盐碱胁迫对莫桑比克罗非鱼TauT2基因表达的影响

Effects of salt-alkali stress on TauT2 gene expression in Oreochromis mossambicus

  • 摘要: 【目的】研究在莫桑比克罗非鱼(Oreochromis mossambicus)中新发现的编码牛磺酸转运蛋白的基因TauT2在盐碱胁迫下对鱼体渗透压调控的作用,为深入阐明鱼类中牛磺酸转运蛋白的功能提供更全面可靠的数据。【方法】通过PCR和直接测序的方法对TauT2基因的编码区序列(CDS)进行分析,用生物信息学分析方法预测其编码蛋白的氨基酸序列及其高级结构,并利用荧光定量PCR检测该基因在肝、肠、肌肉等13个组织中的表达特征,以及在盐碱胁迫(盐25 g/L,碱4 g/L) 96 h内,不同时间点鳃、肾、肠和肝组织中TTauT2基因mRNA的表达水平。【结果】获得的TauT2基因CDS序列全长1881 bp,共编码626个氨基酸,氨基酸序列与斑马拟丽鱼(Maylandia zebra)牛磺酸转运蛋白的一致性最高,为98.72%,与已报道的莫桑比克罗非鱼的tTAUT1蛋白一致性为88.52%,该蛋白具有典型的牛磺酸转运蛋白跨膜结构域。荧光定量PCR结果表明,TauT2基因在肝、肠、肌肉等13个组织均有表达,其中血液中表达量最高,肠中的表达量最低。盐碱胁迫条件下,TauT2基因mRNA表达水平在鳃、肾、肠和肝组织中的表达均呈先升高再下降的变化趋势,鳃和肝达峰值的时间为48 h,肾和肠达峰值的时间分别是24和72 h,达峰值的时间与莫桑比克罗非鱼的tTauT1基因存在明显差异。【结论】莫桑比克罗非鱼在受到盐碱胁迫后,通过提升TauT2基因的表达量来有效调控体内渗透压,为渗透压稳态的维持发挥作用。莫桑比克罗非鱼体内至少有2种不同的牛磺酸转运蛋白,已发现的这2个蛋白氨基酸序列、三级结构及在鱼体不同组织中精细调节体内渗透压的功能存在一定差异。

     

    Abstract: 【Objective】To study osmotic pressure regulation function of the newly-discovered TauT2 gene of taurine transporter in Oreochromis mossambicus under salt-alkali stress, so as to provide reliable data for expounding function of taurine transporter of fish.【Method】 The coding sequence(CDS) of TauT2 gene was analyzed through PCR and sequencing. The amino acid sequence and tertiary structure of the encoded protein were predicted through bioinformatics analysis. Expression characteristics of the gene in 13 tissues including liver, intestine and muscle, mRNA expression of TauT2 gene in gill, kidney, intestine and liver tissues under salt-alkali stress(salt of 25 g/L and alkali of 4 g/L) in different times within 96 h were detected through fluorescence quantitative real-time PCR.【Result】CDS of TauT2 gene was 1881 bp, which encoded 626 amino acids. The amino acid sequence of TauT2 in O. mossambicus had the highest homology of 98.72% with that of taurine transporter in Maylandia zebra, and it was 88.52% homologous with tTauT1 gene in O. mossambicus, respectively. This protein had typical transmembrane domain of taurine transporter. Fluorescence quantitative realtime PCR results showed that the gene TauT2 was detected in 13 tissues suchas liver, intestine and muscle with the highest expression in blood and the lowest in intestine. Under salt-alkali stress, mRNA expression of TauT2 gene in gill, kidney, intestine and liver showed a tendency of first increasing and then decreasing. TauT2 expression of gill and liver peaked at 48 h, and those of kidney and intestine peaked at 24 and 72 h. The time to arrive peak value of TauT2 was significantly different from that of tTauT1 gene in O. mossambicus.【Conclusion】 Under salt-alkali stress, TauT2 gene in O. mossambicus is up-regulated to regulate osmotic pressure to maintain homeostasis of osmotic pressure. There are at least 2 kinds of taurine transporters in O. mossambicus and amino acid sequence, tertiary structure and osmoregulation function between the two taurine transporters are different.

     

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