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The brave new world of transgenic animal
Transgenic animals are just one step in developmental series in the area of biotechnology. Biotechnology has transformed the way in which we understand processes such as engineering and manufacturing.
These terms now include the use of living organisms or their parts to make or modify products, to change the characteristics of plants or animals, or to develop microorganisms for specific uses. The novel uses of biological techniques such as recombinant DNA technology, cell fusion techniques, mono and polyclonal technology and biological processes for commercial production have altered traditional distinctions and methods.
The biological tools are being used to enhance animal health and performance, and as a mechanism to use animals for the production of scarce life saving pharmaceuticals.
For better understanding of term transgenic animals, it is necessary to review the basic components and functions of living organisms.
Genes and genome
Animals are made of billions of cells all working together. Each cell has a complete “instruction manual” or genome that is inherited from the parents to the animal as a combination of their genomes. The genome resides in the nucleus of the cell.
Genes are found within the genome and serve as the “words” in an instruction manual. When a cell reads a specific word (expresses a gene), a specific protein is produced. Proteins give an individual cell, and therefore the animal, its form and function. Genes (words) are written using the four-letter alphabets A, C, G, T. the letters stand for four chemicals called bases, which together compose DNA.
DNA is universal in nature, meaning that the four chemical bases of DNA are the same in all living organisms. Consequently, a gene from one organism can function in another organism.
The word transgenic is subjected to put a new gene into an animal’s genome. It is a great discovery of scientists that how to genetically modify (GM) when and/or where in an animal a gene is expressed. For example, it is possible to produce new proteins in the milk of a cow and nowhere else in the body. The complex interactive processes of living mammals are not reproducible in vitro (taking place in a test tube; outside a living body). However, transgenic animals produce a means of anatomical and physiological changes in a complex system.
One way to produce transgenic animal is through microinjection technology. Once identified and isolated, the piece of DNA comprising the gene to be transferred is injected into a fertilized egg of the desired animal using a very small glass needle under a microscope. In approximately one percent of the injected eggs, the gene becomes a new “word” in the egg’s “instruction manual” by physically combining with the egg’s genome. Ideally the new gene integrates into the genome before the egg begins to divide. If this occurs, every cell in the animal can contain the new protein and the animal will pass the gene onto its offspring. After the gene has been injected, the fertilized egg is implanted into a surrogate mother in whose body it develops fully into a transgenic animal.
Current uses of transgenic animals are as bioreactor for production of pharmaceuticals, as models of human disease, and as organ banks. A representative, but non-inclusive list of purposes for which transgenic animals have been used indicates the wide-ranging application of this biotechnology.
• In medical research, transgenic animals used to identify the functions of specific factors in complex homeostatic system through over- or under-expression of a modified gene (the inserted transgene)
• In toxicology, as responsive test animals (detection of toxicants)
• In mammalian developmental genetics;
• In molecular biology, the analysis of regulation of gene expression makes use of the evaluation of a specific genetic change at the level of whole animal;
• In the pharmaceutical industry, targeted production of pharmaceutical proteins, drug production and product efficacy testing;
• In biotechnology, as producer of specific proteins;
• Genetically engineered hormones to increase milk yield, meat production; genetic engineering of livestock and in aquaculture affecting modification of animal physiology and/or anatomy; cloning procedures to reproduce specific blood lines; and
• Developing animals specially create for use in xenografting.
Important general consideration includes the extent to which the experience, acquired in the laboratory with regard to husbandry, should influence industry standards. These standards for keeping animals created specifically as living machines for the producing proteins, antibodies, etc.
What words are appropriate to describe and evaluate the condition of animals now used as production units? The successful cloning of Dolly the sheep underlines the fact that the innovative developments in animal science are part of the main stream of biotechnology. In addition, the use of xenografts, at least at the public health level makes animal and human welfare inseparable.
The writer is a freelance contributor
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