De Sousa P A, Watson A J, Schultz R M
Departments of Obstetrics and Gynaecology and Physiology, University of Western Ontario, London,Ontario, Canada N6A 5C1.
Biol Reprod. 1998 Oct;59(4):969-77. doi: 10.1095/biolreprod59.4.969.
In the present study the abundance of mRNAs for eukaryotic translation initiation factors eIF-1A (formerly known as eIF-4C), -2alpha, -4A, -4E, and -5 was examined in in vivo-derived mouse embryos throughout preimplantation development using a semiquantitative reverse transcription-polymerase chain reaction assay. Although the mRNA profile for each gene is unique, only mRNA for eIF-1A transiently increases during embryonic gene activation (EGA) at the 2-cell stage, and this was confirmed by an independent hybridization-based assay. In in vitro-developed bovine embryos, mRNA for eIF-1A was transiently detected at the 8-cell stage, when the major activation of the genome occurs in this species. As in the mouse, detection in 8-cell bovine embryos was sensitive to the transcriptional inhibitor alpha-amanitin. It was also observed at the same time relative to cleavage in embryos cultured in defined medium under a reduced oxygen environment, and in medium supplemented with serum and somatic cells in 5% CO2 in air. Neither the chronology of early cleavage divisions nor the yield of bovine blastocysts differed in these culture media. Our results suggest that transient expression of eIF-1A in the mouse and cow is a conserved pattern of gene expression associated with EGA in mammals.
在本研究中，使用半定量逆转录-聚合酶链反应分析法，在植入前发育全过程的体内来源小鼠胚胎中检测了真核生物翻译起始因子eIF-1A（以前称为eIF-4C）、-2α、-4A、-4E和-5的mRNA丰度。尽管每个基因的mRNA谱都是独特的，但只有eIF-1A的mRNA在2细胞期胚胎基因激活（EGA）期间短暂增加，这一点通过基于杂交的独立检测得到了证实。在体外发育的牛胚胎中，当该物种基因组发生主要激活时，在8细胞期短暂检测到eIF-1A的mRNA。与小鼠一样，在8细胞牛胚胎中的检测对转录抑制剂α-鹅膏蕈碱敏感。在低氧环境下限定培养基中培养的胚胎以及在含5%二氧化碳的空气中添加血清和体细胞的培养基中培养的胚胎中，相对于卵裂，也在同一时间观察到了这种情况。在这些培养基中，早期卵裂分裂的时间顺序和牛囊胚的产量均无差异。我们的结果表明，eIF-1A在小鼠和牛中的短暂表达是与哺乳动物EGA相关的一种保守基因表达模式。
