TRANSGENESIS

TRANSGENESIS:

Modification of germ cells by gene manipulation in vitro is called transgenesis/ transfection/ transformation.

TRANSGENIC ANIMAL:

Animal carrying new gene(s) called transgenic. Particular variants of species into which a new gene(s) has been inserted.

Every cell of the animal carries new genetic information within the genome.

Why Transformation is performed?

1. To incorporate trait to enhance the conventional animal product
2. To incorporate traits for biosynthesis of new product
3. Study of gene expression in mammalian development
4. Study of tissue specific expression
5. Study of genetic basis of various diseases
6. Gene function study through knockouts
7. Minimize the time requirement to introduce a trait that is needed in breeding

Transgenic Mice Production

Embryonic Stem (ES) Cell Method

Cells of the blastocyst stage of a developing mouse can proliferate in cell culture and still retain the capability of differentiating into all other types, including germ line cells, after they are reintroduced into another blastocyst embryo. Such cells are called pluripotent embryonic stem cells.

Another advantage: the transgenes can be targeted to introduced into a prefixed location.

Production of Chimeric Mouse :

An early embryo is isolated from the fertilized mouse of black colour. The ES cells of trophoblast stage of embryo are grown on culture medium. A small number of ES cells can be injected into blastocoel space of an embryo of a white (albino) mouse through microinjection technique. The ES cells of black mouse intermingle with that of albino. The microinjected embryo is transplanted into the uterus of a surrogate mother (another mouse of which ova we not used). The progeny born has black and white skin colour. Such mouse was called chimera or chimeric mouse.

Fig: Production of Transgenic Mice 

Application of Transgenic Mice

1. Understanding gene regulation
2. Immunological specificity understanding and antibody development
3. Drug production
4. Onset and progress of human disease e.g. Alzheimer disease, arthritis, muscular dystrophy, tumorigenesis etc.