TRANSGENIC MILK-BOON OF MODERN ANIMAL BIOTECHNOLOGY

Introduction

Over centuries animal breeding practices were

performed to improve the genetic potential of animals

and to introduce new traits, through genetic selection.

But the number of gene combinations achieved through

this process has limitations, since breeding is only

possible between animals of same or closely related

species. Transgenesis is a revolutionary technology

which introduces new genes to a species, which belong

to an entirely different species. The chemical

combination of DNA is same in all eukaryotic species.

Theoretically genes can be transferred between any

species. So the resulting species will be having the

desired characteristics of another species. Result of

human genome project and other similar projects to

reveal the genetic code has opened new arenas in

medical research in combination with transgenics.

By genetic engineering, the gene for a protein drug of interest can be transferred into another organism that will produce large amounts of the drug. Transgenic technology led to the emergence of a new kind of farming from research and development labs of several universities and small biotechnology companies- they even changed the spelling to “pharming”. “Pharming” is the production of human pharmaceuticals in farm animals.

Gene “Pharming” enables production of

recombinant biologically active proteins in the

mammary glands of transgenic animals. This

technology overcomes the limitations of conventional

and recombinant production system for pharmace-

utical proteins. Mammary gland is the preferred

production site, mainly because the qualities of protein

that can be produced in this organ using mammary

gland specific promoter elements and established

methods for extraction and purification of that proteins.Numerous monoclonal antibodies are being

produced in the mammary gland of transgenic goats.

Cloned transgenic cattle can produce a recombinant for all organisms, the fine details of gene control differ. A gene from a bacterium will not often work correctly if group it is introduced unmodified into a eukaryotic animal cel

The genetic engineer first of all constructs a transgene containing the gene of interest plus some extra DNA Now that correctly controls the function of the gene in the new animal. This transgene has then to be inserted into a new animal. Many genes are only expressed in particular tissues and are controlled by special segment of DNA next to the gene called promoter sequence more When constructing a transgene, scientists generally substitute the donor’s promoter sequence with one that is specially designed to ensure that the gene will began function in the correct tissues of the recipient animal This is crucial when, for example the gene need to be expressed in milk of animal

though, Milk-producing transgenic animals are especially useful for production of medicines, nutritional

supplements and pharmaceuticals. Products such as insulin, growth hormone, and blood anti-clotting factors have already been obtained from the milk of transgenic cows, sheep, or goats. Research is also underway to manufacture milk through transgenesis for treatment of debilitating diseases such as phenylketonuria (PKU),

hereditary emphysema, and cystic fibrosis. Milk composition can be altered in several ways- changing the concentration of unsaturated fatty acids reducing the lactose content, removing ß- lactoglobulin and combining nutraceuticals in milk. By combining nutritional and genetic interventions, researchers are milk components that have implications in health as well as treatment. Cows, goats and sheep are utilized for the production of more than 60 therapeutic proteins including plasma proteins, monoclonal antibodies and vaccines. In 1997, the first transgenic cow, Rosie, produced human alpha-lactalbumin -enriched milk at

2.4 grams per litre. This transgenic milk is a more nutritionally balanced product than natural bovine milk

and could be given to babies or the elderly with special nutritional or digestive needs Lactoferrin, the iron-binding protein plays an important role in stimulating the immune system and acting as a first line of defence against infection. Its level in human milk is about 1 g/l (in human colostrum160 about 7 g/l) and that in cow’s milk is only about one- tenth that in human milk. A New Zealand research developed a genetically modified dairy herd capable

of producing ‘medicinal milk’ containing recombinant human lactoferrin (rhLF) by transgenic technology. Argentinean scientists have developed a cow which can secrete human insulin in its milk. This insulin will be purified from cow milk and used for treatment of Diabetes Mellitus. When compared to conventional methods of insulin production this method is much cost effective. In 2001, two scientists in Canada spliced spider genes into the cells of lactating goats. The goats to manufacture silk along with their milk and secrete tiny silk strands from their body by the bucketful. By extracting polymer strands from the milk and weaving them into thread, the scientists can create a light, flexible material that could be used in such applications as military uniforms, medical micro sutures, and tennis racket str ings. The major advantage of transgenic technology is that proteins can be produced at a low cost compared to the method using mammalian cell culture. However various ethical, legal and social aspects of biotechnological research need to be addressed before the implementation of transgenic herds.