DNA methylation is a type of chemical modification of DNA that can be inherited and subsequently removed without changing the original DNA sequence. As such, it is part of the epigenetic code and is also the most well characterized epigenetic mechanism.
DNA methylation involves the addition of a methyl group to DNA — for example, to the number 5 carbon of the cytosine pyrimidine ring — with the effect of reducing gene expression. DNA methylation at the 5 position of cytosine has been found in every vertebrate examined. In adult somatic tissues, DNA methylation typically occurs in a CpG dinucleotide context; non-CpG methylation is prevalent in embryonic stem cells.
In plants, cytosines are methylated both symmetrically (CpG or CpNpG) and asymmetrically (CpNpNp), where N can be any nucleotide. Some organisms, such as fruit flies, exhibit virtually no DNA methylation
DNA Methylation
Metabolomics
Metabolomics is the "systematic study of the unique chemical fingerprints that specific cellular processes leave behind" - specifically, the study of their small-molecule metabolite profiles.The metabolome represents the collection of all metabolites in a biological organism, which are the end products of its gene expression. Thus, while mRNA gene expression data and proteomic analyses do not tell the whole story of what might be happening in a cell, metabolic profiling can give an instantaneous snapshot of the physiology of that cell. One of the challenges of systems biology is to integrate proteomic, transcriptomic, and metabolomic information to give a more complete picture of living organisms.
Protein analysis
Protein analysis , and biomolecular NMR.contains a broad selection of products for Western blotting, protein electrophoresis, protein quantitation, protein chromatography, custom peptides, mass spectrometry, x-ray crystallography
Stem Cell Biology
Stem and progenitor cell research is a complex and very exciting field that promises fantastic curative discoveries in numerous areas from cancer to diabetes to neurogenerative diseases. Sigma-Aldrich offers an comprehensive and unprecedented number of products to support scientists in the discovery efforts in this area. These products are necessities in many areas including isolation, differentiation, genomics and epigenetics, functional profiling, and in vivo/in vitro tracking. Applications such as transfection, cell and protein characterization, RNAi, ADMET, and imaging are instrumental in the development of stem cells in regenerative medicine and drug discovery. The products contained within this Web site are considered tools for stem cell science and support our customers in their efforts to develop cardiac, hematopoietic, endocrine, and neurological disease therapies either in the areas of basic research, regenerative medicine, or drug efficacy and safety screening.
Proteomics
Proteomics research defines the dynamic nature of gene expression and regulation with detailed protein profiling, protein-protein interactions, and structural biology studies. Sigma's innovative technologies and products provide an integrated approach for proteomic analysis of both native and recombinant fusion proteins
Epigenetics
Epigenetics is the study of heritable changes in gene expression without a change in DNA sequence. The best understood Epigenetic mechanism, DNA methylation, refers to the addition of a methyl group by the enzyme DNA Methyltransferase to the 5-carbon of cytosine in a CpG dinucleotide. Methylation in regulatory regions adjacent to genes generally acts to suppress gene expression and/or regulation potentially having an impact on cellular function. Once a cell has an established DNA Methylation pattern, methlyated sites are inherited by daughter cells which have important implications in cellular function. Epigenetic research has demonstrated that aberrant DNA methylation is present in several disease states including cancer, in addition to other genetic diseases. Carcinogenesis can occur when DNA methylation acts to silence tumor suppressor genes, leading to heritable alterations of these genes.
DNA Replication
DNA replication is the process of copying a double-stranded DNA molecule to form two double-stranded molecules.The process of DNA replication is a fundamental process used by all living organisms as it is the basis for biological inheritance. As each DNA strand holds the same genetic information, both strands can serve as templates for the reproduction of the opposite strand. The template strand is preserved in its entirety and the new strand is assembled from nucleotides. This process is called "semiconservative replication". The resulting double-stranded DNA molecules are identical; proofreading and error-checking mechanisms exist to ensure near perfect fidelity.
In a cell, DNA replication must happen before cell division can occur. DNA synthesis begins at specific locations in the genome, called "origins", where the two strands of DNA are separated..RNA primers attach to single stranded DNA and the enzyme DNA polymerase extends the primers to form new strands of DNA, adding nucleotides matched to the template strand. The unwinding of DNA and synthesis of new strands forms a replication fork. In addition to DNA polymerase, a number of other proteins are associated with the fork and assist in the initiation and continuation of DNA synthesis.
DNA replication can also be performed artificially, using the same enzymes used within the cell. DNA polymerases and artificial DNA primers are used to initiate DNA synthesis at known sequences in a template molecule. The polymerase chain reaction (PCR), a common laboratory technique, employs artificial synthesis in a cyclic manner to rapidly and specifically amplify a target DNA fragment from a pool of DNA.
Cloning
A major problem in biochemical research is obtaining sufficient quantities of the substance of interest. These difficulties have been largely eliminated in recent years through the development of molecular cloning techniques. The clone is a collection of identical organisms that are all replicas of a single ancestor. Methods of creating clones of desired properties, usually called genetic engineering and recombinant DNA technology, deserve much of the credit for the dramatic rise of biotechnology since the mid-70'. The main idea of molecular cloning is to insert a DNA segment of interest into an autonomously replicating DNA molecule, called acloning vector, so that the DNA segment is replicated with the vector. Such vectors could be, for instance, plasmids (circular DNAs occuring in some bacteria). Reproduction of DNA segments in appropriate hosts, results in the production of large amount of the inserted DNA segment. A DNA to be cloned is usually a fragment of a genome of interest, obtained by application of restriction enzymes. Most restriction enzymes cleave duplex DNA at specific palindromic sites, generally two fragments that have single strand ends that are complimentary with each other (known as 'sticky ends'). Therefore, a restriction fragment can be inserted into a cut made in a cloning vector by the same restriction enzyme, because the segment ends stick (chemically bond) to the loose ends of the vector. Such a recombinant DNA molecule is inserted into a fast reproducing host cell, and is duplicated in the process of the host's reproduction. The cells containing the recombinant DNA are then isolated from non-infected cells using an antibiotic substance which the original vector is resistant to .
Sequencing
Sequencing is the operation of determining the nucleotide sequence of a given molecule. There are There are several approaches to sequencing, but generally, the most successful is based on gel electrophoresis. As mentioned earlier, the DNA polymerase enzyme catalyzes the replication reaction of DNA. DNA polymerase extends the chain by adding nucleotides to its end. Current biotechnology enables synthesis of nucleotides which cause the strand to terminate. For instance, A* denotes an Adenine molecule which does not allow other molecules to extend the strand after itself. By catalyzing DNA replication in an environment containing mixtures of normal Adenine and sythesized Adenine* instead of only Adenine, it is possible to create DNA strands of different lengths. By applying gel electrophoresis to these molecules, it is possible to determine the lengths of all the strings and from it to conclude the location of all Adenines in the tested DNA strand. In a similar fashion it is possible to locate other nucleotides and eventually to fully sequence a whole segment of DNA. Using this method, sequences of 500-800 nucleotides can be mapped.
