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HUMAN Genetics:specific African Genetic Dispersion: Case Stufy: THE KHOISAN / Genetic Engineering Will Change Everything Forever!!! / A Genetic History Of Homo Sapiens. (2) (3) (4)

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Application Of Biotechnology For The Genetic Improvement Of Livestock by Nobody: 5:56pm On Jul 06, 2017

Copied from www.kelscience.net Edited 15/02/17 Chapter one 1.1 Introduction Genetic engineering is the process of taking genes and segments of DNA from one species and putting them into another species, thus breaking the species barrier and artificially modifying the DNA of various species. These procedures are of use to identify, replicate, modify and transfer the genetic material of cells, tissues or complete organisms (Karp, 2002). The techniques are generally related to the direct manipulation of DNA oriented to the expression of particular genes (Hugon, 2006). “Recombinant DNA” (rDNA) is defined as a DNA sequence artificially obtained by combining genetic material from different organisms, as is the case for a plasmid containing a gene of interest (Rossana et al, 2010). Several developments provided the necessary stimulus for gene manipulation to become a reality. The first major step forward in the ability to chemically modify genes occurred when American biologist Martin Gellert and his colleagues from the National Institutes of Health purified and characterized an enzyme in Escherichia coli responsible for the actual joining, or recombining, of separate pieces of DNA. They called their find "DNA joining enzyme," and this enzyme is now known as DNA ligase. This enzyme can join two segments of DNA together, a prerequisite for the construction of recombinant molecules, and can be regarded as a sort of molecular glue. A second major step forward in gene modification was the discovery of restriction enzymes, a major milestone in the development of genetic engineering. These enzymes were discovered at approximately the same time as the first DNA ligases by Swiss biologist Werner Arber and his colleagues while they were investigating a phenomenon called hostcontrolled restriction of bacteriophages. Restriction enzymes are essentially molecular scissors that cut DNA at precisely defined sequences. Such enzymes can be used to produce fragments of DNA that are suitable for joining to other fragments. Thus, by 1970, the basic tools required for the construction of recombinant DNA were available (Desmond, 2008). Today global life sciences companies are beginning to exploit the new advances in biology in a myriad of ways, laying the economic framework for the Biotech Century. Therefore, the objective of this review is to highlight: (i) the state of the art of genetic engineering, (ii) the potential and approved applications of genetic engineering in biological and medical sciences and (iii) the limitations of its applications. Chapter two 2.1 Biotechnology and Animal Production Based on the central tenet “P = G + E”, namely that the Phenotype of an animal reflects its intrinsic genetic aptitude or Genotype as expressed in a given Environment, animal breeders have adopted a two-pronged approach towards improving the quality of their production. On the one hand, they have learned to master the environmental component by improving animal husbandry and nutrition practices, disease prophylaxis and treatment. On the other hand, artificial selection has allowed to continuously improving the genetic make-up of domestic species. The implementation of sophisticated biometrical methods in breeding schemes has lead to spectacular genetic progress during the second half of this century (Nogueira M.F.G. (2001). Biotechnology has been adopted in the arsenal of tools aimed at improving both the nurture (E) as well as nature (G) components of the equation. Applications of biotechnology to improve the environmental component have recently been reviewed by Robinson and McEvoy (1993) and include: - Genetically engineering forage species, either to increase their productivity, or to improve their nutritional value, - Genetically engineering microorganisms to produce food additives, - Genetically engineering the gut micro flora, - Production of therapeutic or prophylactic compounds - including vaccines - from genetically engineered microorganisms, - Production of hormones or hormone analogues from genetically engineered microorganisms, 2.2 Biotechnology for the Genetic Improvement of Livestock Animal breeding operates through the selection of genetically superior animals as parents for subsequent generations. So far artificial selection could therefore only be applied to traits which are “naturally” exhibiting genetic variation in the selected populations, i.e. traits characterised by some degree of “heritability”. The rate of genetic progress or of response to selection is a function of: - The accuracy of selection, i.e. the precision in the identification of genetically superior animals; - The generation interval, the shorter the generation interval, the faster the genetic progress; - The selection intensity, i.e. the more the future parental individuals deviate from the average breeding value of their contemporaries, the higher the genetic improvement they will cause. Biotechnology is being applied to enhance genetic progress through these four factors: increase genetic variation (or the molecular substrate of breeding programmes), increase the accuracy of selection, and reduce the generation interval and to increase the selection intensity. Three major topics can be distinguished in the area of biotechnology applied to the genetic improvement of livestock: - Reproductive technologies, - Livestock genomics and marker assisted selection (MAS) - Livestock transgenics (Pandey U.K. (2009). 