is being done. During the test, the table moves in and out of the scanner, a ring-shaped machine that completely surrounds the table. You might feel a bit confined by the ring you have to lie in while the pictures are being taken.

In recent years, spiral CT (also known as helical CT) has become available in many medical centers. This type of CT scan uses a faster machine. The scanner part of the machine rotates around the body continuously, allowing doctors to collect the images much more quickly than standard CT. As a result, you do not have to hold your breath for as long while the image is taken. This lowers the chance of blurred images occurring as a result of breathing motion. It also lowers the dose of radiation received during the test. The slices it images are thinner, which yields more detailed pictures.

Mesothelioma and Early Lung Cancer Identified by Screening

2009-07-03T09:29:00.000-07:00

Exposure to asbestos fibers is a known risk factor for lung cancer and the cause of mesothelioma. Although asbestos is still not completely banned in the U.S., it was phased out of American industry to a large degree beginning in the 1970s. However because asbestos-related diseases can take 20 to 40 years to emerge after people have been exposed, former asbestos workers and those exposed to products containing this carcinogen continue to be diagnosed with asbestos caused cancers.

As researchers search for better treatments and even a cure for these diseases, they are also focusing on new diagnostic methods that might identify the cancers earlier. Early diagnosis is particularly crucial with mesothelioma, because many patients survive only one year after they first start to show signs, and symptoms are often difficult to distinguish from those of other lung diseases.

One potential screening method uses low-dose computed tomography (LDCT) to evaluate the lungs and their lining (pleura). LDCT can locate plaques in the lungs, which are a sign of asbestos exposure and have been linked to an increased cancer risk.

Currently, there are no recommendations about using LDCT or any other method to screen people who have been exposed to asbestos, and screening isn’t routinely done. “There are currently no methods for the early detection of mesothelioma available,” says lead author Heidi Roberts, MD, Associate Professor of Radiology at the University of Toronto. “This is why we are doing the research.”

To determine the effectiveness of LDCT as a screening tool for asbestos-related lung cancers, Dr. Roberts and her colleagues recruited 516 people (most of them men) who had been exposed to asbestos at least 20 years before, or who had known plaques. Participants were given LDCT scans of the chest. Patients who had abnormal scans were given follow-up tests. Those with normal test results were invited to have an annual LDCT scan.

Of the 516 participants, 357 had evidence of plaques. Based on the results of the first scan and annual scans, six of the patients were diagnosed with lung cancers and four were diagnosed with mesothelioma.

Although LDCT was able to detect advanced mesothelioma, as well as early- and late-stage lung cancers, it was not able to diagnose early mesothelioma. The study authors say they need to continue screening patients to help them get a better idea of what early mesothelioma looks like. Also, they say adding biomarkers (substances in the blood that indicate the presence of cancer) to the screening process may provide greater sensitivity to help diagnose those at very high risk for mesothelioma.

Even as techniques are fine-tuned, screening is just one step of a three-tiered effort to combat these cancers, according to Dr. Roberts. “The second step is the parallel development of biomarkers, and the third step is the parallel development of treatment strategies,” she says. “These have to be developed hand-in-hand in order to make this a useful and meaningful tool.”

Mesothelium

2009-07-03T09:26:00.000-07:00

The mesothelium is a membrane that forms the lining of several body cavities: the pleura (thoracal cavity), peritoneum (abdominal cavity including the mesentery) and pericardium (heart sac). Mesothelial tissue also surrounds the male internal reproductive organs (the tunica vaginalis testis) and covers the internal reproductive organs of women (the tunica serosa uteri). Mesothelium that covers the internal organs is called visceral mesothelium, while the layer that covers the body walls is called the parietal mesothelium. The mesothelium is composed of an extensive monolayer of specialized cells (mesothelial cells) that line the body's serous cavities and internal organs. The main purpose of these cells is to produce a lubricating fluid that is released between layers, providing a slippery, non-adhesive and protective surface to facilitate intracoelomic movement. The mesothelium is also implicated in the transport and movement of fluid and particulate matter across the serosal cavities, leukocyte migration in response to inflammatory mediators, synthesis of pro-inflammatory cytokines, growth factors and extracellular matrix proteins to aid in serosal repair, and the release of factors to promote the disposition and clearance of fibrin (such as plasminogen). It is an antigen presenting cell. Furthermore, the secretion of glycosaminoglycans and lubricants may protect the body against infection and tumor dissemination. Role in disease • Mesothelioma: (cancer of the mesothelium) is a disease in which cells of the mesothelium become abnormal and divide without control or order. They can invade and damage nearby tissues and organs. Cancer cells can also metastasize (spread) from their original site to other parts of the body. Most cases of mesothelioma begin in the pleura or peritoneum. More than 90% of mesothelioma cases are linked to asbestos exposure. • Intra-abdominal adhesions: Normally, the mesothelium secretes plasminogen, which removes fibrin deposits. During surgical procedures, the mesothelium may be damaged. Its fibrinolytic capacity becomes insufficient and fibrin accumulates, causing fibrous adhesions between opposing surfaces. These adhesions cause intestinal obstruction and female infertility if it occurs in the abdomen, and may impair cardiac and lung function in the thorax. • Ultrafiltration failure: The peritoneal mesothelium is implicated in the long-term development of ultrafiltration failure in peritoneal dialysis patients. The presence of supra-physiological glucose concentrations, acidity, and glucose degradation products in peritoneal dialysis fluids contribute to the fibrosis of the peritoneal mesothelium, either by epithelial-mesenchymal transition or increased proliferation of existing fibroblasts. A fibrosed peritoneum results in the increased passage of solutes across the peritoneum and ultrafiltration failure.

Mesothelioma

2009-07-03T09:18:00.000-07:00

Mesothelioma is a form of cancer that is almost always caused by exposure to asbestos. In this disease, malignant cells develop in the mesothelium, a protective lining that covers most of the body's internal organs. Its most common site is the pleura (outer lining of the lungs and internal chest wall), but it may also occur in the peritoneum (the lining of the abdominal cavity), the heart, the pericardium (a sac that surrounds the heart) or tunica vaginalis.

Most people who develop mesothelioma have worked on jobs where they inhaled asbestos particles, or they have been exposed to asbestos dust and fiber in other ways. Washing the clothes of a family member who worked with asbestos can also put a person at risk for developing mesothelioma. Unlike lung cancer, there is no association between mesothelioma and smoking, but smoking greatly increases risk of other asbestos-induced cancer. Compensation via asbestos funds or lawsuits is an important issue in mesothelioma (see asbestos and the law).

The symptoms of mesothelioma include shortness of breath due to pleural effusion (fluid between the lung and the chest wall) or chest wall pain, and general symptoms such as weight loss. The diagnosis may be suspected with chest X-ray and CT scan, and is confirmed with a biopsy (tissue sample) and microscopic examination. A thoracoscopy (inserting a tube with a camera into the chest) can be used to take biopsies. It allows the introduction of substances such as talc to obliterate the pleural space (called pleurodesis), which prevents more fluid from accumulating and pressing on the lung. Despite treatment with chemotherapy, radiation therapy or sometimes surgery, the disease carries a poor prognosis. Research about screening tests for the early detection of mesothelioma is ongoing.

