Discovery of an Accretion Streamer and a Slow Wide-angle Outflow around FUOri...
Methods for producing_transgenic_animals
1.
2. -Transgenic animals are animals that
develop from a fertilized egg with a
foreign gene insert carry that gene in
every cell.
Transgene is the foreign gene.-
3. For transgenesis, DNA can be introduced into
mice by one of the following methods;
-Retroviral vectors that infects the cells of an early
stage embryo prior to implantation into a receptive
female.
-Microinjection into the enlarged sperm nucleus (the
male pronucleus) of a fertilized egg
-Introduction of genetically engineered embryonic
stem cells into an early stage developing embryo
prior to implantation into a receptive female.
-Transfer of diploid somatic nuclei into an
enucleated oocyte.
4. microinjection of DNA is currently the preferred
method for producing transgenic mice.
1-the gene of interest is usually a cloned
recombinant DNA molecule.
2-this gene could be micro injected into early
mouse embryo (fertilized egg) which contain two
pronuclei , one from the sperm (male) and one
from the egg (female(
3-a few hundred copies of the foreign DNA in
about 2 picoliters of solutions are microinjected
directly into one of the pronuclei.
5. 4-the injected embryos are then
transferred to the oviduct of a foster
mother, and upon subsequent
implantation in the uterus.
--The number that have the foreign DNA
integrated into their chromosomes is
between a few percent and 40 percent.
-the introduced DNA appears to integrate
randomly without preference for a particular
chromosome location.
6.
7. •The production of transgenic animals by
microinjection of DNA into fertilized eggs.
8.
9.
10. 5-three weeks after the birth ,the offspring
are checked for the presence of the
transgene by southern blotting of DNA
extracted from a small piece of the tail.
-Screening can be performed rapidly using
the polymerase chain reaction (PCR) if
suitable primers are available.
11. 1-Analysis of DNA regulatory elements.
2-Expression of proteins during differentiation.
3-Potential role of oncogene products on growth,
differentiation and induction of tumorigenesis.
4-Transgenic mice can be used to model human
disease .the aim is to ultimately replace defect
gene in developing embryo (gene therapy(
12. .In fact , transgenic animal model
hold promise for future
methodologies to correct genetic
diseases early in fetal development
.
Editor's Notes
DNA microinjection
transfer of a desired gene construct (of a single gene or a combination of genes that are recombined and then cloned) from another member of the same species or from a different species into the pronucleus of a reproductive cell19
the manipulated cell, which first must be cultured in vitro (in a lab, not in a live animal) to develop to a specific embryonic phase, is then transferred to the recipient female
Retrovirus-mediated gene transfer
retroviruses used as vectors to transfer genetic material into the host cell, resulting in a chimera, an organism consisting of tissues or parts of diverse genetic constitution
chimeras are inbred for as many as 20 generations until homozygous (carrying the desired transgenic in every cell) transgenic offspring are born
Embryonic stem cell-mediated gene transfer
isolation of totipotent stem cells (stem cells that can develop into any type of specialized cell) from embryos
the desired gene is inserted into these cells
cells containing the desired DNA are incorporated into the host's embryo, resulting in a chimeric animal
