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?
- To
incorporate trait to enhance the conventional animal product
- To
incorporate traits for biosynthesis of new product
- Study of
gene expression in mammalian development
- Study of
tissue specific expression
- Study of
genetic basis of various diseases
- Gene
function study through knockouts
- 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
- Understanding
gene regulation
- Immunological
specificity understanding and antibody development
- Drug
production
- Onset and
progress of human disease e.g. Alzheimer disease, arthritis, muscular
dystrophy, tumorigenesis etc.