Gel Electrophoresis
Gel electrophoresis is a technique used to separate a mixture of digested DNA fragments. An electrical field is used to move the negatively charged DNA molecules through porous agarose gel. Fragments of the same size and shape move at the same speed, and because smaller molecules travel faster then larger molecules, the mixture is separated into bands.
The amount of exposure the DNA receives to restriction enzymes determines the portion of possible sites that were actually separated. Therefore, by applying different exposures to the same DNA sequence, we can measure all possible lengths of DNA fragments, that one can obtain using a particular enzyme. From this information we can attempt to find out where the sites are located in the original molecule. This problem is known as:
Restriction Enzymes
One of the basic tools used in biotechnology is restriction enzymes. In natural circumstances, one of the main roles of these enzymes is to break foreign DNA entering the cell. A restriction enzyme breaks the phosphodiester bonds of a DNA upon appearance of a certain cleavage sequence. Each such enzyme is characterized by a different cleavage sequence. Today there are more then 150 known different cleavage sites, namely, different nucleotide configurations that known enzymes can digest.
What is a Genome??
Life is specified by genomes. Every organism, including humans, has a genome that contains all of the biological information needed to build and maintain a living example of that organism. The biological information contained in a genome is encoded in its deoxyribonucleic acid (DNA) and is divided into discrete units called genes. Genes code for proteins that attach to the genome at the appropriate positions and switch on a series of reactions called gene expression.
Why we study Mitochondrial??
There are many diseases caused by mutations in mitochondrial DNA (mtDNA). Because the mitochondria produce energy in cells, symptoms of mitochondrial diseases often involve degeneration or functional failure of tissue. For example, mtDNA mutations have been identified in some forms of diabetes, deafness, and certain inherited heart diseases. In addition, mutations in mtDNA are able to accumulate throughout an individual's lifetime. This is different from mutations in nuclear DNA, which has sophisticated repair mechanisms to limit the accumulation of mutations. Mitochondrial DNA mutations can also concentrate in the mitochondria of specific tissues. A variety of deadly diseases are attributable to a large number of accumulated mutations in mitochondria. There is even a theory, the Mitochondrial Theory of Aging, that suggests that accumulation of mutations in mitochondria contributes to, or drives, the aging process. These defects are associated with Parkinson's and Alzheimer's disease, although it is not known whether the defects actually cause or are a direct result of the diseases. However, evidence suggests that the mutations contribute to the progression of both diseases.
Why is there a separate Mitochondrial Genome??
The energy-conversion process that takes place in the mitochondria takes place aerobically, in the presence of oxygen. Other energy conversion processes in the cell take place anaerobically, or without oxygen. The independent aerobic function of these organelles is thought to have evolved from bacteria that lived inside of other simple organisms in a mutually beneficial, or symbiotic, relationship, providing them with aerobic capacity. Through the process of evolution, these tiny organisms became incorporated into the cell, and their genetic systems and cellular functions became integrated to form a single functioning cellular unit. Because mitochondria have their own DNA, RNA, and ribosomes, this scenario is quite possible. This theory is also supported by the existence of a eukaryotic organism, called the amoeba, which lacks mitochondria. Therefore, amoeba must always have a symbiotic relationship with an aerobic bacterium. |
Organelle DNA
Not all genetic information is found in nuclear DNA. Both plants and animals have an organelle—a "little organ" within the cell— called the mitochondrion. Each mitochondrion has its own set of genes. Plants also have a second organelle, the chloroplast, which also has its own DNA. Cells often have multiple mitochondria, particularly cells requiring lots of energy, such as active muscle cells. This is because mitochondria are responsible for converting the energy stored in macromolecules into a form usable by the cell, namely, the adenosine triphosphate (ATP) molecule. Thus, they are often referred to as the power generators of the cell.
Unlike nuclear DNA (the DNA found within the nucleus of a cell), half of which comes from our mother and half from our father, mitochondrial DNA is only inherited from our mother. This is because mitochondria are only found in the female gametes or "eggs" of sexually reproducing animals, not in the male gamete, or sperm. Mitochondrial DNA also does not recombine; there is no shuffling of genes from one generation to the other, as there is with nuclear genes.
The four DNA bases
Each DNA base is made up of the sugar 2'-deoxyribose linked to a phosphate group and one of the four bases depicted above: adenine (top left), cytosine (top right), guanine (bottom left), and thymine (bottom right). | |
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| The DNA that constitutes a gene is a double-stranded molecule consisting of two chains running in opposite directions. The chemical nature of the bases in double-stranded DNA creates a slight twisting force that gives DNA its characteristic gently coiled structure, known as the double helix. The two strands are connected to each other by chemical pairing of each base on one strand to a specific partner on the other strand. Adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). Thus, A-T and G-C base pairs are said to be complementary. This complementary base pairing is what makes DNA a suitable molecule for carrying our genetic information—one strand of DNA can act as a template to direct the synthesis of a complementary strand. In this way, the information in a DNA sequence is readily copied and passed on to the next generation of cells. | |
Physical structure of a Human Genome
Nuclear DNA
Inside each of our cells lies a nucleus, a membrane-bounded region that provides a sanctuary for genetic information. The nucleus contains long strands of DNA that encode this genetic information. A DNA chain is made up of four chemical bases: adenine (A) and guanine (G), which are called purines, and cytosine (C) and thymine (T), referred to as pyrimidines. Each base has a slightly different composition, or combination of oxygen, carbon, nitrogen, and hydrogen. In a DNA chain, every base is attached to a sugar molecule (deoxyribose) and a phosphate molecule, resulting in a nucleic acid or nucleotide. Individual nucleotides are linked through the phosphate group, and it is the precise order, or sequence, of nucleotides that determines the product made from that gene.
What is a Gene therapy???
A gene is a linear sequence of DNA that codes for a particular protein. On rare occasions, usually during the division of the cell, the nucleotide sequence (the order of the DNA base pairs) of a gene can get jumbled up and mutated, so that the resultant protein is faulty. Such a mutation event is the root cause of genetic diseases such as cystic fibrosis, adenosine deaminase (ADA) deficiency and sickle-cell anaemia. For example, people who suffer from cystic fibrosis produce a faulty cellular transport protein called cystic fibrosis transmembrane conductance regulator, which results in the build-up of mucous in their lungs.