DNA Extraction From Fresh Bone

2009-06-03T20:39:00.000-07:00

Extract nucleic acids, such as DNA, from bone samples in order to analyze gene expressions, to look for somatic mutations of tumors or other pathological tissue, or for genotyping archive material when other sources of DNA are not available. You can use several kits that have already provided by biotech companies. But, if you are extracting DNA from large number samples, you can use a homemade method as described here to be effective in cost. There are four procedures that ascertain the successful extraction of nucleic acids from tissue: 1. disrupting the tissue so that extraction reagents can reach the cells. 2. disrupting the cell membranes so that nucleic acids are liberated. 3. separation of the nucleic acid from other cellular components. 4. precipitation and solubilization of the nucleic acid. Materials 1. DNA extraction buffer: Add 17.6 mL of 0.75 M sodium citrate, pH 7.0, 26.4 mL of 10% sodium lauryl sarkosyl, and 250 g of guanidinium isothiocyanate to 293 mL of distilled water and mix well. Add 7.2 microliter of beta-mercaptoethanol/mL of lysis buffer on the day of use All chemicals should be of molecular biology grade. The solutions can be stored at 4oC for up to 3 months. 2. 0.5 M ETDA: Add 93.05 g of EDTA to 300 mL of distilled water and add 10 N NaOH to pH 8.0. Make up to 500 mL. Autoclave. Tris–EDTA: Add 1 mL of 1 M Tris to 200 microliters of 0.5 M EDTA. Make up to 100 mL with distilled water. 3. 3 M Sodium acetate, pH 5.2: Add 401.8 g of sodium acetate to 800 mL of distilled water. Adjust pH to 5.1 with glacial acetic acid. Make up to 1 L with distilled water. Autoclave. 4. General Reagents: Tris-saturated phenol pH 7.8–8.0 (Sigma), Chloroform, Isopropanol 100%, Ethanol. Methods 1. Collect the bone sample in a sterile container containing phosphate-buffered saline (PBS) and transport to the laboratory within 1–2 h. If the DNA extraction is not initiated immediately, freeze the sample at –20oC or below for later use. 2. Place the bone tissue in a clean glass Petri dish. Using bone cutters or a strong sharp pair of scissors, isolate a piece of bone measuring about 1 cm3 and transfer to a clean 5-mL bijoux container. 3. Add 1 mL of DNA extraction buffer and homogenize the tissue with the scissors until a slurry solution is obtained. 4. Transfer 500 microliters aliquots of slurry into screw-capped conical-bottomed 1.5-mL Eppendorf tubes. 5. Add one volume of Tris-saturated phenol, followed by one volume of chloroform per tube. Mix well by inverting the tubes a few times or by shaking. Do not vortex, because vortex-mixing causes long strands of DNA to shear. 6. Centrifuge the tubes at 10,000 g for 20 min to separate the phases. 7. Transfer the upper layer to a fresh centrifuge tube (taking note of the volume), being careful not to disturb the milky layer at the interface. Repeat steps 5–7 if the interface is disturbed. 8. Add one volume of ice-cold isopropanol and 0.1 volumes of 3 M sodium acetate to the supernatant. Mix well and allow to stand for 15 min on ice. 9. Centrifuge the tubes at 10,000g for 20 min to pellet the DNA. Orientate the Eppendorf tube so that you can identify where the DNA pellet lies. A pellet should be visible the bottom of the tube. 10. Aspirate and discard the supernatant, taking care not to disturb the pellet. Wash the sample with 1.75 mL of ice-cold ethanol and centrifuge at 10,000g for 5 min. Aspirate and discard the supernatant and then repeat the wash. 11. Dissolve the DNA pellets in 10–50 microliters of water or Tris–EDTA buffer (you can pool DNA from the same sample at this stage) and quantitate by spectrophotometry or with Hoechst 33258. Hoechst 33258 is a DNA-specific dye that can be used to quantitate DNA. 12. Store the sample frozen at –20oC or below.

Benefits of Ayurvedic Medicines

2009-06-03T20:29:00.000-07:00

• By using ayurvedic and herbal medicines you ensure physical and mental health without side effects. The natural ingredients of herbs help bring “arogya” to human body and mind. ("Arogya" means free from diseases). The chemicals used in preparing allopathy medicines have impact on mind as well. One should have allopathy medicine only when it is very necessary. • According to the original texts, the goal of Ayurveda is prevention as well as promotion of the body’s own capacity for maintenance and balance. • Ayurvedic treatment is non-invasive and non-toxic, so it can be used safely as an alternative therapy or alongside conventional therapies. • Ayurvedic physicians claim that their methods can also help stress-related, metabolic, and chronic conditions. • Ayurveda has been used to treat acne, allergies, asthma, anxiety, arthritis, chronic fatigue syndrome, colds, colitis, constipation, depression, diabetes, flu, heart disease, hypertension, immune problems, inflammation, insomnia, nervous disorders, obesity, skin problems, and ulcers. Ayurvedic Terms Explained Dosha: In Ayurvedic philosophy, the five elements combine in pairs to form three dynamic forces or interactions called doshas. It is also known as the governing principles as every living things in nature is characterized by the dosha. Ayurvedic Facial: Purportedly, a "therapeutic skin care experience" that involves the use of "dosha-specific" products and a facial massage focusing on "marma points." Ayurvedic Nutrition (Ayurvedic Diet): Nutritional phase of Ayurveda. It involves eating according to (a) one's "body type" and (b) the "season." The alleged activity of the doshas--three "bodily humors," "dynamic forces," or "spirits that possess"--determines one's "body type." In Ayurveda, "body types" number seven, eight, or ten, and "seasons" traditionally number six. Each two-month season corresponds to a dosha; for example, the two seasons that correspond to the dosha named "Pitta" (see "Raktamoksha") constitute the period of mid-March through mid-July. But some proponents enumerate three seasons: summer (when pitta predominates), autumn, and winter (the season of kapha); or Vata season (fall and winter), Kapha season (spring), and Pitta season (summer). According to Ayurvedic theory, one should lessen one's intake of foods that increase ("aggravate") the ascendant dosha.

Serial analysis of gene expression

2009-06-03T20:26:00.000-07:00

Serial analysis of gene expression (SAGE) is a technique used by molecular biologists to produce a snapshot of the messenger RNA population in a sample of interest in the form of small tags that correspond to fragments of those transcripts. The original technique was developed by Dr. Victor Velculescu at the Oncology Center of Johns Hopkins University and published in 1995. Several variants have been developed since, most notably a more robust version, LongSAGE, RL-SAGEand the most recent SuperSAGE that enables very precise annotation of existing genes and discovery of new genes within genomes because of an increased tag-length of 25–27 bp. Overview SAGE experiments proceed as follows: 1. Isolate the mRNA of an input sample (e.g. a tumour). 2. Extract a small chunk of sequence from a defined position of each mRNA molecule. 3. Link these small pieces of sequence together to form a long chain (or concatemer). 4. Clone these chains into a vector which can be taken up by bacteria. 5. Sequence these chains using modern high-throughput DNA sequencers. 6. Process this data with a computer to count the small sequence tags. Applications Although SAGE was originally conceived for use in cancer studies, it has been successfully used to describe the transcriptome of other diseases and in a wide variety of organisms. Comparison to DNA microarrays The general goal of the technique is similar to the DNA microarray. However, SAGE is a sequence-based sampling technique. Observations are not based on hybridization, which result in more qualitative, digital values. In addition, the mRNA sequences do not need to be known a priori, so genes or gene variants which are not known can be discovered. Microarray experiments are much cheaper to perform, so large-scale studies do not typically use SAGE. Quantifying gene expressions is more exact in SAGE because it involves directly counting the number of transcripts whereas spot intensities in microarrays fall in non-discrete gradients and are prone to background noise.

Ayurveda

2009-06-03T18:45:00.000-07:00

Ayurveda is a system of traditional medicine native to India, and practiced in other parts of the world as a form of alternative medicine. In Sanskrit, the word Ayurvedacomprises the words āyus, meaning 'life' and veda, meaning 'science'. Evolving throughout its history, Ayurveda remains an influential system of medicine in South Asia. The earliest literature of Ayurveda appeared during the Vedic period in India. The Sushruta Samhita and the Charaka Samhita were influential works on traditional medicine during this era. Ayurvedic practitioners also claim to have identified a number of medicinal preparations and surgical procedures for curing various ailments and diseases. Ayurveda is considered to be a form of complementary and alternative medicine (CAM) within the western world, where several of its methods—such as herbs, massage, and Yoga as exercise or alternative medicine—are applied on their own as a form of CAM treatment. Ayurveda stresses the use of vegetable drugs Fats are used both for consumption and for external use. Hundreds of vegetable drugs are employed, including cardamom and cinnamon. Some animal products may also be used, for example milk, bones, and gallstones etc. Minerals—including sulfur, arsenic, lead, copper sulfate, gold—are also consumed as prescribed.. This practice of adding minerals to herbal medicine is known as Rasa Shastra. In some cases alcohol is used as a narcotic for the patient undergoing an operation. The advent of Islam introduced opium as a narcotic. Both oil and tar are used to stop bleeding. Oils may be used in a number of ways including regular consumption as a part of food, anointing, smearing, head massage, and prescribed application to infected areas. The proper function of channels—tubes that exist within the body and transport fluids from one point to another—is seen as vital, and the lack of healthy channels may lead to disease and insanity. Sushruta identifies that blockages of these channels may lead to rheumatism, epilepsy, paralysis, and convulsions as fluids and channels are diverted from their ideal locations. Sweating is favored as a manner in which to open up the channels and dilute the Doshas causing the blockages and harming a patient—a number of ways to take steam bathing and other steam related cures are recommended so that these toxins are released.

