COELOMOCYTES IN C.ELEGANS--CELL FATE DETERMINATION

秀丽隐杆线虫将作为研究细胞发育过程中命运规范的模型系统。本研究的重点是如何在不同的中胚层命运之间做出选择。在高等真核生物中，中胚层的模式对正常发育至关重要，因为这些细胞有助于血液、器官和结缔组织的形成。这一过程涉及细胞内在和外在因素的复杂相互作用，从而在正确的时间和正确的地点形成不同类型的组织。不能正确地指定中胚层命运可导致严重的发育缺陷或死亡。由于基因组测序和已知秀丽隐杆线虫所有体细胞的谱系，该系统允许在细胞水平上快速表征基因活动。两种方法将用于解决中胚层模式的问题。首先，将进行遗传筛选，以分离改变中胚层细胞（称为体腔细胞）规格的突变。这些细胞为研究非肌肉中胚层的命运提供了极好的机会，因为它们来自谱系的三个不同部分，并且在胚胎发生时很晚才出生。体腔细胞规格缺陷将使用组织特异性标记物进行检测。突变和相应的基因将使用标准的遗传和分子技术进行表征。基因功能将被表征使用激光消融，镶嵌分析，和表达研究。其次，胚胎操作实验，即激光消融，将进行确定细胞内在线索和感应信号的相对贡献。这些研究有望深入了解发育过程中细胞命运规范的基本机制。此外，由于已知许多参与类似过程的分子在癌细胞中被激活，这项工作可能会增加我们对肿瘤形成和转移的理解。

The nematode Caenorhabditis elegans will be used as a model system to study cell fate specification during development. This research is focused on addressing how choices between different mesodermal fates are made. In higher eukaryotes, patterning of mesoderm is essential for proper development, since these cells contribute to blood, organs, and connective tissues. This process involves the complex interplay of cell intrinsic and extrinsic factors so that the different tissue types are formed at the correct time and in the correct place. Failure to properly specify mesodermal fates can lead to severe developmental defects or death. Since the genome is sequenced and since lineage of all somatic cells of C. elegans are known, this system allows for the rapid characterization of gene activities at a cellular level. Two approaches will be used to address questions of mesodermal patterning. First, genetic screens will be performed to isolate mutations which alter the specification of mesodermal cells called coelomocytes. These cells provide an excellent opportunity to studying non-muscle mesodermal fates since they arise from three different parts of the lineage and they are born very late during embryogenesis. Defects in coelomocyte specification will be assayed using tissue specific markers. The mutations and corresponding genes will be characterized using standard genetic and molecular techniques. Gene function will be characterized using laser ablations, mosaic analyses, and expression studies. Second, embryo manipulation experiments, i.e. laser ablations, will be performed to determine the relative contributions of cell intrinsic cues and inductive signals. These studies are expected to provide insight into the basic mechanisms of cell fate specification during development. In addition, since many of the molecules involved in similar processes are known to be activated in cancer cells, this work may increase our understanding of tumor formation and metastasis.