Toxic Effects Of Glyphosate On The Fish Pelteobagrus Fulvidraco

Glyphosate is the most widely used herbicide in the world,and its extensive use inevitably leads to the pollution of the surrounding aquatic environment,which may have toxic effects on non-target aquatic organisms such as fish.However,the research on the toxicity of glyphosate to fish is still in its infancy.Pelteobagrus fulvidraco is a scaleless fish with high sensitivity to drugs,and has become one of the emerging organisms for aquatic environmental monitoring and toxicological experiments.Therefore,this study uses glyphosate as a research drug to systematically reveal the toxic effects of glyphosate on P.fulvidraco by studying its acute toxic effects,as well as its damage to different tissue structures,antioxidant system,cell apoptosis,and immune system.This result will provide a reference basis for the scientific and reasonable use of glyphosate and its ecological risk assessment.The main research results are as follows:（1）The results of the acute toxicity test showed that the half lethal concentrations(LC₅₀)of glyphosate to P.fulvidraco for 24,48,72,and 96 h were 227.38,221.08,213.45,and200.38 mg/L,respectively,indicating that glyphosate was a low-toxicity drug to P.fulvidraco.（2）The results of the subchronic exposure test of glyphosate on the antioxidant system of different tissues of P.fulvidraco were as follows:compared with the control group（0mg/L）,the activities of SOD and CAT in the gill,liver,and kidney tissues of P.fulvidraco decreased with the increase of glyphosate concentration during the entire exposure period,and the activities of SOD and CAT in the high concentration group（20 mg/L）significantly decreased at 168 h（P<0.05）,showing a concentration-effect relationship.The activities of GPx and MDA content increased with the increase of glyphosate concentration and the extension of exposure time,and the high concentration group significantly increased（P<0.05）at 168 h,showing a concentration-time effect relationship.The gene expression levels of Sod,Cat,Gpx,and Gst in gill,liver,kidney,and spleen tissues showed a decreasing trend with the increase of glyphosate concentration,with a good concentration-effect relationship.（3）The results of the effects of glyphosate exposure on the expression of apoptosis-related genes in P.fulvidraco were as follows:compared with the control group,the expression levels of Caspase-3,Caspase-9,P53,Bax,Cyt-c,ERK and JNK genes in the gill,liver,kidney,and spleen tissues of P.fulvidraco increased with the increase of glyphosate concentration and exposure time.However,the expression level of Bcl-2 gene and the ratio of Bcl-2/Bax decreased with the increase of glyphosate concentration and the prolongation of exposure time,and the high concentration group had significant differences compared with the control group at 168 h（P<0.05）.Overall,the expression levels of apoptosis-related genes in P.fulvidraco showed a good concentration-time-effect relationship during glyphosate exposure.（4）The results of the effect of glyphosate exposure on the expression of immune related genes in P.fulvidraco showed that during the entire exposure period,compared with the control group,the expression levels of immunity genes IL-8,TNF-α,IFN,and NF-k B in the gill,liver,kidney,and spleen tissues of P.fulvidraco increased with the increase of glyphosate concentration and exposure time,while the expression levels of IL-10,Ig M,Ig D,C3,and LZM decreased with the increase of glyphosate concentration and the prolongation of exposure time,and the high concentration group had significant differences compared with the control group at 168 h（P<0.05）.（5）The results of subchronic exposure test with glyphosate on the histological structure of P.fulvidraco were as follows:when exposed to the high concentration group for 168 hours,the gill cells of P.fulvidraco became swollen,deformed,vacuolized,and the nucleus shifted,with the tip of the gill filaments swollen;The liver cells were swollen and vacuolated,and the nuclei were displaced and dissolved,indicating that high concentrations of glyphosate can cause damage to the gill and liver structures of P.fulvidraco.In summary,glyphosate could cause oxidative damage to the gill,liver,kidney,and spleen tissues of P.fulvidraco,affect the cell apoptosis mechanism and immune function by up-regulating the expression of apoptosis related genes（Caspase-3,Caspase-9,P53,Cyt-c,Bax,ERK and JNK）and downregulating the expression of Bcl-2,Bcl-2/Bax.Meanwhile,glyphosate could also upregulate the expression of immune related genes（IL-8,TNF-α,IFN and NF-k B）and downregulate of the expression of immunity genes（IL-10,Ig M,Ig D,C3,and LZM）,and finally induced the damage to the gill and liver tissues of P.fulvidraco.These results indicate that glyphosate has oxidative,apoptotic,and immune toxicity effects on P.fulvidraco.