Tg(Iap11-1-lacZ)22Thei

The transgene construct comprises the long terminal repeat (LTR) and part of the 5' untranslated sequence from the transposition competent intracisternal A particle associated with the interleukin 3 gene in the WEHI-3B mouse leukemia cell line (Iap11-1, also known as Iap(Il-3) or IAP-IL3) driving expression of the E. coli lacZ coding sequence modified to express beta-galactosidase with an amino-terminal nuclear localization signal (NLS-lacZ), which is followed by the intron and polyadenylation signal from the simian virus 40 (SV40) large T antigen gene. From densitometric Southern blot analysis, line 22 is estimated to carry 60 transgene copies. Reverse transcription-polymerase chain reaction (RT-PCR) analysis demonstrates presence of mature (spliced) mRNA at a high level in testis and at a 10-fold lower level in brain of transgenic mice, but not in kidney, liver, spleen, intestine, thymus or heart. X-gal staining reveals expression of the reporter enzyme only in the testis, with staining limited to groups of cells along the seminiferous tubules. Histochemical examination of tissues from embryonic day (E)13.5 through adulthood shows expression to be restricted to gonocytes and premeiotic, undifferentiated Type A spermatogonia. (J:34385)