CENTRIOLE DUPLICATION IN C ELEGANS EMBRYOS

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。中心粒是一种细胞器，在纤毛和鞭毛的形成中起重要作用，参与胞质分裂、细胞周期控制和中心体组织。S细胞的单个中心体作为纺锤极遗传，每个细胞周期只复制一次，这一过程是通过控制中心粒复制来调节的。严格控制中心粒复制，确保两极纺锤体的形成和倍性的保持。多年来，人们已经知道女儿的中心粒与长辈的中心粒或母亲的中心粒成直角聚集。这一现象的意义以及子代中心粒组装的途径仍然是个谜。我们正在使用子项目0067中描述的相关光和EM断层扫描方法来研究线虫胚胎中的中心粒复制。我们的初步结果表明，这种生物体中的子代中心粒组装始于中央管的形成，就像原核的出现一样。中央管在原核迁移过程中拉长，单线态微管在管上的组装发生在原核旋转过程中。利用EM-CT结合RNA干扰和修复显微镜，我们发现证据表明，管的形成和延长需要SAS-5/SAS-6蛋白和由Spd-2和Zyg-1介导的上游信号。我们进一步表明，虽然中心管的组装仍然发生，但在没有SAS-4的情况下，单线态微管不能组装，这表明在组装步骤中特别需要它。我们在线虫中描述的中心粒组装途径可能为进一步研究其他含有中心粒的生物体中的中心粒组装提供一个框架。这部作品正在写出来准备出版。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Centrioles are organelles that play essential roles in the formation of cilia and flagella, and they participate in cytokinesis, cell cycle control and centrosome organization. The cell¿s single centrosome, which is inherited as a spindle pole, duplicates only once per cell cycle, a process that is regulated through the control of centriole duplication. Centriole duplication is strictly controlled to ensure the formation of a bipolar spindle and the maintenance of ploidy. It has been know for many years that daughter centrioles assemble at right angles to the older, or ¿mother¿ centriole. The significance of this and the pathway for daughter centriole assemble remain mysterious. We are using the correlative light and EM tomography approach described in Subproject 0067 to study centriole duplication in staged C. elegans embryos. Our initial results showed that daughter centriole assembly in this organism begins with the formation of a central tube, just as the pronuclei appear. The central tube elongates during pronuclear migration, and the assembly of singlet microtubules on the tube occurs during pronuclear rotation. Using EM-tomography in combination with RNA interference and restoration microscopy we have found evidence suggesting that tube formation and elongation requires the SAS-5/SAS-6 proteins and an upstream signal mediated by SPD-2 and ZYG-1. We further show that although the assembly of the central tube still occurs, singlet microtubules fail to assemble in the absence of SAS-4, suggesting that it is required specifically at that step of assembly. The centriole assembly pathway we describe here in C. elegans may provide a framework for further studies on centriole assembly in other centriole bearing organisms. This work is being written up for publication.