title: The first evidence of cholinesterases in skin mucus of carps and its applicability as biomarker of organophosphate exposure.
abstract: The presence of cholinesterase (ChE) activity in skin mucus of three carps, Cirrhinus mrigala, Labeo rohita, and Catla catla and its applicability as biomarker of the organophosphorus insecticide exposure were investigated. Biochemical characterization, using specific substrates and inhibitors, indicated that measured esterase activity in skin mucus was mainly owing to ChEs. Significant difference in the proportion of acetylcholinesterase and butyrylcholinesterase activities was observed in skin mucus of three carps. Enzyme kinetic analysis, using the substrate acetylthiocholine iodide revealed significantly high Vmax value in C. catla compared to that in L. rohita and C. mrigala. In contrast, Vmax value using the substrate butyrylthiocholine iodide was significantly high in C. mrigala than in L. rohita and C. catla. In vitro treatment of skin mucus of three carps, with the organophosphorus insecticide Nuvan®, showed strong inhibition of ChE activities. In vivo experiments conducted using C. mrigala and exposing the fish to the sublethal test concentrations (5 and 15 mg/L) of the insecticide also revealed significant inhibition of ChE activity in mucus. In C. mrigala, exposed to the sublethal test concentrations of the insecticide for 4 days and then kept for recovery for 16 days, mucus ChE activity recovered to the control level. Thus, ChE activity in skin mucus could be considered a good biomarker of the organophosphorus insecticide exposure to fish and a useful tool in monitoring environmental toxicity.
authors.affiliation: Skin Physiology Laboratory, Centre of Advanced Study, Department of Zoology, Banaras Hindu University, Varanasi 221 005, India.
authors.forename: Ashwini Kumar
authors.initials: AK
authors.lastname: Nigam
authors.forename: Nidhi
authors.initials: N
authors.lastname: Srivastava
authors.forename: Amita Kumari
authors.initials: AK
authors.lastname: Rai
authors.forename: Usha
authors.initials: U
authors.lastname: Kumari
authors.forename: Ajay Kumar
authors.initials: AK
authors.lastname: Mittal
authors.forename: Swati
authors.initials: S
authors.lastname: Mittal
mesh_terms: D000110:Acetylcholinesterase / Q000032:analysis / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002347:Carps / Q000378:metabolism*; D002802:Cholinesterases / Q000032:analysis / Q000378:metabolism*; D003530:Cyprinidae / Q000378:metabolism*; D004006:Dichlorvos / Q000633:toxicity; D004784:Environmental Monitoring; D007306:Insecticides / Q000633:toxicity*; D007700:Kinetics; D009093:Mucus / Q000201:enzymology*; D010755:Organophosphates / Q000633:toxicity*; D012867:Skin / Q000187:drug effects* / Q000201:enzymology; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D007306:Insecticides; D010755:Organophosphates; D014874:Water Pollutants, Chemical; D004006:Dichlorvos; D000110:Acetylcholinesterase; D002802:Cholinesterases