Svendsen P C, McGhee J D
Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
Development. 1995 May;121(5):1253-62. doi: 10.1242/dev.121.5.1253.
We describe the homeobox gene ceh-10 from the nematode Caenorhabditis elegans. The homeodomain of ceh-10 is closely related to the homeodomains of two genes recently cloned from the vertebrate retina, Chx10 from mice and Vsx-1 from goldfish. We show that the sequence conservation extends well beyond the homeodomain and includes a region (named the CVC domain) of roughly 60 amino acids immediately C-terminal to the homeodomain. As assayed in transgenic worms, the promoter region of ceh-10 directs expression of a lacZ reporter gene to a small number of neurons. We draw a parallel between the bipolar cells of the inner nuclear layer of the vertebrate retina, which express Chx10 and Vsx-1, and an interneuron in C. elegans called AIY, which expresses ceh-10. AIY receives synaptic input from a sensory cell, just as do bipolar cells of the vertebrate retina. In C. elegans, the sensory cell AFD is not known to be photosensitive but is known to be thermosensitive; moreover, a cell with similar position in the amphids of other nematodes has been suggested indeed to be photosensitive. Our results emphasize the highly conserved nature of sensory regulatory mechanisms and suggest one way in which photosensitive organelles might have originated in evolution.
我们描述了线虫秀丽隐杆线虫中的同源异型框基因ceh-10。ceh-10的同源异型结构域与最近从脊椎动物视网膜中克隆的两个基因的同源异型结构域密切相关，即小鼠的Chx10和金鱼的Vsx-1。我们发现，序列保守性不仅延伸到同源异型结构域之外，还包括同源异型结构域C端紧邻的一个约60个氨基酸的区域（命名为CVC结构域）。在转基因蠕虫中检测发现，ceh-10的启动子区域可将lacZ报告基因的表达导向少数神经元。我们将表达Chx10和Vsx-1的脊椎动物视网膜内核层双极细胞与秀丽隐杆线虫中表达ceh-10的中间神经元AIY进行了比较。AIY从感觉细胞接收突触输入，脊椎动物视网膜的双极细胞也是如此。在秀丽隐杆线虫中，感觉细胞AFD不被认为具有光敏感性，但已知具有热敏感性；此外，有人提出，在其他线虫的两性感觉器中处于相似位置的细胞确实具有光敏感性。我们的结果强调了感觉调节机制的高度保守性，并提出了一种光敏感细胞器在进化中可能起源的方式。
