Tg(Camk2a-cre/folA)1Amax

A cDNA sequence encoding a mutant destabilizing form (DD) of bacterial dihydrofolate reductase (ecDHFR; folA) attached to cre recombinase cDNA was inserted downstream of the Camk2a promoter in a targeting vector. The construct also contained 5' and 3' introns flanking the DD-cre sequence as well as a 3' SV40 polyadenylation signal. The linearized construct was used for pronuclear injection and two founders carrying the transgene were identified by PCR. These were bred to Ai9 reporter mice and treated with trimethoprim (TMP) to stabilize the cre protein. One line showed high levels of recombination with TMP treatment with low levels of constitutive cre activity in cortex except for the dentate gyrus. The other line showed very low leakiness of cre activity but also low TMP-induced recombination and was not used for biochemical or behavioral studies. (J:201125)