Gene networks specifying cell lineages in a polychaete

描述(由申请人提供)：不对称细胞分裂的使用是在发育过程中产生细胞类型多样性的核心。这一过程已经在秀丽线虫和黑腹果蝇中用遗传和分子方法进行了广泛的研究。然而，这两种生物在进化上都具有很高的衍生性，可能是相对密切的亲缘关系。因此，在没有与更远相关和更少派生的实验系统相比较的情况下，很难定义关键调控通路的保守核心成分。为此，我们建议启动对一种更有可能类似原始状态的双边生物的研究，即环节动物Platynereis umerilii。这种海洋多毛类显示出连接无脊椎动物和脊椎动物的发育特征，并提供了令人印象深刻的技术优势。在扁豆的早期胚胎发生中，典型的不对称细胞分裂产生了不同的创始细胞谱系，例如被称为4d的中胚层细胞谱系。使用RNA干扰可以很容易地获得数千个同步的胚胎阶段，胚胎是透明的，基因功能可以降低。为了确定早期发育的重要调控因子，我们建议建立一个杜默里氏拟青霉EST文库和一个原位数据库，并使用亲本dsRNA干扰和靶基因的特定抑制物来检查基因需求。我们还将使用微阵列技术来检测突变胚胎中基因表达的全球变化。我们的目标是探索和开发这一用于研究不对称细胞分裂和神经系统发育的新模型系统，并将其用作定义细胞机械中最高度保守、功能要求最高的核心部件的比较工具。新发现的和保守的基因座也将在线虫和果蝇中进行研究。

DESCRIPTION (provided by applicant): The use of asymmetric cell division is central to generating cell type diversity during development. This process has been studied extensively using genetic and molecular approaches in both Caenorhabditis elegans and Drosophila melanogaster. However, both of these organisms are evolutionarily very high derived and may be relatively closely related. Thus it is difficult to define conserved core components of key regulatory pathways without comparison to a more distantly related and less derived experimental system For this purpose, we propose to initiate studies of a bilaterian organism more likely to resemble a primitive state, the annelid Platynereis dumerilii. This marine polychaete exhibits developmental features that link invertebrates and vertebrates, and provides impressive technical advantages. During early embryogenesis of Platynereis stereotypic asymmetric cell divisions generate distinct founder cell lineages, such as a mesodermal cell lineage called 4d. Thousands of synchronous embryonic stages can be easily obtained, the embryos are transparent and gene function can be reduced using RNA interference. To identify important regulators of early development, we propose to generate a P. dumerilii EST library and an in situ data base, and to examine gene requirements using both parental dsRNA interference and specific inhibitors of target genes. We also will employ microarray techniques to examine global changes in gene expression in mutant embryos. Our goals are to explore and exploit this new model system for studies of asymmetric cell division and nervous system development, and to use it as a comparative tool for defining the most highly conserved, functionally required core components of cellular machineries. Newly discovered and conserved loci will also be studied in C. elegans and Drosophila.