Kanka J
Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Rumburska 89, 27721 Libechov, Czech Republic.
Theriogenology. 2003 Jan 1;59(1):3-19. doi: 10.1016/s0093-691x(02)01267-0.
The pre-implantation period of mammalian development includes the formation of the zygote, the activation of the embryonic genome (EGA), and the beginning of cellular differentiation. During this period, protamines are replaced by histones, the methylated haploid parental genomes undergo demethylation following formation of the diploid zygote, and maternal control of development is succeeded by zygotic control. Superimposed on this activation of the embryonic genome is the formation of a chromatin-mediated transcriptionally repressive state requiring enhancers for efficient gene expression. The development of this transcriptionally repressive state most likely occurs at the level of chromatin structure, because inducing histone hyperacetylation relieves the requirements for enhancers. Characterization of zygotic mRNA expression patterns during the pre-implantation period and their relationship to successful development in vitro and in vivo will be essential for defining optimized culture conditions and nuclear transfer protocols. The focus of this review is to summarize recent advances in this field and to discuss their implications for developmental biology.
哺乳动物发育的植入前期包括合子的形成、胚胎基因组激活（EGA）以及细胞分化的开始。在此期间，鱼精蛋白被组蛋白取代，甲基化的单倍体亲代基因组在二倍体合子形成后发生去甲基化，发育的母体控制被合子控制所取代。在胚胎基因组的这种激活之上，形成了一种染色质介导的转录抑制状态，高效的基因表达需要增强子。这种转录抑制状态的发展很可能发生在染色质结构水平，因为诱导组蛋白高度乙酰化可缓解对增强子的需求。表征植入前期合子mRNA表达模式及其与体内外成功发育的关系，对于确定优化的培养条件和核移植方案至关重要。本综述的重点是总结该领域的最新进展，并讨论其对发育生物学的意义。