2.3 Genetic Engineering The first successful gene transfer method in animals (mouse) was based on the microinjection of foreign DNA into zygotic pronuclear. However, microinjection has several major shortcomings including low efficiency, random integration and variable expression patterns which mainly reflect the site of integration. Research has focused on the development of alternate methodologies for improving the efficiency and reducing the cost of generating transgenic livestock (Singer P.A. (2002). To date, somatic cell nuclear transfer, which has been successful in 13 species, holds the greatest promise for significant improvements in the generation of transgenic livestock. Furthermore, there are some common ways of manipulating the animal genome (Courbois C (2010). 2.4 Method Retroviral Vector Of the various gene transfer method, the retroviral vectors has the advantage of being an effective means of integrating_ the transgene into the genome of a recipient cell. However, these, vectors can transfer only small pieces (~ 8 kilobases) of DNA, which, because of the size constraint, may lack essential adjacent sequences for regulating the expression of the transgenic (Squire et al. 1989). Major drawback of this method is that the retrovirus may well revert to a pathogenic form to cause diseases such as cancer etc (Kelly V.A. (2008). 2.5 Applications of Genetic Engineering 2.5.1 Disease resistance Animal biotechnology offers a number of approaches to fight diseases in animals. Firstly, through genetic selection, livestock producers can select for certain traits that are associated with disease resistance and populations of animals that are less vulnerable to diseases could be developed. Secondly, through genetic engineering, breeders can integrate disease resistance genes from new sources, allowing for improved animal health. Disease resistance benefits not only livestock producers and their animals, but consumers also benefit as a result of safer animal products in the market, and a reduction in the incidence of humantransmissible diseases such as avian influenza (Alison and Davis, 2009). Increased disease resistance can be achieved by introducing resistance-conferring gene constructs into animals or by depleting a susceptibility gene or locus from the animal. Hence gain of function (additive) as well as loss of function (deletive, knockout) gene transfer experiments can be used. Gene transfer experiments are often hampered by the lack of identified major genes or loci responsible for resistance traits (Muller and Brem, 1998). 2.5.2 Increasing meat and milk production The application of genetic engineering to increase milk and meat is a “value-added” opportunity in animal agriculture as it increases the concentration of existing proteins or producing entirely new proteins (Scott and Mattew, 2011). For example, the presence of 10 to 20% altered casein in milk produced by a transgenic cow could increase proteolysis and thereby promote the faster ripening of cheese. Results of experiments with transgenic mice illustrated the positive effects of adding genes such as the casein gene (Gutiérrez-Adán et al., 1996) or human lysozyme gene (Mega et al., 2006) to the milk protein system (James and Gary, 2000). The effects of genes encoding growth hormonereleasing factor (GRF) or insulin-like growth factor I (IGFI) were reported in growth studies in mice and sheep (Murray et al., 1999). In pigs, there are evidences of transgene effects that reduced body fat and increased muscle fiber diameter by increasing IGF-I levels and growth hormone with no serious pathological side effects (Hugon, 2006). 2.5.3 Improving hair and fiber The quality, color, yield and ease of harvest of hair, wool and fiber for fabric and yarn production have been an area of focus in livestock production. The manipulation of the quality, length, fineness and crimp of wool, hair and fiber from sheep and goats has been examined using transgenic methods (Scott and Mattew, 2011). The objectives aimed to improve sheep for wool production and to modify the properties of the fiber. Because cystein seems to be the limiting amino acid for wool synthesis, the approach is to increase its production through transfer of cystein biosynthesis from bacterial genes to sheep genome (Murray et al., 1999). 