Patent ID: 7282621

Claim:
A transgenic mouse whose genome comprises: (a) in a first chromosome of a chromosome pair, a first polynucleotide comprising a first promoter operably linked to a first chimeric sequence encoding an N-terminal portion of a first marker and a C-terminal portion of a second marker separated by a first target site of a recombinase; and (b) at a homologous location of a second chromosome of the chromosome pair, a second polynucleotide comprising a second promoter operably linked to a second chimeric sequence encoding an N-terminal portion of the second marker and a C-terminal portion of the first marker separated by a second target site of the recombinase, wherein presence of the recombinase promotes recombination between the target sites of the first and second chromosomes; wherein recombinase-promoted somatic mitotic recombination between the target sites yields alternative pairs of X- or Z-segregated progeny cells, wherein the X-segregated progeny cells comprise a first progeny cell comprising the first chromosome, and a recombined variant of the second chromosome comprising the second promoter operably linked to a sequence encoding the N- and C-terminal portions of the second marker; and a second progeny cell comprising the second chromosome, and a recombined variant of the first chromosome comprising the first promoter operably linked to a sequence encoding the N- and C-terminal portions of the first marker, and wherein the Z-segregated progeny cells comprise a first progeny cell comprising the first chromosome and the second chromosome, and a second progeny cell comprising a recombined variant of the first chromosome comprising the first promoter operably linked to a sequence encoding the N- and C-terminal portions of the first marker; and a recombined variant of the second chromosome comprising the second promoter operably linked to a sequence encoding the N- and C-terminal portions of the second marker, wherein the first X-segregated progeny cell produces a second marker-specific signal, the second X-segregated progeny cell produces a first marker marker-specific signal, the first Z-segregated progeny cell produces neither a first nor second marker-specific signal, and the second Z-segregated progeny cell produces both a first and a second marker specific-signal.