盐度胁迫对幼体大海马基因转录表达的影响

EFFECTS OF SALINITY STRESS ON ANSCRIPTION AND EXPRESSION IN JUVENILE HIPPOCAMPUS KUDA BLEEKER

  • 摘要: 为探究大海马(Hippocampus kuda Bleeker)幼体在高盐、低盐胁迫条件下的基因表达水平的变化规律, 对实验条件下的大海马幼体的肝脏样品进行了转录组测序。对照组(CK, 25‰)、高盐(HS-test, 31‰)和低盐 (LS-test, 17‰)胁迫组共获得71794个单基因簇(Unigenes), N50为1780 bp, 平均长度为820.71 bp。高盐胁迫组与对照组比较, 共获得2740个差异表达基因 (DEGs), 其中495个DEGs上调, 2245个DEGs下调; 与对照组相比, 低盐胁迫组共获得3715个DEGs, 其中1854个DEGs上调, 1861个DEGs下调。高/低盐胁迫组DEGs经 KEGG 数据库富集发现, 高/低盐度胁迫均能导致大海马幼体体内氨基酸代谢、免疫代谢、能量和脂肪酸代谢相关基因受到影响。其中, 低盐胁迫时能量代谢和氨基酸代谢的相关基因显著上调, 高盐胁迫时脂肪酸代谢的相关基因显著下调, 而高/低盐胁迫时免疫代谢的相关基因都显著上调。从经过盐度胁迫的大海马幼体的肝脏转录组中分别筛选到免疫相关基因GstHsp70、Hsp90、SodBcl-2、Gadd45αTcrβTap2和Traf3, 脂肪酸代谢相关基因Fadsd6、FasSqleCyp51、Elovl6和Slc27a6, 能量代谢相关基因VlcadPdha1、Mdh1、Idh3bG6pdSdhd, 及一些氨基酸代谢相关基因GldcAtp6v1e1、SmsFadhAslAss1和Glud1等, 可作为大海马幼体响应环境盐度变化应激的候选基因。研究结果为盐度胁迫下大海马幼体的稳态调控机制的研究奠定了一定基础, 有助于在养殖实践中预防极端的盐度改变对大海马幼体所造成的影响。

     

    Abstract: Salinity is an important environmental factor that affects the life cycle of aquatic organisms, including their growth, development and reproduction. In fish, acute salinity changes cause a series of physiological responses. Hippocampus kuda is an important economic resource and can adapt to a wide range of salinity levels, while the juveniles are highly sensitive to salinity stress, which may cause pathological signs or diseases by alleviating the immune roles and then lead to mass mortality. The survival rate of cultivated H. kuda is low in China because of the toxic effects of salinity stress on juvenile seahorse. To understand molecular mechanisms of its low survival rate, this study used high-throughput sequencing technology to analyze differentially expressed genes (DEGs) in juvenile seahorse hepatopancreatic tissues treated with normal-salinity water (CK, salinity=25‰), low-salinity water (LS-test, salinity=17‰), and high-salinity water (HS-test, salinity=31‰) respectively for 12h. According to the result of RNA-Seq, a total of 71794 unigenes were produced among control group, high-salinity stress group and low-salinity stress group, and the sequence N50 value was 1780 bp, with an average length of 820.71 bp. Compared with the control group, there were 2740 differently expressed genes selected in high salinity group, of which 495 genes were up-regulated and 2245 were down-regulated. On the other hand, 3715 differently expressed genes were selected in low-salinity group, of which 1854 genes were up-regulated and 1861 genes were down-regulated. Ten dysregulated DEGs (Gst, Bcl-2, Fas, Vlcad, Pdha1, Mdh1, Idh3b, G6pd, Gadd45α and SOD) were confirmed by qRT-PCR. According to the result of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, the DEGs were mainly related to metabolism and immune responses. With respect to metabolism, the low-salinity group had enhanced energy and amino acid metabolism, while high-salinity group had reduced lipid metabolism related genes expression. Both high- and low-salinity group had enhanced immune metabolism pathways. Based on our results, we collected the lipid metabolism related genes (Fadsd6, Fas, Sqle, Cyp51, Elovl6 and Slc27a6), amino acid metabolism related genes (Gldc, Atp6v1e1, Sms, Fadh, Asl, Ass1 and Glud1), energy metabolism related genes (Vlcad, Pdha1, Mdh1, Idh3b, G6pd and Sdhd) and immune related genes (Gst, Hsp70, Hsp90, Sod, Bcl-2, Gadd45α, Tcrβ, Tap2 and Traf3) of H. kuda as genetic indicators to identify the stressor. This study will promote the discovery of the molecular mechanism of salt stress adaptation of aquatic organisms, and provides a reference for ambient salinity control in aquaculture.

     

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