盐度胁迫对缢蛏渗透压、游离氨基酸及肌肽合成酶基因的影响  

Effects of Salinity Stress on Osmotic Pressure,Free Amino Acid Levels,and the Carnosine Synthetase Gene of Sinonovacula constricta

作　　者：安思琪 何琳[1] 范建勋 原居林[3] 林志华[1] AN Siqi;HE Lin;FAN Jianxun;YUAN Julin;LIN Zhihua(College of Biological&Environmental Sciences,Zhejiang Wanli University,Ningbo 315100,China;Sanmen County Aquatic Technology Extension Station,Sanmen 317199,China;Zhejiang Institute of Freshwater Fisheries,Huzhou 313098,China)

机构地区：[1]浙江万里学院生物与环境学院,浙江宁波315100 [2]三门县水产技术推广站,浙江三门317199 [3]浙江省淡水水产研究所,浙江湖州313098

出　　处：《渔业科学进展》2024年第4期97-111,共15页Progress in Fishery Sciences

基　　金：浙江省重点研发计划(2022C02027);台州市农业科技项目(21nyb01);浙江省一流学科“生物工程”学生创新项目(CX2021016)共同资助。

摘　　要：缢蛏(Sinonovacula constricta)为广盐性贝类,自身存在抵抗外界盐度胁迫的渗透调节机制。为探究缢蛏在适应盐度胁迫过程中发挥渗透调节作用的主要游离氨基酸(freeaminoacids,FAA)及其降解途径,本研究测定了不同盐度(5、20和35)胁迫下缢蛏组织的渗透压、FAA含量,并结合其肌肽合成酶基因(carnosine synthase, Sc-CARNS)的表达及相关生理指标的变化研究了Sc-CARNS基因的功能。结果显示,缢蛏鳃、足和血淋巴中渗透压和总游离氨基酸含量随着盐度的升高而升高,且各组织渗透压都在盐度胁迫24h后达到稳态。此时,缢蛏鳃、足和血淋巴中随盐度变化含量变化最明显的FAA分别为Ala、Gly、Glu、Pro,Ala、Gly、Arg、Tua和Ala、Ser、Thr、Gly。前期研究结果显示,在缢蛏盐度胁迫转录组中,Sc-CARNS表达上调,与盐度调节相关。Sc-CARNS在缢蛏肌肉型组织中表达量最高。低盐胁迫下,Sc-CARNS m RNA表达量和肌肽含量显著升高(P<0.05),丙氨酸(Ala)含量变化趋势与肌肽相反。受RNA干扰后,正常盐度和低盐胁迫下,Sc-CARNS基因在足中m RNA表达量和肌肽含量先下降后升高,丙氨酸含量变化则相反,48h干扰效率和含量变化最高,且肌肽与丙氨酸是1∶1的转化。结果表明,缢蛏属于渗透压随变者,体内FAA中的丙氨酸在渗透调节方面的贡献率最大,肌肽合成酶(CARNS)是丙氨酸代谢为肌肽的关键酶,参与渗透压调节过程。本研究揭示了低盐胁迫下缢蛏渗透压调节的关键机理,为揭示竹蛏科(Solenida)贝类独特的盐度耐受性机制提供了依据。Sinonovacula constricta is one of the four traditional cultured shellfish in China.The salinity in the aquaculture water body is easily affected by tides,seasonal rainfall,and high temperatures,and often fluctuates to different degrees.This affects the physiological activities of S.constricta and causes a series of changes in the structure of the osmoregulation organs,osmotic pressure,ion transport,and free amino acid(FAA)content in the body to adapt to the changes in environmental salinity.Aquatic animals can regulate cell volume and maintain osmotic pressure balance through FAAs.This mechanism has been proven in aquatic animals,such as Meretrix lusoria,Crassostrea gigas,Haliotis discus hannai,Penaeus vannamei,and Portunus trituberculatus.The common FAAs that regulate osmotic pressure in bivalves mainly include Ala,Gly,Pro,and Tau.Whether FAAs play an osmoregulation role in S.constricta,whether their involvement in osmoregulation is similar to that in other shellfish,and what the metabolic pathway is of main FAAs deserve further study.This study explored the changes of osmotic pressure and FAAs in the gill,foot,and hemolymph of S.constricta after salinity stress and analyzed the sequence characteristics,tissue expression,and mRNA expression characteristics after salinity stress and RNA interference(RNAi)of the Sc-CARNS gene,and the changes of alanine and carnosine contents.The osmotic pressure and FAA contents in the gills,foot,and hemolymph of S.constricta under different salinities(5,20,and 35)were measured by freezing point osmometer and automatic amino acid analyzer.At the same time,the expression of the Sc-CARNS gene in the foot under different salinities(5,20,and 35)was analyzed by RT-qPCR and RNAi technology.The content of alanine was determined with the shellfish alanine ELISA kit.The content of carnosine was determined by phthalaldehyde colorimetry.The results showed that the osmotic pressure in the gills,foot,and hemolymph of S.constricta significantly decreased within 1–72 h under low salt stress(P<

关 键 词：缢蛏 盐度 渗透压 游离氨基酸 肌肽合成酶 

分 类 号：Q494[生物学—生理学]