The earliest applications of gene therapy were based on the principle that a disease is caused by a faulty gene (or combination of genes), and if such genes can be replaced with ‘correct’ versions, the disease might be controlled, prevented or cured. Gene therapy is being applied to many different genetic diseases, both congenital (since birth) and acquired. However, most diseases involve multiple genetic factors (they are polygenic). Until the precise involvement of different genes (their regulation and expression) in the disease process and the proteins they encode is established, gene therapy is most likely to be clinically effective as a preventative or curative treatment for single-gene defects such as ADA deficiency, familial hypercholesterolaemia. and cystic fibrosis. Several clinical trials employing gene therapy protocols have already been completed, with some success in patients who have cystic fibrosis and ADA deficiency, although the effectiveness of the protocols was not as dramatic as first envisaged, mainly owing to the inefficiency of the gene transfer vectors that were used.
Originally known as ‘genetic replacement therapy’ during the early 1980s, ‘gene therapy’ has now outgrown its original definition and is applied to all manner of protocols that involve an element of gene transfer, either in vivo or ex vivo, and not necessarily a gene that is known to cause a disease. In vivo gene transfer is the introduction of genes to cells at the site they are found in the body, for example to skin cells on an arm, or to lung epithelial cells following inhalation of the gene transfer vector. Ex vivo gene transfer is the transfer of genes into viable cells that have been temporarily removed from the patient and are then returned following treatment (e.g. bone marrow cells). Gene therapy can be subdivided into somatic cell gene transfer (that is transfer to normal diploid cells), which is the focus of this review, and germline gene transfer (transfer to haploid sperm or egg cells of the reproductive system). The ethical issues associated with germline gene therapy are far more complex than those surrounding somatic cell gene transfer, because the genes are transferred not only to treated individuals but also to their progeny. Germline gene therapy is being widely used for the production of transgenic animals for research, and increasingly for agriculture and biotechnology, but the long-term effects of each transferred gene in animals will need to be carefully monitored and analysed, as well as the significance of any residual vector DNA if applicable. The benefits that the use of germline gene therapy in humans could bring are significant. The development of serious and distressing inherited genetic diseases could be prevented before birth and eliminated in subsequent generations. However, because of the potential for abuse and eugenics, gene therapy in humans needs to be widely discussed and the associated safety issues evaluated before this approach can be used for the treatment of diseases.
Viral gene delivery
For millions of years, viruses have been transferring genes into all types of cells, including plant, animal and human cells. The experimental technique of viral gene delivery was developed from this natural ability, which offers many intrinsic advantages to scientists and clinicians: . specific cell-binding and entry properties, efficient targeting of the transgene to the nucleus of the cell and .the ability to avoid intracellular degradation. The general principle involved in the development of most viral vector systems is that an intact wild-type virus is modified for safe use and effective gene transfer; for example, the specific genes that are involved in viral replication can be modified or deleted, thus rendering the new recombinant virus ‘replication defective’ and safer for use in gene therapy protocols . Usually, the transgene that is to be delivered by the virus must be inserted into the viral genome, using molecular biological techniques; transgenes are often inserted into the space created by the removal of viral replication genes. In general, the more severely attenuated the viral vector is from its wild-type state (i.e. the greater the number of virulence-associated genes that have been removed), the safer the virus is for use in gene therapy protocols. The size of the transgene has to be matched to the potential space in the viral genome; if the new viral genome is too large, it cannot be packaged into an infectious particle. Because many of the viruses that are used as vectors lack replication genes and therefore cannot replicate in normal cells, the recombinant virus with its transgene must be grown up to higher titres in a packaging cell line. This is a cell line that contains all of the complementary genes that the virus requires to replicate (i.e. those that were previously removed). The recombinant viral particles can then be purified as live infectious virus from the packaging cell line and used to infect (transduce) cells or tissues in vivo or ex vivo.
Retroviral vectors
Gene transfer vector
Vectors are the vehicles that are used in gene therapy to transfer the gene(s) of interest [transgene(s)] to the target cells, which will then go on to express the therapeutic protein encoded by the transgene(s). The most important factor in any gene transfer protocol., apart from the gene of interest, is the choice of vector, which can result in either success or failure. Unfortunately, there is no such thing as a ‘good universal vector’; all of the vectors that are currently available have both advantages and disadvantages. For example, one vector might be able to enter target cells very efficiently but once there invokes a strong immune response, resulting in that cell being killed by the immune system. Many factors must be taken into consideration when choosing a vector. The most import ones are: the length of time that the transgene needs to be expressed, the dividing state of the target cells, the type of target cell, the size of the transgene, the potential for an immune response against the vector to be induced, and whether this is deleterious, the ability to administer the vector more than once, the ease of production of the vector, the facilities available, safety issues and regulatory issues. Table 1 (tab001jfo) outlines the advantages, disadvantages and major differences of the gene delivery vectors that are currently in research and clinical use.
Routes of administration cell targets for gene therapy vectors
Intrathymic administration
The application of the process of intrathymic T-cell development to transplantation and tolerance induction was first described by Posselt and colleagues.Self tolerance (the failure to respond to antigen borne on self tissue) develops as T-lymphocyte precursor cells that are CD4- and CD8- (‘double negative’) pass through the thymus. Because the T cells are exposed to antigen on thymic epithelial cells, any T cells that have a high-affinity interaction with antigen in the thymus, and are therefore potentially autoreactive cells, are ‘negatively selected’ by the process of clonal deletion. Cells that have TCRs that have no (or an extremely low) affinity for intrathymic antigen, yet still have a high-affinity interaction with self MHC, are ‘positively selected’; they can thus mature and go on to populate and expand into larger clonal populations in the periphery. For a recent review of the mechanisms of the induction of intrathymic tolerance, see Turvey and colleagues .
Knechtle and colleagues .showed it was possible to induce tolerance using a gene therapy strategy in a rat model. First, they took syngeneic recipient muscle cells and then transfected them in vitro with an MHC class I gene derived from the donor. These cells were then injected into the thymus of the recipient. Next, the peripheral immune system of the recipient was depleted of potentially alloreactive T cells using anti-lymphocyte serum. This was then followed by a liver transplant from the donor, to which the recipient was found to be unresponsive. In a subsequent study (Ref. 38), the MHC class I complementary DNA (cDNA) from the donor strain rat was introduced directly into the thymus to transfect recipient thymic cells in situ; analysis using the polymerase chain reaction (PCR) detected the transient expression of donor DNA in the thymus (and later in the spleen, which was probably due to the export of transfected thymocytes out of the thymus).
