mouse strain STOCK Tg(tetO-Pdx1,lacZ)958.1Macd mouse strain A mouse strain containing a transgene in which bicistronic Pdx1-lacZ (transgene) is driven by the TRE promoter (NCBI Gene ID: ). Mice hemizygous and homozygous for the transgenic insert are viable, fertile, of normal size, and do not display any behavioral abnormalities. Expression of the bicistronic transgene is directed by a heptameric tetO repeat fused to a minimal promoter (collectively the tetracycline-response element, or TRE). Transgenic mice do not express lacZ until a tetracycline-transactivator (tTA) protein is introduced; thereafter Pdx1 and lacZ from the transgene are expressed. All cells expressing transgenic Pdx1 coexpress the reporter. Further, mRNA levels of the transgene and endogenous Pdx1 fluctuate in concert during development. This mouse was originally designed to be mated to an apancreatic targeted mutant with the coding sequence of the Pdx1 locus replaced with that for tTAoff (see BCBC #M541). The combined mutations allow normal pancreatic development and function until doxycycline treatments render the mouse conditionally null of the endogenous gene. For this configuration, rescue of pancreatic development is most effective when the transgene locus is homozygous. This allows embryonic developmental arrest at desired stages or cessation of function in adult mice by administration of tetracycline/doxycycline. This transgenic strain may be useful in studies of pancreatic development and endocrine/exocrine function and diabetes. This strain can also be bred with other tTA strains for regulating Pdx1 expression in other contexts. Person: Mark A. Magnuson, Jill Lindner, Jean-Philippe Cartailler STOCK Tg(tetO-Pdx1,lacZ)958.1Macd Vanderbilt University Medical Center