斑马鱼母源因子在胚胎发育中的作用

Maternal Factors Regulate Embryonic Development in Zebrafish

动物受精时,精子主要是将雄原核释放到卵子中,形成的合子中雌、雄原核融合为合子核,但受精卵基因组在前几次有丝分裂过程中不转录,合理的逻辑性推测是其早期发育完全依赖于卵质中储存的RNA和蛋白质,即母源因子.上世纪80年代对无脊椎动物的正向遗传研究发现,母源因子在卵子和胚胎极性的决定、早期胚胎的图式形成等方面发挥了决定性作用.过去10多年来,通过对斑马鱼和小鼠突变体的研究,也证明母源因子在脊椎动物胚胎早期发育中起着重要作用.本文主要综述斑马鱼母源因子在卵母细胞的极性、卵子的激活、早期细胞分裂、母源mRNA的清除、合子基因转录激活以及胚层的形成和分化、体轴的建立等方面的作用,相关知识对于研究人类生育障碍和先天性疾病的发生机制和诊治有借鉴意义.

During fertilization in animals, a sperm launches its pronucleus into the egg. The zygotic diploid nucleus is formed by fusion of male and female pronuclei, however, the zygotic genome is transcriptionally inactive during the first few mitotic divisions. A logic speculation is that early embryonic development relies on maternal factors such as RNA and proteins that are supplied by the egg. Forward genetic studies in invertebrates, mainly performed in the 1980＇s, uncover essential roles of maternal factors in determining the oocyte polarities, the embryonic axes and pattern formation, In the past two decades, analyses of maternal mutants in zebrafish and mice also reveal important functions of maternal factors in embryonic development. This review mainly focuses on identified functions of maternal factors in developmental processes of the zebrafish embryo, including oocyte maturation, egg activation, blastomere cleavage, clearance of maternal mRNAs, zygotic genome activation as well as germ layer induction and patterning and body axis formation. The findings in model animals will provide a base for studying mechanisms of human infertility, miscarriage and birth defects.