背景:门,胎盘动物,黄蜂,和Porifera出现在原始和氘代动物分裂之前,大约6亿年前。这些早期的后生动物很有趣,因为它们可以为我们提供各种组织和器官进化的重要信息,比如眼睛和神经系统。一般来说,cnidarians有简单的神经系统,使用神经肽进行神经传递,但是一些属于Cubozoa类(盒子水母)的刺眼动物有先进的图像形成眼睛,可能与复杂的神经支配有关。这里,我们描述了一个新的转录组数据库。
结果:基于Illumina和PacBio测序技术的联合使用,我们制作了一个高度连续的转录组数据库。然后,我们开发了一个软件程序来发现该数据库中的神经肽前激素水平。该脚本使我们能够注释七个新的T.cystophora神经肽前激素cDNA:一个编码19个拷贝的具有pQWLRGRFamide结构的肽;一个编码六个拷贝的不同RFamide肽;一个编码六个拷贝的pQPPGVWamide;一个编码八个不同的神经肽拷贝,具有C末端LWamide序列;一个编码肽的13个拷贝,其中一个编码一个RRAC其中最常见的序列为CTGQMCWFRamide。我们还可以在长方体Alatinaalata中鉴定出这7种前激素的直系同源物,Carybdeaxaymacana,ChironexFleckeri,和quadrumanus。此外,使用TBLASTN筛查,我们可以注释四个类鞭子糖蛋白激素亚基,五个视蛋白,和52个其他家族-AG蛋白偶联受体(GPCRs),其中还包括两个富含亮氨酸的重复序列,这些重复序列包含T.cystophora中的G蛋白偶联受体(LGRs)。这两种LGR是糖蛋白激素的潜在受体,而其他GPCRs是上述神经肽的候选受体。
结论:通过结合Illumina和PacBio测序技术,我们已经产生了一个新的高质量的从头转录组组装体,它应该是一个有价值的资源,用于鉴定参与视神经和其他行为的神经元成分。
BACKGROUND: The phyla Cnidaria, Placozoa, Ctenophora, and Porifera emerged before the split of proto- and deuterostome animals, about 600 million years ago. These early metazoans are interesting, because they can give us important information on the evolution of various tissues and organs, such as eyes and the nervous system. Generally, cnidarians have simple nervous systems, which use neuropeptides for their neurotransmission, but some cnidarian medusae belonging to the class Cubozoa (box jellyfishes) have advanced image-forming eyes, probably associated with a complex innervation. Here, we describe a new transcriptome database from the cubomedusa Tripedalia cystophora.
RESULTS: Based on the combined use of the Illumina and PacBio sequencing technologies, we produced a highly contiguous transcriptome database from T. cystophora. We then developed a software program to discover neuropeptide preprohormones in this database. This script enabled us to annotate seven novel T. cystophora neuropeptide preprohormone cDNAs: One coding for 19 copies of a peptide with the structure pQWLRGRFamide; one coding for six copies of a different RFamide peptide; one coding for six copies of pQPPGVWamide; one coding for eight different neuropeptide copies with the C-terminal LWamide sequence; one coding for thirteen copies of a peptide with the RPRAamide C-terminus; one coding for four copies of a peptide with the C-terminal GRYamide sequence; and one coding for seven copies of a cyclic peptide, of which the most frequent one has the sequence CTGQMCWFRamide. We could also identify orthologs of these seven preprohormones in the cubozoans Alatina alata, Carybdea xaymacana, Chironex fleckeri, and Chiropsalmus quadrumanus. Furthermore, using TBLASTN screening, we could annotate four bursicon-like glycoprotein hormone subunits, five opsins, and 52 other family-A G protein-coupled receptors (GPCRs), which also included two leucine-rich repeats containing G protein-coupled receptors (LGRs) in T. cystophora. The two LGRs are potential receptors for the glycoprotein hormones, while the other GPCRs are candidate receptors for the above-mentioned neuropeptides.
CONCLUSIONS: By combining Illumina and PacBio sequencing technologies, we have produced a new high-quality de novo transcriptome assembly from T. cystophora that should be a valuable resource for identifying the neuronal components that are involved in vision and other behaviors in cubomedusae.