小鼠体内外受精植入前胚胎全基因组甲基化模式比较

为考察体外受精、操作及培养环境对体外受精的小鼠植入前胚胎全基因组DNA甲基化模式的影响,本研究以体内受精的植入前胚胎作为对照,采用间接免疫荧光法检测小鼠体内外受精植入前胚胎基因组DNA甲基化模式.实验结果表明,体外受精各期植入前胚胎呈现出与之相应时期的体内受精植入前胚胎不同的DNA甲基化模式和水平,原核期甲基化水平较高,2-4-、8-细胞期明显降低,而桑葚胚和囊胚期又略有升高.各期体外受精植入前胚胎的基因组DNA甲基化水平都比同时期体内受精胚胎的甲基化水平低.本实验结果部分显示了体外受精、操作及培养环境可能对正常的DNA甲基化模式产生影响,造成体外受精植入前胚胎甲基化模式异常.

Comparison of Genomic-wide Methylation Patterns in in vivo and in vitro Fertilization Mouse Preimplantation Embryos

In order to investigate the influences of in vitro fertilization, operation and culture environment on mouse IVF preimplantation embryos, the DNA methylation patterns of in vivo fertilization and IVF mouse preimplantation embryos were investigated by immunofluorescence staining with an antibody against 5-methylcytosine (5-MeC). Using in vivo fertilized preimplantation embryos as the control, we examined genomic-wide DNA methylation patterns of in vivo fertilization and IVF mouse preimplantation embryos. The result showed that IVF mouse preimplantation embryos present different genomic-wide DNA methylation pattern compared to in vivo fertilization mouse preimplantation embryos. The methylation level was higher in pronuclear stage, and reduced in 2-, 4-, 8-cell stage and furthermore slightly higher in morula and blastocyst stage. The DNA methylation levels of IVF embryos at different developmental stages were lower than those of in vivo fertilization embryos. In vitro fertilization, manipulation and culture environment might affect the DNA methylation pattern and result in abnormal methylation pattern of in vitro fertilization embryos.