Engsontia Patamarerk, Sanderson Alan P, Cobb Matthew, Walden Kimberly K O, Robertson Hugh M, Brown Stephen
Faculty of Life Sciences, University of Manchester, Manchester, UK.
Insect Biochem Mol Biol. 2008 Apr;38(4):387-97. doi: 10.1016/j.ibmb.2007.10.005. Epub 2007 Oct 22.
The Tribolium castaneum genome sequence reveals a large number of odorant receptor (Or) genes compared to those found in other insects whose olfactory genomes have been studied-341 Or genes and pseudogenes, encoding 259 intact odorant receptor proteins. An RT-PCR study of larvae and adults revealed that only 145 (64%) of 233 genes with successful genomic DNA amplifications were expressed. No expression of the other 87 genes was detected at any age, suggesting either that these genes are not expressed in this particular strain, or that they are induced only in certain environmental or developmental conditions. TcOR1, the ortholog of the Drosophila Or83b (DmOr83b) gene, which is required for the function of olfactory receptor proteins in Drosophila, was expressed in extracts from adult and larval heads and in extracts from adult bodies. Expression of 41 TcOr genes was detected in extracts from larval head tissue and 111 in extracts from adult head tissue (both figures exclude TcOr1). Twenty-eight TcOrs were detected only in adult bodies. Beetle pupae were injected with TcOr1 dsRNA; unlike sham-injected and control beetles, these knock-down beetles showed no significant response to the Tribolium aggregation pheromone, supporting the hypothesis that TcOr1 plays a similar decisive role in olfaction to DmOr83b. The substantial number of Ors poses the question of why Tribolium has such a large olfactory receptor repertoire, and underlines the need for more studies of the natural history of this species.
与其他已研究嗅觉基因组的昆虫相比，赤拟谷盗的基因组序列显示出大量的气味受体（Or）基因——341个Or基因和假基因，编码259个完整的气味受体蛋白。一项针对幼虫和成虫的逆转录聚合酶链反应（RT-PCR）研究表明，在233个成功扩增基因组DNA的基因中，只有145个（64%）表达。在任何年龄段都未检测到其他87个基因的表达，这表明要么这些基因在该特定品系中不表达，要么它们仅在特定的环境或发育条件下被诱导表达。果蝇的Or83b（DmOr83b）基因对于果蝇嗅觉受体蛋白的功能是必需的，其直系同源基因TcOR1在成虫和幼虫头部提取物以及成虫身体提取物中均有表达。在幼虫头部组织提取物中检测到41个TcOr基因的表达，在成虫头部组织提取物中检测到111个（这两个数字均不包括TcOr1）。仅在成虫身体中检测到28个TcOrs。向甲虫蛹注射TcOr1双链RNA；与假注射和对照甲虫不同，这些敲低的甲虫对赤拟谷盗聚集信息素没有明显反应，这支持了TcOr1在嗅觉中发挥与DmOr83b类似的决定性作用的假设。大量的Or基因引发了一个问题，即为什么赤拟谷盗有如此庞大的嗅觉受体库，并强调了对该物种自然史进行更多研究的必要性。