The above approaches have used either live cells transfected with DNA or naked DNA itself to deliver donor MHC genes. Adenovirus could be used to improve the efficiency of gene therapy that has been achieved using DNA transfection. Adenovirus vectors (as discussed later in the section entitled ‘Adenovirus’) are ideal for use in intrathymic applications because they can be generated at high titres and can transduce a range of cell types. Not only can genes be transferred to the antigen-presenting thymic epithelial cells and possibly to the developing thymocytes, but central tolerance (tolerance that is established in lymphocytes developing in central lymphoid organs such as the thymus, spleen and bone marrow) to the immunogenic adenoviral antigens can be induced, as shown by Ilan and colleagues Their work demonstrated that intrathymic inoculation of the recombinant adenovirus inhibited the appearance of neutralising antibodies and CTLs against the recombinant adenovirus.
Genes associated w/ chronic rejection
Damage to an allograft can continue for years after transplantation, and despite improvements in immunosuppressive drugs and organ preservation, chronic rejection is still the most important factor in the failure of transplanted grafts .. Histologically, during chronic rejection, smooth muscle cells are seen to proliferate in the vasculature of the transplanted organ, sometimes resulting in transplant atherosclerosis; several factors can contribute to this end point. Adhesion molecules such as intercellular adhesion molecule 1 (ICAM-1 or CD54; and growth factors such as vascular endothelial-cell growth factor are upregulated, and inducible nitric oxide synthase is imbalanced ..
ICAM-1
ICAM-1 is a member of the Ig superfamily and is very important in both cellular adhesion and T-cell co-stimulation. Strategies to reduce T-cell activation by eliminating the effects of ICAM-1 have been carried out successfully in clinical trials involving renal allograft patients and the use of antibodies targeted against the ICAM-1 molecule.. In a study of 18 patients, the anti-ICAM-1 antibody (BIRR1) was given to those patients who had received renal grafts from cadaver donors and were at a high risk for delayed graft function. An adequate level of BIRR1 in the serum (>10 mg/ml) was found to significantly reduce the incidence of both delayed graft function (p<0.01)>
Blockage of co-stimulatory signal
In addition to the production of an intracellular first signal following specific TCR-MHC interaction, full activation of a T cell requires a second co-stimulatory signal, which can be provided by the interaction of CD28 and B7-1 or B7-2 (CD80 or CD86, respectively). Cytotoxic T-lymphocyte antigen 4 (CTLA-4; also called CD152) is an alternative ligand for CD80 and CD86, and is homologous with CD28. CTLA-4 is believed to play a role in the negative regulation of T-cell activation. The blockage of this co-stimulatory signal, for example using a fusion protein, has been shown in many murine and primate studies to inhibit cell-mediated and humoral immune responses in vivo. In one such study that used an adenoviral vector to deliver a CTLA-4Ig gene [a fusion protein comprising CTLA-4 and an immunoglobulin (Ig)] intravenously following cardiac allograft transplantation, the median survival time was increased from 6 days in the control group to 23 days in the group treated with the adenoviral vector expressing the CTLA-4Ig transgene . In another investigation by Chahine and colleagues .., transgene for CTLA-4Ig was transfected to both syngeneic and allogeneic mouse muscle precursor cells (myoblasts) and co-transplanted with allogeneic pancreatic islet cells under the kidney capsule of diabetic mice. Syngeneic myoblasts significantly prolonged the survival of the islets from 11 days to 31.7 days; no beneficial effect was observed for the transfected allogeneic myoblasts. The syngeneic myoblasts actively secreted CTLA-4Ig, to create local immunosuppression in the environment of the allogeneic islets, and thus allow them to function. When the myoblasts were allogeneic themselves, the MHC disparity with the recipient was enough to destroy them, thus preventing any CTLA-4Ig from being produced.
Immunosuppresives cytokiness
The delivery of genes that encode immuno-modulatory molecules to the site of the graft, or to the graft itself, has much scope for reducing the harmful local immune response against foreign tissue that occurs in acute and chronic rejection.
Cytokines are soluble mediators of the immune system, and some of them have immunosuppressive effects. The viral form of interleukin 10 (vIL-10) is a protein that is encoded by the Epstein-Barr virus; it is structurally homologous to mouse and human IL-10 but does not possess the T-cell co-stimulatory properties that IL-10 does. Thus, it is a useful tool in gene transfer to tissue where T-cell activation needs to be switched off or downregulated. DeBruyne and colleagues. have demonstrated that gene transfer of vIL-10 to a murine cardiac allograft via vasculature perfusion using DNA-liposome complexes prolonged graft survival (16 days compared with 8 days for untreated grafts). The result was attributed to the vIL-10 gene, because treatment with either an antisense plasmid to vIL-10 or a monoclonal antibody targeted against vIL-10 reversed the graft-prolongation effect. Other cytokine genes, such as transforming growth factor beta (TGF-b), have also been shown to have a significant immunosuppressive effect . This type of approach is not intended to induce immunological tolerance, but might be useful for the delivery of local immunosuppression.
Genes of interest in transplantation
MHC
The MHC is a highly conserved yet polymorphic gene locus. MHC molecules are surface proteins that present intracellularly processed peptides in a helical groove to their ligand, the T-cell receptor (TCR). Cognate interaction between an MHC molecule presenting peptide on an antigen-presenting cell and a specific TCR on a T cell can result in T-cell activation if the appropriate co-stimulatory molecules are present on the antigen-presenting cell. MHC class I molecules consist of three alpha domains and a b2 microglobulin chain, which is not encoded by the MHC gene locus. MHC class II molecules consist of two alpha domains and two beta domains. Peptides that are presented on the class I molecule are usually derived from intracellular proteins, whereas class II molecules present extracellularly derived peptides. The mechanism by which these peptides are transported to the immature MHC molecule is also very different for class I and class II MHC molecules, and has been recently reviewed in this journal (Ref. 7). The MHC is the major identification molecule that triggers allograft rejection, because it determines the difference between self (syngeneic) and non-self (allogeneic). When searching for a suitable organ donor, it is the MHC antigens that are matched between donor and recipient, to give the graft as good a chance as possible of functioning. In defined situations, this potency of the MHC has been exploited to tip the balance of the immune system from immunity to tolerance. The exposure of the recipient of a graft to donor MHC antigens before transplantation to induce tolerance was first investigated in a mouse model by Billingham and colleagues in 1953, when cells from a donor strain were introduced into a recipient mouse in utero
Following this first attempt, and further studies, pre-transplantation blood transfusions (although not necessarily from graft donors) have been used in the clinic as a means of delivering MHC alloantigens before transplantation, but with limited success. However, the use of blood products also carries inherent risks, such as infections and transfusion reactions; thus, a novel therapy using a more specific approach would eliminate the risks of sensitising transplant recipients to alloantigens that are present in the blood. The delivery of donor genes to cells or tissues in a recipient would offer a highly specific therapy, one that is free from the risks associated with foreign cells and allows transplant recipients to be pre-treated with foreign genes before donor tissue becomes available.
