Abdel-Latief Mohatmed
Department of Applied Zoology, Animal Ecology, Institute of Biology, Freie Universität Berlin, Berlin, Germany.
PLoS One. 2007 Dec 19;2(12):e1319. doi: 10.1371/journal.pone.0001319.
Chemoperception in invertebrates is mediated by a family of G-protein-coupled receptors (GPCR). To date nothing is known about the molecular mechanisms of chemoperception in coleopteran species. Recently the genome of Tribolium castaneum was sequenced for use as a model species for the Coleoptera. Using blast searches analyses of the T. castaneum genome with previously predicted amino acid sequences of insect chemoreceptor genes, a putative chemoreceptor family consisting of 62 gustatory receptors (Grs) and 26 olfactory receptors (Ors) was identified. The receptors have seven transmembrane domains (7TMs) and all belong to the GPCR receptor family. The expression of the T. castaneum chemoreceptor genes was investigated using quantification real- time RT-PCR and in situ whole mount RT-PCR analysis in the antennae, mouth parts, and prolegs of the adults and larvae. All of the predicted TcasGrs were expressed in the labium, maxillae, and prolegs of the adults but TcasGr13, 19, 28, 47, 62, 98, and 61 were not expressed in the prolegs. The TcasOrs were localized only in the antennae and not in any of the beetles gustatory organs with one exception; the TcasOr16 (like DmelOr83b), which was localized in the antennae, labium, and prolegs of the beetles. A group of six TcasGrs that presents a lineage with the sugar receptors subfamily in Drosophila melanogaster were localized in the lacinia of the Tribolium larvae. TcasGr1, 3, and 39, presented an ortholog to CO(2) receptors in D. melanogaster and Anopheles gambiae was recorded. Low expression of almost all of the predicted chemoreceptor genes was observed in the head tissues that contain the brains and suboesophageal ganglion (SOG). These findings demonstrate the identification of a chemoreceptor family in Tribolium, which is evolutionarily related to other insect species.
无脊椎动物的化学感受由一类G蛋白偶联受体（GPCR）介导。迄今为止，对于鞘翅目昆虫化学感受的分子机制尚不清楚。最近，为了将赤拟谷盗作为鞘翅目的模式物种，对其基因组进行了测序。通过对赤拟谷盗基因组与先前预测的昆虫化学感受器基因氨基酸序列进行blast搜索分析，鉴定出一个由62个味觉受体（Grs）和26个嗅觉受体（Ors）组成的假定化学感受器家族。这些受体具有七个跨膜结构域（7TMs），均属于GPCR受体家族。利用定量实时RT-PCR和原位全组织RT-PCR分析，研究了赤拟谷盗化学感受器基因在成虫和幼虫触角、口器及前足中的表达情况。所有预测的TcasGrs在成虫的下唇、上颚和前足中均有表达，但TcasGr13、19、28、47、62、98和61在前足中未表达。TcasOrs仅定位在触角中，在甲虫的任何味觉器官中均未定位，但有一个例外；TcasOr16（类似于DmelOr83b），定位在甲虫的触角、下唇和前足中。一组与黑腹果蝇糖受体亚家族具有谱系关系的六个TcasGrs定位在赤拟谷盗幼虫的叶状突中。记录到TcasGr1、3和39与黑腹果蝇和冈比亚按蚊中的CO(2)受体存在直系同源关系。在含有脑和咽下神经节（SOG）的头部组织中，几乎所有预测的化学感受器基因都表现出低表达。这些发现证明了在赤拟谷盗中鉴定出一个与其他昆虫物种具有进化关系的化学感受器家族。
