Partial deletion of the Y chromosome removes the effect of paternal genome imprinting on periovum sensitivity to hyaluronidase in mice.

Cumulus-oocyte complexes from the two consomic strains of mice, B10.BR and B10.BR-Ydel (with a partial deletion of the Y chromosome) and the BALB/c strain, as well as reciprocal F1 and F2 hybrids, were tested for their susceptibility to attack by hyaluronidase. The cumulus cell dispersal was significantly more rapid in the eggs of B10.BR females and of F1 and F2 hybrid females sired by the B10.BR males than in those of BALB/c females and hybrids sired by BALB/c males. These results confirm the earlier data of Bander et al. (1989) which were interpreted as evidence of paternal imprinting of the C57BL genome. In contrast, cumulus cell dispersal in the eggs of females sired by B10.BR-Ydel males was significantly slower than in females sired by B10.BR males, and did not differ from that in the BALB/c strain. The results suggest that the partial deletion of the Y chromosome abolished the effect of paternal genome imprinting which is observed in the B10.BR strain.