The transfer of MHC genes is also useful in animal models to study the effects of allogeneic MHC antigens on the immune cells of a recipient without the influence of other alloantigens. Such an approach was first carried out by Madsen and colleagues (Ref. 9), when a single MHC class I gene from a donor was transfected into a recipient-type mouse cell line and administered to a recipient. Not only was unresponsiveness to a subsequent cardiac allograft achieved in this study, but it showed that the recipient did not need to be exposed to all of the mismatched donor MHC molecules. Although these experiments proved that this strategy could work, transfected recipient cells are not a practical choice in a clinical setting. The next step was made by Wong and colleagues ; bone marrow cells from recipient mice were transduced (infected with virus) ex vivo with an MHC class I gene using a retroviral gene therapy vector. This approach also resulted in long-term unresponsiveness to a fully allogeneic cardiac allograft, but rejection of a third-party graft, which had MHC class I genes that the recipient had not previously been exposed to.
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Three Types of Cloning
It is unfortunate that the term "cloning" refers to three very different procedures with three very different goals. It is also unfortunate that the first thought many people have when they hear the term is of horror movies which have showed the creation of human monsters or of armies of superhuman soldiers with subhuman brains. The reality of cloning is very different.,there are three different types of cloning,such as;Embryo cloning,Adult DNA cloning and Therapeutic cloning.
Therapeutic cloning
Therapeutic cloning (a.k.a. biomedical cloning): This is a procedure whose initial stages are identical to adult DNA cloning. However, the stem cells are removed from the pre-embryo with the intent of producing tissue or a whole organ for transplant back into the person who supplied the DNA. The pre-embryo dies in the process. The goal of therapeutic cloning is to produce a healthy copy of a sick person's tissue or organ for transplant. This technique would be vastly superior to relying on organ transplants from other people. The supply would be unlimited, so there would be no waiting lists. The tissue or organ would have the sick person's original DNA; the patient would not have to take immunosuppressant drugs for the rest of their life, as is now required after transplants. There would not be any danger of organ rejection.
Adult DNA cloning
Adult DNA cloning (a.k.a. reproductive cloning) This technique which is intended to produce a duplicate of an existing animal. It has been used to clone a sheep and other mammals. The DNA from an ovum is removed and replaced with the DNA from a cell removed from an adult animal. Then, the fertilized ovum, now called a pre-embryo, is implanted in a womb and allowed to develop into a new animal. As of 2002-JAN, It had not been tried on humans. It is specifically forbidden by law in many countries. There are rumors that Dr. Severino Aninori has successfully initiated a pregnancy through reproductive cloning. It has the potential of producing a twin of an existing person. Based on previous animal studies, it also has the potential of producing severe genetic defects. For the latter reason alone, many medical ethicists consider it to be a profoundly immoral procedure when done on humans.
Embryo cloning
Embryo cloning: This is a medical technique which produces monozygotic (identical) twins or triplets. It duplicates the process that nature uses to produce twins or triplets. One or more cells are removed from a fertilized embryo and encouraged to develop into one or more duplicate embryos. Twins or triplets are thus formed, with identical DNA. This has been done for many years on various species of animals; only very limited experimentation has been done on humans
Human Cloning
At the upcoming 59th session of the General Assembly you will decide whether I am a criminal or not. By the same token you will tell the 13 cloned children that are alive today and all the future ones, whether they are the result of a crime or of the desire of loving parents. You will tell these belated twins whether it is criminal to be a twin or not.
Centuries ago, twins were killed because primitive people thought they were evil. Today ethicists are telling you the same about cloned children, will you let them decide for you? Reproductive cloning is giving life to a few individuals and cannot harm any one. The Hollywood stories of monstruous defects have no real scientific bases if you listen to real experts and I would be happy to demonstrate this to you. In the future, reproductive cloning will enable all of us to live eternally. This is what Rael, founder of the Raelian Movement and of Clonaid, announced 30 years ago (see www.rael.org ) and what is slowly demonstrated in more and more laboratories around the world as they are working on brain mapping and personality transfer. By declaring human cloning a crime against humanity, you will just slow down an unescapable process as sooner or later, not only will we beat most of the diseases thanks to stem cells but we will also beat death thanks to cloning and a majority of people on this planet will request it.
The real crime against Humanity is to deny the right to live forever, deny the right to explore science freely and its wonderful benefits. I will be available any time to explain more about what Clonaid has acheived as I believe it is a major step for humanity. I am proud of what my team of scientists has achieved. I strongly urge you to listen to what they have to say and to what the parents of cloned children have to say.
Production of novel substances in crop plants.
Biotechnology is being applied for novel uses other than food. For example, oilseed can be modified to produce fatty acids for detergents, substitute fuels and petrochemicals.[citation needed] Potato, tomato, rice, and other plants have been genetically engineered to produce insulinand certain vaccines. If future clinical trials prove successful, the advantages of edible vaccines would be enormous, especially for developing countries. The transgenic plants may be grown locally and cheaply. Homegrown vaccines would also avoid logistical and economic problems posed by having to transport traditional preparations over long distances and keeping them cold while in transit. And since they are edible, they will not need syringes, which are not only an additional expense in the traditional vaccine preparations but also a source of infections if contaminated. In the case of insulin grown in transgenic plants, it might not be administered as an edible protein, but it could be produced at significantly lower cost than insulin produced in costly, bioreactors.
Reduced dependence on Fertilizers, pesticides and other agrochemicals
Most of the current commercial applications of modern biotechnology in agriculture are on reducing the dependence of farmers on agrochemicals. For example, Bacillus thuringiensis (Bt) is a soil bacterium that produces a protein with insecticidal qualities. Traditionally, a fermentation process has been used to produce an insecticidal spray from these bacteria. In this form, the Bt toxin occurs as an inactive protoxin, which requires digestion by an insect to be effective. There are several Bt toxins and each one is specific to certain target insects. Crop plants have now been engineered to contain and express the genes for Bt toxin, which they produce in its active form. When a susceptible insect ingests the transgenic crop cultivar expressing the Bt protein, it stops feeding and soon thereafter dies as a result of the Bt toxin binding to its gut wall. Bt corn is now commercially available in a number of countries to control corn borer (a lepidopteran insect), which is otherwise controlled by spraying (a more difficult process).
Improved taste,texture or appearance of food
Modern biotechnology can be used to slow down the process of spoilage so that fruit can ripen longer on the plant and then be transported to the consumer with a still reasonable shelf life. This improves the taste, texture and appearance of the fruit. More importantly, it could expand the market for farmers in developing countries due to the reduction in spoilage.
