Effects Of Glufosinate Ammonium On Oxidative Stress,Non-specific Immunity And Biotransformation Enzymes In Red Swamp Crayfish(Procambarus Clarkii)

Glufosinate-ammonium(GLA),as an organophosphorus herbicide,is commonly used in agricultural production and can enter the aquatic environment via surface runoff,posing a potential risk to nontarget aquatic life.And GLA is also the main herbicides used in the agricultural field of the rice-crayfish farming system in China.However,little is known about the toxic effect of GLA in the red swamp crayfish(Procambarus clarkii).In this study,the adult crayfish were exposed to various concentrations of GLA(0、1、10 and 100mg/L)for 21 d,and the histopathological changes,oxidative stress,non-specific immune markers and expression of biotransformation enzymes were examined to investigate the toxic effects of GLA in crayfish.The main results were as follows:1.The water samples of the breeding ditches,water inlets and water outlets were collected from a local commercial farm(Jian Li,Hubei,China)during June to October2021.The content of GLA in all samples was below the detection limit.The GLA content of crayfish collected from the same farm was 0.036±0.003mg/kg ww in the hepatopancreas,and was 0.070±0.010mg/kg ww in muscle,respectively,which were lower than the maximum residue limit in food(0.1mg/kg).2.A dose-dependant accumulation of GLA was found in the hepatopancreas of crayfish exposed to GLA(1,10 and 100 mg/L).1 mg/L GLA exposure caused the expansion of hepatic tubules.The increased transport vesicle and hepatocytes vacuolation were found in the 10 mg/L treatment group.However,hepatocytes were lysed in the 100mg/L treatment group.The score value for tissue damage was 0.933 ±0.044,3.167 ± 0.300 and 4.083 ± 0.220 in the 1,10 and 100 mg/L group,respectively.3.GLA exposure at 1 or 10 mg/L increased the level of ROS and MDA.However,the increased ROS with decreased MDA was found in 100 mg/L GLA treated crayfish.The change of activity of SOD was similar to MDA content.Additionally,a dosedependent decrease in CAT and GSH activity was found in the heptopancreas.And significant decrease intotal hemocyte counts(THC)and significant changes in the proportion of hemocyte subsets were observed in our study.Meanwhile,the activity of AKP and LZM was decreased in a dose-dependent manner after GLA treatment.The inhibited activity of ACP only found in the 100 mg/L GLA group,but the activity of PO was not affected.4.A dose-dependent increase in transcriptional level of cypb and gst was observed in the hepatopancreas after treatment with GLA.In conclusion,GLA can induce oxidative stress in hepatopancreas of crayfish,inhibits the activity of enzymes related to non-specific immune function and promotes the transcription of biotranformation enzymes.This study provides important insights into the toxic effects of organophosphorus herbicides on crustaceans.