Maternal Control of Ascidian Development

海鞘发育的母体控制

• 批准号: 0080060
• 负责人: William Smith
• 金额: $ 35.25万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0080060&HistoricalAwards=false
• 关键词: Maternal; Control; Ascidian; Development

0080060SmithZygotic development begins with the fusion of sperm and egg. While sperm provides only the male pronucleus, the egg contributes, in addition to the female pronucleus, the egg cytoplasm which contains molecules essential for proper development of the embryo. These "maternal factors" in the egg control numerous process include sperm recognition, cell-cycle activation, and determination of the primary axes and germ layers. Ascidians, which are primitive members of the chordate phylum, have classically been used to study the role of maternal factors in early development. In fertilized ascidian eggs extensive rearrangement of egg cytoplasm can be observed. The partitioning of distinct cytoplasmic factors specifies many tissue types including muscle and endoderm.This project will use newly developed genetic methods in ascidians to analyze maternal control of early development. Ascidians are particularly well suited for this type of analysis. The species to be used in this project, Ciona savignyi, is a hermaphrodite with the capacity for self fertilization. These properties streamline procedures for identification and recovery of mutants. Briefly, adult C. savignyi are first treated with the chemical mutagen ENU. Sperm from the ENU-treated animals is crossed to wild-type eggs to generate heterozygous F1s. The F1s are grown to maturity (10-12 weeks), and then sperm and eggs are collected from each and mixed to make a self-fertilized F2 generation. One-quarter of the F2s will be homozygous for each mutant locus carried by an F1. When the F2s reach maturity, the eggs are dissected, crossed with wild-type sperm, and then screened for mutant phenotypes. If a potential mutant is observed, sperm from the same animal is crossed to wild-type eggs in order to recover the mutation. A pilot screen has shown that this screen is feasible, and a number of candidate mutants are being characterized. Funding from this proposal will be used to complete the pilot screen, perform an expanded screen, and characterize recovered mutants in order to better understand the nature of the mutations.

[00:80 . 60]合子发育始于精子和卵子的融合。精子只提供雄性原核，而卵子除了提供雌性原核外，还提供卵细胞质，其中含有胚胎正常发育所必需的分子。这些“母体因子”在卵子中控制着许多过程，包括精子识别、细胞周期激活、主轴和胚层的决定。海鞘是脊索动物门的原始成员，一直被用来研究母体因素在早期发育中的作用。在受精卵中，可以观察到卵细胞质的广泛重排。不同细胞质因子的分配规定了许多组织类型，包括肌肉和内胚层。本项目将使用新开发的海鞘遗传方法来分析母体对海鞘早期发育的控制。海鞘人特别适合这种类型的分析。在这个项目中使用的物种是一种具有自我受精能力的雌雄同体。这些特性简化了识别和恢复突变体的程序。简单地说，首先用化学诱变剂ENU处理成虫。经过enu处理的动物的精子与野生型卵子杂交，产生杂合的F1s。将f1生长到成熟（10-12周），然后从每只f1中收集精子和卵子并混合，形成自受精的F2代。对于一个F1携带的每个突变位点，四分之一的F2s将是纯合的。当F2s成熟时，卵细胞被解剖，与野生型精子杂交，然后筛选突变表型。如果观察到潜在的突变，则将同一动物的精子与野生型卵子杂交，以恢复突变。试点筛选表明，这种筛选是可行的，一些候选突变体正在被表征。来自该提案的资金将用于完成试点筛选，进行扩大筛选，并表征恢复的突变体，以便更好地了解突变的性质。