Pvalb^{tm5.1(cre/folA)Hze}

ES cells previously targeted with a T2A-Cre vector immediately downstream of the parvalbumin translational STOP codon were re-targeted with a "T2A-hDHFR/Cre" vector and a FLP-expressing plasmid to facilitate recombination. Correctly re-targeted ES cells had (from 5' to 3') a partial Pvalb intron 3 sequence containing an frt3 site, a partial Pvalb exon 4 sequence up to (but not including) the endogenous stop codon, a T2A in-frame with the Pvalb coding sequence, a dCre fusion gene that is in-frame with the Pvalb codingsequence, the Pvalb 3' UTR sequence from exon 4, an AttB site, a PGK-hygromycin-SV40polyA cassette (with an mRNA spice donor-frt5 site-mRNA spice acceptor in the hygromycin gene), and an AttP site. The dCre fusion gene ( destabilized Cre, hDHFR/Cre or ecDHFR/Cre) is Cre recombinase fused at its N terminus to the first 159 amino acids of the E.coli K-12 strain chromosomal dihydrofolate reductase gene (DHFR or folA) with the G67S mutation and modified to include the R12Y/Y100I destabilizing domain mutations. Correctly re-targeted ES cells were injected into recipient blastocysts. The resulting chimeric animals were bred to PhiC31-expressing mice to delete the AttB/AttP-flanked sequences and replace them with the recombined AttB/AttP site (AttL). With trimethoprim induction, cre expression (by ISH detection) is efficient in scattered cells throughout the cortex, as well as restricted populations in the cerebellum, medulla, pons, pallidum, and thalamus. (J:199219, J:220523)