De novo transcriptome assemblies of red king crab (Paralithodes camtschaticus) and snow crab (Chionoecetes opilio) molting gland and eyestalk ganglia. Red king crab and snow crab assemblies

Red king crab (Paralithodes camtschaticus) and snow crab (Chionoecetes opilio) are deep-sea crustaceans widely distributed in the North Pacific and Northwest Atlantic Oceans. These giant predators have invaded the Barents Sea over the past decades, and climate-driven temperature changes might influence their distribution and abundance in the sub-Arctic region. Molting and growth in crustaceans are strongly affected by temperature, but the underlying molecular mechanisms are little known, particularly in cold-water species. Here, we describe multiple regulatory factors in the two high-latitude crabs by developing de novo transcriptomes from the molting gland (Y-organ or YO) and eye stalk ganglia (ESG), in addition to the hepatopancreas and claw muscle of red king crab. The Halloween genes encoding the ecdysteroidogenic enzymes were expressed in YO, and the ESG contained multiple neuropeptides, including molt-inhibiting hormone (MIH), crustacean hyperglycemic hormone (CHH), and ion-transport peptide (ITP). Both crabs expressed a diversity of growth-related factors, such as mTOR, AKT, Rheb and AMPKα, and stress-responsive factors, including multiple heat shock proteins. Temperature effects on the expression of key regulatory genes were quantified by qPCR in adult red king crab males kept at 4 °C or 10 °C for two weeks during intermolt. The Halloween genes tended to be upregulated in YO at high temperature, while the ecdysteroid receptor and several growth regulators showed tissue-specific responses to elevated temperature. Constitutive and heat-inducible heat shock proteins were expressed in a temperature-dependent manner, suggesting that adult red king crabs are able to acclimate to increased water temperatures.

阿拉斯加帝王蟹（Red king crab, *Paralithodes camtschaticus*）与雪蟹（snow crab, *Chionoecetes opilio*）是广泛分布于北太平洋及西北大西洋海域的深海甲壳类动物。近数十年来，这类大型捕食者已入侵巴伦支海，而气候驱动的水温变化可能会影响它们在亚北极区域的分布范围与种群丰度。甲壳动物的蜕皮与生长过程受水温影响显著，但其背后的分子调控机制却鲜为人知，在冷水性物种中更是如此。本研究通过构建两种高纬度蟹类蜕皮腺（Y器官，YO）与眼柄神经节（ESG）的从头转录组（de novo transcriptome），并额外对阿拉斯加帝王蟹的肝胰腺与螯肌开展测序，解析了这两种蟹体内的多种调控因子：编码蜕皮激素合成酶的霍尔登基因（Halloween genes）在YO中表达，而ESG中则含有多种神经肽，包括蜕皮抑制激素（MIH）、甲壳动物高血糖激素（CHH）与离子转运肽（ITP）。两种蟹类均表达多种生长相关因子，如雷帕霉素靶蛋白（mTOR）、蛋白激酶B（AKT）、Ras同源富集蛋白（Rheb）与腺苷酸活化蛋白激酶α亚基（AMPKα），同时还表达多种应激响应因子，包括各类热休克蛋白。本研究通过实时定量聚合酶链反应（qPCR），对蜕皮间期的成年雄性阿拉斯加帝王蟹开展分组实验：将其分别置于4℃与10℃水温下饲养两周，随后定量检测关键调控基因的表达量受水温的影响情况。结果显示，高温环境下霍尔登基因在YO中的表达量呈上调趋势；而蜕皮激素受体与多种生长调控因子则表现出组织特异性的温度响应模式。组成型与热诱导型热休克蛋白的表达均呈现温度依赖性，这表明成年阿拉斯加帝王蟹能够适应水温升高的环境。