Gene expression

2009-05-28T22:13:00.000-07:00

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as rRNA genes or tRNA genes, the product is a functional RNA. Several steps in the gene expression process may be modulated, including the transcription, RNA splicing, translation, and post-translational modification of a protein. Gene regulation gives the cell control over structure and function, and is the basis for cellular differentiation, morphogenesis and the versatility and adaptability of any organism. Gene regulation may also serve as a substrate for evolutionary change, since control of the timing, location, and amount of gene expression can have a profound effect on the functions (actions) of the gene in the organism. Transcription The gene itself is typically a long stretch of DNA and does not perform an active role. It is a blueprint for the production of RNA. The production of RNA copies of the DNA is called transcription, and is performed by RNA polymerase, which adds one RNA nucleotide at a time to a growing RNA strand. This RNA is complementary to the DNA nucleotide being transcribed; i.e. a T on the DNA means an A is added to the RNA. However, in RNA the nitrogen-containing base Uracil is inserted instead of Thymine wherever there is an Adenine on the DNA strand. Therefore, the mRNA complement of a DNA strand reading "TAC" would be transcribed as "AUG". RNA processing Transcription creates a primary transcript of RNA at the place where the gene was located. This transcript is often altered before being translated. RNA processing, also known as post-transcriptional modification, can start during transcription, as is the case for splicing, where the spliceosome removes introns from newly formed RNA. Introns are RNA segments which are not found in the mature RNA, although they can function as precursors, e.g. for snoRNAs, which are RNAs that direct modification of nucleotides in other RNAs. In some cases large aggregates of RNA and RNA processing factors are formed, notably in the nucleolus where ribosomal RNA is processed by snoRNAs and their partner enzymes. These cleave the primary ribosomal RNA transcripts into the correct segments and alter some of its nucleosides, for instance into pseudouridine. RNA export While some RNAs function in the nucleus, many other RNAs in eukaryotes are transported through the nuclear pores and into the cytosol, including all the RNA types involved in protein synthesis. In some cases RNAs are additionally transported to a specific part of the cytoplasm, such as a synapse; they are then towed by motor proteins that bind through linker proteins to specific sequences (called "zipcodes") on the RNA. Translation For most RNA, the mature RNA is the gene product (see non-coding RNA). In the case of messenger RNA however, the RNA is but an information carrier for the synthesis of a protein. Each triplet of nucleotides of the coding region of a messenger RNA corresponds to a binding site for a transfer RNA. Transfer RNAs carry amino acids, and these are chained together by the ribosome. The ribosome helps transfer RNA bind to messenger RNA and takes the amino acid from each transfer RNA and makes a structure-less protein out of it. Some proteins have parts that should be within a membrane, these parts are moved into the membrane by the signal recognition particle which binds to the ribosome when it finds a signal sequence on the nascent amino acid chain.

Cleave DNA Using Restriction Endonulease:

2009-05-28T22:08:00.000-07:00

In order to manipulate DNA you have to posses the ability to cleave DNA at specific sites by using bacterial enzyme, which is restriction endonulease. Restriction endonucleases are bacterial enzymes that cleave duplex DNA at specific target sequences with the production of defined fragments. The name of the enzyme (such as BamHl, EcoRl, AluI, and so on) tells us about the origin of the enzyme but does not give us any information about the specificity of cleavage. The recognition site for most of the commonly used enzymes is a short palindromic sequence, usually either 4, 5, or 6 bp in length, such as AGCT (for AZul),GAATTC (for EcoRl), and so on. Each enzyme cuts the palindrome at a particular site, and two different enzymes may have the same recognition sequence but cleave the DNA at different points within that sequence. Materials 1. 10X stock of the appropriate restriction enzyme buffer. 2. DNA to be digested in either water or TE (10 mM Tris-HCl pH 8.3, 1 mM ethylenediaminetetraacetic acid [EDTA]). 3. Bovine serum albumin (BSA) at a concentration of 1 mg/mL. BSA is routinely included in restriction digests to stabilize low protein concentrations and to protect against factors that cause denaturation. 4. Sterile distilled water. Good-quality sterile distilled water should be used in restriction digests. Water should be free of ions and organic compounds, and must be detergent free. 5. The correct enzyme for the digest. 6. 5X Loading buffer: 50% (v/v) glycerol, 100 mM Na2EDTA, pH 8, 0.125% (w/v) bromophenol blue, 0.125% (w/v) xylene cyanol. 7. 100 mM Spermidine. Digests of genomic DNA are dramatically improved by the inclusion of spermidine in the digest mixture to a final concentration of 1 mM since the polycationic spermidine binds negatively charged contaminants. Spermidine can cause precipitation of DNA at low temperatures, so it should not be added while the reaction is kept on ice. Methods 1. Thaw all solutions, with the exception of the enzyme, and then place on ice. 2. Decide on a final volume for the digest, usually between 10 and 50 microliters, and then into a sterile Eppendorf tube, add 1/10 vol of reaction buffer, 1/10 vol BSA, between 0.5 and 1 micrograms of the DNA to be digested, and sterile distilled water to the final volume. The amount of DNA to be digested depends on subsequent steps. A reasonable amount for a plasmid digestion to confirm the presence of an insertion would be 500 ng-l microgram, depending on the size of the insert. The smaller the insert, the more DNA should be digested to enable visualization of the insert after agarose gel analysis. 3. Take the restriction enzyme stock directly from the -20oC freezer, and remove the desired units of enzyme with a clean sterile pipet tip. Immediately add the enzyme to the reaction and mix. Stock restriction enzymes are very heat labile and so should be removed from -20oC storage for as short a time as possible and placed on ice. 4. Incubate the tube at the correct temperature (see Note 12) for approx 1 h. Genomic DNA can be digested overnight. Note that the incubation temperature for the vast majority of restriction endonucleases is 37oC but that this is not true for all enzymes. 5. An aliquot of the reaction (usually 1-2microliter) may be mixed with a 5X concentrated loading buffer and analyzed by gel electrophoresis. Hopefully this method can help your work.

Therapeutic cloning

2009-05-01T18:29:00.000-07:00

If reproductive cloning has few friends -- aside from some renegade scientists and cultists who insist they'll use it to help infertile couples -- a related technology poses much tougher ethical questions.

Therapeutic cloning does not strive to make whole humans. Instead, it makes embryos as a source of embryonic stem cells for therapeutic purposes. Because embryonic stem cells can grow into any body cell, they might be cultured into nerve cells, skin cells, even hair follicles for the bald. The obvious use of therapeutic cloning would be treating deadly diseases like diabetes and Parkinson's, where a specific type of cell has died. It's a good bet that replacing those cells would restore health.

Therapeutic cloning research would end in this country, however, if restrictive legislation passes the Senate. Sen. Sam Brownback, for example, writes that "The prospect of creating new human life solely to be exploited and destroyed in this way has been condemned on moral grounds by many as displaying a profound disrespect for life."

But society is already willing to tolerate the death of lab-created embryos during in-vitro fertilization, says medical ethicist Dan Wikler. "Anyone who would says we should not embark on this kind of therapeutic cloning would, on pain of inconsistency, be opposed to routine IVF, where embryo are created in advance, with big chance of being destroyed as surplus."

