College of the Environment and Ecology, Xiamen University, Xiamen 361102, China.
Guangdong Provincial Key Laboratory of Marine Biology, College of Science, Shantou University, Shantou 515063, China.
Aquat Toxicol. 2021 Nov;240:105970. doi: 10.1016/j.aquatox.2021.105970. Epub 2021 Sep 16.
Increasing salinity levels in marine and estuarine ecosystems greatly influence developmental, physiological and molecular activities of inhabiting fauna. Marine medaka (Oryzias melastigma), a euryhaline research model, has extraordinary abilities to survive in a wide range of aquatic salinity. To elucidate how marine medaka copes with salinity differences, the responses of Oryzias melastigma after being transferred to different salt concentrations [0 practical salinity units (psu), 15 psu, 30 psu (control), 45 psu] were studied at developmental, histochemical and transcriptome levels in the gill and liver tissues. A greater number of gills differentially expressed genes (DEG) under 0 psu (609) than 15 psu (157) and 45 psu (312), indicating transcriptomic adjustments in gills were more sensitive to the extreme hypotonic environment. A greater number of livers DEGs were observed in 45 psu (1,664) than 0 psu (87) and L15 psu (512), suggesting that liver was more susceptible to hypertonic environment. Further functional analyses of DEGs showed that gills have a more immediate response, mainly in adjusting ion balance, immune and signal transduction. In contrast, DEGs in livers were involved in protein synthesis and processing. We also identified common DEGs in both gill and liver and found they were mostly involved in osmotic regulation of amino sugar and nucleotide sugar metabolism and steroid biosynthesis. Additionally, salinity stresses showed no significant effects on most developmental and histochemical parameters except increased heartbeat with increasing salinity and decreased glycogen after transferred from stable conditions (30 psu) to other salinity environments. These findings suggested that salinity-stress induced changes in gene expressions could reduce the effects on developmental and histochemical parameters. Overall, this study provides a useful resource for understanding the molecular mechanisms of fish responses to salinity stresses.
在海洋和河口生态系统中，盐度的增加极大地影响着栖息动物的发育、生理和分子活动。海洋型稻花鱼（Oryzias melastigma）是一种广盐性研究模型，具有在广泛的水生盐度范围内生存的非凡能力。为了阐明海洋型稻花鱼如何应对盐度差异，本研究在鳃和肝脏组织中，从发育、组织化学和转录组水平上研究了海洋型稻花鱼从不同盐度[0 实用盐度单位（psu）、15 psu、30 psu（对照）、45 psu]转移后的反应。在 0 psu（609 个）下，鳃中差异表达基因（DEG）的数量多于 15 psu（157 个）和 45 psu（312 个），表明在极端低盐环境下，鳃的转录组调整更为敏感。在 45 psu（1664 个）下，肝脏中观察到的 DEG 数量多于 0 psu（87 个）和 L15 psu（512 个），表明肝脏对高盐环境更为敏感。进一步对 DEG 的功能分析表明，鳃有更直接的反应，主要是在调节离子平衡、免疫和信号转导方面。相比之下，肝脏中的 DEGs 参与了蛋白质的合成和加工。我们还鉴定了鳃和肝脏中共同的 DEGs，并发现它们主要参与了氨基糖和核苷酸糖代谢以及类固醇生物合成的渗透压调节。此外，除了随着盐度增加心跳增加和从稳定条件（30 psu）转移到其他盐度环境后糖原减少之外，盐度胁迫对大多数发育和组织化学参数没有显著影响。这些发现表明，盐度胁迫引起的基因表达变化可以减少对发育和组织化学参数的影响。总的来说，本研究为了解鱼类对盐度胁迫的分子机制提供了有用的资源。
