长期饥饿胁迫下厚壳贻贝的生理生化响应及性腺转录组

Physiological and biochemical responses and gonad transcriptome analysis of Mytilus coruscus under long-term starvation

为探究贻贝在饥饿胁迫下的生理生化响应及分子适应机制,本研究以2龄厚壳贻贝为对象,开展了正常投喂(对照组)和饥饿处理(饥饿组)条件下的存活率统计、能量代谢相关酶活性测定以及性腺转录组测序及分析。结果显示,厚壳贻贝在90 d的饥饿处理下存活率高达86%。饥饿胁迫下贻贝性腺中磷酸烯醇式丙酮酸羧激酶(PEPCK)活性显著增加,己糖激酶(HK)、磷酸果糖激酶(PFK)、琥珀酸脱氢酶(SDH)、苹果酸脱氢酶(MDH)活性均显著降低。通过Illumina Hiseq×10高通量测序平台对对照组和饥饿组厚壳贻贝性腺组织进行转录组测序,分别获得31596762和26810506个在其基因组上具有唯一注释的有效数据,并筛选出4130个差异表达基因,包括2082个上调和2048个下调表达基因。GO功能分析结果显示,差异基因主要在富集在代谢过程、细胞器组织以及酶活性等功能。KEGG富集分析结果表明,差异基因显著富集在DNA复制、错配修复、碱基切除修复等与细胞分裂有关的代谢通路上。研究表明,贻贝在饥饿下通过降低细胞的能量代谢以及减缓细胞分裂等生理活动来维持饥饿胁迫下的生存。本研究初步揭示了厚壳贻贝在饥饿胁迫下的生理生化响应和分子调控机制,为今后深入解析贻贝应对饥饿胁迫的分子策略提供重要的理论依据,同时为揭示其适应饥饿胁迫的能量利用和再分配以及生理对策提供新的思路。

Food is the main source of energy for animals,and food abundance affects animal bioenergetics in terms of how energy is allocated among growth,maturation,and reproduction.However,food resources are sometimes insufficient for mussel because of weather conditions,specific periods of their reproductive cycles and food restriction.Marine mussels are one of the most important marine genera globally and are widely distributed in estuarine and marine environments,as well as in the subtidal and intertidal zones,and are commercially important.In order to explore the physiological and biochemical responses and molecular adaptation mechanism of mussels under starvation stress,the survival rate statistics,energy metabolism related enzyme activity determination and gonad transcriptome sequencing and analysis were carried out on two-year Mytilus coruscus under normal feeding(control group)and starvation treatment(starvation group).The results showed that the survival rate of M.coruscus reached 86%after 90 days of starvation.Under starvation stress,the activities of phosphoenolpyruvate carboxykinase(PEPCK)were significantly increased,but the activities of hexokinase(HK),phosphofructokinase(PFK),succinate dehydrogenase(SDH)and malate dehydrogenase(MDH)were significantly decreased(P<0.05).By Illumina Hiseq X10 high-throughput sequencing platform,31596762 and 26810506 effective data with unique annotation on the genome of the control group and the starvation group were obtained,and 4130 differentially expressed genes were screened.There were 2082 up-regulated and 2048 down-regulated genes.GO functional analysis showed that differential genes were mainly enriched in metabolic process,organelle tissue and enzyme activity.KEGG enrichment analysis showed that differential genes were significantly enriched in metabolic pathways related to cell division,such as DNA replication,mismatch repair and base excision repair.The results of this experiment showed that mussels could maintain their survival under starvation stress by reducing energy metabolism and slowing down cell division.This study preliminarily reveals the physiological and biochemical responses and molecular regulation mechanism of M.coruscus under starvation stress,which provides important theoretical basis for further analysis of the molecular strategies of mussels in response to starvation stress,and also provides new ideas for revealing their energy utilization and redistribution and physiological countermeasures to adapt to starvation stress.