Flagellar Length Control in Chlamydomonas: The Role of Intraflagellar Transport and Turnover

细胞如何调节细胞器的大小是细胞生物学中的一个基本问题。 在这个项目中，真核生物鞭毛将被用作研究细胞器大小调节的模型系统，通过将测量大小的问题减少到一个单一的维度：长度。 鞭毛经历连续的翻转，并且长度控制机制必须平衡组装和拆卸的速率以维持稳态长度。 已经提出了几种模型来解释这种平衡。 一种模型依赖于鞭毛内运输（IFT）的固有长度依赖性，这是一种在鞭毛内发生的主动运输过程。 基于先前的IFT研究，据预测，运输效率将降低鞭毛长度的增加，导致组装和拆卸之间的平衡点发生在一个独特的长度。 另一种模型提出，长度由耦合到反馈控制系统的长度传感器调节。 本计画将借由研究鞭毛长度突变体的机制基础来测试这些模型。 平衡点模型预测，这样的突变体必须影响运输或营业额。 遗传学和显微镜的组合将被用来测试是否长度改变突变体可以完全解释的周转率或运输的变化。 该项目将为本科生和研究生提供研究培训。

How cells regulate organelle size is a fundamental question in cell biology. In this project the eukaryotic flagellum will be used as a model system for studies of organelle size regulation, by reducing the problem of measuring size to a single dimension: length. Flagella undergo continuous turnover, and the length control mechanism must balance the rates of assembly and disassembly to maintain a steady-state length. Several models have been proposed to explain this balance. One model relies on the inherent length-dependence of intraflagellar transport (IFT), an active transport process that occurs within flagella. Based on prior studies of IFT, it is predicted that the efficiency of transport will decrease as flagellar length increases, leading to a balance-point between assembly and disassembly occurring at a unique length. An alternative model proposes that length is regulated by a length-sensor coupled to a feedback control system. This project will test these models by examining the mechanistic basis of flagellar length mutants. The balance point model predicts that such mutants must affect either transport or turnover. A combination of genetics and microscopy will be used to test whether length-altering mutants can be entirely explained by changes in the rates of turnover or transport. This project will provide research training for undergraduate and graduate students.