GENETICS OF CAENORHABDITIS ELEGANS SPERM MORPHOGENESIS

秀丽隐杆线虫精子形态发生的遗传学

• 批准号: 6053522
• 负责人: STEVEN W. L'HERNAULT
• 金额: $ 25.17万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-08-01 至 2004-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6053522
• 关键词: Caenorhabditis elegans; alleles; cell differentiation; cytogenetics; developmental genetics; electrophysiology; gene expression; gene mutation; genetic mapping; genetic recombination; genetic regulation; genetically modified animals; histogenesis; immunocytochemistry; molecular cloning; northern blottings; polymerase chain reaction; site directed mutagenesis; southern blotting; spermatogenesis; suppressor mutations; voltage /patch clamp

When cells divide, organelles and macromolecules can be partitioned unequally between daughters. This process of asymmetric partitioning during division is central to cellular differentiation and the long range goal of this study is to understand its genetic control. We study the genetic control of asymmetric partitioning during Caenorhabditis elegans spermatocyte development, which offers some of the advantages of a unicellular system within a metazoan organism. C. elegans primary spermatocytes will develop into spermatids in vitro in simple, chemically defined media that lacks added growth factors, hormones or accessory cells. Many mutants specifically disrupt the distinctive asymmetric partitioning required for C. elegans spermatocytes to properly divide and differentiate into spermatids. Such spermatogenesis-defective (spe) mutants affect a specific, cytologically obvious organelle that can be easily followed during spermatocyte differentiation. These organelles, the ER/Golgi derived fibrous body-membranous organelles (FB-MOs), are key players in asymmetric partitioning and they do not function properly in the spe mutants that are the subject of this proposal. The mutants to be studied fall into two distinctive phenotypic classes. Class I mutants show cytologically evident defects in FB-MO morphology and proper asymmetric partitioning does not occur because of these defects. Class II mutants initiate FB-MO morphogenesis normally, but fail to properly position these organelles because the machinery required for proper asymmetric partitioning is defective. These proposed analyses of Class I and Class II mutants will reveal the mechanism of asymmetric partitioning and how FB-MOs participate in this important process. This analysis will test the hypothesis that specific gene products actively segregate the FB-MOs during morphogenesis. The discovery that wild type FB-MOs contain the SPE-4 protein (a homolog of the Alzheimer's disease-causing presenilins), and that this protein is missing in the Class I mutant spe-4, has heightened the significance of and interest in this organelle. The role of presenilin homologs during asymmetric partitioning can only be determined in a metazoan system and the single-celled nature of C. elegans spermatocytes facilitates cell biological analyses. Asymmetric partitioning is a generally important problem that will provide insights into the pathologic changes occurring during diseases such as cancer and Alzheimer's disease. Additionally, C. elegans spermatogenesis is the best model for this process in the many medically and agriculturally important parasitic nematodes that are difficult to study in the laboratory.

当细胞分裂时，细胞器和大分子可以在子细胞之间不均等地分配。 这种分裂过程中的不对称分配是细胞分化的核心，本研究的长期目标是了解其遗传控制。 我们研究了秀丽隐杆线虫精母细胞发育过程中不对称分配的遗传控制，这提供了后生动物生物体内单细胞系统的一些优势。 C.线虫初级精母细胞在体外在简单的、化学成分确定的培养基中发育成精子细胞，该培养基不添加生长因子、激素或辅助细胞。 许多突变体特异性地破坏了C.精母细胞正常分裂并分化为精子细胞。 这样的精子发生缺陷（spe）突变体影响一个特定的，细胞学上明显的细胞器，可以很容易地在精母细胞分化。 这些细胞器，ER/高尔基体衍生的纤维体膜细胞器（FB-MO），是不对称分配的关键球员，他们不正常的功能，在spe突变体，这是本提案的主题。 待研究的突变体分为两类不同的表型。 I类突变体表现出FB-MO形态的细胞学明显缺陷，并且由于这些缺陷而没有发生适当的不对称分配。 II类突变体正常启动FB-MO形态发生，但未能正确定位这些细胞器，因为适当的不对称分配所需的机器是有缺陷的。 I类和II类突变体的这些拟议的分析将揭示不对称分配的机制以及FB-MO如何参与这一重要过程。 该分析将检验特定基因产物在形态发生期间主动分离FB-MO的假设。 野生型FB-MO含有SPE-4蛋白（引起阿尔茨海默病的早老素的同源物），并且该蛋白在I类突变体SPE-4中缺失的发现，提高了对该细胞器的重要性和兴趣。 早老素同系物在不对称分配中的作用只能在后生动物系统中确定，而C。精母细胞有助于细胞生物学分析。 不对称分配是一个普遍重要的问题，将提供洞察疾病，如癌症和阿尔茨海默氏病期间发生的病理变化。 此外，C.在许多医学和农业上重要的寄生线虫中，线虫精子发生是这一过程的最佳模型，这些线虫难以在实验室中进行研究。