The first genetically modified food product was a tomato which was transformed to delay its ripening . Researchers in Indonesia, Malaysia, Thailand, Philippines and Vietnam are currently working on delayed-ripening papaya in collaboration with the University of Nottingham and Zeneca.
Increases Nutritional qualities of food crops
Proteins in foods may be modified to increase their nutritional qualities. Proteins in legumes and cereals may be transformed to provide the amino acids needed by human beings for a balanced diet . A good example is the work of Professors Ingo Potrykus and Peter Beyer on the so-called Goldenrice™(discussed below).
Reduced Vulnerability of crops to environmental stresses
Crops containing genes that will enable them to withstand biotic and abiotic stresses may be developed. For example, drought and excessively salty soil are two important limiting factors in crop productivity. Biotechnologists are studying plants that can cope with these extreme conditions in the hope of finding the genes that enable them to do so and eventually transferring these genes to the more desirable crops. One of the latest developments is the identification of a plant gene, At-DBF2, from thale cress, a tiny weed that is often used for plant research because it is very easy to grow and its genetic code is well mapped out. When this gene was inserted into tomato and tobacco cells, the cells were able to withstand environmental stresses like salt, drought, cold and heat, far more than ordinary cells. If these preliminary results prove successful in larger trials, then At-DBF2 genes can help in engineering crops that can better withstand harsh environments Researchers have also created transgenic rice plants that are resistant to rice yellow mottle virus (RYMV). In Africa, this virus destroys majority of the rice crops and makes the surviving plants more susceptible to fungal infections .
Advatages of Biotechnology in Agriculture
Improve yield from crops
Using the techniques of modern biotechnology, one or two genes may be transferred to a highly developed crop variety to impart a new character that would increase its yield . However, while increases in crop yield are the most obvious applications of modern biotechnology in agriculture, it is also the most difficult one. Current genetic engineering techniques work best for effects that are controlled by a single gene. Many of the genetic characteristics associated with yield (e.g., enhanced growth) are controlled by a large number of genes, each of which has a minimal effect on the overall yield . There is, therefore, much scientific work to be done in this area.
Cloning
Cloning involves the removal of the nucleus from one cell and its placement in an unfertilized egg cell whose nucleus has either been deactivated or removed.
There are two types of cloning:
1. Reproductive cloning. After a few divisions, the egg cell is placed into a uterus where it is allowed to develop into a fetus that is genetically identical to the donor of the original nucleus.
2. Therapeutic cloning.The egg is placed into a Petri dish where it develops into embryonic stem cells, which have shown potentials for treating several ailments.
In February 1997, cloning became the focus of media attention when Ian Wilmut and his colleagues at the Roslin Institute announced the successful cloning of a sheep, named Dolly, from the mammary glands of an adult female. The cloning of Dolly made it apparent to many that the techniques used to produce her could someday be used to clone human beings.[14] This stirred a lot of controversy because of its ethical implications.
Human Genome Project
The Human Genome Project is an initiative of the U.S. Department of Energy (“DOE”) that aims to generate a high-quality reference sequence for the entire human genome and identify all the human genes.
The DOE and its predecessor agencies were assigned by the U.S. Congress to develop new energy resources and technologies and to pursue a deeper understanding of potential health and environmental risks posed by their production and use. In 1986, the DOE announced its Human Genome Initiative. Shortly thereafter, the DOE and National Institutes of Health developed a plan for a joint Human Genome Project (“HGP”), which officially began in 1990.
The HGP was originally planned to last 15 years. However, rapid technological advances and worldwide participation accelerated the completion date to 2005. Already it has enabled gene hunters to pinpoint genes associated with more than 30 disorders.
Gene therapy
Gene therapy may be used for treating, or even curing, genetic and acquired diseases like cancer and AIDS by using normal genes to supplement or replace defective genes or to bolster a normal function such as immunity. It can be used to target somatic (i.e., body) or germ (i.e., egg and sperm) cells. In somatic gene therapy, the genome of the recipient is changed, but this change is not passed along to the next generation. In contrast, in germline gene therapy, the egg and sperm cells of the parents are changed for the purpose of passing on the changes to their offspring.
There are basically two ways of implementing a gene therapy treatment:
1. Ex vivo, which means “outside the body” – Cells from the patient’s blood or bone marrow are removed and grown in the laboratory. They are then exposed to a virus carrying the desired gene. The virus enters the cells, and the desired gene becomes part of the DNA of the cells. The cells are allowed to grow in the laboratory before being returned to the patient by injection into a vein.
2. In vivo, which means “inside the body” – No cells are removed from the patient’s body. Instead, vectors are used to deliver the desired gene to cells in the patient’s body.
Currently, the use of gene therapy is limited. Somatic gene therapy is primarily at the experimental stage. Germline therapy is the subject of much discussion but it is not being actively investigated in larger animals and human beings.
As of June 2001, more than 500 clinical gene-therapy trials involving about 3,500 patients have been identified worldwide. Around 78% of these are in the United States, with Europe having 18%. These trials focus on various types of cancer, although other multigenic diseases are being studied as well. Recently, two children born with severe combined immunodeficiency disorder (“SCID”) were reported to have been cured after being given genetically engineered cells.
Gene therapy faces many obstacles before it can become a practical approach for treating disease.[10] At least four of these obstacles are as follows:
1. Gene delivery tools. Genes are inserted into the body using gene carriers called vectors. The most common vectors now are viruses, which have evolved a way of encapsulating and delivering their genes to human cells in a pathogenic manner. Scientists manipulate the genome of the virus by removing the disease-causing genes and inserting the therapeutic genes. However, while viruses are effective, they can introduce problems like toxicity, immune and inflammatory responses, and gene control and targeting issues.
2. Limited knowledge of the functions of genes. Scientists currently know the functions of only a few genes. Hence, gene therapy can address only some genes that cause a particular disease. Worse, it is not known exactly whether genes have more than one function, which creates uncertainty as to whether replacing such genes is indeed desirable.
3. Multigene disorders and effect of environment. Most genetic disorders involve more than one gene. Moreover, most diseases involve the interaction of several genes and the environment. For example, many people with cancer not only inherit the disease gene for the disorder, but may have also failed to inherit specific tumor suppressor genes. Diet, exercise, smoking and other environmental factors may have also contributed to their disease.
4. High costs. Since gene therapy is relatively new and at an experimental stage, it is an expensive treatment to undertake. This explains why current studies are focused on illnesses commonly found in developed countries, where more people can afford to pay for treatment. It may take decades before developing countries can take advantage of this technology.
