低盐胁迫下LXRα激动剂添加和RNA干扰对大菱鲆(Scophthalmus maximus)幼鱼脂质代谢的影响

EFFECTS OF LXRαAGONIST ADDITION AND RNA INTERFERENCE ON LIPID METABOLISM OF JUVENILE TURBOT SCOPHTHALMUS MAXIMUS UNDER LOW SALT STRESS

大菱鲆是我国重要的养殖经济鱼类,随着养殖水域逐渐向滩涂和内陆拓展,亟待研究其低盐适应性机制,进而为培育耐低盐良种提供参考。通过腹腔注射干扰剂dsRNA以及激动剂T091317,以进一步检测下游脂质代谢相关基因的表达以及血清脂代谢产物的变化。研究设置两个盐度梯度(5和30),每个盐度设置4个处理组(干扰组、激动组、生理盐水组和空白对照组),实验周期72 h。结果显示:在dsRNA注射后,肝脏中LXRα基因的相对表达量呈现出显著的抑制作用,尤其是在盐度30下;盐度5的肝脏组以及不同盐度的肠道组中,干扰效果不明显。激动剂注射后LXRα基因的相对表达量在不同盐度组中均呈现了激动效应,但维持时间较短。低盐可以抑制SREBP-1、CYP7A1和ApoA-IV基因的表达,当LXRα基因受到抑制或激动后,三者尽管表达趋势不同,但整体上均呈现出相应的干扰和激动效应。血清生化结果显示,低盐显著抑制了TG和HDL的含量,对T-CHO以及LDL的含量无显著影响。30盐度下,当LXRα基因受到抑制或激动后,TG的含量呈现出相应的干扰和激动效应。以上表明在腹腔注射干扰剂dsRNA以及激动剂后,都能够相应的导致LXRα基因表达量降低或者升高。LXRα基因受到抑制后,可以引起下游转录因子SREBP-1基因表达的降低,进而抑制了TG的合成,因此血清中甘油三酯的含量可以进一步作为大菱鲆耐低盐选育的表型。

The turbot(Scophthalmus maximus)is an important economically valuable fish in China's aquaculture industry.As aquaculture environments area expands to the tidal flats and inner areas,it is imperative to study the mechanisms of low-salinity adaptation in turbot to provide a reference for breeding low-salinity-tolerant varieties.This study investigates the expression of downstream lipid metabolism-related genes and changes in serum lipid metabolic products through intraperitoneal injection of the inhibitor dsRNA and the agonist T091317.Two salinity gradients(5 and 30)were set,with four treatment groups for each salinity(interference group,agonist group,physiological saline group,and blank control group),and the experimental period lasted for 72 h.The results showed that the relative expression of the LXRαgene in the liver was significantly inhibited after dsRNA injection,especially at a salinity of 30;however,the interference effect was not significant in the liver at 5 and in the intestinal groups at different salinities.After injection of the agonist,the relative expression of the LXRαgene showed an agonistic effect in different salinity groups,but the duration was short.Low salinity inhibited the expression of SREBP-1,CYP7A1,and ApoA-IV genes.When the LXRαgene was inhibited or activated,despite different expression trends,all three genes showed corresponding interference and activation effects overall.Serum biochemical results showed that low salinity significantly inhibited the levels of TG and HDL,with no significant effect on T-CHO and LDL levels.At a salinity of 30,when the LXRαgene was inhibited or activated,the TG content showed corresponding interference and activation effects.The above results indicate that intraperitoneal injection of the inhibitor dsRNA and the agonist can correspondingly lead to a decrease or increase in LXRαgene expression.Inhibition of the LXRαgene can lead to a reduction in the expression of the downstream transcription factor SREBP-1 gene,thereby inhibiting TG synthesis.Therefore,the serum triglyceride content can be further used as a phenotype for selecting low-salinity-tolerant turbot.