Patent ID: 9096870
Filing Date: 2015-08-04
Classification: A01K,C12N,C12Y

Abstract:
1. A method for making a genetically modified mouse, comprising: (a) introducing a donor mouse ES cell into a host mouse embryo, wherein the donor mouse ES cell comprises at a genomic locus of interest a modified allele, and wherein the donor mouse ES cell comprises (i) a selection cassette that comprises a selectable marker operably linked to a first promoter, wherein the selection cassette is flanked upstream and downstream with a first and a second recombinase recognition site, wherein the first and the second recombinase recognition sites are orientated relative to one another to direct an excision, and wherein the modified allele is not flanked with the first and the second recombinase recognition sites, and, (ii) a second promoter operably linked to a gene encoding a recombinase that recognizes the first and the second recombinase recognition site and wherein the recombinase gene is operably linked with a 3′-UTR that comprises an miRNA recognition site that is recognized by an miRNA that is active in an undifferentiated cell but is not active in a differentiated cell so that the nucleotide sequence flanked by the first and the second recombinase recognition site is excised from a genome of the differentiated cell where the recombinase gene is expressed; (b) implanting the host mouse embryo comprising the donor mouse ES cell of step (a) into a mouse capable of gestating the host embryo; (c) maintaining the mouse of step (b) under conditions sufficient for gestation; and, (d) obtaining from the mouse of step (c) a genetically modified mouse that lacks the selectable marker in its genome and comprises the modified allele.