INCIA, UMR 5287 CNRS, Université de Bordeaux, allée Geoffroy St Hillaire, CS 50023, 33 615 Pessac Cedex, France.
Gen Comp Endocrinol. 2019 Jul 1;278:3-11. doi: 10.1016/j.ygcen.2018.04.027. Epub 2018 Apr 26.
Phasmid neuropeptide genes were identified in the genomes of two phasmids, Timema cristinae and Clitarchus hookeri. The two species belong to two sisters groups, the Timematodea and Euphasmatodea respectively. Neuropeptide genes were identified using the BLAST+ program on the genome assemblies and the absence of some neuropeptides was confirmed by the concomitant absence of their G-protein coupled receptors. Both genomes were assembled using short reads and the average coverage of the genome is more than 166 times for both species. This makes it virtually impossible that there would not be a single short read for at least one of the conserved transmembrane regions of a GPCR coded by such a genome. Hence, when not a single read can be found for a specific GPCR, it can be concluded that the particular gene is absent from that species. Most previously identified insect neuropeptides are used by these two species. Of the three arthropod allatostatin C related peptides, only allatostatins CC and CCC are present. Both species lack leucokinin, while sulfakinin and dilp8 signaling is absent from Clitarchus, but present in Timema. Interestingly, whereas Timema has lost a vasopressin-related peptide, the gene coding such a peptide is amplified in the Clitarchus genome. Furthermore, while Clitarchus has a specific tryptopyrokinin gene, Timema does not and in this species tryptopyrokinin is coded only by the pyrokinin and periviscerokinin genes. Finally, both species have genes coding EFLamide and its GPCR; in phasmids these genes codes for one (Clitarchus) or two (Timema) EFLamide paracopies.
在两种叶䗛，Timema cristinae 和 Clitarchus hookeri 的基因组中鉴定出了肽基因。这两个物种分别属于两个姐妹群，即叶䗛目和直翅目。使用 BLAST+程序在基因组组装上鉴定出了神经肽基因，并且由于缺乏其 G 蛋白偶联受体，同时也确认了一些神经肽的缺失。这两个基因组都使用短读长组装，两种物种的基因组平均覆盖率都超过了 166 倍。因此，对于这样一个基因组编码的 GPCR 的保守跨膜区，不可能没有一个单独的短读长。因此，当找不到特定 GPCR 的单个读长时，可以得出该特定基因在该物种中不存在的结论。这两种物种使用了大多数先前鉴定的昆虫神经肽。在三种昆虫的 allatostatin C 相关肽中，只有 allatostatins CC 和 CCC 存在。这两个物种都缺乏 leucokinin，而 sulfakinin 和 dilp8 信号在 Clitarchus 中不存在，但在 Timema 中存在。有趣的是，虽然 Timema 失去了一种与加压素相关的肽，但编码这种肽的基因在 Clitarchus 基因组中被扩增。此外，虽然 Clitarchus 有一个特定的 tryptopyrokinin 基因，但 Timema 没有，在这个物种中，tryptopyrokinin 仅由 pyrokinin 和 periviscerokinin 基因编码。最后，这两个物种都有编码 EFLamide 和其 GPCR 的基因；在叶䗛目中，这些基因编码一个（Clitarchus）或两个（Timema）EFLamide 副拷贝。