2.5.4 Enhancing growth rates and carcass composition The production of genetically engineered livestock has been instrumental in providing new insights into the mechanisms of gene action governing growth. Using transgenic technology, it is possible to manipulate growth factors, growth factor receptors and growth modulators. Transgenic sheep and pigs have been used to examine postnatal growth of mammals. Growth hormone (GH) and IGF genes were incorporated and expressed at various levels in genetically engineered animals. Transgenic livestock and fish that contain an exogenous GH gene were produced. Altering the fat or cholesterol composition of carcass is another benefit that can be delivered via genetic engineering. By changing the metabolism or uptake of cholesterol and/or fatty acids, the content of fat and cholesterol of meats, eggs and cheeses could be lowered. There is a possibility of introducing beneficial fats such as the omega-3 fatty acids from fish or other animals in livestock (Lai et al., 2006). Receptors such as the low-density lipoprotein (LDL) receptor gene and hormones like leptin are also potential targets that would decrease fat and cholesterol in animal products (Scott and Mattew, 2011). 2.5.5 Improving reproductive performance and fecundity Several genes that may profoundly affect reproductive performance were identified. These included the estrogen receptor (ESR) and the Boroola fecundity (FECB) genes. A specific form of the ESR gene is associated with 1.4 more pigs born per litter than is typical in lines of pigs that do not contain this specific ESR gene type (Rothschild et al., 1994). Introduction of a mutated or polymorphic ESR gene could increase litter size in pigs. A single major gene for fecundity, the FECB gene that allows for increased ovulation rate was identified in Merino sheep (Piper et al., 1985). Each copy of this gene increases ovulation rate by approximately 1.5 ova per cycle (Scott and Mattew, 2011). 2.5.6 Vaccine production Most conventional vaccines are killed microorganisms, inactivated bacterial toxins or live attenuated organisms. However, because the immune system acts only on a few protective immunogens, most molecular components of killed vaccines are redundant and or can cause adverse effects. Nowadays new technologies offer alternatives to classical vaccines (Sussan and Asa, 1998). 2.5.7 Live genetically modified vaccines Live genetically modified vaccines could be viruses or bacteria with one or more genes deleted or inactivated, orthey can be vaccines carrying a foreign gene from another disease agent, which is referred to as vaccine vectors. Deletion of a gene or genes is to inactivate or attenuate the disease agent. Generally two (doubleknockout) or more genes are deleted or inactivated so the vaccine remains stable and cannot revert to a pathogenic agent (Uzzau et al., 2005). 2.5.8 Recombinant inactivated vaccines Recombinant inactivated vaccines are subunit vaccines containing only part of the whole organism. Subunitvaccines are synthetic peptides that represent the most basic portion of a protein that induces an immune Biochem Biotechnol Res 18 response. Subunit vaccines consist of whole proteins extracted from the disease agent or expressed from cloned genes in the laboratory. Several systems can be used to express recombinant proteins, including expression systems that are cell free or that use whole cells. Whole-cell expression systems include prokaryotic (bacteria-based) systems such as E. coli, and eukaryotic (mammalian, avian, insect, or yeast-based) systems. Another type of recombinant subunit vaccines, called virus like particles (VLPs), can be created when one or more cloned genes that represent the structural proteins of a virus are expressed simultaneously and self assemble into VLPs. These VLPs are immunogenic. Because subunit vaccines do not replicate in the host, they usually are administered with an adjuvant (Mark et al., 2008). 2.5.9 Genetic vaccines Genetic vaccines are circular pieces of DNA, called plasmids, which contain a foreign gene from a disease agent and a promoter that is used to initiate the expression of the protein from that gene in the target animal (Rodriguez and Whitton, 2000). Plasmids can be maintained in bacteria (usually E. coli) and have been designed to accept foreign genes for expression in animals. Recombinant plasmids containing a foreign gene are purified from bacteria, and “naked” DNA is injected directly into an animal, intramuscularly or intradermally (Mark et al., 2008). In addition to genes coding for immunogenic proteins, genetic vaccines are designed to include different immune-stimulatory genes that trigger different compartments of the immune system, depending on the type of immunity desired. Unique features of DNA vaccines are intrinsic sequences embedded in the DNA, so-called CpG motifs. These unmethylated motifs were shown to act as an adjuvant, stimulating the innate immune responses and enhancing the effectiveness of the vaccine (Mark et al., 2008). 2.5.10 Plant based vaccines A novel approach for developing subunit vaccines has emerged as a result of the use of plants as hosts’ biological bioreactors (Schuyler, 2008). Plant-based vaccines consist of protein subunits. A good candidate antigen must first be identified in order to develop the vaccine. Edible plant derived vaccines take advantage of the ability of some antigens to induce an immune response when delivered orally. Foreign genes from disease agents are inserted into potatoes, soybeans, and corn plants and fed to animals and the expressed proteins from these foreign genes immunized the animals against the disease agent (Streatfield, 2005). 