The Effects Of Ovary Preservation In Different Conditions On GV Chromatin Configuration And Histone Epigenetic Modifications Of Mice Oocytes

Researches about the regulatory mechanism of chromatin configuration transformation of oocyte at GV stage and the relationship it with histone epigenetic modification and the development potential are of important significance to clarify the maturation mechanism of oocyte and to improve oocyte quality and the development potential.Although previous studies have shown that NSN would transform into SN before maturation and oocytes with SN configuration have higher developmental potential than NSN, its mechanism is not clear. Results related to core histone modification of GV oocytes were conflict with chromatin configuration change and gene activity change, and it is particularly worth exploring using a system where the SN chromatin configuration can be uncoupled from these histone modifications. We chose mice aged 18-19 days, after ovariectomizing we preserved in vitro for simulating the transport process, and then study the effects of ovary preservation in different conditions on GV chromatin configuration, development potential and histone modification in oocyte.The results of our study show that:(1) oocyte chromatin became more condensed and abnormal chromatin increased after ovary preservation;(2) 37? preserving for 1h got the highest development potential among the five groups. As the temperature goes up and the time goes by, the development potential of the oocytes falls down;(3) As the temperature goes up and the time goes by, histone acetylation of H3K14, H4K12 and H4K16, histone methylation of H3K4 and H3K9 and histone phosphorylation of H3S10 decrease gradually, which are coincidence with the development potential of the oocytes;(4) As the temperature goes up and the time goes by, apoptosis rate of granulosa cells goes by and the expression level of FasL increased;(5) As the temperature goes up and the time goes by, the expression level of Fas increased in oocytes.From the results, we can know that ovary preservation at high temperature increases the condensation phenomenon, heterochromatin ring of not strict SN configuration goes further condensed and then distance between adjacent heterochromatic mass goes bigger and the ring becomes incomplete; high temperature decreased oocyte development potential which is coincidence with the histone epigenetic modification; FasL/Fas signal pathway plays a role in granulosa cells apoptosis during the ovarian preservation in vitro, a mild apoptosis promotes the development potential of oocytes and high levels of apoptosis inhibits the development potential of oocytes.