Kaplan J M, Horvitz H R
Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Proc Natl Acad Sci U S A. 1993 Mar 15;90(6):2227-31. doi: 10.1073/pnas.90.6.2227.
After light touch to its nose, the nematode Caenorhabditis elegans halts forward locomotion and initiates backing. Here we show that three classes of neurons (ASH, FLP, and OLQ) sense touch to the nose and hence are required for this avoidance response. ASH, FLP, and OLQ have sensory endings that contain axonemal cilia. Mutant animals that have defective ciliated sensory endings as well as laser-operated animals that lack ASH, FLP, and OLQ fail to respond to touch to the nose. Together with the previous work of others, these results demonstrate that C. elegans has at least five morphologically distinct classes of mechanosensory neurons. Interestingly, the ASH neuron also acts as a chemosensory neuron; it mediates the avoidance of noxious chemicals. Since ASH possesses both chemosensory and mechanosensory modalities, this neuron might be functionally analogous to vertebrate nociceptors, which mediate the sensation of pain.
轻触线虫秀丽隐杆线虫的鼻子后，它会停止向前移动并开始后退。我们在此表明，三类神经元（ASH、FLP和OLQ）感知鼻子的触觉，因此这种回避反应需要它们。ASH、FLP和OLQ具有包含轴丝纤毛的感觉末梢。具有有缺陷的纤毛感觉末梢的突变动物以及缺乏ASH、FLP和OLQ的激光手术动物对鼻子的触摸没有反应。与其他人之前的工作一起，这些结果表明秀丽隐杆线虫至少有五类形态上不同的机械感觉神经元。有趣的是，ASH神经元也作为化学感觉神经元起作用；它介导对有害化学物质的回避。由于ASH同时具有化学感觉和机械感觉模式，该神经元在功能上可能类似于介导疼痛感觉的脊椎动物伤害感受器。
