title: Effects of the herbicides clomazone, quinclorac, and metsulfuron methyl on acetylcholinesterase activity in the silver catfish (Rhamdia quelen) (Heptapteridae).
abstract: Fingerlings of the silver catfish (Rhamdia quelen) were exposed to three herbicides widely used in rice culture in south Brazil: clomazone, quinclorac, and metsulfuron methyl. LC50 was determined and acetylcholinesterase (AChE) activity was evaluated in brain and muscle tissue of fish exposed to different herbicide concentrations after 96h (short term). The LC50 value (nominal concentration) was 7.32 mg/L for clomazone and 395 mg/L for quinclorac, but was not obtained for metsulfuron-methyl since all fingerlings survived the highest concentration of 1200 mg/L. Brain and muscle AChE activity in unexposed fish were 17.9 and 9.08 micromol/min/g protein, respectively. Clomazone significantly inhibited AChE activity in both tissues, achieving maximal inhibition of about 83% in brain and 89% in muscle tissue. In contrast, quinclorac and metsulfuron methyl caused increases in enzyme activity in the brain (98 and 179%, respectively) and inhibitions in muscle tissue (88 and 56%, respectively). This study demonstrated short-term effects of exposure to environmentally relevant concentrations of rice field herbicides on AChE activity in brain and muscle tissue of silver catfish.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105.900 Santa Maria, RS, Brazil.
authors.forename: Denise
authors.initials: D
authors.lastname: dos Santos Miron
authors.forename: Márcia
authors.initials: M
authors.lastname: Crestani
authors.forename: Maria
authors.initials: M
authors.lastname: Rosa Shettinger
authors.forename: Vera
authors.initials: V
authors.lastname: Maria Morsch
authors.forename: Bernardo
authors.initials: B
authors.lastname: Baldisserotto
authors.forename: Miguel
authors.initials: M
authors.lastname: Angel Tierno
authors.forename: Gilberto
authors.initials: G
authors.lastname: Moraes
authors.forename: Vania Lucia Pimentel
authors.initials: VL
authors.lastname: Vieira
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D001190:Arylsulfonates / Q000633:toxicity*; D001921:Brain / Q000201:enzymology; D002397:Catfishes / Q000502:physiology*; D006540:Herbicides / Q000633:toxicity*; D007555:Isoxazoles / Q000633:toxicity*; D007928:Lethal Dose 50; D018482:Muscle, Skeletal / Q000201:enzymology; D012275:Oryza; D023303:Oxazolidinones / Q000633:toxicity*; D011804:Quinolines / Q000633:toxicity*; D013534:Survival; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D001190:Arylsulfonates; D006540:Herbicides; D007555:Isoxazoles; D023303:Oxazolidinones; D011804:Quinolines; D014874:Water Pollutants, Chemical; C050296:metsulfuron methyl; C489048:quinclorac; C095255:clomazone; D000110:Acetylcholinesterase