Molecular Biology of the Oocyte

母性效应基因：在小鼠卵细胞减数分裂成熟过程中终止的转录，只有在两细胞胚胎的胚胎基因组被强烈激活后才恢复。这种卵母细胞和胚胎基因转录之间的过渡期决定了储存的母体因子在早期哺乳动物发育中的作用。这些成分由母体效应基因编码，在卵子发生过程中积累，并为受精、胚胎基因组激活和卵裂期胚胎发生提供必要的途径。使用小鼠转基因，在这些过程中，个别或复杂的母体因素的作用进行了研究。 施肥：哺乳动物精卵识别的分类特异性导致受精，主要是由透明质酸介导的，透明质酸是排卵卵周围的细胞外基质。虽然是3-4个糖蛋白的简单结构，但这种精子与透明体结合的分子基础一直存在争议。目前的研究调查：1）细胞外透明体形成的分子生物学; 2）支持分类群特异性精卵识别的透明体基质的分子要求; 3）导致配子融合所必需的顶体胞吐作用的机制;和4）防止受精后多精受精的过程。 早期发育：小鼠胚胎基因组的激活在单细胞受精卵的晚期开始，并在双细胞分裂阶段完全进行。在着床前小鼠发育中，当八个卵裂球紧密形成极化桑椹胚时，就建立了预示内细胞团和胚外滋养外胚层的初始细胞谱系。母性效应基因在哺乳动物这些过程中的作用构成了一个快速发展的调查领域。目前的研究调查：1）影响小鼠早期发育的新的母体效应基因; 2）最近描述的母体编码的皮层下复合体的组分;和3）复合体的丢失影响卵裂阶段胚胎发生的机制。

Maternal Effect Genes: Transcription that terminates during meiotic maturation of mouse eggs, resumes only after robust activation of the embryonic genome of the two-cell embryo. This interregnum between oocyte and embryonic gene transcription dictates a role for stored maternal factors in early mammalian development. Encoded by maternal effect genes, these components accumulate during oogenesis and provide pathways essential for fertilization, activation of the embryonic genome and cleavage stage embryogenesis. Using mouse transgenesis, the role of individual or complexes of maternal factors is investigated in these processes. Fertilization: The taxon-specificity of sperm-egg recognition in mammals that results in fertilization is mediated primarily by the zona pellucida, an extracellular matrix surrounding ovulated eggs. Although a simple structure of 3-4 glycoproteins, the molecular basis of this sperm binding to the zona pellucida has been controversial. Current studies investigate: 1) the molecular biology of the formation of the extracellular zona pellucida; 2) molecular requirements of the zona pellucida matrix to support taxon-specific sperm-egg recognition; 3) mechanism that result in acrosome exocytosis necessary for gamete fusion; and 4) the processes by which post-fertilization polyspermy is prevented. Early Development: Activation of the embryonic genome in mice begins late in the one-cell zygote and is fully underway by the two-cell cleavage stage. Initial cell lineages that presage the inner cell mass and extra-embryonic trophectoderm are established when eight blastomeres compact to form polarized morulae in pre-implantation mouse development. The role of maternal effect genes in these processes in mammals constitute a rapidly evolving area of inquiry. Current studies investigate: 1) novel maternal effect genes that affect early mouse development; 2) components of a recently described maternally encoded subcortical complex; and 3) mechanisms by which the loss of the complex affects cleavage stage embryogenesis.