Huo Da, Sun Lina, Li Xiaoni, Ru Xiaoshang, Liu Shilin, Zhang Libin, Xing Lili, Yang Hongsheng
Chinese Academy of Sciences Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
G3 (Bethesda). 2017 Nov 6;7(11):3681-3692. doi: 10.1534/g3.117.1129.
The sea cucumber, an important economic species, has encountered high mortality since 2013 in northern China because of seasonal environmental stress such as hypoxia, high temperature, and low salinity. MicroRNAs (miRNAs) are important in regulating gene expression in marine organisms in response to environmental change. In this study, high-throughput sequencing was used to investigate alterations in miRNA expression in the sea cucumber under different levels of dissolved oxygen (DO). Nine small RNA libraries were constructed from the sea cucumber respiratory trees. A total of 26 differentially expressed miRNAs, including 12 upregulated and 14 downregulated miRNAs, were observed in severe hypoxia (DO 2 mg/L) compared with mild hypoxia (DO 4 mg/L) and normoxic conditions (DO 8 mg/L). Twelve differentially expressed miRNAs were clustered in severe hypoxia. In addition, real-time PCR revealed that 14 randomly selected differentially expressed miRNAs showed significantly increased expressions in severe hypoxia and the expressions of nine miRNAs, including key miRNAs such as Aja-miR-1, Aja-miR-2008, and Aja-miR-184, were consistent with the sequencing results. Moreover, gene ontology and pathway analyses of putative target genes suggest that these miRNAs are important in redox, transport, transcription, and hydrolysis under hypoxia stress. Notably, novel-miR-1, novel-miR-2, and novel-miR-3 were specifically clustered and upregulated in severe hypoxia, which may provide new insights into novel "hypoxamiR" identification. These results will provide a basis for future studies of miRNA regulation and molecular adaptive mechanisms in sea cucumbers under hypoxia stress.
海参是一种重要的经济物种，自2013年以来，由于缺氧、高温和低盐度等季节性环境压力，中国北方的海参遭遇了高死亡率。微小RNA（miRNA）在调节海洋生物对环境变化的基因表达方面起着重要作用。在本研究中，采用高通量测序技术研究了不同溶解氧（DO）水平下海参miRNA表达的变化。从海参的呼吸树构建了9个小RNA文库。与轻度缺氧（DO 4 mg/L）和常氧条件（DO 8 mg/L）相比，在严重缺氧（DO 2 mg/L）条件下共观察到26个差异表达的miRNA，其中12个上调，14个下调。12个差异表达的miRNA在严重缺氧条件下聚类。此外，实时PCR显示，随机选择的14个差异表达的miRNA在严重缺氧时表达显著增加，包括Aja-miR-1、Aja-miR-2008和Aja-miR-184等关键miRNA在内的9个miRNA的表达与测序结果一致。此外，对假定靶基因的基因本体和通路分析表明，这些miRNA在缺氧胁迫下的氧化还原、运输、转录和水解过程中起重要作用。值得注意的是，novel-miR-1、novel-miR-2和novel-miR-3在严重缺氧时特异性聚类并上调，这可能为新型“缺氧miRNA”的鉴定提供新的见解。这些结果将为今后研究海参在缺氧胁迫下的miRNA调控和分子适应性机制提供依据。
