Role of the Basal Body in Axoneme Assembly

纤毛是高度保守的细胞器，存在于真核生物的所有主要系统发育类群中。它们已经被适应于单细胞的运动和细胞层上的流体运输。在多细胞动物中，它们在胚胎发育和不同细胞类型的信号通路中扮演着特殊的角色。典型纤毛中的9个二联体微管是从9个三联体微管的模板中生长出来的，这些三联体微管构成了基底体(中心粒)的壁。基底体与质膜的对接为纤毛的组装提供了场所。纤毛组装和维持所需的鞭毛内运输组件汇聚在基底体。纤毛组装的启动依赖于基底体远端的三重微管向二重微管的转化。本项目以单细胞、双鞭毛绿藻衣藻为模型系统，研究了一类在基体与质膜的对接以及纤毛组装所需的三重微管向二重微管转化方面存在缺陷的“单”突变体。这些过程的分子基础是通过UNI1和UNI2基因产物的生化特征来研究的。目前正在研究磷酸化在Uni2蛋白功能中的作用。Uni1和Uni2蛋白的功能正在通过突变表型、蛋白质的亚细胞定位和蛋白质相互作用的分析来检测。广泛的影响这个项目通过为本科生提供指导研究经验，将研究和教育结合在一起。学生在进行研究的同时接受细胞生物学、分子生物学和遗传学学科的培训。这些项目帮助学生培养批判性思维能力和书面和口头科学交流的技能。

Scientific researchCilia are highly conserved organelles present in all major phylogenetic groups of eukaryotic organisms. They have been adapted for motility of single cells and for fluid transport over cell layers. In multicellular animals, they play specialized roles in embryo development and in signaling pathways in diverse cell types. The nine doublet microtubules in typical cilia grow from a template of nine triplet microtubules that compose the wall of the basal body (centriole). Basal body docking with the plasma membrane provides a site for assembly of a cilium. Components of intraflagellar transport, required for ciliary assembly and maintenance, converge at the basal body. Initiation of ciliary assembly depends on the conversion of triplet microtubules to doublet microtubules at the distal end of the basal body. Using as a model system the unicellular, biflagellate green alga Chlamydomonas reinhardtii, this project investigates a class of "uni" mutants with defects in docking of basal bodies with the plasma membrane and in the conversion of triplet microtubules to doublet microtubules required for ciliary assembly. The molecular basis of these processes is investigated through biochemical characterization of the products of the UNI1 and UNI2 genes. The role of phosphorylation in the function of the Uni2 protein is being studied. The functions of the Uni1 and Uni2 proteins are being examined through analysis of mutant phenotypes, subcellular localization of the proteins, and protein interactions.Broader ImpactsThis project integrates research and education by providing mentored research experiences for undergraduate students. Students receive training in cell biology, molecular biology, and genetics disciplines while carrying out research. The projects help students to develop the ability for critical thinking and the skills for written and oral science communication.