of Construction Transgenic Mice
Introduced DNA inserts (randomly) into the genome at the single cell stage This DNA insertion will be present in every cell of the adult mouse Expression of the DNA may be analyzed
Expression of the Transgene
A promoter of a gene of interest is fused (attached) to a reporter gene, whose expression can be detected by a chromogenic (color producing) reaction. The localized expression of a gene (in space and time) can give important clues to its function.
Gene knock-outs by homologous recombination
In homologous mammals, recombination occurs infrequently compared with non-homologous integration of DNA DNA is transfected into mouse embryonic stem (ES) cells A selection plus counter-selection scheme allows identification of those cells with homologous DNA integrations The modified ES cells are introduced into an embryo to produce a mouse with a germ-line gene knock-out The mouse is bred to produce a fully heterozygous (non-mosaic) knockout mouse Further matings are carried out to construct homozygous knock-out