Step-response analysis of chemotaxis in Caenorhabditis elegans
Step-response analysis of chemotaxis in Caenorhabditis elegans
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DOI：
10.1523/jneurosci.5133-04.2005
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发表时间：
2005-03-30
影响因子：
5.3
通讯作者：
Lockery, SR
中科院分区：
文献类型：
--
作者：
Miller, AC;Thiele, TR;Lockery, SR
秀丽隐杆线虫趋化性背后的感觉运动转化在正常实验条件下很难直接测量。因此，这种转变的关键特征仍然是模糊的，比如它的时间过程和对刺激幅度的依赖。在这里，我们提出了一个全面的转化特征，通过诱导引诱剂浓度的逐步时间变化在基质内获得，因为蠕虫爬过它。我们发现阶跃响应是复杂的，具有多个阶段，并且对刺激的符号和幅度具有非线性依赖。然而，阶跃反应可以简化为一个简单的动力学模型，预测趋化性试验的结果。模型分析表明，趋化性分别是趋近反应和回避反应对浓度升高和降低的综合作用。令人惊讶的是，在化学梯度测定中，ASE化学感觉神经元是趋化性的必要条件，消融ASE化学感觉神经元消除了回避反应，但保留了趋近反应。这些结果表明，这种转化可以被分解成可以分配给已识别神经元的组件。
The sensorimotor transformation underlying Caenorhabditis elegans chemotaxis has been difficult to measure directly under normal assay conditions. Thus, key features of this transformation remain obscure, such as its time course and dependence on stimulus amplitude. Here, we present a comprehensive characterization of the transformation as obtained by inducing stepwise temporal changes in attractant concentration within the substrate as the worm crawls across it. We found that the step response is complex, with multiple phases and a nonlinear dependence on the sign and amplitude of the stimulus. Nevertheless, the step response could be reduced to a simple kinetic model that predicted the results of chemotaxis assays. Analysis of the model showed that chemotaxis results from the combined effects of approach and avoidance responses to concentration increases and decreases, respectively. Surprisingly, ablation of the ASE chemosensory neurons, known to be necessary for chemotaxis in chemical gradient assays, eliminated avoidance responses but left approach responses intact. These results indicate that the transformation can be dissected into components to which identified neurons can be assigned.