Studies On Expression Patterns Of HAT1 Gene In Cattle Oocytes And Early Embryos

Histone acetylation and de-acetylation can change the structure of chromatin, involving in gene expression regulation and nuclear reprogramming. Histone acetyltransferase 1 (HAT1) takes part in the acetylation modification of new synthesized histones in cytoplasm and regulation acetylation level of histones. Investigation the expression patterns of HAT1 in oocytes' maturation and early embryonic development process is of great significance in understanding the genesis of early animals.High quality mRNA was purified from cattle germinal vesicle (GV) oocytes and reverse transcripted to cDNA. Two pairs of specific primers were designed according to the cattle's sequence in GenBank, for amplifing the target gene HAT1 and internal control gene SDHA. With the cDNA as template we successfully amplified the HAT1 and SDHA fragment, which were cloned and sequenced in the following. The amplification efficiency of HAT1 and SDHA genes were 106 percent and 97 percent respectively, so it could be used for statistically and quantitatively analysing the expression patterns of these genes with the 2^{-△△Ct} method.Then, we collected experiment samples of GV oocytes, metaphaseⅡ(MⅡ) oocytes and 2～4 cells, 8～16 cells, morulas and blastocysts, which were prepared by in vitro fertilization (IVF) and parthenogenetic activation (PA) respectively. The expression pattern of HAT1 was studied using real-time quantitative PCR, and the results show that:the relative expression levels of HAT1 in cattle GV oocytes, M II oocytes, and IVF embryos of 2～4 cells, 8～16 cells, morula and blastocyst were 1.00, 0.56, 0.09, 0.55, 0.43 and 0.31 respectively. And PA embryos in 2～4 cells, 8～16 cells, morula and blastocyst stages were 0.55, 0.55, 0.48 and 0.46 respectively. The highest expression level of HAT1 was from the GV oocytes, and the lowest expression level in 4 cells of IVF embryos(P<0.05); while in PA embryos, the relative expression levels of mRNA is stably.The above results indicate that the low expression of HAT1 gene in early embryos are of great important for the paternal chromatin reprogramming after fertilization; while the relative stable expression of HAT1 in PA embryos may be correlative with the absence of paternal gene in the embryo development.