Chromatin acetylation in human oocytes

Abstract

Objectives: The frequency of aneuploidies in human oocytes is extremely high. It is hypothesized that the cause may be due to abnormal chromatin (histone) acetylation/deacetylation. The aim of our study was to analyzed the acetylation/deacetylation pattern in spare human oocytes. Materials and Methods: Human spare oocytes (311), in other words oocytes that were not mature when collected from follicles or control oocytes (bovine, mouse), were fixed with paraformaldehyde and then labeled with antibodies against acetylated histones. Results: Labeling against AcH4/K12 or hyperacetylated H4 showed high intensity of the fluorescence signal in all immature (germinal vesicle staged) and approximately 50% of the maturing (mature) oocytes. Conclusion: In conclusion, the labeling of human oocytes (chromosomes) showed very inconsistent patterns of acetylation/deacetylation, what may suggest they did not reach the metaphase II stage at the time of follicle aspiration, and were epigenetically abnormal. It may also explain the high frequency of chromosomal abnormalities in human oocytes.