PDF(Pubmed)
Abstract：
During the early development of marine invertebrates, planktic larvae usually occur, and their body surfaces often form specific types of cilia that are involved in locomotion and feeding. The echiuran worm Urechis unicinctus sequentially undergoes the formation and disappearance of different types of body surface cilia during embryonic and larval development. The morphological characteristics and molecular mechanisms involved in the process remain unclear. In this study, we found that body surface cilia in U. unicinctus embryos and larvae can be distinguished into four types: body surface short cilia, apical tufts, circumoral cilia and telotrochs. Further, distribution and genesis of the body surface cilia were characterized using light microscope and electron microscope. To better understand the molecular mechanism during ciliogenesis, we revealed the embryonic and larval transcriptome profile of the key stages of ciliogenesis in U. unicinctus using RNA-Seq technology. A total of 29,158 differentially expressed genes (DEGs) were obtained from 24 cDNA libraries by RNA-Seq. KEGG pathway enrichment results showed that Notch, Wnt and Ca2+ signaling pathways were significantly enriched during the occurrence of apical tufts and circumoral cilia. Furthermore, all DEGs were classified according to their expression pattern, and DEGs with similar expression pattern were grouped into a module. All DEG co-expression modules were correlated with traits (body surface short cilia, apical tufts, circumoral cilia and telotrochs) by WGCNA, the results showed DEGs were divided into 13 modules by gene expression patterns and that the genes in No. 7, No. 8 and No. 10 modules were to be highly correlated with the occurrence of apical tufts, circumoral cilia and telotrochs. The top 10 hub genes in the above three modules were identified to be highly correlated with ciliogenesis, including the reported cilium-related gene Cnbd2 and unreported cilium-related candidate genes FAM181B, Capsl, Chst3, TMIE and Innexin. Notably, Innexin was included in the top10 hub genes of the two modules (No. 7 and No. 8), suggesting that Innexin may play an important role in U. unicinctus apical tufts, circumoral cilia and telotrochs genesis. This study revealed the characteristics of ciliogenesis on the body surface of U. unicinctus embryos and larvae, providing basic data for exploring the molecular mechanism of ciliogenesis on the body surface.
摘要：
在海洋无脊椎动物的早期发育过程中，浮游幼虫通常发生，和他们的身体表面经常形成特定类型的纤毛，参与运动和喂养。在胚胎和幼虫发育过程中，棘球蠕虫会依次经历不同类型的体表纤毛的形成和消失。该过程的形态特征和分子机制尚不清楚。在这项研究中,我们发现Unicinctus胚胎和幼虫的体表纤毛可以分为四种类型：体表短纤毛，顶端簇绒，包绕纤毛和telotrochs。Further,利用光学显微镜和电子显微镜对体表纤毛的分布和发生进行了表征。为了更好地了解纤毛发生过程中的分子机制，我们使用RNA-Seq技术揭示了U.unicincus纤毛发生关键阶段的胚胎和幼虫转录组概况。通过RNA-Seq从24个cDNA文库中获得了总共29,158个差异表达基因（DEGs）。KEGG通路富集结果表明,Notch,Wnt和Ca2+信号通路在根尖簇和包绕纤毛的发生过程中显著富集。此外，所有DEGs都根据它们的表达模式进行分类，和具有相似表达模式的DEG被分组为一个模块。所有DEG共表达模块均与性状相关(体表短纤毛，顶端簇绒，包络线纤毛和telotrochs）由WGCNA，结果表明，根据基因表达模式，DEGs分为13个模块，而No.7号8和不10个模块与根尖簇的发生高度相关，包绕纤毛和telotrochs。以上三个模块中的前10个hub基因被鉴定为与纤毛发生高度相关，包括已报道的纤毛相关基因Cnbd2和未报道的纤毛相关候选基因FAM181B，Capsl,Chst3，TMIE和Innexin。值得注意的是,Innexin包含在两个模块的top10hub基因中（编号：7号8),这表明Innexin可能在根尖的美国独营杆菌中起重要作用，包绕纤毛和telotrochs起源。这项研究揭示了U.unicincus胚胎和幼虫体表纤毛发生的特征，为探索体表纤毛发生的分子机制提供基础数据。