Wikler maintains that the quest to save existing lives deserves moral standing. "Anyone who would says that the chance to save a life through therapeutic cloning is wrong, would have to explain why they have not been upset by the practices that go on under IVF, which is basically the same thing."

Therapeutic cloning

2009-05-01T18:28:00.000-07:00

Cloning

2009-05-01T18:19:00.000-07:00

Cloning Cloning in biology is the process of producing populations of genetically-identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments (molecular cloning), cells (cell cloning), or organisms. More generally, the term refers to the production of multiple copies of a product such as digital media or software. Cellular cloning Cloning a cell means to derive a population of cells from a single cell. In the case of unicellular organisms such as bacteria and yeast, this process is remarkably simple and essentially only requires the inoculation of the appropriate medium. However, in the case of cell cultures from multi-cellular organisms, cell cloning is an arduous task as these cells will not readily grow in standard media. A useful tissue culture technique used to clone distinct lineages of cell lines involves the use of cloning rings (cylinders). According to this technique, a single-cell suspension of cells which have been exposed to a mutagenic agent or drug used to drive selection is plated at high dilution to create isolated colonies; each arising from a single and potentially clonally distinct cell. At an early growth stage when colonies consist of only a few of cells, sterile polystyrene rings (cloning rings), which have been dipped in grease are placed over an individual colony and a small amount of trypsin is added. Cloned cells are collected from inside the ring and transferred to a new vessel for further growth.

Cell culture

2009-05-01T18:14:00.000-07:00

Cell culture is the process by which prokaryotic or eukaryotic cells are grown under controlled conditions. In practice the term "cell culture" has come to refer to the culturing of cells derived from multicellular eukaryotes, especially animal cells. The historical development and methods of cell culture are closely interrelated to those of tissue culture and organ culture. Applications of cell culture Mass culture of animal cell lines is fundamental to the manufacture of viral vaccines and many products of biotechnology. Biological products produced by recombinant DNA (rDNA) technology in animal cell cultures include enzymes, synthetic hormones, immunobiologicals (monoclonal antibodies, interleukins, lymphokines), and anticancer agents. Although many simpler proteins can be produced using rDNA in bacterial cultures, more complex proteins that are glycosylated (carbohydrate-modified) currently must be made in animal cells. An important example of such a complex protein is the hormone erythropoietin. The cost of growing mammalian cell cultures is high, so research is underway to produce such complex proteins in insect cells or in higher plants. Tissue culture and engineering Cell culture is a fundamental component of tissue culture and tissue engineering, as it establishes the basics of growing and maintaining cells ex vivo. Vaccines Vaccines for polio, measles, mumps, rubella, and chickenpox are currently made in cell cultures. Due to the H5N1 pandemic threat, research into using cell culture for influenza vaccines is being funded by the United States government. Novel ideas in the field include recombinant DNA-based vaccines, such as one made using human adenovirus (a common cold virus) as a vector,or the use of adjuvants.

Types of cells

2009-05-01T18:13:00.000-07:00

Cells are often categorized by their source: * Autologous cells are obtained from the same individual to which they will be reimplanted. Autologous cells have the fewest problems with rejection and pathogen transmission, however in some cases might not be available. For example in genetic disease suitable autologous cells are not available. Also very ill or elderly persons, as well as patients suffering from severe burns, may not have sufficient quantities of autologous cells to establish useful cell lines. Moreover since this category of cells needs to be harvested from the patient, there are also some concerns related to the necessity of performing such surgical operations that might lead to donor site infection or chronic pain. Autologous cells also must be cultured from samples before they can be used: this takes time, so autologous solutions may not be very quick. Recently there has been a trend towards the use of mesenchymal stem cells from bone marrow and fat. These cells can differentiate into a variety of tissue types, including bone, cartilage, fat, and nerve. A large number of cells can be easily and quickly isolated from fat, thus opening the potential for large numbers of cells to be quickly and easily obtained. Several companies have been founded to capitalize on this technology, the most successful at this time being Cytori Therapeutics. * Allogeneic cells come from the body of a donor of the same species. While there are some ethical constraints to the use of human cells for in vitro studies, the employment of dermal fibroblasts from human foreskin has been demonstrated to be immunologically safe and thus a viable choice for tissue engineering of skin. * Xenogenic cells are these isolated from individuals of another species. In particular animal cells have been used quite extensively in experiments aimed at the construction of cardiovascular implants. * Syngenic or isogenic cells are isolated from genetically identical organisms, such as twins, clones, or highly inbred research animal models. * Primary cells are from an organism. * Secondary cells are from a cell bank. * Stem cells (see main article: stem cell) are undifferentiated cells with the ability to divide in culture and give rise to different forms of specialized cells. According to their source stem cells are divided into "adult" and "embryonic" stem cells, the first class being multipotent and the latter mostly pluripotent; some cells are totipotent, in the earliest stages of the embryo. While there is still a large ethical debate related with the use of embryonic stem cells, it is thought that stem cells may be useful for the repair of diseased or damaged tissues, or may be used to grow new organs.

Tissue engineering

2009-05-01T18:11:00.000-07:00

Tissue engineering is the use of a combination of cells, engineering and materials methods, and suitable biochemical and physio-chemical factors to improve or replace biological functions. While most definitions of tissue engineering cover a broad range of applications, in practice the term is closely associated with applications that repair or replace portions of or whole tissues (i.e., bone, cartilage, blood vessels, bladder, etc.). Often, the tissues involved require certain mechanical and structural properties for proper functioning. The term has also been applied to efforts to perform specific biochemical functions using cells within an artificially-created support system (e.g. an artificial pancreas, or a bioartificial liver). The term regenerative medicine is often used synonymously with tissue engineering, although those involved in regenerative medicine place more emphasis on the use of stem cells to produce tissues. A commonly applied definition of tissue engineering, as stated by Langer and Vacanti, is "an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function or a whole organ".Tissue engineering has also been defined as "understanding the principles of tissue growth, and applying this to produce functional replacement tissue for clinical use." A further description goes on to say that an "underlying supposition of tissue engineering is that the employment of natural biology of the system will allow for greater success in developing therapeutic strategies aimed at the replacement, repair, maintenance, and/or enhancement of tissue function." Powerful developments in the multidisciplinary field of tissue engineering have yielded a novel set of tissue replacement parts and implementation strategies. Scientific advances in biomaterials, stem cells, growth and differentiation factors, and biomimetic environments have created unique opportunities to fabricate tissues in the laboratory from combinations of engineered extracellular matrices ("scaffolds"), cells, and biologically active molecules. Among the major challenges now facing tissue engineering is the need for more complex functionality, as well as both functional and biomechanical stability in laboratory-grown tissues destined for transplantation. The continued success of tissue engineering, and the eventual development of true human replacement parts, will grow from the convergence of engineering and basic research advances in tissue, matrix, growth factor, stem cell, and developmental biology, as well as materials science and bioinformatics.

Biochemical engineering

2009-05-01T18:08:00.000-07:00

Biochemical engineering is a branch of chemical engineering or biological engineering that mainly deals with the design and construction of unit processes that involve biological organisms or molecules, such as bioreactors. Biochemical engineering is often taught as a supplementary option to chemical engineering or biological engineering due to the similarities in both the background subject curriculum and problem-solving techniques used by both professions. Its applications are used in the food, feed, pharmaceutical, biotechnology, and water treatment industries.

