Transgenic Animals| Cloning |Microinjection of genes| Vortex Mixing | Gene pharming| Ant thrombin IProcedure of cloning

Transgenic animal

The animals that are produced by introducing desired genes in them.

Simple methods to develop transgenic animal

1. Microinjection of Genes:

There can be microinjection of foreign genes into the eggs by hand.

2.Vortex Mixing:

The eggs are placed in an agitator with DNA and the silicon carbide needles. The needles make small holes through which the DNA can enter, these eggs are fertilized and then produce transgenic offspring.

The technique of producing transgenic animals has following applications. 

1. Higher Growth Rate of Animals:

The genes for bovine (cattle) growth hormone are injected by this technique into mar' types of animal eggs. Thus many larger fishes, cows, pigs, rabbits and sheep are produced by this procedure.

2. Gene Pharming:

The use of transgenic farm animals to produce pharmaceuticals is called gene Pharming,a number of firms are using this technique. In this technique the genes of therapeutic (antibodies) and diagnostic proteins are incorporated into the animal's DNA.Thus these proteins appear in the animal's milk. The scientists are trying to produce drugs for the treatment of cystic fibrosis, cancer, blood diseases and other disorders. Ant thrombin III is produced by a herd, goats. It prevents the blood clotting during surgery.

Procedure of Producing Transgenic Mammals for Gene Pharming:

DNA containing the gene of interest is injected into donor eggs. The egg is fertilized in vitro (in test tube) and zygote is formed. The zygotes are placed in host females. The off spring are developed, female offspring become mature. The product is secreted in the milk. The scientists of United States Department of Agriculture have produced genetic engineered mice that produce human growth hormone in their urine instead of milk. 

Urine is preferred over milk for selection of biotechnology product.

Cloning of Transgenic Animals:

The production of the genetically identical copies of the organisms or cells asexual reproduction is called cloning. The animals are genetically engineered to produce a biotechnology product. Now identical copies of these animals are obtained by asexual reproduction through cloning.

Cloning requires only the genes of one animal. So cloning is a form of asexual reproduction. In 1997, scientists at the Roslin institute in Scotland produced a cloned sheep called Dolly. Since then calves and goats have been cloned.

Procedure of Cloning:

The eggs are enucleated (remove nucleus). A 2n nuclei of adult cells are injected into this enucleated egg.The modified cell is implanted in the uterus and development begins, offspring is produced. The off spring have the genotype and phenotype of the adult that donated the nuclei. Therefore, the adult has been cloned.

For cloning of Mice, following procedure was adapted

The 2n nuclei were taken from cumulus cells

Cumulus cells are those that cling to an egg after ovulation occurs