低盐胁迫对刺参 4 个盐度调节相关基因表达丰度的影响

从刺参(Apostichopus japonicus)低盐转录组数据库中选取与应激(热休克蛋白70基因)和离子传递(甘氨酸转运蛋白基因、锌转运蛋白基因、神经乙酰胆碱受体基因)相关的4个差异表达基因,利用qRT-PCR技术分析这4个基因在不同组织中的表达水平及低盐对其表达丰度的影响.结果表明甘氨酸转运蛋白基因在刺参呼吸树中表达水平最高,肠次之,体腔液表达较低;锌指蛋白基因和神经乙酰胆碱受体基因均在体腔液中表达最高,肠次之,在呼吸树中不表达;热休克蛋白70基因在体腔液中表达量最高,其次是呼吸树和肠组织.低盐胁迫下这4种基因的表达量均随着胁迫时间的延长呈波动性增减,其中甘氨酸转运蛋白在体腔液中的表达低于正常表达水平,在胁迫后3h时达到最低表达量.神经乙酰胆碱受体基因除在体腔液中48 h出现明显的上调外,在体腔液其他时间点和肠组织中处于下调表达状态.低盐胁迫下这4个基因表达丰度的变化,说明这些基因或作为功能蛋白直接参与机体的代谢调节,或作为调控蛋白调节胁迫功能蛋白的表达和活性来提高刺参对低盐胁迫的耐受能力.研究结果可为刺参盐度调节适应机制的研究奠定基础.

Expression of genes involved in salinity regulation in sea cucumber, Apostichopus japoninus under low salinity stress

 We evaluated the effect of changes in salinity on four genes involved in salinity regulation (glycine transporter, zinc finger protein, heat shock protein 70, neuronal acetylcholine receptor) in Apostichopus japonicus using real-time quantitative PCR. The basal level of glycine transport gene expression was highest in the respiratory tree, followed by intestinal tissue and coelomic fluid. The level of zinc transporter and acetylcholine receptor gene expression was highest in the coelomic fluid, and expression was not detected in the respiratory tree. Expression of the Hsp70 gene was highest in the coelomic fluid, followed by the respiratory tree and intestine. Exposure to low salinity stress resulted in changes in glycine transporter gene expression in all tissues. Expression peaked in the intestine and respiratory tree after 72 h and 1.5 h, respectively. Conversely, expression in coelomic fluid decreased and was at its lowest level after 3 h. Expression of the zinc transporter gene also changed in response to low salinity stress. Expression peaked after 24 h in the intestinal tissue and after 6 h in the coelomic fluid. Neuronal acetylcholine receptor gene expression was initially down-regulated in the intestine during exposure to the low salinity stress. However, there was a significant increase in expression in the coelomic fluid at 48 h. The expression of Hsp70 mRNA peaked after 48 h in both coelomic fluid and respiratory tree and after 12 h in intestinal tissue. Quantitative analysis of the expression of these genes revealed significant differences among the different tissues and different exposure times. The expression profiles suggested that the four genes can be used as indicators of salinity stress. Given the changes in expression, the protein products of the four genes are likely involved in the regulation of metabolism as function proteins, or control the expression and the activity of the stress proteins as regulatory proteins, to improve the salinity stress tolerance of A. japonicus. Our results provide a foundation for studying the mechanism adaption of sea cucumber for the future study. Key words: Apostichopus japonicus; low salinity stress; glycine transporter; zinc finger protein; neuronal acetylcholine receptor; Hsp70