Lethal and Toxic Effects of Cypermethrin on Exopalaemon carinicauda
Cypermethrin(CYP)is a kind of pyrethroids insecticide commonly used in agricultural production,which is highly toxic to aquatic crustaceans.In order to investigate the toxic effects of CYP on marine crustaceans,our study took Exopalaemon carinicauda as the study model.By combining 96 h-LC50 with environmental concen-tration,the shrimp was exposed to different concentrations(8 ng·L-1,16 ng·L-1 and 32 ng·L-1)for 10 days,the effects of which on hepatopancreas tissue structure,damage level,detoxification metabolism and antioxidant levels were determined;meanwhile,Na+/K+-ATPase activity in gill tissue and acetylcholinesterase(AChE)activity in muscle tissue were also determined,so as to obtain physiological response characteristics of CYP.The results showed that 24 h-LC50,48 h-LC50,72 h-LC50 and 96 h-LC50 of E.carinicauda was 65 ng·L-1,50 ng·L-1,38 ng· L-1 and 32 ng·L-1 for CYP,which belonged to the highly toxic substances.After exposure to CYP at different con-centrations for 6 days,hepatopancreas tissue structure was broken,basal membrane rupture,vacuolation and cell necrosis occurred.Exposure to 16 ng·L-1 and 32 ng·L-1 of CYP,the activity of phase I metabolizing enzyme 7-ethoxy-isooxazolone-deethylase(EROD)and phase Ⅱ metabolizing enzyme glutathione S-transferase(GST)in-creased first and then decreased.Oxidative stress-related index superoxide dismutase(SOD)under 16 ng·L-1 CYP exposure showed inhibition and induction,while the activity of catalase(CAT)and total antioxidant capacity(T-AOC)showed inhibition after induction.Malondialdehyde(MDA)and 8-hydroxydeoxyguanosine(8-OHdG)contents showed a dose-dependent effect and significantly increased with the increase of concentration.Na+/K+-ATPase and AChE activities were significantly inhibited during the whole exposure phase after 32 ng·L-1 CYP exposure.In summary,CYP is a highly toxic substance to white shrimp,and exposure to CYP will cause varying degrees of tissue structural damage to the hepatopancreas of white shrimp;it will cause oxidative stress response in the body,causing oxidative damage,affecting the detoxification and metabolic processes,leading to imbalance in the body's osmotic pressure regulation and disorder of nerve signaling.The results of this study supplemented the toxic data of the chloride marine crustaceans,and provided a theoretical basis for ecological risk assessment of SPs in coastal waters and estuary areas.
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