ABSTRACT
@#【Objective】To investigate the impact of long- term storage time on epigenetic modification of histone in human cleavage stage embryos.【Methods】According to the length of storage time，donated embryos after slow-freezing were divided into 3 groups ：6-year group ，9-year group ，and 12-year group ，while the control group consisted of donated fresh embryos. Immunocytochemistry was performed to compare the expression levels of HDAC1， H3K9ac， H3K4me3 ，and H3K9me3 among 4 groups. Transcription levels of HDAC1 ，SUV39H1 ，SETDB1 ，and KDM5A were analyzed through Single-Cell qRT-PCR.【Results】The relative abundances of HDAC1 and SUV39H1 mRNA showed no significant differences among 4 groups（P > 0.05）. SETDB1 exhibited a climbing pattern as storage time increased，but no significant difference was observed（P > 0.05）. There were no differences in H3K9 trimethylation and H3K9 methylation among 4 groups. However ，the expression level of KDM5A increased with the increasing storage time（P < 0.05）.【Conclusions】 Storage time did not affect the expression of deacetylase HDAC1，methylase SUV39H1 and SETDB1. H3K9ac/me3 and H3K4me3 also exhibited no significant difference as the storage time increases. However ，the increasing storage length might induce the elevating expression of demethylase KDM5A，which may be associated with inhibition of embryonic transcription.