Li Jingjing, Sun Jinsheng, Dong Xuewang, Geng Xuyun, Qiu Gaofeng
National Demonstration Center for Experimental Fisheries Science Education, Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China.
Tianjin Diseases Prevention and Control Center of Aquatic Animals, Tianjin, China.
PeerJ. 2019 Jun 28;7:e7182. doi: 10.7717/peerj.7182. eCollection 2019.
Chinese mitten crab () is an economically important freshwater aquaculture species and is a model species for research on the mechanism of molting. This study aimed to identify important candidate genes associated with the molting process and to determine the role of gills in the regulation of molting with the help of transcriptomic analysis. The transcriptomes of crabs at different molting stages-postmolt (PoM), intermolt (InM), premolt (PrM) and ecdysis (E)-were de novo assembled to generate 246,232 unigenes with a mean length of 851 bp. A total of 86,634 unigenes (35.18% of the total unigenes) were annotated against reference databases. Significantly upregulated genes were identified in postmolt compared to intermolt (1,475), intermolt compared to premolt (65), premolt compared to ecdysis (1,352), and ecdysis compared to postmolt (153), and the corresponding numbers of downregulated genes were 1,276, 32, 1,573 and 171, respectively. Chitin synthase, endochitinase, chitinase A, chitinase 3, chitinase 6 and chitin deacetylase 1 were upregulated during the postmolt and ecdysis stages, while phosphoglucomutase 3 (PGM3), glucosamine 6-phosphate deaminase (GNPDA) and glucosamine glycoside hydrolase (nagZ) were upregulated during the intermolt and premolt stages compared to the other stages. The upregulated genes were enriched in several lipid-related metabolic pathways, such as "fatty acid elongation", "glycerophospholipid metabolism" and "sulfur metabolism". Meanwhile, three signaling pathways, including the "phosphatidylinositol signaling system", the "calcium signaling pathway" and the "GnRH signaling pathway" were also enriched. Tetraspanin-18, an important effector gene in the lysosomal pathway involved in cell apoptosis, up-regulate with the beginning of molting (in premolt stage) and reach the top in the ecdysis stage, and barely expressed in the intermolt stage. The expression variations in the tetraspanin-18 gene indicated that it may play an important role in the beginning of molting cycle, which might be regulated by the stress of salinity. This study revealed that the gills could participate in chitin degradation, in reestablishment of the exoskeleton and the signaling process. Based on transcriptomic analysis of the gills, we not only explored novel molecular mechanisms of molting in but also acquired foundational genetic data for .
中华绒螯蟹是一种具有重要经济价值的淡水养殖物种，也是蜕皮机制研究的模式物种。本研究旨在通过转录组分析鉴定与蜕皮过程相关的重要候选基因，并确定鳃在蜕皮调控中的作用。对处于不同蜕皮阶段（蜕壳后期（PoM）、蜕皮间期（InM）、蜕壳前期（PrM）和蜕皮期（E））的蟹的转录组进行从头组装，共生成246,232个单基因，平均长度为851 bp。共有86,634个单基因（占单基因总数的35.18%）在参考数据库中得到注释。与蜕皮间期相比，蜕壳后期显著上调的基因有1475个，与蜕壳前期相比，蜕皮间期上调的基因有65个，与蜕皮期相比，蜕壳前期上调的基因有1352个，与蜕壳后期相比，蜕皮期上调的基因有153个，相应的下调基因数量分别为1276、32、1573和171个。几丁质合酶、内切几丁质酶、几丁质酶A、几丁质酶3、几丁质酶6和几丁质脱乙酰酶1在蜕壳后期和蜕皮期上调，而磷酸葡萄糖变位酶3（PGM3）、6-磷酸葡糖胺脱氨酶（GNPDA）和氨基葡萄糖糖苷水解酶（nagZ）在蜕皮间期和蜕壳前期相对于其他阶段上调。上调的基因富集在几个脂质相关的代谢途径中，如“脂肪酸延长”、“甘油磷脂代谢”和“硫代谢”。同时，还富集了三个信号通路，包括“磷脂酰肌醇信号系统”、“钙信号通路”和“GnRH信号通路”。四跨膜蛋白-18是溶酶体途径中参与细胞凋亡的重要效应基因，在蜕皮开始时（蜕壳前期）上调，并在蜕皮期达到最高水平，在蜕皮间期几乎不表达。四跨膜蛋白-18基因的表达变化表明它可能在蜕皮周期开始时起重要作用，这可能受盐度胁迫调控。本研究表明鳃可参与几丁质降解、外骨骼重建和信号传导过程。基于鳃的转录组分析，我们不仅探索了中华绒螯蟹蜕皮的新分子机制，还获得了中华绒螯蟹的基础遗传数据。
