Post by skyship on Sept 11, 2009 13:01:26 GMT -5
I find this quite revealing.
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Knock-out
A general term (sometimes abbr. GKO, gene knock-out) relating to artificially generated null mutations (referred to also as loss-of-function mutations) of a gene.
Such mutants, which are devoid, for example, of a particular cytokine or receptor function, are created by a process called homologous recombination, targeted deletion, or targeted disruption. It essentially involves the inactivation of an endogenous fully functional gene by insertion of cloned sequences.
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Principle of gene targeting involving the use of insertion or replacement type vectors.
(a) Use of insertion type vectors involves a single cross-over between genomic target sequences and homologous sequences at either end of the targeting vector. The neomycin resistance gene contained within the vector serves as a positive selectable marker.
(b) Gene targeting using replacement type vectors requires two cross-over events. The positive selection marker (neo) is retained while the negative selectable marker (HSV thymidine kinase) is lost. The advantage of this system is the fact that cells harboring randomly and unspecifically integrated gene constructs still carry the thymidine kinase gene. These cells can be eliminated selectively by using thymidine kinase as a selective marker. One disadvantage of the system may be the time required to handle ES cells in vitro. These cells have a certain tendency to differentiate and this can favor the subsequent generation of genetic mosaics rather than the desired germ line integration when the cells are used to create transgenic animals.
www.copewithcytokines.de/cope.cgi?key=Knock-out
Is this the joke on Humans? well it is one way to tell the story:
So, are these things made up? or is this the truth
www.copewithcytokines.de/cope.cgi?key=Joke
skyship
=========
Knock-out
A general term (sometimes abbr. GKO, gene knock-out) relating to artificially generated null mutations (referred to also as loss-of-function mutations) of a gene.
Such mutants, which are devoid, for example, of a particular cytokine or receptor function, are created by a process called homologous recombination, targeted deletion, or targeted disruption. It essentially involves the inactivation of an endogenous fully functional gene by insertion of cloned sequences.
=============
Principle of gene targeting involving the use of insertion or replacement type vectors.
(a) Use of insertion type vectors involves a single cross-over between genomic target sequences and homologous sequences at either end of the targeting vector. The neomycin resistance gene contained within the vector serves as a positive selectable marker.
(b) Gene targeting using replacement type vectors requires two cross-over events. The positive selection marker (neo) is retained while the negative selectable marker (HSV thymidine kinase) is lost. The advantage of this system is the fact that cells harboring randomly and unspecifically integrated gene constructs still carry the thymidine kinase gene. These cells can be eliminated selectively by using thymidine kinase as a selective marker. One disadvantage of the system may be the time required to handle ES cells in vitro. These cells have a certain tendency to differentiate and this can favor the subsequent generation of genetic mosaics rather than the desired germ line integration when the cells are used to create transgenic animals.
www.copewithcytokines.de/cope.cgi?key=Knock-out
Is this the joke on Humans? well it is one way to tell the story:
So, are these things made up? or is this the truth
www.copewithcytokines.de/cope.cgi?key=Joke
skyship