2.5.11 Gene therapy Gene therapy is fundamentally an attempt to grasp hereditary diseases at their origin. The underlying idea is to repair a mutation in a gene (Cornel, 2007). It is the use of DNA as a pharmaceutical agent to treat disease. It derives its name from the idea that DNA can be used to supplement or alter genes within an individual's cells to a treat disease. The most common form of gene therapy involves using DNA that encodes a functional, therapeutic gene to replace a mutated gene. Other forms involve directly correcting a mutation, or using DNA that encodes a therapeutic protein drug (rather than a natural gene). In gene therapy, DNA that encodes a therapeutic protein is packaged within a "vector", which is used to getthe DNA inside cells within the body. Once inside, the DNA becomes expressed by the cell machinery, resulting in the production of therapeutic protein (Sheridan, 2011). 2.6Animal Genetics and Breeding Genetic improvement of livestock depends on access to genetic variation and effective methods for exploiting this variation. Genetic diversity constitutes a buffer against changes in the environment and is a key in selection and breeding for adaptability and production on a range of environments. In developed countries, breeding programmes are based upon performance recording and this has led to substantial improvements in animal production (Oishi T., (2009). In horn of Africa the distinct disadvantages for setting up successful breeding programmes are: infrastructure needed for performance testing is normally lacking because herd sizes are normally small and variability between farms, farming systems and seasons are large; reproductive efficiency is low, due mainly to poor nutrition, especially in cattle; and communal grazing precludes implementation of systematic breeding and animal health programmes. Reproductive biotechnology provides means whereby reproductive performance may be modified at a number of points Okpokwasili GC (2007).The main objectives of using reproductive biotechnologies in livestock are to increase production, reproductive efficiency and rates of genetic improvement Okpokwasili GC (2007).Various biotechnology methods are used in improving the breeding stock of animals. 2.7 Limitations of Genetic Engineering 2.7.1Environmental impacts Potential risks for the environment include unintended effects on non-target organisms, ecosystems and biodiversity. Insect-resistant GM crops have been developed by expression of a variety of insecticidal toxins from the bacterium B. thuringiensis (Bt). Detrimental effects on beneficial insects, or a faster induction of resistant insects (depending on the specific characteristics of the Bacillus thuringiensis proteins, expression in pollen and areas of cultivation), have been considered in the area of a number of insect-protected GM crops (Sears et al., 2001). 2.7.2 Health hazards There are crucial scientific questions concerning the health effects of genetic engineering and genetically engineered organisms. It has been argued that random insertion of genes in may cause genetic and phenotypic instabilities (Ho, 2002). If DNA and proteins from genetically engineered organisms persist in, and are taken up from the mammalian gastrointestinal tract, this could theoretically, ultimately lead to development of chronic disease conditions (Tereje and Jack, 2007). 2.7.3 Religious, cultural and ethical Issues The current and potential impact of rapid developments in biotechnology to effect new innovations in medicine and drug development, as well as such diverse areas as crime detection, agriculture, pollution control and industrial processes, brings into question how these techniques can be used constructively without damaging the cornerstones of religious ethics, namely respect for human life (Curran and Koszarycz, 2004). Revolutionary innovations in genetic engineering, the decoding of the human genome now make it possible for vegetables in our food chain to bear animal transgenes (Conrad and Harold, 2009). 1 Like

Re: Application Of Biotechnology For The Genetic Improvement Of Livestock by Nobody: 5:58pm On Jul 06, 2017

Chapter three 3.1 Conclusion The development of transgenic livestock is one of the most exciting areas of biotechnology. Already transgenesis has been applied to a wide range of species, and involves a large number of different genes. The ultimate product applications of the technology can be found in the agricultural, food and pharmaceutical industries. Technological changes are occurring rapidly; recent successes in ‘cloning’ are likely to revolutionise the development and precision by which transgenic livestock can be developed. 3.2 Recommendations In all circumstances, biotechnologies development and use requires the involvement of stakeholders in a systematic design to enhance research and development as well as transfer of the biotechnologies to target groups. Government and National Agricultural Research Systems are responsible for a majority of the processes required to successfully develop and transfer relevant biotechnologies. To deliver biotechnologies for use by target groups, there is need for cooperation between Government and benefiters. Hand down, more emphasis must be put to launch a massive campaign to popularize biotechnology among livestock farmers and undertake necessary steps to assist them accordingly. 1 Like