Regulating the mid-blastula transition in zebrafish

描述(由申请人提供)：我们目前对早期胚胎发育的大部分遗传学理解都来自于旨在鉴定合子突变的筛查。越来越明显的是，许多早期发育是独立于合子基因组的。在早期胚胎发育过程中，母体提供的mRNA和蛋白质对DNA复制、细胞分裂和图案形成至关重要。胚泡中期过渡(MBT)是母体和受精卵发育程序之间的交界点，它需要母体基因才能正确执行。在MBT阶段，卵裂期的快速细胞分裂变慢，合子基因的表达随之显著增加。 这一建议将有助于阐明脊椎动物MBT进展的机制。它试图描述最近发现的一种母性效应突变体，尖叫停止(SRH)，它阻止了斑马鱼MBT的发育。拟议的实验将研究SRH在检查点调节中的作用，这一过程对果蝇和非洲爪哇的MBT都很重要。我将确定SRH基因的分子同一性，这可能是一个作用于MBT的新因素。此外，我将进行母体效应突变筛选，以确定SRH的其他等位基因，以及在MBT上也起作用的新基因。

DESCRIPTION (provided by applicant): Much of our current genetic understanding of early embryonic development is derived from screens designed to identify zygotic mutations. It is becoming increasingly evident that much of early development is independent of the zygotic genome. Maternal supplies of mRNA and protein are critical for DNA replication, cell division, and patterning during early embryogenesis. The mid-blastula transition (MBT) is the interface between the maternal and zygotic developmental program, and it requires maternal genes for its proper execution. At the MBT, the rapid cell divisions of the cleavage period slow, and a major increase in zygotic gene expression ensues. This proposal will help elucidate the mechanisms involved in the progression of the MBT in vertebrates. It seeks to characterize a recently identified maternal-effect mutant, screeching halt (srh), which arrests development at the MBT in zebrafish. The proposed experiments will investigate the role of srh in checkpoint regulation, a process important to the MBT in both Drosophila and Xenopus. I will determine the molecular identity of the srh gene, which is likely a novel factor acting in the MBT. In addition, I will perform a maternal-effect mutagenesis screen to identify additional alleles of srh, as well as novel genes that also function at the MBT.