Genetic Version

2009-04-10T11:19:00.000-07:00

In a strange genetic version of the Russian doll, scientists have discovered the genome of a bacterial parasite nestled inside the genome of its host. The findings, published today in the journal Science, suggest that organisms might quickly acquire new genes and functions through the large-scale transfer of genes. The parasite, known as Wolbachia, invades the eggs and sperm of many different types of insects, ensuring that it is passed down to the host's offspring. In this case, scientists discovered the bacterium's genome within the chromosome of its fruit-fly host. While microbiologists have previously seen cases of gene swapping between microbes or between parasites and their hosts, this is the first example of such an extensive exchange. According to a press release from the University of Rochester, "This study establishes the widespread occurrence and high frequency of a process that we would have dismissed as science fiction until just a few years ago," says W. Ford Doolittle, Canada Research Chair in Comparative Microbial Genomics at Dalhousie University, who is not connected to the study. "This is stunning evidence for increased frequency of gene transfer." "It didn't seem possible at first," says [Jack] Werren, professor of biology at the University of Rochester and a world-leading authority on the parasite, called Wolbachia. "This parasite has implanted itself inside the cells of 70 percent of the world's invertebrates, coevolving with them. And now, we've found at least one species where the parasite's entire or nearly entire genome has been absorbed and integrated into the host's. The host's genes actually hold the coding information for a completely separate species." A similar phenomenon may have happened in our own distant past. "In our very own cells and those of nearly all plants and animals are mitochondria, special structures responsible for generating most of our cells' supply of chemical energy. These were once bacteria that lived inside cells, much like Wolbachia does today. Mitochondria still retain their own, albeit tiny, DNA, and most of the genes moved into the nucleus in the very distant past. Like Wolbachia, they have passively exchanged DNA with their host cells. It's possible Wolbachia may follow in the path of mitochondria, eventually becoming a necessary and useful part of a cell. In a way, Wolbachia could be the next mitochondria," says Werren. "A hundred million years from now, everyone may have a Wolbachia organelle."

Gene expression

2009-04-10T11:07:00.000-07:00

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as rRNA genes or tRNA genes, the product is a functional RNA. Several steps in the gene expression process may be modulated, including the transcription step and translation step and the post-translational modification of a protein. Gene regulation gives the cell control over structure and function, and is the basis for cellular differentiation, morphogenesis and the versatility and adaptability of any organism. Gene regulation may also serve as a substrate for evolutionary change, since control of the timing, location, and amount of gene expression can have a profound effect on the functions (actions) of the gene in the organism. Transcription The gene itself is typically a long stretch of DNA and does not perform an active role. It is a blueprint for the production of RNA. The production of RNA copies of the DNA is termed transcription, and is performed by RNA polymerase, which adds one RNA nucleotide at a time to a growing RNA strand. This RNA is complementary to the DNA nucleotide being read, i.e. a T on the DNA means an A is added to the RNA. However, In RNA the nitrogen base Uracil is inserted instead of Thymine. Wherever there is an Adenine on the DNA strand, a Uracil is inserted into the complementary RNA strand. I.e the mRNA complement of a DNA strand reading "TAC" would be transcribed as "AUG", which is translated into the amino acid methionine, which is generally the starting point in a messenger RNA for expressing a protein. RNA processing Transcription creates a primary transcript of RNA at the place where the gene was located. This transcript often needs to be altered by enzymes. RNA processing, also known as post-transcriptional modification, can start already during transcription, as is the case for e.g. splicing where the spliceosome removes introns from newly formed parts of the RNA.[ Introns are RNA segments which are not found in the mature RNA, although they can function as precursors for e.g. snoRNA which are a group of RNAs that direct nucleotide modification of other RNAs. In some cases large aggregates of RNA and RNA processing factors are formed, notably the nucleolus where ribosomal RNA localises to be processed by snoRNAs and their partner enzymes. These chop the primary ribosomal RNA transcripts into the correct segments and alter some of its nucleotides into e.g. pseudouridine. RNA export While some RNAs function in the nucleus, many other RNAs in eukaryotes need to be transported through the nuclear pores and into the cytosol, including all the RNA types involved in protein synthesis.[ In some cases the RNA is additionally transported to a specific part of the cytoplasm, such as a synapse, they are then towed by motor proteins that bind through linker proteins to specific sequences (called "zipcodes") on the RNA. Translation For most RNA, the mature RNA is the gene product (see non-coding RNA). In the case of messenger RNA however, the RNA is but an information carrier for the synthesis of a protein. Each triplet of nucleotides of the coding region of a messenger RNA corresponds to a bindning site for a transfer RNA. Transfer RNAs carry amino acids, and these are chained together by the ribosome. The ribosome helps transfer RNA bind to messenger RNA and takes the amino acid from each tranfer RNA and makes a structure-less protein out of it. Some proteins have parts that should be within a membrane, these parts are moved into the membrane by the signal recognition particle which binds to the ribosome when it finds a signal sequence on the nascent amino acid chain. Folding Enzymes called chaperones assist the newly formed protein to attain (fold into) the 3-dimensional structure it needs to function. Similarly, RNA chaperones help RNAs attain their functional shapes. Protein export Many proteins that are destined for other parts of the cell than the cytosol. A commonly used mechanism for transporting these proteins to where they should be is translocation to the endoplasmatic reticulum, followed by transport via the Golgi apparatus.

Vomitoxin

2009-04-10T11:06:00.000-07:00

Vomitoxin, also known as deoxynivalenol (DON), is a type B trichothecene, an epoxy-sesquiterpeneoid. This mycotoxin occurs predominantly in grains such as wheat, barley, oats, rye, and maize, and less often in rice, sorghum, and triticale. The occurrence of deoxynivalenol is associated primarily with Fusarium graminearum (Gibberella zeae) and F. culmorum, both of which are important plant pathogens which cause Fusarium head blight in wheat and Gibberella ear rot in maize. A direct relationship between the incidence of Fusarium head blight and contamination of wheat with deoxynivalenol has been established. The incidence of Fusarium head blight is strongly associated with moisture at the time of flowering (anthesis), and the timing of rainfall, rather than the amount, is the most critical factor. Furthermore, deoxynivalenol contents are significantly affected by the susceptibility of cultivars towards Fusarium species, previous crop, tillage practices, and fungicide use F. graminearum grows optimally at a temperature of 25 °C and at a water activity above 0.88. F. culmorum grows optimally at 21 °C and at a water activity above 0.87. The geographical distribution of the two species appears to be related to temperature, F. graminearum being the commoner species and occurring in warmer climates. Deoxynivalenol has been implicated in incidents of mycotoxicoses in both humans and farm animals. When compared to other trichothecene mycotoxins which can form in grains and forages, vomitoxin is relatively mild. Reduced feed intake, and the accompanying decrease in performance, are the only symptoms of vomitoxin toxicity livestock producers will likely encounter. This response to vomitoxin appears to occur through the central nervous system. Vomitoxin belongs to a class of mycotoxins (tricothecenes) which are strong protein inhibitors. Inhibition of protein synthesis following exposure to vomitoxin causes the brain to increase its uptake of the amino acid tryptophan and, in turn, its synthesis of serotonin. Increased levels of serotonin are believed to be responsible for the anorexic effects of DON and other tricothecenes. Irritation of the gastrointestinal tract may also play a role in reducing feed intake... This fact may also partially explain the high incidence of pars esaughageal stomach ulcers observed in sows off feed during feed refusal. • Human foods: Vomitoxin is not a known carcinogen as with aflatoxin. Large amounts of grain with vomitoxin would have to be consumed to pose a health risk to humans. The FDA has established a level of 1 ppm (parts per million) restriction of vomitoxin. • Companion animals: Dogs and cats are restricted to 5 ppm and of grains and grain byproducts and that the grains not exceed 40% percent of the diet. • Livestock and farm animals: In animals and livestock, vomitoxin causes a refusal to feed and lack of weight gain when fed above advised levels. Restrictions are set at 10 ppm for poultry and ruminating beef and feedlot cattle older than 4 months. Ingredients may not exceed 50% of the animal's diet. Dairy cow limits are set at 2 ppm.

