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Transgenic Organisms. Transgenic Organisms. The Transgenism is one of the thrust areas of Biotechnology /Genetic Engineering . The methods of gene transfer lead to the production of Transgenic animals and plants. These Transgenic organisms are called Genetically Modified Organisms.
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Transgenic Organisms The Transgenism is one of the thrust areas of Biotechnology /Genetic Engineering. The methods of gene transfer lead to the production of Transgenic animals and plants. These Transgenic organisms are called Genetically Modified Organisms.
Transgenic animal is one that carries a foreign gene that has been deliberately inserted into its genome. The foreign gene is constructed using recombinant DNA methodology. In addition to a structural gene, the DNA usually includes other sequences to enable it to be incorporated into the DNA of the host and to be expressed correctly by the cells of the host.
Transgenic sheep and goats have been produced that express foreign proteins in their milk. Transgenic chickens are now able to synthesize human proteins in the "white" of the eggs. Transgenic mice have provided the tools for exploring many biological questions Normal mice cannot be infected with polio virus. They lack the cell-surface molecule that, in humans, serves as the receptor for the virus. So normal mice cannot serve as an inexpensive, easily-manipulated model for studying the disease. However, transgenic mice expressing the human gene for the polio virus receptor can be infected by polio virus and even develop paralysis and other pathological changes characteristic of the disease in humans
Transfection & Molecular farming The uptake of genes by the cells in animals is called transfection. The transfected cells are used for a variety of purposes: production of transgenic animals of commercial value. production of chemicals and pharmaceutical drugs. study of structure and function of genes. The production of Transgenic animals of commercial value such as livestock animals and fishes is called as Molecular farming.
Gene transfer methods In transfection, fertilized eggs / embryos or the cultured cells are employed. The Embryonic Stem Cell Method The Pronucleus Method Transfer of genes to fertilized eggs or embryos. The transfection of fertilized egg involves either the transfer of whole nuclei or whole chromosomes; or their fragments or the DNA segments.
For the transfer of whole nuclei, The cells are treated with cytochalasin B and enucleated. The enucleated cells are incubated with the desired karyoplasts for the induction in presence of Polyethylene Glycol (PEG). For transfer of whole chromosomes, metaphase cells are subjected to hypotonic lysis and individual chromosomes or fragments are isolated and then icubated with whole cells / eggs for transfection.
Microinjection of DNA segments: In this the fertilized eggs are injected with DNA segments for integration. DNA integrated eggs are then used for getting transgenic animals. Transfer of genes to cultured cells: stem cells are undifferentiated precursor cells, the genes can be delivered through retroviruses or Directly by techniques of microinjection using particle gun, electoporation or by the use of lysosomes.
Uses: • Transgenic animals are more efficient than their normal counterpart in feed assimilation. • They exhibit faster growth and hence achieve the marketable size sooner. • Meat quality is good. • They are resistant to certain diseases. • Serve as bioreactors for obtaining valuable recombinant proteins and pharmaceuticals from their milk or urine or blood.
Transgenic pigs have also been produced by fertilizing normal eggs with sperm cells that have incorporated foreign DNA. This procedure, called sperm-mediated gene transfer (SMGT) may someday be able to produce transgenic pigs that can serve as a source of transplanted organs for humans
Transgenic Chickens grow faster and in large numbers can be grown in close quarters; synthesize several grams of protein in the "white" of their eggs.
