Changes In Histone Acetylation During Oocyte Growth In Old Mouse

The changes in the acetylation of histone were observed in oocytes at different developmental stages which were detected from 3-to 4- week-old C57/B6 mice and 40-to 42- week-old C57/B6 mice respectively by immunofluorescence staining, and the mRNA expression levels of Hdacl and Hdac3 in oocytes at different developmental stages in young and old mouse were examined by RT-PCR. Our results showed: (1) The acetylation levels of histone (H4/K12,H4/K16,H4/K5 and H3/K14) increased gradually with the growth of the oocytes and reached the maximum at fully grown stage, then it almost disappeared except that of H4/K12 at MⅡstage. Compared with young mouse, the acetylation levels of histone in fully grown oocytes decreased in old mouse.(2) The expression levels of Hdac-1 and Hdac-3 mRNA gradually decreased in both young and old mousc before "fully grown" stage, then increased at MⅡstage in old mouse. Compared with young mouse, the expression levels of Hdac1 mRNA in oocytcs before "fully grown" stage decreased significantly in old mouse (P＜0.01); the expression levels of Hdac3 mRNA in oocytes between these mice have no significant difference. These results indicated that both histone acetylation and the expressions of HDACs showed the anomaly in the oocytes of old mouse.