Study On The Toxicity Of T-2 Toxin On Hepatopancreas Of Chinese Mitten Crab (Eriocheir Sinensis) And The Protective Effect Of Arginine

T-2 toxin,which belongs to the type A trichothecene mycotoxins group,is one of the most toxic trichothecene mycotoxins produced by Fusarium spp.T-2 toxin is widespread in nature,mainly polluting grains and feed,posing a threat to the health of human and animal.T-2 toxin has toxic effects on multiple organs of animals,and the liver is an important target organ of T-2 toxin.T-2 toxin can cause liver damage,intestinal toxicity and reproductive toxicity in aquatic animals.Researching and exploring ways to alleviate the toxic effects of T-2 toxins on aquatic animals is of great significance to the development of the aquaculture industry.Arginine(Arg),as an essential amino acid,has many physiological functions such as antioxidation and regulating the body’s immunity.The effects of dietary T-2 toxin on apoptosis and autophagy in hepatopancreas of Chinese mitten crab and the protective effects of Arg on hepatopancreas injury induced by T-2 toxin were studied in this experiment.The main research contents and results are as follows:Experiment 1 Effects of T-2 toxin on apoptosis and autophagy in hepatopancreas of Chinese mitten crab(Eriocheir sinensis)T-2 toxin causes multifunctional cell damage through various ways,thereby causing toxic effects on multiple organs of the body.In this experiment,0,1,2 and 4mg/kg T-2 toxin were added to the feed,fed with Chinese mitten crab for 5 weeks.And the Drosophila Schneider 2(S2)cells were treated with T-2 toxin(0,5,10 and 20 n M)for 24 h in vitro.In vivo and in vitro experiments were combined to explore the effects of T-2 toxin on apoptosis and autophagy of hepatopancreas in Chinese mitten crab.The results showed that T-2 toxin decreased the weight gain rate and inhibited the growth of crabs.T-2 toxin induced excessive reactive oxygen species production in hepatopancreas and S2 cells,decreased the activities of SOD,GSH-PX and GSH,increased the content of MDA,induced oxidative stress and increased the apoptosis rate.T-2 toxin up-regulated the expression of apoptosis-related genes Caspase-3,Caspase-7 and Bax,inhibited the expression of Bcl-2,increased the ratio of Bax/Bcl-2,and increased the activity of Caspase-3 and Caspase-9 in Drosophila S2 cells.down-regulated the expression of Bcl-2,and increased the activity of Caspase-3and Caspase-9 in S2 cells.T-2 toxin also caused damage to the hepatopancreas microstructure in the crabs,and damaged the morphology of S2 cells.In addition,T-2toxin induced the production of autophagosomes in the hepatopancreas of crabs,and up-regulated the expression levels of autophagy-related genes Beclin-1,ATG9,ATG5,ATG12,ATG7 and ATG8/LC3 in the hepatopancreas,which were induced the occurrence of autophagy.The results of the present study indicate that T-2 toxin caused oxidative stress in hepatopancreas of crabs,activated the mitochondrial apoptotic pathway to cause cell apoptosis,and could also induce autophagy of hepatopancreas cells,which had serious toxic effects on hepatopancreas of Chinese mitten crab.Experiment 2 Protective effects of dietary arginine on hepatopancreas injury induced by T-2 toxin in Chinese mitten crab(Eriocheir sinensis)T-2 toxin is a secondary metabolite produced by Fusarium spp.that is a major cereal and animal feed contaminant.T-2 toxin has numerous adverse effects on animals,including hepatotoxicity.It is very important to explore the methods and ways to alleviate the toxic effects of T-2 toxin on animals.Arginine has many physiological functions,which are closely associated with the regulation of immune response and antioxidant capacity.The objective of the present study was to evaluate the protective effects of different levels of Arg on hepatopancreas injury induced by T-2 toxin in Chinese mitten crab.Crabs were fed with diets containing 1.53%,2.31%,3.17% and 4.87% arginine respectively.T-2 toxin(1.5 mg/kg BW)was injected 8weeks later,and samples were collected 24 h after injection.According to the results,3.17% Arg in the diet decreased ALT,AST and ALP activity in the haemolymph significantly,when compared with the levels of activity in the T-2 toxin group.Arg supplementation also increased SOD and GSH-PX activity,while decreasing MDA concentrations in the hepatopancreas,when compared with the levels in the T-2 toxin group.In addition,3.17% Arg in the diet increased ACP and ALP activity in the hepatopancreas,as well as ALB concentrations in the haemolymph,when compared with the T-2 toxin group.Dietary Arg also regulated the expression of antioxidant enzyme-related genes(mt Mn SOD,cyt Mn SOD and CAT),immune related genes(pro PO,Relish and LITAF)and apoptosis related genes(Caspase-3,Caspase-7,Bax and Bcl-2)to alleviate the damage associated with the T-2 toxin.Furthermore,Arg ameliorated damage to the hepatopancreas microstructure in the crabs.The results of the present study indicate that dietary Arg could enhance the antioxidant,immune capacity and reduce cell apoptosis of Chinese mitten crab to alleviate hepatopancreas injury induced by T-2 toxin.