Preliminary Study On The Response Mechanism And Genetic Basis Of Chinese Tongue Sole (Cynoglossus Semilaevis) To High Temperature Stress

Chinese tongue sole(Cynoglossus semilaevis)is a kind of warm-temperate offshore large-scale bottom fish.It has the characteristics of gentle temperament,low food level and small activity range.It is an important industrial aquaculture fish in China ’s coastal areas.The high temperature of natural seawater in summer will lead to the death of cultured Chinese tongue sole and reduce the income of culture,which is an important problem in the process of culture and promotion of tongue sole.In order to solve this problem,this paper first selected a full-sib family to carry out high temperature stress experiment,collected the fins of the offspring,constructed a highdensity genetic linkage map and located the loci related to high temperature tolerance.At the same time,the same batch of Chinese tongue sole was selected,and the liver and other tissue samples were collected at five time points of 0,3,6,12 and 24 h under high temperature stress.The RNA of liver tissue was extracted for transcriptome sequencing and analysis,and the liver homogenate was made.The activities of superoxide dismutase(SOD),catalase(CAT)and other enzymes were measured,and liver sections were made.HE staining and TUNEL staining were performed to observe the cell damage of liver tissue at different time points under high temperature treatment,so as to analyze the regulation mechanism of high temperature adaptation of half-smooth tongue sole at the levels of tissue morphology,physiological and biochemical indexes,genome and gene expression.The results showed that the high temperature stress of Chinese tongue sole could cause pathological changes and significant apoptosis of liver tissue.During the high temperature stress,the activities of SOD,CAT and other enzymes changed accordingly.A high-density genetic linkage map of Chinese tongue sole was constructed.There were 21282,24933 and 34591 markers on the female map,male map and integrated map,respectively,with an average interval of 0.078 c M,0.005 c M and 0.054 c M,respectively.Four high-temperature tolerance QTL intervals were mapped by the map,and 88 candidate genes were contained in the interval.Through liver transcriptome sequencing,401 significant differential genes were screened,and KEGG enrichment analysis was performed on the GO annotation of the differential genes,which were enriched into 21 terms and 89 pathways.It includes complement and coagulation cascades(ko04610),platelet activation(ko04611),lipid metabolism(ko00561),estrogen signaling pathway(ko04915)and so on.Through the joint analysis of transcriptome significant difference genes,hub genes and significant module genes,17 candidate genes related to high temperature stress of half-smooth tongue sole were screened.Among them,10 candidate genes related to high temperature resistance were selected for quantitative PCR verification,and the results were basically consistent with the transcriptome.In this study,the mechanism of high temperature resistance of Chinese tongue sole was preliminarily analyzed from different levels of cell morphology,physiological and biochemical indexes,genome and gene expression.The results provided an important theoretical basis for the breeding of high temperature resistant varieties of Chinese tongue sole.