A Genome within a Genome

2009-04-09T11:17:00.000-07:00

DNA Transcription

2009-04-01T10:35:00.000-07:00

DNA transcription is a process that involves the transcribing of genetic information from DNA to RNA. DNA is housed within the nucleus of our cells. It controls cellular activity by coding for the production of enzymes and proteins. The information in DNA is not directly converted into proteins, but must first be copied into RNA. This ensures that the information contained in the DNA does not become tainted. DNA consists of four nucleotide bases [adenine (A), guanine (G), cytosine (C) and thymine (T)] that are paired together (A-T and C-G) to give DNA its double helical shape. DNA is transcribed by an enzyme called RNA polymerase. Specific nucleotide sequences tell RNA polymerase where to begin and where to end. RNA polymerase attaches to the DNA at a specific area called the promoter region. The DNA strand opens and allows RNA polymerase to transcribe only a single strand of DNA into a single stranded RNA polymer called messenger RNA (mRNA). Like DNA, RNA is composed of nucleotide bases. RNA however, contains the nucleotides adenine, guanine, cytosine and uricil (U). When RNA polymerase transcribes the DNA, guanine pairs with cytosine and adenine pairs with uricil. RNA polymerase moves along the DNA until it reaches a terminator sequence. At that point, RNA polymerase releases the mRNA polymer and detaches from the DNA. Since proteins are constructed in the cytoplasm of the cell by a process called translation, mRNA must cross the nuclear membrane to reach the cytoplasm. Once in the cytoplasm, mRNA along with ribosomes and another RNA molecule called transfer RNA, work together to produce proteins. Proteins can be manufactured in large quantities because a single DNA sequence can be transcribed by many RNA polymerase molecules at once.

Steps of DNA Replication

2009-04-01T10:29:00.000-07:00

1)The first major step for the DNA Replication to take place is the breaking of hydrogen bonds between bases of the two antiparallel strands. The unwounding of the two strands is the starting point. The splitting happens in places of the chains which are rich in A-T. That is because there are only two bonds between Adenine and Thymine (there are three hydrogen bonds between Cytosine and Guanine). Helicase is the enzyme that splits the two strands. The initiation point where the splitting starts is called "origin of replication".The structure that is created is known as "Replication Fork".

2) One of the most important steps of DNA Replication is the binding of RNA Primase in the the initiation point of the 3'-5' parent chain. RNA Primase can attract RNA nucleotides which bind to the DNA nucleotides of the 3'-5' strand due to the hydrogen bonds between the bases. RNA nucleotides are the primers (starters) for the binding of DNA nucleotides. 3) The elongation process is different for the 5'-3' and 3'-5' template. a)5'-3' Template: The 3'-5' proceeding daughter strand -that uses a 5'-3' template- is called leading strand because DNA Polymerase ä can "read" the template and continuously adds nucleotides (complementary to the nucleotides of the template, for example Adenine opposite to Thymine etc). b)3'-5'Template: The 3'-5' template cannot be "read" by DNA Polymerase ä. The replication of this template is complicated and the new strand is called lagging strand. In the lagging strand the RNA Primase adds more RNA Primers. DNA polymerase å reads the template and lengthens the bursts. The gap between two RNA primers is called "Okazaki Fragments". The RNA Primers are necessary for DNA Polymerase å to bind Nucleotides to the 3' end of them. The daughter strand is elongated with the binding of more DNA nucleotides. 4) In the lagging strand the DNA Pol I -exonuclease- reads the fragments and removes the RNA Primers. The gaps are closed with the action of DNA Polymerase (adds complementary nucleotides to the gaps) and DNA Ligase (adds phosphate in the remaining gaps of the phosphate - sugar backbone). Each new double helix is consisted of one old and one new chain. This is what we call semiconservative replication. 5) The last step of DNA Replication is the Termination. This process happens when the DNA Polymerase reaches to an end of the strands. We can easily understand that in the last section of the lagging strand, when the RNA primer is removed, it is not possible for the DNA Polymerase to seal the gap (because there is no primer). So, the end of the parental strand where the last primer binds isn't replicated. These ends of linear (chromosomal) DNA consists of noncoding DNA that contains repeat sequences and are called telomeres. As a result, a part of the telomere is removed in every cycle of DNA Replication. 6) The DNA Replication is not completed before a mechanism of repair fixes possible errors caused during the replication. Enzymes like nucleases remove the wrong nucleotides and the DNA Polymerase fills the gaps. Similar processes also happen during the steps of DNA Replication of prokaryotes though there are some differences.

RNA - Transcription

2009-04-01T10:27:00.000-07:00

Introduction:

The differences in the composition of RNA and DNA have already been noted. In addition, RNA is not usually found as a double helix but as a single strand. However, the single polynucleotide strand may fold back on itself to form portions which have a double helix structure like the tertiary structure of proteins.

The biosynthesis of RNA, called transcription, proceeds in much the same fashion as the replication of DNA and also follows the base pairing principle. Again, a section of DNA double helix is uncoiled and only one of the DNA strands serves as a template for RNA polymerase enzyme to guide the synthesis of RNA. After the synthesis is complete, the RNA separates from the DNA and the DNA recoils into its helix.

The transcription of a single RNA strand is illustrated in the graphic on the left. One major difference is that the heterocyclic amine, adenine, on DNA codes for the incorporation of uracil in RNA rather than thymine as in DNA. Remember that thymine is not found in RNA and do not confuse the replacement of uracil in RNA for thymine in DNA in the transcription process. For example, thymine in DNA still codes for adenine on RNA not uracil, while the adenine on DNA codes for uracil in RNA.

Note that the new RNA (red) is identical to non coding DNA with the exception of uracil where thymine was located in DNA.

There are three major types of RNA which will be fully explained in a later section. Although RNA is synthesized in the nucleus, it migrates out of the nucleus into the cytoplasm where it is used in the synthesis of proteins.

RNA Transcription Process:

The RNA transcription process occurs in three stages: initiation, chain elongation, and termination.

The first stage occurs when the RNA Polymerase-Promoter Complex binds to the promoter gene in the DNA. This also allows for the finding of the start sequence for the RNA polymerase. The promoter enzyme will not work unless the sigma protein is present (shown in blue in graphic). Specific sequences on the non coding strand of DNA are recognized as the signal to start the unwinding process.

Transcription

2009-04-01T10:24:00.000-07:00

Transcription is the synthesis of RNA under the direction of DNA. RNA synthesis, or transcription, is the process of transcribing DNA nucleotide sequence information into RNA sequence information. Both nucleic acid sequences use complementary language, and the information is simply transcribed, or copied, from one molecule to the other. DNA sequence is enzymatically copied by RNA polymerase to produce a complementary nucleotide RNA strand, called messenger RNA (mRNA), because it carries a genetic message from the DNA to the protein-synthesizing machinery of the cell. One significant difference between RNA and DNA sequence is the presence of U, or uracil in RNA instead of the T, or thymine of DNA. In the case of protein-encoding DNA, transcription is the first step that usually leads to the expression of the genes, by the production of the mRNA intermediate, which is a faithful transcript of the gene's protein-building instruction. The stretch of DNA that is transcribed into an RNA molecule is called a transcription unit. A DNA transcription unit that is translated into protein contains sequences that direct and regulate protein synthesis in addition to coding the sequence that is translated into protein. The regulatory sequence that is before (upstream (-), towards the 5' DNA end) the coding sequence is called 5' untranslated region (5'UTR), and sequence found following (downstream (+), towards the 3' DNA end) the coding sequence is called 3' untranslated region (3'UTR). Transcription has some proofreading mechanisms, but they are fewer and less effective than the controls for copying DNA; therefore, transcription has a lower copying fidelity than DNA replication. As in DNA replication, RNA is synthesized in the 5' → 3' direction (from the point of view of the growing RNA transcript). Only one of the two DNA strands is transcribed. This strand is called the template strand, because it provides the template for ordering the sequence of nucleotides in an RNA transcript. The other strand is called the coding strand, because its sequence is the same as the newly created RNA transcript (except for uracil being substituted for thymine). The DNA template strand is read 3' → 5' by RNA polymerase and the new RNA strand is synthesized in the 5'→ 3' direction. A polymerase binds to the 3' end of a gene (promoter) on the DNA template strand and travels toward the 5' end.

