Regulation of Sperm Development in C. elegans

摘要复杂的后生动物包含令人难以置信的各种细胞类型。这种变化反映了不同细胞发挥的特殊作用：红细胞运输氧气，肌肉细胞产生力量，神经元传递电脉冲。一个单一的细胞，受精卵，是如何产生如此显著的多样性的？在很大程度上，细胞分化是由特定细胞类型基因的表达决定的。表达在空间和时间上都受到限制，在组织和阶段特定的模式中诱导特定步骤或过程所需的基因组。表达模式由转录因子的活性控制，这些转录因子通常在调节级联中发挥作用。这项拟议研究的目标是了解线虫精细胞分化的发育程序。这个模型系统提供了将细胞学和遗传学研究与全基因组分析相结合的机会，以在分子水平上了解细胞分化的复杂过程。对几乎完整的基因组进行DNA微阵列筛选，发现了1343个在精子产生过程中被诱导的基因。这些富含精子的基因使细胞独特地适应其角色，因此是进一步分析的重点。拟议的实验旨在根据表达模式将这些基因分组，并确定这些分组在精子发育的不同阶段发挥作用。其策略是识别调节精子丰富基因表达的转录因子；分离这些转录因子中的突变；并表征这些突变导致的生育、精子细胞发育和基因表达方面的缺陷。这项研究的更广泛的影响是为细胞发育的基本机制提供见解。将功能角色分配给以前未确定特征的基因将为研究其他生物体中的同源物提供角色和途径。此外，拟议的研究将在实验室提供关键的学生培训。这些实验在设计上是模块化的，因此适合于本科生研究项目(包括一个单一的实验)，同时保持足够的综合性，当组合在一起时，用于研究生/博士后研究项目。

Summary Complex metazoans contain an incredible variety of cell types. Such variety reflects the specialized roles performed by different cells: the transport of oxygen by red blood cells, the generation of force by muscle cells, the transmission of electrical impulses by neurons. How does a single cell, the fertilized egg, give rise to such remarkable diversity? In large part, cellular differentiation is determined by the expression of cell-type-specific genes. Expression is restricted both spatially and temporally, with groups of genes required for a particular step or process induced in tissue and stage-specific patterns. The expression patterns are governed by the activity of transcription factors that typically function in a regulatory cascade. The goal of the proposed research is to understand the developmental program that governs sperm cell differentiation in the nematode Caenorhabditis elegans. This model system provides the opportunity to combine cytological and genetic studies with genome-wide analyses to understand the complex process of cellular differentiation at the molecular level. DNA microarray screens of nearly the complete genome have identified 1,343 genes that are induced during sperm production. Those spermenriched genes make the cell uniquely suited to its role and thus are the focus of further analysis. The proposed experiments are designed to divide those genes into groups on the basis of expression patterns, and to identify the different stages of sperm development at which those groups function. The strategy is to identify transcription factors that regulate expression of sperm-enriched genes; to isolate mutations in those transcription factors; and to characterize the defects in fertility, sperm cell development, and gene expression that result from those mutations. The broader impact of this research is to provide insights into the fundamental mechanisms of cellular development. The assignment of functional roles to previously uncharacterized genes will suggest roles and avenues of investigation for homologs in other organisms. In addition, the proposed research will provide critical student training in the laboratory. The experiments are modular by design, and thus appropriate for undergraduate research projects (encompassing a single experiment) while remaining sufficiently comprehensive, when combined, for graduate/postdoctoral research projects.