RESUMO
The action of diflubenzuron (DFB) was evaluated in a freshwater fish, Prochilodus lineatus, after exposure to 0.06, 0.12, 0.25, or 0.50 mg L(-1) DFB for 14 days. Erythrocyte nuclear abnormalities (ENA), the gill activity of Na(+)/K(+)-ATPase, H(+)-ATPase and carbonic anhydrase (CA), and lipid peroxidation (LPO) and histopathological changes in the gills and liver were determined. The number of micronuclei increased in fish exposed to 0.25 and 0.50 mg L(-1) DFB. Plasma Cl(-) and the CA activity decreased, while the activity of Na(+)/K(+)-ATPase and of H(+)-ATPase increased in fish exposed to 0.25 and 0.50 mg L(-1) DFB. LPO did not change in the gills but increased in the liver of fish exposed to 0.25 and 0.50 mg L(-1) DFB. In the gills, histopathological changes indicated disperse lesions and slight to moderate damage in fish exposed to 0.50 mg L(-1) DFB, whereas in the liver, these changes were significantly greater in fish exposed to 0.25 and 0.50 mg L(-1) DFB, indicating moderate to severe damage. Continuous exposure to DFB is potentially toxic to P. lineatus, causing heath disorders when the fish is exposed to the two highest DFB concentrations, which are applied to control parasites in aquaculture and to control mosquito populations in the environment.
Assuntos
Diflubenzuron/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Biomarcadores/metabolismo , Caraciformes/metabolismo , Água Doce/química , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Brânquias/patologia , Peroxidação de Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Testes de Mutagenicidade , ATPase Trocadora de Sódio-Potássio/metabolismoRESUMO
This study evaluates the contaminants in water and their bioaccumulation in the gills and liver of two ecologically distinct fish species, Astyanax fasciatus and Pimelodus maculatus, living in the reservoir of the Furnas hydroelectric power station located in Minas Gerais in the southeastern Brazil. The histological alterations in these organs are also examined. Water and fish were collected in June and December from five sites (site 1: FU10, site 2: FU20, site 3: FU30, site 4: FU40 and site 5: FU50) in the reservoir, and agrochemicals and metals selected based on their use in the field crops surrounding the reservoir were analyzed in the water and in the fish gills and livers. The concentrations of the organochlorines aldrin/dieldrin, endosulfan and heptachlor/heptachlor epoxide as well as the metals copper, chromium, iron and zinc in the gills and livers of both fish species were higher in June than in December; the liver accumulated higher concentrations of contaminants than the gills. The organochlorine metolachlor was detected only in the liver. The histological pattern of changes was similar in both species with regard to contaminant accumulation in the gills and liver. Fish from FU10, the least contaminated site, exhibited normal gill structure and moderate to heavy liver damage. Fish collected at FU20 to FU50, which were contaminated with organochlorines and metals, showed slight to moderate gill damage in June and irreparable liver damage in the livers in June and December. The histological changes in the gills and liver were suitable to distinguishing contaminated field sites and are therefore useful biomarkers for environmental contamination representing a biological end-point of exposure.