Transgenic mice

In article <C8M9Er.I47 at cosy.sbg.ac.at>, hartla at dsbgpx.edvz.sbg.ac.at wrote:
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> Dear collegue!
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> I am looking for a transgenic mouse with a transgene copy number as high as possible. We are studying tissue regeneration after transplantation and intend to use the transgene as a cell marker to distiguish transplant-derived cells from host cells. The mouse strain we used until now carries 50 copies of a transgene and the obtained signal is very weak. Thus, it is difficult to identify transgenic cells within a non-transgenic tissue section. To avoid tissue rejection, we also need mice of a compatibl
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> tic background as a host for transgenic implants. Please, keep in mind that expression of the transgene could interfere with histocompatibility in some systems as well.

I thought there was a transgenic mouse with the lac operon inserted
that produced blue cells when substrate was added to the culture.  An
article in Science referred to the strain, maybe a year ago?

Steve HOlland