The Dna Testing Process

2009-03-26T20:05:00.001-07:00

DNA testing is becoming increasingly used to determine genetic links between individuals as a highly accurate and individual way of identifying people and their relationships with one another. The process itself is one carried out in advanced laboratories under the strictest of lab conditions to ensure no cross-contamination and improve result accuracy. As such DNA testing can be said to present with a high degree of accuracy any particular biological relationship that may exist, particularly in paternity disputes where samples of both the mother and the father are provided. Preparing For the DNA Test and Collecting Samples Normally a DNA testing kit is sent to the person who ordered the test by the company from whom the order was made. The test begins with samples being collected from everyone preparing to undertake the test. In most cases, that will mean the mother, the father (alleged) and the child concerned. Samples are taken by the way of oral swabs, which collect cheek cells which are then dried and passed on for testing. In order to prepare the sample, it is first important to make sure that the cotton of the swab never touches any other surface including your hands, and that you have a number of swabs for each person taking the test to ensure reliability in the end results. Press the swab into the inside of the cheek and behind the lips, as well as the tongue area in order to get as good as possible a sample from the mouth. Having left to dry for around an hour, the swab should be carefully sealed off before the collation and mailing process. Testing the Samples After all the samples have been collected and labelled accordingly, they should be sent off to the laboratory for the DNA testing analysis. At this stage, the samples will be individually examined and DNA will be extracted from within the cells present in the sample. The same will be done for both the other two parties to the test and the results of the DNA profiles will be compared. The person analysing your results will be looking for a 50/50 split between your alleles, contained within the DNA, between those found on your mother and father. As you can only inherit genes already carried by one or both parents, no alleles can be present in the child's DNA that are not present in that of either parent. Naturally, this is where it becomes obvious when there is and is not a genetic link between those taking the DNA test. Further to that, the results are processed through the appropriate systems and a conclusion is reached, having covered 16 of the locus which are used as the template by which samples are matched. Receiving the DNA Test Results Once the DNA test is completed, the result will be sent to the participants via email, letter, fax or as otherwise agreed. The DNA test report should show the individual profile of each person that submitted a sample for the paternity test. Also the result should show the percentage probability of the stated relationship, for example in a DNA paternity test this is normally in excess of 99.99%. There's no doubt about it - DNA testing is here to stay. Whilst most people are not very knowledgeable on how DNA paternity testing works, it is probably a good idea to gain some level of understanding given the way in which DNA testing is likely to continue to affect our lives over the coming decades. With growing calls for more extensive DNA databases and records for crime prevention, DNA testing and analysis looks set to remain at the forefront of the civil liberties/state interests debate.

Dna Testing to Find Your Ancestors

2009-03-26T20:03:00.000-07:00

The use of DNA testing for determining a person’s ancestry is becoming more and common. By linking your maternal DNA (mitochondrial DNA) and your paternal DNA (the y-chromosome), these ancestry databases are effectively able to link you to other people to whom you may be related and thereby determining to some degree your ancestral lineage and where your ancestors came from. DNA Ancestry Testing – Y-Chromosome and Mitochondial DNA The first thing that genealogists look for is a father-to-son linkage, tracked down the Y chromosome which only men posses. Therefore, they are able to observe the Y chromosome that appears in other people and compare them, to determine where a paternal link may be present. This comparison, in essence, allows for the genealogist to try and find paternal linkages amongst people. The other thing that can be done is to link maternal DNA. This in particular is a very powerful testing method that allows for accurate tracking back over many generations because of the mitochondria. Unlike DNA found in the nucleus, which can be altered and changes as environments change, mitochondrial DNA is a direct connection from child to mother that can’t be altered along the way. By taking a sample of the mitochondrial DNA, which is different than the DNA found in the nucleus, the genealogist can determine a maternal linkage. By taking this information, they can, once again, find, perhaps those long lost cousins or celebrity ancestors. DNA Ancestry Testing – Matching to a DNA Database However, can this really be effective at tracing family lines? How can they tell you who you’re related to throughout history? Some online ancestry websites create a database of DNA against which your can be matched. By taking a simple mouth swab and run the DNA tests, they then save the DNA profile that is collected. However, the key is for them to continuously compare other people’s DNA profiles to what your profile is. In essence, this will create a massive database that will determine instantly if a piece of code is a direct comparison to yours. So, as the database grows more and more, more and more relatives and ancestors can be discovered for more and more people. DNA Ancestry Testing – Determine geographical ancestry Furthermore, these DNA tests are able to help you find out where you come from. It’s argued that 170,000 years ago, humans left Africa and migrated elsewhere across the globe. Some went to Europe, some went to southern Africa, while others went to Asia to settle. By comparing the DNA profile of a person to that of researched ethnic groups, it is possible to provide information about where people are from. DNA testing has become a very useful method for people to find long lost relatives. Furthermore, the argument of the true nature of one’s ethnic origins can finally be resolved by DNA testing processes. Of course, as the databases grow and more research is conducted on, the usefulness of these types of tests will increase greatly.

How Is Dna Testing Done

2009-03-26T19:38:00.000-07:00

DNA testing is done for many different reasons. DNA evidence can link an alleged criminal to a crime scene. DNA paternity and maternity testing can identify a child's father or mother. DNA relationship testing can determine if two individuals are full or half siblings. DNA ancestry testing can determine ethnic origins and genealogical roots. How DNA testing is done depends on the results desired and the samples available. DNA fingerprinting (or profiling as it's also known) is the process of analyzing and comparing two DNA samples. Only identical twins have the exact same DNA sequence, everyone else's DNA is unique. This makes DNA the perfect way to link individuals to each other or to locations where they have been. The entire DNA chain is incredibly long, much to long to examine all of it. Human DNA is made up of about 3.3 billion base pairs. The differences between DNA samples occur only in small segments of the DNA--the rest of the DNA is pretty much the same. DNA testing focuses on those segments that are known to differ from person to person. As DNA testing has evolved over time, the testing methods have become more precise and are able to work with much smaller DNA samples. Early DNA testing was done using dime-size drops of blood. Today's tests can extract DNA from the back of a licked stamp. The DNA must be extracted from whatever sample is provided. DNA must be isolated and purified before it can be compared. In essence, it has to be "unlocked" from the cell in which it exists. The cell walls are usually dissolved with a detergent. Proteins in the cell are digested by enzymes. After this process, the DNA is purified, concentrated, and tested. DNA testing is done most often today using a process called "short tandem repeats," or STR. Human DNA has several regions of repeated sequences. These regions are found in the same place on the DNA chain, but the repeated sequences are different for each individual. The "short" tandem repeats (repeated sequences of two to five base pairs in length) have been proven to provide excellent DNA profiling results. STR is highly accurate--the chance of misidentification being one in several billion. source:articlebase

Cadaverine

2009-03-21T09:35:00.000-07:00

Cadaverine is a foul-smelling molecule produced by protein hydrolysis during putrefaction of animal tissue. Cadaverine is a toxic diamine with the formula NH2(CH2)5NH2, which is similar to putrescine. Cadaverine is also known by the names 1,5-pentanediamine and pentamethylenediamine.

Cadaverine

SIMPLY:

A syrupy colorless poisonous ptomaine C5H14N2 formed by decarboxylation of lysine especially in putrefaction of flesh

Production

Cadaverine is the decarboxylation product of the amino acid lysine.

However, this diamine is not purely associated with putrefaction. It is also produced in small quantities by living beings. It is partially responsible for the distinctive smell of urine and semen.

Examination of the serosal fluid following in vitro luminal perfusion of rat intestinal segments with 1 mg/ml histamine for 2 hr showed that histamine constituted only 22.1% of the total serosal radioactivity. The remainder of the radioactivity was comprised of histamine metabolites. When equimolar amounts of either aminoguanidine and cadaverine were added to the luminal perfusate, the percentage of the serosal radioactivity as histamine increased to 67.0 and 60.4%, respectively. However, when equal amounts of histamine and anserine were added to the luminal perfusate, only 30.6% of the translocated within 2 hr was histamine. In all cases, the gross translocation rate based on the percentage of total serosal radioactivity for total radioisotope was unchanged by the addition of these substances to the luminal perfusate. The results indicate that the potentiation of histamine toxicity by putrefactive amines, such as cadaverine, results from the inhibition of histamine metabolism which leads to increased uptake of unmetabolized histamine. The results do not support the hypothesis that potentiation occurs via an overall increase in the absorption of histamine and its metabolites due to some disruption in the barrier function of the intestine.

