Response Mechanism Of Glycolipid Metabolism Pathway In Grass Carp Under Microplastic And Aeromonas Hydrophila Stress

Grass carp is an important freshwater aquaculture fish in my country.It is often faced with many abiotic and biotic factors in the breeding process.Grass carp usually resists external stress by enhancing specific metabolic processes.There are many factors for resistance to abiotic stress.Microplastic stimulation is an important reason.This study took the transcriptome as the breakthrough point to study the physiological effects of grass carp under two concentrations of microplastic stress,the influence of biochemical indicators,differentially expressed genes and enriched signaling pathways,revealing the main reasons for lipid metabolism disorders under the stimulation of microplastics;anti-microbial stress is mainly anti-pathogenic bacteria,and Aeromonas hydrophila is selected as the stimulus source.Taking miRNA as an entry point,we explored the regulatory mechanism of non-codingRNA on the glycolysis process under bacterial infection,and revealed the molecular mechanism by which cells can resist bacterial infection by enhancing the glycolysis process.The main findings obtained are as follows:1.Grass carp were exposed to two concentrations of MPs(1000 and 100 μg/L),and fluorescent signals were detected in liver digestive fluid.Grass carp exposed to MPs for 21 days exhibited hepatocyte vacuolation and growth inhibition.At the end of the exposure period,fish treated with MPs exhibited suppression of the antioxidant system and enhancement of oxidative stress compared with the control group.Transcriptome analysis of grass carp was then performed to reveal the molecular mechanisms of response to MPs.In total,1,554 differentially expressed genes(DEGs)were identified.The results of GO and KEGG pathway analysis of DEGs identified energy metabolism-related pathways and peroxisome proliferator-activated receptor(PPAR)signaling pathways.2.Four key genes related to metabolism were cloned and characterized in grass carp,and their mRNA expression profiles and transcriptional responses to microplastic stimulation were explored.Their mRNAs are widely expressed in various tissues.Microplastic stimulation increased the mRNA levels of apoe,ppar-α,cyp1a1,and ugt1a1,indicating that microplastics disrupt the normal metabolic process of grass carp,lead to lipid metabolism disorders,and significantly activate exogenous metabolic pathways.Cytochrome P450 family 1 subfamily A member 1(CYP1A1)and UDP glucuronyltransferase family 1 member A1(UGT1A1)are expressed at high levels for a long time to maintain metabolic homeostasis in vivo.3.Through the grass carp transcriptome database obtained in the laboratory,the differentially expressed miR-146 b was screened in the resistant and susceptible populations,and the lncRNA: Tmem110-IT and downstream target gene: pfkfb3 regulated by miR-146 b was predicted by software.The dual-luciferase reporter system further confirmed the targeting relationship between them,indicating that the ceRNA regulatory network exists in grass carp.And by measuring the glycolytic flux and viability of grass carp cells,it was found that Tmem110-IT helps cells to increase glycolytic flux under bacterial infection,thereby providing cell viability.