Uses of Genetic testing
- Determining sex
- Carrier screening, or the identification of unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to manifest
- Prenatal diagnostic screening
- Newborn screening
- Presymptomatic testing for predicting adult-onset disorders
- Presymptomatic testing for estimating the risk of developing adult-onset cancers
- Confirmational diagnosis of symptomatic individuals
- Forensic/identity testing
Some genetic tests are already available, although most of them are used in developed countries. The tests currently available can detect mutations associated with rare genetic disorders like cystic fibrosis, sickle cell anemia, and Huntington’s disease. Recently, tests have been developed to detect mutation for a handful of more complex conditions such as breast, ovarian, and colon cancers. However, gene tests may not detect every mutation associated with a particular condition because many are as yet undiscovered, and the ones they do detect may present different risks to different people and populations.[8]
Genetics testing
Genetic testing allows the genetic diagnosis of vulnerabilities to inherited diseases, and can also be used to determine a person's ancestry. Every person carries two copies of every gene, one inherited from their mother, one inherited from their father. The human genome is believed to contain around 25,000 - 35,000 genes. In addition to studying chromosomes to the level of individual genes, genetic testing in a broader sense includes biochemical tests for the possible presence of genetic diseases, or mutant forms of genes associated with increased risk of developing genetic disorders. Genetic testing identifies changes in chromosomes, genes, or proteins. Most of the time, testing is used to find changes that are associated with inherited disorders. The results of a genetic test can confirm or rule out a suspected genetic condition or help determine a person's chance of developing or passing on a genetic disorder. Several hundred genetic tests are currently in use, and more are being developed.
Pharmaceutical Products
Most traditional pharmaceutical drugs are relatively simple molecules that have been found primarily through trial and error to treat the symptoms of a disease or illness. Biopharmaceuticals are large biological molecules known as proteins and these usually (but not always, as is the case with using insulin to treat type 1 diabetes mellitus) target the underlying mechanisms and pathways of a malady; it is a relatively young industry. They can deal with targets in humans that may not be accessible with traditional medicines. A patient typically is dosed with a small molecule via a tablet while a large molecule is typically injected.
Small molecules are manufactured by chemistry but large molecules are created by living cells such as those found in the human body: for example, bacteria cells, yeast cells, animal or plant cells.
Modern biotechnology is often associated with the use of genetically altered microorganisms such as E. coli or yeast for the production of substances like synthetic insulin or antibiotics. It can also refer to transgenic animals or transgenic plants, such as Bt corn. Genetically altered mammalian cells, such as Chinese Hamster Ovary (CHO) cells, are also used to manufacture certain pharmaceuticals. Another promising new biotechnology application is the development of plant-made pharmaceuticals.
Biotechnology is also commonly associated with landmark breakthroughs in new medical therapies to treat hepatitis B, hepatitis C, cancers, arthritis, haemophilia, bone fractures, multiple sclerosis, and cardiovascular disorders. The biotechnology industry has also been instrumental in developing molecular diagnostic devices than can be used to define the target patient population for a given biopharmaceutical. Herceptin, for example, was the first drug approved for use with a matching diagnostic test and is used to treat breast cancer in women whose cancer cells express the protein HER2.
Modern biotechnology can be used to manufacture existing medicines relatively easily and cheaply. The first genetically engineered products were medicines designed to treat human diseases. To cite one example, in 1978 Genentech developed synthetic humanized insulin by joining its gene with a plasmid vector inserted into the bacterium Escherichia coli. Insulin, widely used for the treatment of diabetes, was previously extracted from the pancreas of cows and/or pigs. The resulting genetically engineered bacterium enabled the production of vast quantities of synthetic human insulin at low cost.
Since then modern biotechnology has made it possible to produce more easily and cheaply human growth hormone, clotting factors for hemophiliacs, fertility drugs, erythropoietin and other drugs.Most drugs today are based on about 500 molecu
Most traditional pharmaceutical drugs are relatively simple molecules that have been found primarily through trial and error to treat the symptoms of a disease or illness. Biopharmaceuticals are large biological molecules known as proteins and these usually (but not always, as is the case with using insulin to treat type 1 diabetes mellitus) target the underlying mechanisms and pathways of a malady; it is a relatively young industry. They can deal with targets in humans that may not be accessible with traditional medicines. A patient typically is dosed with a small molecule via a tablet while a large molecule is typically injected.
Small molecules are manufactured by chemistry but large molecules are created by living cells such as those found in the human body: for example, bacteria cells, yeast cells, animal or plant cells.
Modern biotechnology is often associated with the use of genetically altered microorganisms such as E. coli or yeast for the production of substances like synthetic insulin or antibiotics. It can also refer to transgenic animals or transgenic plants, such as Bt corn. Genetically altered mammalian cells, such as Chinese Hamster Ovary (CHO) cells, are also used to manufacture certain pharmaceuticals. Another promising new biotechnology application is the development of plant-made pharmaceuticals.
Biotechnology is also commonly associated with landmark breakthroughs in new medical therapies to treat hepatitis B, hepatitis C, cancers, arthritis, haemophilia, bone fractures, multiple sclerosis, and cardiovascular disorders. The biotechnology industry has also been instrumental in developing molecular diagnostic devices than can be used to define the target patient population for a given biopharmaceutical. Herceptin, for example, was the first drug approved for use with a matching diagnostic test and is used to treat breast cancer in women whose cancer cells express the protein HER2.
Modern biotechnology can be used to manufacture existing medicines relatively easily and cheaply. The first genetically engineered products were medicines designed to treat human diseases. To cite one example, in 1978 Genentech developed synthetic humanized insulin by joining its gene with a plasmid vector inserted into the bacterium Escherichia coli. Insulin, widely used for the treatment of diabetes, was previously extracted from the pancreas of cows and/or pigs. The resulting genetically engineered bacterium enabled the production of vast quantities of synthetic human insulin at low cost.
Since then modern biotechnology has made it possible to produce more easily and cheaply human growth hormone, clotting factors for hemophiliacs, fertility drugs, erythropoietin and other drugs. Most drugs today are based on about 500 molecular targets. Genomic knowledge of the genes involved in diseases, disease pathways, and drug-response sites are expected to lead to the discovery of thousands more new targets.
Pharmacogenomics
Pharmacogenomics is the study of how the genetic inheritance of an individual affects his/her body’s response to drugs. It is a coined word derived from the words “pharmacology” and “genomics”. It is hence the study of the relationship between pharmaceuticals and genetics. The vision of pharmacogenomics is to be able to design and produce drugs that are adapted to each person’s genetic makeup.
