CIS EFFECT OF LACZ SEQUENCES IN TRANSGENIC MICE

Transgenic mice carrying the 3-hydroxy-3-methylglutarylCoA reductase ( HMG) promoter driving the Escherichia coil beta-galactosidase (lacZ) g ene did not display the expected ubiquitous and constitutive expressio n in HMG-lacZ transgenic mice. The same promoter is however able to dr ive ubiquitous expression of the chloramphenicol acetyltransferase (ca t) gene. Two lines of double HMG-lacZ and HMG-cat transgenic mice were obtained in which the two constructs were integrated at the same geno mic sites. These mice expressed both reporter genes, but exclusively i n the testes. These results suggest that the lacZ sequence might inter fere negatively with the expression of the adjacent HMG-cat transgene.