[Transgenerational transmission of bovine satellite DNA in transgenic mice]

Genetical, cytogenetical and molecular analysis was made for 5 generations of mice transgenic for bovine satellite DNA (Sat). In all cases transgenic mice were generated by crosses of transgenic males and females with normal (CBA x C57B1) mice. No abnormalities in the founder development were noticed. A normal (near 50 %) ratio of transgenic and nontransgenic offsprings was observed in blastocysts. However, profound differences occurred in the rate of transgene bearing offsprings, depending on the sex of grandparents rather than of parents. The grandfather Sat transmission resulted in the appearance of 0-52.4 % transgenic grandchildren, whereas the grandmother transmission ended in the theoretically expected rate. This means that stabilization of transsatellite took place upon the female germ line transmission (a positive grandmother effect). It is essential that in hemizygous transsatellite mice Sat integration led to the occurrence of mammary tumors, inflammation of uterine horns, and infringement of mother care of transgenic females. Simultaneous FISH and G-banding showed Sat to be localized in the internal region of chromosome 12 near Pax 9 and Brms 11 genes. Commonly, these genes are implicated in tumorigenesis as their expression decreases. Thus, a kind of silencing effect of these genes' expression may be supposed.