CRANIOFACIAL MORPHOGENESIS IN ZEBRAFISH

颅面畸形是由发育错误引起的，当形成胚胎模式的基因功能不正常时，就可能发生这种情况。 了解面部骨骼是如何形成的，以及控制其形成的基因，对于最终理解遗传性颅面疾病的基础至关重要。 斑马鱼为这些研究提供了一个有用的动物模型：斑马鱼胚胎适合于发育和遗传研究。 它的胚胎头部骨骼与人类有相当大的相似性。 斑马鱼和人类骨骼发育模式的基因在进化过程中高度保守，因此从斑马鱼获得的理解可以直接应用于人类发育。 这项建议是要严格审查一段时间约一天的胚胎发育在斑马鱼时，细胞形成的面部骨骼的雏形。 一个“形态发生级联”假说提出，在遗传控制下，咽弓原基中的神经嵴衍生细胞经历了一系列短的重排，在每一步，完善骨骼预图案。第一个具体目标是通过在级联的连续步骤中进行命运映射来识别将形成特定面部骨骼元素的细胞。 第二个目标是直接观察完整胚胎中的细胞，通过共聚焦显微镜（4d分析）进行延时记录，以了解预测的细胞重排是否以及如何发生。这两个目标的实现将揭示构建头部骨骼单个元素的细胞行为。第三个具体目标是研究级联遗传学，通过分析颅面突变体和模式基因克隆同源。 已经通过这些技术确定了分级上游调控基因，并且主要焦点将是确定和表征在级联中执行下游步骤的新基因。

Craniofacial malformations arise by errors in development, as can occur when genes that pattern the embryo do not function correctly. Learning about how the facial skeleton forms, as well as the genes that control its formation, is essential for the eventual understanding of the bases of inherited craniofacial disorders. The zebrafish provides a useful animal model for such studies: The zebrafish embryo is amenable for developmental and genetic investigation. Its embryonic head skeleton shares considerable similarity with that of humans. Genes that pattern zebrafish and human skeletal development have been highly conserved during evolution, hence understanding gained from zebrafish can apply directly to human development. This proposal is to examine critically a period of about a day of embryonic development in the zebrafish when cells form the rudiments of the facial skeleton. A "morphogenetic cascade" hypothesis proposes that, under genetic control, neural crest-derived cells in the pharyngeal arch primordia undergo a short series of rearrangements that, at each step, refine skeletal prepatterning. The first specific aim is to identify the cells, by fate mapping at successive steps of the cascade, that will form specific facial skeletal elements. The second aim is to watch the cells in the intact embryo directly, by making time-lapse recordings with a confocal microscope (4d-analysis), to learn whether and precisely how the predicted cellular rearrangements occur. Accomplishment of these two aims will reveal the cellular behaviors that build individual elements of the head skeleton. The third specific aim is to study the cascade genetically, by analyzing craniofacial mutants and patterning genes cloned by homology. Hierarchically upstream regulatory genes have already been identified by these techniques and the principal focus will be to identify and characterize new genes that execute that later, downstream, steps in the cascade.