Pharmacogenomics results in the following benefits:
1. Development of tailor-made medicines. Using pharmacogenomics, pharmaceutical companies can create drugs based on the proteins, enzymes and RNA molecules that are associated with specific genes and diseases. These tailor-made drugs promise not only to maximize therapeutic effects but also to decrease damage to nearby healthy cells.
2. More accurate methods of determining appropriate drug dosages. Knowing a patient’s genetics will enable doctors to determine how well his/ her body can process and metabolize a medicine. This will maximize the value of the medicine and decrease the likelihood of overdose.
3. Improvements in the drug discovery and approval process. The discovery of potential therapies will be made easier using genome targets. Genes have been associated with numerous diseases and disorders. With modern biotechnology, these genes can be used as targets for the development of effective new therapies, which could significantly shorten the drug discovery process.
4. Better vaccines. Safer vaccines can be designed and produced by organisms transformed by means of genetic engineering. These vaccines will elicit the immune response without the attendant risks of infection. They will be inexpensive, stable, easy to store, and capable of being engineered to carry several strains of pathogen at once.
Applications of Biotechnology
- Red biotechnology is applied to medical processes. Some examples are the designing of organisms to produce antibiotics, and the engineering of genetic cures through genomic manipulation.
- Green biotechnology is biotechnology applied to agricultural processes. An example would be the selection and domestication of plants via micropropagation. Another example is the designing of transgenic plants to grow under specific environmental conditions or in the presence (or absence) of certain agricultural chemicals. One hope is that green biotechnology might produce more environmentally friendly solutions than traditional industrial agriculture. An example of this is the engineering of a plant to express a pesticide, thereby eliminating the need for external application of pesticides. An example of this would be Bt corn. Whether or not green biotechnology products such as this are ultimately more environmentally friendly is a topic of considerable debate.
- White biotechnology , also known as industrial biotechnology, is biotechnology applied to industrial processes. An example is the designing of an organism to produce a useful chemical. Another example is the using of enzymes as industrial catalysts to either produce valuable chemicals or destroy hazardous/polluting chemicals (examples using oxidoreductases are given in Feng Xu (2005) “Applications of oxidoreductases: Recent progress” Ind. Biotechnol. 1, 38-50 [1]). White biotechnology tends to consume less in resources than traditional processes used to produce industrial goods.
- Blue biotechnology is a term that has been used to describe the marine and aquatic applications of biotechnology, but its use is relatively rare.
- The investments and economic output of all of these types of applied biotechnologies form what has been described as the bioeconomy.
- Bioinformatics is an interdisciplinary field which addresses biological problems using computational techniques, and makes the rapid organization and analysis of biological data possible. The field may also be referred to as computational biology, and can be defined as, "conceptualizing biology in terms of molecules and then applying informatics techniques to understand and organize the information associated with these molecules, on a large scale."[5] Bioinformatics plays a key role in various areas, such as functional genomics, structural genomics, and proteomics, and forms a key component in the biotechnology and pharmaceutical sector.
History of Biotechnology
The most practical use of biotechnology, which is still present today, is the cultivation of plants to produce food suitable to humans. Agriculture has been theorized to have become the dominant way of producing food since the Neolithic Revolution. The processes and methods of agriculture have been refined by other mechanical and biological sciences since its inception. Through early biotechnology farmers were able to select the best suited and highest-yield crops to produce enough food to support a growing population. Other uses of biotechnology were required as crops and fields became increasingly large and difficult to maintain. Specific organisms and organism byproducts were used to fertilize, restore nitrogen, and control pests. Throughout the use of agriculture farmers have inadvertently altered the genetics of their crops through introducing them to new environments and breeding them with other plants--one of the first forms of biotechnology. Cultures such as those in Mesopotamia, Egypt, and Iran developed the process of brewing beer. It is still done by the same basic method of using malted grains (containing enzymes) to convert starch from grains into sugar and then adding specific yeasts to produce beer. In this process the carbohydrates in the grains were broken down into alcohols such as ethanol. Later other cultures produced the process of Lactic acid fermentation which allowed the fermentation and preservation of other forms of food. Fermentation was also used in this time period to produce leavened bread. Although the process of fermentation was not fully understood until Louis Pasteur’s work in 1857, it is still the first use of biotechnology to convert a food source into another form.
Combinations of plants and other organisms were used as medications in many early civilizations. Since as early as 200 BC, people began to use disabled or minute amounts of infectious agents to immunize themselves against infections. These and similar processes have been refined in modern medicine and have led to many developments such as antibiotics, vaccines, and other methods of fighting sickness.
In the early twentieth century scientists gained a greater understanding of microbiology and explored ways of manufacturing specific products. In 1917, Chaim Weizmann first used a pure microbiological culture in an industrial process, that of manufacturing corn starch using Clostridium acetobutylicum to produce acetone, which the United Kingdom desperately needed to manufacture explosives during World War I.[3]
The field of modern biotechnology is thought to have largely begun on June 16, 1980, when the United States Supreme Court ruled that a genetically-modified microorganism could be patented in the case of Diamond v. Chakrabarty.[4] Indian-born Ananda Chakrabarty, working for General Electric, had developed a bacterium (derived from the Pseudomonas genus) capable of breaking down crude oil, which he proposed to use in treating oil spills. A university in Florida is now studying ways to prevent tooth decay. They altered the bacteria in the tooth called Streptococcus mutans by stripping it down so it could not produce lactic acid.
Biotechnology
Biotechnology is often used to refer to genetic engineering technology of the 21st century, however the term encompasses a wider range and history of procedures for modifying biological organisms according to the needs of humanity, going back to the initial modifications of native plants into improved food crops through artificial selection and hybridization. Bioengineering is the science upon which all Biotechnological applications are based. With the development of new approaches and modern techniques, traditional biotechnology industries are also acquiring new horizons enabling them to improve the quality of their products and increase the productivity of their systems.
Before 1971, the term, biotechnology, was primarily used in the food processing and agriculture industries. Since the 1970s, it began to be used by the Western scientific establishment to refer to laboratory-based techniques being developed in biological research, such as recombinant DNA or tissue culture-based processes, or horizontal gene transfer in living plants, using vectors such as the Agrobacterium bacteria to transfer DNA into a host organism. In fact, the term should be used in a much broader sense to describe the whole range of methods, both ancient and modern, used to manipulate organic materials to reach the demands of food production. So the term could be defined as, "The application of indigenous and/or scientific knowledge to the management of (parts of) microorganisms, or of cells and tissues of higher organisms, so that these supply goods and services of use to the food industry and its consumers.[2]
and Biotechnology combines disciplines like genetics, molecular biology, biochemistry, embryologycell biology, which are in turn linked to practical disciplines like chemical engineering, information technology, and robotics.