Veenstra Jan A
Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (CNRS UMR5287), University of Bordeaux , Pessac , France.
PeerJ. 2016 May 26;4:e2043. doi: 10.7717/peerj.2043. eCollection 2016.
Background. Neuropeptides are important regulators of physiological processes and behavior. Although they tend to be generally well conserved, recent results using trancriptome sequencing on decapod crustaceans give the impression of significant differences between species, raising the question whether such differences are real or artefacts. Methods. The BLAST+ program was used to find short reads coding neuropeptides and neurohormons in publicly available short read archives. Such reads were then used to find similar reads in the same archives, and the DNA assembly program Trinity was employed to construct contigs encoding the neuropeptide precursors as completely as possible. Results. The seven decapod species analyzed in this fashion, the crabs Eriocheir sinensis, Carcinus maenas and Scylla paramamosain, the shrimp Litopenaeus vannamei, the lobster Homarus americanus, the fresh water prawn Macrobrachium rosenbergii and the crayfish Procambarus clarkii had remarkably similar neuropeptidomes. Although some neuropeptide precursors could not be assembled, in many cases individual reads pertaining to the missing precursors show unambiguously that these neuropeptides are present in these species. In other cases, the tissues that express those neuropeptides were not used in the construction of the cDNA libraries. One novel neuropeptide was identified: elongated PDH (pigment dispersing hormone), a variation on PDH that has a two-amino-acid insertion in its core sequence. Hyrg is another peptide that is ubiquitously present in decapods and is likely a novel neuropeptide precursor. Discussion. Many insect species have lost one or more neuropeptide genes, but apart from elongated PDH and hyrg all other decapod neuropeptides are present in at least some insect species, and allatotropin is the only insect neuropeptide missing from decapods. This strong similarity between insect and decapod neuropeptidomes makes it possible to predict the receptors for decapod neuropeptides that have been deorphanized in insects. This includes the androgenic insulin-like peptide that seems to be homologous to drosophila insulin-like peptide 8.
背景。神经肽是生理过程和行为的重要调节因子。尽管它们通常倾向于高度保守，但最近对十足目甲壳类动物进行转录组测序的结果给人一种物种间存在显著差异的印象，这就引发了一个问题，即这种差异是真实存在的还是人为造成的。方法。使用BLAST+程序在公开可用的短读文库中查找编码神经肽和神经激素的短读序列。然后利用这些短读序列在同一文库中查找相似的短读序列，并使用DNA组装程序Trinity尽可能完整地构建编码神经肽前体的重叠群。结果。以这种方式分析的七种十足目物种，中华绒螯蟹、平背蜞、拟穴青蟹、凡纳滨对虾、美洲螯龙虾、罗氏沼虾和克氏原螯虾，其神经肽组非常相似。尽管一些神经肽前体无法组装，但在许多情况下，与缺失前体相关的单个短读序列明确表明这些神经肽存在于这些物种中。在其他情况下，表达这些神经肽的组织未用于构建cDNA文库。鉴定出一种新的神经肽：延长型色素分散激素（PDH），它是PDH的一种变体，其核心序列中有两个氨基酸插入。Hyrg是另一种在十足目中普遍存在的肽，可能是一种新的神经肽前体。讨论。许多昆虫物种已经失去了一个或多个神经肽基因，但除了延长型PDH和hyrg之外，所有其他十足目神经肽至少在一些昆虫物种中存在，而促咽侧体素是十足目中唯一缺失的昆虫神经肽。昆虫和十足目神经肽组之间的这种高度相似性使得预测在昆虫中已去孤儿化的十足目神经肽的受体成为可能。这包括似乎与果蝇胰岛素样肽8同源的雄激素胰岛素样肽。