Bacteriocin

2009-03-21T09:29:00.000-07:00

Bacteriocins are proteinaceous toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). They are typically considered to be narrow spectrum antibiotics, though this has been debated They are phenomenologically analogous to yeast and paramecium killing factors, and are structurally, functionally, and ecologically diverse.

Methods of classification

Alternative methods of classification include: method of killing (pore forming, dnase, nuclease, murein production inhibition, etc), genetics (large plasmids, small plasmids, chromosomal), molecular weight and chemistry (large protein, polypeptide, with/without sugar moiety, containing atypical amino acids like lanthionine) and method of production (ribosomal, post ribosomal modifications, non-ribosomal).

Class I bacteriocins

The class I bacteriocins are small peptide inhibitors and include nisin.

Class II bacteriocins

The class II bacteriocins are small heat-stable proteins. The action of Class IIa bacteriocins seems to involve disruption of mannose transport into target cells. Class IIb bacteriocins form pores in the membranes of target cells and disrupt the proton gradient of target cells. Other bacteriocins can be grouped together as Class IIc. These have a wide range of effects on membrane permeability, cell wall formation and pheromone actions of target cells.

Class III bacteriocins

Large, heat-labile protein bacteriocins.

Medical significance

Bacteriocins are of interest in medicine because they are made by non-pathogenic bacteria that normally colonize the human body. Loss of these harmless bacteria following antibiotic use may allow opportunistic pathogenic bacteria to invade the human body.

Bacteriocins have also been suggested as a cancer treatment. They have shown distinct promise as a diagnostic agent for some cancers, , but their status as a form of therapy remains experimental and outside the main thread of cancer research. Partly this is due to questions about their mechanism of action and the presumption that anti-bacterial agents have no obvious connection to killing mammalian tumor cells. Some of these questions have been addressed, at least in part.

In the long quest for medical applications, bacteriocins have also been tested as AIDS drugs.

Production

There are many ways to demonstrate bacteriocin production, depending on the sensitivity and labor intensiveness desired. To demonstrate their production, technicians stab inoculate multiple strains on separate multiple nutrient agar Petri dishes, incubate at 30 °C for 24 h., overlay each plate with one of the strains (in soft agar), incubate again at 30 °C for 24 h. After this process, the presence of bacteriocins can be inferred if there are zones of growth inhibition around stabs. This is the simplest and least sensitive way. It will often mistake phage for bacteriocins. Some methods prompt production with UV radiation, Mitomycin C, or heat shock. UV radiation and Mitomycin C are used because the DNA damage they produce stimulates the SOS response. Cross streaking may be substituted for lawns. Similarly, production in broth may be followed by dripping the broth on a nascent bacterial lawn, or even filtering it. Precipitation (ammonium sulfate) and some purification (e.g. column or HPLC) may help exclude lysogenic and lytic phage from the assay.

The Analysis of DNA or RNA

2009-03-10T11:21:00.000-07:00

In order to measure DNA content you can use UV Spectrophotometer with the advantages are nondestructive and allows the sample to be recovered for further analysis or manipulation. Spectrophotometry uses the fact that there is a relationship between the absorption of ultraviolet light by DNA/RNA and its concentration in a sample. In this particular posting, I want to give you facts about the relationship between DNA/RNA with the wavelength in the Spectrophotometer assay. 1. The absorption maximum of DNA/RNA is approx 260 nm. This figure is an average of the absorption of the individual nucleotides that vary between 256 and 281 nm. 2. In the case of RNA, the concentration of a sample containing RNA may be calculated following Equation: 40 x OD260 of the sample = concentration of RNA (microgram/mL) And this equation for DNA concentration: 50 x OD260 of the sample =concentration of DNA (microgram/mL) The equation above describe that when the OD-260 of the sample is 1 the concentration of RNA will be approx 40 micrograms/mL (50 micrograms/mL for DNA). 3. We can also assess the degree of purity of the nucleic acids by examining the absorption at other wavelengths in which protein and polysaccharides have known absorption maxima. Proteins are known to absorb strongly at 280 nm and polysaccharides may be identified by their maximum at 230 nm. 4. Therefore, in assessing the purity degree of the nucleic acid sample we use the ratio of measurements of these three wavelengths 230 nm, 260 nm, and 280 nm. 5. For example a sample containing only RNA following an extraction method is judged as being uncontaminated if the ratio is 1 :2 : 1, and for DNA is 1 : 1.8 : 1 (it reflects OD-230 : 260 : 280 ratio). If there is significant deviation from the ratio, then it is evident that contaminants are present and that further purification of the sample is necessary. In many cases, the purity and the concentration may be further obscured by the presence of reagents that are used in the extraction process itself. Some of these have characteristics that are evident on a spectrophotometric scan that includes the three wavelengths indicated. Therefore, when using spectrophotometry in the analysis of DNA or RNA it is necessary to be aware of the potential problems that may result in misleading ratio. Further, when analyzing ratios and concentrations of DNA or RNA spectrophotometrically it is also necessary not only to derive readings at 280,260, and 230 nm but also to scan throughout the range 200-320 nm. Trace amounts of reagents used in the extraction process can influence adversely and provide misleading data that may affect any subsequent manipulation.

Acetic acid

2009-03-09T09:12:00.000-07:00

Definition of Acetic acid

Acetic acid: The acid most commonly associated with vinegar. Acetic acid is a two-carbon carboxylic acid. Its formula is: CH3COOH. It is the most commercially important organic acid and is used in the manufacture of a broad range of chemical products, such as plastics and insecticides.

Acetic acid, CH3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. Pure, water-free acetic acid (glacial acetic acid) is a colourless liquid that absorbs water from the environment (hygroscopy), and freezes at 16.7 °C (62 °F) to a colourless crystalline solid. It is a weak acid, in that it is only partially dissociated acid in aqueous solution.

Acetic acid is one of the simplest carboxylic acids. It is an important chemical reagent and industrial chemical, used in the production of polyethylene terephthalate mainly used in soft drink bottles; cellulose acetate, mainly for photographic film; and polyvinyl acetate for wood glue, as well as synthetic fibres and fabrics. In households, diluted acetic acid is often used in descaling agents. In the food industry acetic acid is used under the food additive code E260 as an acidity regulator.

The global demand of acetic acid is around 6.5 million tonnes per year (Mt/a), of which approximately 1.5 Mt/a is met by recycling; the remainder is manufactured from petrochemical feedstocks or from biological sources.

Use of Acetic acid

CLINICAL PHARMACOLOGY

Acetic acid is anti-bacterial and anti-fungal; propylene glycol is hydrophilic and provides a low surface tension; benzethonium chloride is a surface active agent that promotes contact of the solution with tissues.

INDICATIONS AND USAGE

For the treatment of superficial infections of the external auditory canal caused by organisms susceptible to the action of the antimicrobial.

CONTRAINDICATIONS

Hypersensitivity to Acetic Acid Otic Solution or any of the ingredients. Perforated tympanic membrane is considered a contraindication to the use of any medication in the external ear canal.

WARNINGS

Discontinue promptly if sensitization or irritation occurs.

PRECAUTIONS

Transient stinging or burning may be noted occasionally when the solution is first instilled into the acutely inflamed ear.

Pediatric Use

Safety and Effectiveness in pediatric patients below the age of 3 years have not been established.

ADVERSE REACTIONS

Stinging or burning may be noted occasionally; local irritation has occurred very rarely.

DOSAGE AND ADMINISTRATION

Carefully remove all cerumen and debris to allow Acetic Acid Otic Solution to contact infected surfaces directly. To promote continuous contact, insert a wick of cotton saturated with the solution into the ear canal; the wick may also be saturated after insertion. Instruct the patient to keep the wick in for at least 24 hours and to keep it moist by adding 3 to 5 drops of the solution every 4 to 6 hours. The wick may be removed after 24 hours but the patient should continue to instill 5 drops of Acetic Acid Otic Solution 3 or 4 times daily thereafter, for as long as indicated. In pediatric patients, 3 to 4 drops may be sufficient due to the smaller capacity of the ear canal.