Koziol Uriel
Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Iguá 4225, CP11400 Montevideo, Uruguay.
Gen Comp Endocrinol. 2018 Oct 1;267:116-127. doi: 10.1016/j.ygcen.2018.06.012. Epub 2018 Jun 20.
Tardigrades are a key group for understanding the evolution of the Ecdysozoa, a large clade of molting animals that also includes arthropods and nematodes. However, little is known about most aspects of their basic biology. Neuropeptide and peptide hormone signaling has been extensively studied in arthropods and nematodes (particularly regarding their roles in molting in arthropods), but very little is known about neuropeptide signaling in other ecdysozoans. In this work, different strategies were used to search for neuropeptide and peptide hormone precursors in the genomes of the tardigrades Hypsibius dujardini and Ramazzottius varieornatus. In general, there is a remarkable similarity in the complement of neuropeptides and their sequences between tardigrades and arthropods. The precursors found in tardigrades included homologs of achatin, allatostatins A, B and C, allatotropin, calcitonin, CCHamide, CCRFa, corazonin, crustacean cardioactive peptide, diuretic hormone 31, diuretic hormone 44, ecdysis triggering hormone, eclosion hormone, gonadotropin-releasing hormone (GnRH), GSEFLamide, insulin-like peptides, ion transport peptide, kinin, neuropeptide F, orcokinin, pigment dispersing hormone, proctolin, pyrokinin, RYamide, short neuropeptide F, sulfakinin, tachykinin, trissin and vasopressin. In most cases, homologs of known cognate receptors for each neuropeptide family could only be identified when the precursors were also present in the genome, further supporting their identification. Some neuropeptide precursor genes have undergone several duplications in tardigrades, including allatostatin A and C, corazonin, GnRH, eclosion hormone, sulfakinin and trissin. Furthermore, four novel families of candidate neuropeptide precursors were identified (two of which could also be found in several arthropods). To the best of my knowledge, this work represents the first genome-wide search for neuropeptide precursors in any ecdysozoan species outside arthropods and nematodes, and is a necessary first step towards understanding neuropeptide function in tardigrades.
缓步动物是理解蜕皮动物门进化的关键类群，蜕皮动物门是一个大型的蜕皮动物进化枝，其中还包括节肢动物和线虫。然而，关于它们基本生物学的大多数方面我们知之甚少。神经肽和肽类激素信号传导在节肢动物和线虫中已得到广泛研究（特别是关于它们在节肢动物蜕皮中的作用），但对于其他蜕皮动物中的神经肽信号传导却知之甚少。在这项工作中，我们采用了不同的策略，在缓步动物杜氏高生熊虫和多变拉马佐蒂熊虫的基因组中搜索神经肽和肽类激素前体。总体而言，缓步动物和节肢动物在神经肽及其序列的组成上有显著的相似性。在缓步动物中发现的前体包括抗利尿肽、抑咽侧体素A、B和C、促咽侧体素、降钙素、CCH酰胺、CCRFa、心侧体素、甲壳类心脏活性肽、利尿激素31、利尿激素44、蜕皮触发激素、羽化激素、促性腺激素释放激素（GnRH）、GSEFL酰胺、胰岛素样肽、离子转运肽、激肽、神经肽F、orcokinin、色素分散激素、促肠肽、速激肽、RY酰胺、短神经肽F、磺基激肽、速激肽、trissin和加压素的同源物。在大多数情况下，只有当基因组中也存在前体时，才能鉴定出每个神经肽家族已知同源受体的同源物，这进一步支持了它们的鉴定。一些神经肽前体基因在缓步动物中经历了多次复制，包括抑咽侧体素A和C、心侧体素、GnRH、羽化激素、磺基激肽和trissin。此外，还鉴定出了四个新的候选神经肽前体家族（其中两个在几种节肢动物中也能找到）。据我所知，这项工作代表了在节肢动物和线虫之外的任何蜕皮动物物种中首次进行全基因组范围的神经肽前体搜索，并且是理解缓步动物中神经肽功能的必要第一步。
