Study On The Growth Mechanism Of Muscle After Persistent High Temperature To Male And Female Nile Tilapia And Alternative Splicing Analysis

Fish is a typical variable-temperature aquatic animal,and its survival,growth,and behavior are closely related to temperature.Heat stress not only affects fish feeding,exercise and breathing,but also disrupts the metabolism process in the body and affects fish growth and development.Therefore,studying the response mechanism of fish to an increase in ambient temperature has become a hot topic.This research focuses on the theme of heat resistance mechanism,using Nile tilapia muscle tissues as an experimental material to fully reveal the adaptive mechanism of tilapia to high temperature.In this experiment,transcriptome sequencing analysis was used to explain the pathways of Nile tilapia response to high temperature,and to clarify the response mechanism of female and male to continuous high temperature treatment.After sustained high temperature treatment,the growth and development of Nile tilapia showed significant differences.After 30 days of high temperature treatment(36 ?),the growth of the experimental group and the control group began to show differences.The growth of the high temperature group was slower,and that of the control group(28 ?)was faster.The speed was significantly slower than that of the control group,both of which showed that males grew faster than females.Then we used TUNEL staining to quantify and analyze apoptotic cells in the brain,muscle and gill tissues of tilapia,and then compared the damage of tissues under high temperature treatment.We found that when these fish were continuously exposed to a high temperature of 36 ?,the apoptotic events mainly occurred in the muscle tissues of tilapia,while other tissues had weaker apoptotic signals,which suggested that the apoptosis occurred in muscle tissue may be a marker for inhibiting fish growth and development.We performed transcriptome sequencing analysis of muscle tissues of different sexes of Nile tilapia after continuous high temperature treatment.Compared with the control group,the statistical results of differentially expressed gene screening showed that the differentially expressed genes of female tilapia increased significantly during 50 days of high temperature culture.The total number of DEGs was 5,219,the genes were upregulated by 2849,and the genes were down-regulated by 2370.The males had the highest differentially expressed genes during 70 days of high temperature culture.The total number of DEGs was 4645,there were 3460 up-regulated genes,and the downregulated genes were 1185.During 70 days of high temperature treatment,the differentially expressed genes in females showed a trend of rising first and then falling,and the number of up-regulated genes were higher than down-regulating genes;while males showed a trend of first falling and then rising,and the up-regulated genes were obvious higher than down-regulated genes after 30 days.Gene Ontology enrichment analysis of differentially expressed genes found that females are mainly enriched in processes such as DNA replication,cell development,cell differentiation,immune response,and inflammatory response.Male fish are mainly concentrated in protein folding,redox coenzyme metabolism,and cell development.And neuronal development.KEGG cluster analysis of female fish after continuous high temperature treatment is mainly concentrated in the "cell cycle","ECM-receptor interaction","DNA replication","cell adhesion molecules" and other pathways;male fish are mainly concentrated in " Purine metabolism "," pyrimidine metabolism "," drug metabolism "," tight connection " and "carbon metabolism " and other pathways.The GO enrichment analysis and KEGG enrichment analysis showed that tilapia's metabolism,immunity,lipid and carbohydrate components and apoptosis significantly changed under high temperature stress.Persistent high temperature stress led to an increase in the number of alternative splicing events in Nile tilapia.The GO enrichment analysis of the differential alternative splicing events generated by high temperature treatment found that it was mainly enriched in biological processes such as calcium ion binding,signal transduction,intracellular signal transduction,Wnt signaling pathway,transcriptional regulation,immune response,etc.In summary,we have discovered the important role that fish muscle tissues play in responding to high temperature stress.The results of this study provide new ideas for the mechanism of fish damage in response to heat stress.