RESUMO
Here, we analyzed the recovery of the reproductive capability in male Cichlasoma dimerus after exposure to sublethal concentrations of 4-tert-octylphenol (OP), a demonstrated estrogenic chemical. Adult fish were exposed to 0, 30, 150 and 300 µg/L OP during 60 days and subsequently transferred to OP-free water for another 60 days. At 150 and 300 µg/L, absence of fertilized spawnings were recorded during the first 4 weeks following OP exposure, which could be explained by the impairment of testis architecture recorded at the highest OP concentrations. The restoration of the testicular organization began by day 14 in OP-free water, when the germinal epithelium re-started to proliferate. Testicular functionality was recovered by day 28, yielding fertilized eggs and viable F1 embryos. These results show that pathological features induced in the testes of C. dimerus by OP exposure are not permanent since fish recover their fertilization capacity after an adequate depuration period.
Assuntos
Ciclídeos/fisiologia , Estrogênios/toxicidade , Fenóis/toxicidade , Reprodução/efeitos dos fármacos , Testículo/efeitos dos fármacos , Animais , Masculino , Testículo/patologiaRESUMO
Exposure to environmental pollutants may disrupt endocrine functions and cause reproductive effects in human and wildlife populations. Various groups of chemicals have estrogen-like effects, including degradation products of alkylphenol polyethoxylates, such as 4-tert-octylphenol (OP). Laboratory studies have shown that exposure of male fish to xenoestrogens results in induction of circulating vitellogenin (Vtg), inhibition of testicular growth, testis abnormalities and formation of intersex gonads. In this study, the impact of the exposure to waterborne OP on reproductive aspects in the South American cichlid fish Cichlasoma dimerus was evaluated using qualitative changes in the levels of Vtg in plasma and surface mucus and histological alterations in the liver and gonads as endpoints. Adult males and females were exposed to OP via immersion during 60 days in aquaria under semi-static conditions, water changes being made every 84 h. Treatment groups were: control (ethanol 0.005%), OP 30, 150 and 300 microg/L. Using Western and Dot blot analysis, Vtg was detected in plasma and mucus of control and treated females and treated males, while no Vtg was observed in samples from control males. Morphological changes in the hepatocytes due to the accumulation of Vtg were observed in OP-exposed males. Impairment of testicular structure became apparent in males treated with the highest OP concentrations. The most salient pathological change was the alteration of lobular organization with increased testicular fibrosis and progressive disruption of spermatogenesis. No major changes were observed in ovarian architecture. Our results indicate that detection of Vtg in surface mucus may be a sensitive and non-invasive biomarker of the endocrine disrupting effects of environmental estrogens, resulting in a useful method for field monitoring.
Assuntos
Disruptores Endócrinos/toxicidade , Proteínas de Peixes/metabolismo , Fígado/efeitos dos fármacos , Perciformes/metabolismo , Fenóis/toxicidade , Testículo/efeitos dos fármacos , Vitelogeninas/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Argentina , Biomarcadores/metabolismo , Relação Dose-Resposta a Droga , Monitoramento Ambiental/métodos , Feminino , Fibrose , Proteínas de Peixes/sangue , Água Doce , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Fígado/metabolismo , Fígado/patologia , Masculino , Muco/metabolismo , Espermatogênese/efeitos dos fármacos , Testículo/metabolismo , Testículo/patologia , Fatores de Tempo , Vitelogeninas/sangueRESUMO
The aim of the present study was to obtain a basic knowledge of the hematology of Cichlasoma dimerus. The morphological features of blood cells were described according to the observations made by light and electron microscopy. Erythrocytes, thrombocytes and four types of leucocytes: lymphocytes, monocytes, heterophils and eosinophils, were distinguished and characterized. Thrombocytes are the most abundant blood cells after erythrocytes and are recognized easily from lymphocytes by morphological features and size. Heterophils and eosinophils are PAS positive. Hematological indices (RBC, WBC, PCV, Hb, MCV, MCH, MCHC and leucocyte differential count) were measured in one blood sample from 30 adult fish captured in Esteros del Riachuelo, Corrientes, Argentina (27 degrees 25'S, 58 degrees 15'W). The reference interval and the mean were determined for each hematological parameter evaluated. Contrary to other species, the percent of heterophils was found to be high in relation to the percent of lymphocytes. Low lymphocyte counts occurred in C. dimerus, as compared to these found in other fishes. Compared to most teleosts, this species has similar mean values for PCV and Hb and slightly higher for RBC. Statistical analysis revealed that differences in hematological parameters between male and female fish were not significant.
Assuntos
Células Sanguíneas/citologia , Ciclídeos/sangue , Animais , Células Sanguíneas/ultraestrutura , Tamanho Celular , Feminino , Hematócrito , MasculinoRESUMO
The effects of a paraquat commercial herbicide formulation on an early stage of the development of Plecostomus commersoni were evaluated. Mortality, opercular ventilation rate, cardiac contraction rate and body length and weight were examined every 12 hr. The effects of the paraquat formulation on the morphology of the branchial epithelium were also examined by light microscopy. The assayed paraquat formulation significantly affected cardiac contraction and opercular ventilation. Ecotoxicologically, this could represent an important deleterious effect for early development of the catfish. Mortality data may not be sufficient for an appropriate evaluation of secondary environmental hazards associated with the application of paraquat formulation because: a) The LC-50 values for Plecostomus commersoni fry were higher than the recommended individual application rate of paraquat for aquatic weed control (0.1-2.0 mg/L). b) The estimated maximum acceptable toxicant concentration (MATC) resulted in a concentration similar to the application rate when calculated from acute toxicity tests. When the MATC was estimated from opercular ventilation or cardiac contraction rates, it was lower and fell within the recommended single application rate.