基于转录组测序的高体鰤温度胁迫响应基因鉴定

Identification of temperature stress responsive genes in greater amberjack(Seriola dumerili) by transcriptome analysis

  • 摘要: 【目的】 基于转录组测序鉴定高体鰤(Seriola dumerili)温度胁迫响应相关基因,为探究高体鰤耐高温机理与响应高温胁迫的分子机制提供理论参考。【方法】 以高体鰤为研究对象,按温度设定分为25℃(T25)、28℃(T28)、31℃(T31)和34℃(T34)4组,各组高体鰤幼鱼在相应温度条件下饲养7 d。试验第7 d,从各组随机选取6尾高体鰤幼鱼,采集肠道组织。利用TRIzol提取肠道组织总RNA,构建cDNA文库并使用Illumina NovaSeq 6000平台进行转录组测序。使用DESeq2筛选差异表达基因(DEGs),并进行GO功能注释和KEGG信号通路富集分析。采用实时荧光定量PCR检测DEGs相对表达量以验证转录组结果。【结果】 T34组中高体鰤幼鱼于饲养第1 d全部死亡,表明其在该温度下产生了严重的高温应激反应。转录组测序分析结果显示,T25、T28和T31组分别获得了5864.48、6506.81和5952.27 Mb高质量碱基和39.40×106、43.67×106和39.93×106条高质量序列,基因映射到高体鰤基因组的平均映射率分别为95.85%、95.80%和93.51%。DEGs筛选结果显示,T25 vs T28组共获得2043个DEGs,T25 vs T31组共获得1218个DEGs。T25 vs T28和T25 vs T31组分别获得12和7个热休克蛋白相关的DEGs,分别有10和6个DEGs显著上调(P<0.05)。此外,还筛选出与免疫功能和应激功能相关的DEGs。GO功能注释分析结果显示,T25 vs T28和T25 vs T31组DEGs注释到分子功能、细胞组分和生物学过程三大功能类别,T25 vs T28组DEGs注释到小分子代谢过程、有机酸代谢过程和小分子生物合成过程等GO功能条目,T25 vs T31组DEGs主要注释到小分子代谢过程、有机酸代谢过程和含氧酸代谢过程等GO功能条目。KEGG信号通路富集分析结果显示,T25 vs T28组DEGs主要富集到蛋白酶体、半胱氨酸和蛋氨酸代谢等信号通路,T25 vs T31组DEGs主要富集到内质网蛋白加工、丝氨酸和苏氨酸代谢等信号通路。实时荧光定量PCR检测验证结果显示,随机选取的7个DEGs在T25 vs T28和T25 vs T31组相对表达量变化趋势与转录组中每千个碱基转录每百万映射片段数(FPKM)变化趋势基本一致,说明转录组结果可靠。【结论】 高体鰤在高温胁迫下能通过激活以热休克蛋白为核心的分子伴侣系统并协同调节先天免疫识别信号通路及内质网应激反应,有效维持细胞蛋白稳态与氧化还原平衡。高体鰤可能具备通过应激蛋白—免疫识别—内质网修复协同网络响应温度胁迫的适应机制。

     

    Abstract: 【Objective】 The aim of this study was to identify genes related to temperature stress response in greater amberjack(Seriola dumerili) based on transcriptome sequencing, which could provide theoretical reference for exploring the mechanism of high temperature tolerance of Seriola dumerili and molecular mechanism of response to high temperature stress. 【Method】 Seriola dumerili were selected as the research objects and divided into 25 ℃ (T25), 28 ℃ (T28), 31 ℃ (T31) and 34 ℃ (T34) groups according to the temperature setting. The Seriola dumerili juveniles in each group were raised under the corresponding temperature conditions for 7 d. On the 7th day of the experiment, 6 Seriola dumerili juveniles were randomly selected from each group and intestinal tissues were collected. Total RNA from intestinal tissues was extracted using TRIzol reagent, cDNA library was constructed and transcriptome sequencing was performed using the Illumina NovaSeq 6000 platform. Differentially expressed genes(DEGs) were screened using DESeq2, and GO functional annotation and KEGG signaling pathway enrichment analysis were performed. Real-time fluorescence quantitative PCR was used to detect the relative expression levels of DEGs to verify the transcriptome results. 【Result】 All the juveniles of Seriola dumerili in the T34 group died on the first day of feeding, indicating that they had a severe high temperature stress response under this temperature. Transcriptome sequencing analysis showed that 5864.48, 6506.81 and 5952.27 Mb high-quality bases and 39.40×106, 43.67×106 and 39.93×106 high-quality sequences were obtained in the T25, T28 and T31 groups respectively. The average mapping rates of genes mapped to the genome of Seriola dumerili were 95.85%, 95.80% and 95.79% respectively. DEGs screening results showed that a total of 2043 DEGs were obtained in the T25 vs T28 group and a total of 1218 DEGs were obtained in the T25 vs T31 group. Twelve and seven heat shock protein related DEGs were obtained in the T25 vs T28 and T25 vs T31 groups respectively, and ten and six DEGs were significantly up-regulated respectively(P<0.05). In addition, DEGs related to immune function and stress function were screened. GO functional annotation and enrichment analysis results showed that the DEGs in T25 vs T28 and T25 vs T31 groups were annotated to 3 functional categories:molecular function, cellular component and biological process. The DEGs in T25 vs T28 group were annotated to GO functional items such as small molecule metabolic process, organic acid metabolic process and small molecule biosynthesis process, and the DEGs in T25 vs T31 group were mainly annotated to GO functional items such as small molecule metabolic process, organic acid metabolic process and oxygen-containing acid metabolic process. KEGG signaling pathway enrichment analysis results showed that the DEGs in T25 vs T28 group were mainly enriched in signaling pathways such as proteasome, cysteine and methionine metabolism, and the DEGs in T25 vs T31 group were mainly enriched in signaling pathways such as endoplasmic reticulum protein processing, serine and threonine metabolism. Real-time fluorescence quantitative PCR detection verification results showed that the relative expression change trend of the 7 DEGs selected in T25 vs T28 and T25 vs T31 groups was basically consistent with the fragments per kilobase of exon model per million mapped fragments(FPKM) variation trend in transcriptome, indicating that the transcriptome data were reliable. 【Conclusion】 Under high temperature stress, Seriola dumerili effectively maintains cellular protein homeostasis and redox balance by activating a molecular chaperone system centered on heat shock proteins and synergistically regulating the innate immune recognition signaling pathway and endoplasmic reticulum stress response. Seriola dumerili may have an adaptive mechanism to respond to temperature stress through a stress proteinimmune recognition-endoplasmic reticulum repair synergistic network.

     

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