Zhang Yin, Wu Qingyang, Fang Shaobin, Li Shengkang, Zheng Huaiping, Zhang Yueling, Ikhwanuddin Mhd, Ma Hongyu
Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, 243 Daxue Road, Shantou, 515063, China.
STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou, 515063, China.
BMC Genomics. 2020 Aug 14;21(1):559. doi: 10.1186/s12864-020-06965-5.
Mud crab, Scylla paramamosain, a euryhaline crustacean species, mainly inhabits the Indo-Western Pacific region. Wild mud crab spawn in high-salt condition and the salinity reduced with the growth of the hatching larvae. When the larvae grow up to megalopa, they migrate back to estuaries and coasts in virtue of the flood tide, settle and recruit adult habitats and metamorphose into the crablet stage. Adult crab can even survive in a wide salinity of 0-35 ppt. To investigate the mRNA profile after salinity stress, S. paramamosain megalopa were exposed to different salinity seawater (low, 14 ppt; control, 25 ppt; high, 39 ppt).
Firstly, from the expression profiles of Na+/K+/2Cl- cotransporter, chloride channel protein 2, and ABC transporter, it turned out that the 24 h might be the most influenced duration in the short-term stress. We collected megalopa under different salinity for 24 h and then submitted to mRNA profiling. Totally, 57.87 Gb Clean Data were obtained. The comparative genomic analysis detected 342 differentially expressed genes (DEGs). The most significantly DEGs include gamma-butyrobetaine dioxygenase-like, facilitated trehalose transporter Tret1, sodium/potassium-transporting ATPase subunit alpha, rhodanese 1-like protein, etc. And the significantly enriched pathways were lysine degradation, choline metabolism in cancer, phospholipase D signaling pathway, Fc gamma R-mediated phagocytosis, and sphingolipid signaling pathway. The results indicate that in the short-term salinity stress, the megalopa might regulate some mechanism such as metabolism, immunity responses, osmoregulation to adapt to the alteration of the environment.
This study represents the first genome-wide transcriptome analysis of S. paramamosain megalopa for studying its stress adaption mechanisms under different salinity. The results reveal numbers of genes modified by salinity stress and some important pathways, which will provide valuable resources for discovering the molecular basis of salinity stress adaptation of S. paramamosain larvae and further boost the understanding of the potential molecular mechanisms of salinity stress adaptation for crustacean species.
锯缘青蟹（Scylla paramamosain）是一种广盐性甲壳类动物，主要栖息于印度 - 西太平洋地区。野生锯缘青蟹在高盐环境中产卵，随着孵化幼体的生长，盐度逐渐降低。当幼体发育至大眼幼体阶段时，它们借助涨潮迁移回河口和海岸，定居并进入成体栖息地，然后变态为蟹幼体阶段。成年蟹甚至能在0 - 35‰的广泛盐度范围内生存。为了研究盐度胁迫后的mRNA谱，将锯缘青蟹大眼幼体暴露于不同盐度的海水中（低，14‰；对照，25‰；高，39‰）。
首先，从钠/钾/2氯协同转运蛋白、氯通道蛋白2和ABC转运蛋白的表达谱来看，24小时可能是短期胁迫中受影响最大的时间段。我们收集了在不同盐度下处理24小时的大眼幼体，然后进行mRNA谱分析。总共获得了57.87 Gb的Clean Data。比较基因组分析检测到342个差异表达基因（DEGs）。差异最显著的基因包括γ-丁酰甜菜碱双加氧酶样蛋白、易化型海藻糖转运蛋白Tret1、钠/钾转运ATP酶亚基α、硫氰酸酶1样蛋白等。显著富集的通路有赖氨酸降解、癌症中的胆碱代谢、磷脂酶D信号通路、FcγR介导的吞噬作用和鞘脂信号通路。结果表明，在短期盐度胁迫下，大眼幼体可能通过调节代谢、免疫反应、渗透调节等机制来适应环境变化。
本研究首次对锯缘青蟹大眼幼体进行全基因组转录组分析，以研究其在不同盐度下的胁迫适应机制。结果揭示了许多受盐度胁迫影响的基因和一些重要通路，这将为发现锯缘青蟹幼体盐度胁迫适应的分子基础提供有价值的资源，并进一步加深对甲壳类动物盐度胁迫适应潜在分子机制的理解。
