Toxicity assessment of 2,4-D and MCPA herbicides in primary culture of fish hepatic cells.

In this study, we used primary cultures of fish hepatic cells as a tool for evaluating the effects of environmental contamination. Primary hepatic cell cultures derived from the subtropical fish Metynnis roosevelti were exposed to different concentrations (0.275, 2.75 and 27.5 µg L(-1)) of the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA). Cellular respiratory activity was evaluated by polarography using three substrates: 0.5 M glucose, 0.5 M succinate and 0.5 M α-ketoglutarate. Significant changes were observed in cellular oxygen consumption with 0.5 M α-ketoglutarate. Even at low concentrations, 2,4-D and MCPA were potent uncouplers of oxidative phosphorylation. Primary cultures of M. roosevelti liver cells may provide a useful tool for the evaluation of environmental contaminant effects. A review of regulations regarding permitted concentrations of these herbicides is needed.

Assessment of the sublethal toxicity of organochlorine pesticide endosulfan in juvenile common carp (Cyprinus carpio).

This study is aimed at evaluating the sublethal effects of endosulfan (EDS) in juvenile common carp (Cyprinus carpio). For this purpose, fish were exposed for 15 days to the technical EDS (95% pure) diluted in dimethyl sulfoxide (DMSO) 0.1% of the total volume in water solution in a semi-static system at sublethal concentration (1 µg/L). Subsequently, the liver somatic index (LSI) and factor condition (K) were determined. The total cytocrome P450 (CYP), CYP1A isoform, and the ethoxyresorufin-O-deethylase (EROD) activity were determined from the hepatic microsomal fraction as well as the activity of the oxidative stress enzyme system such as superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione peroxidase (GP(X)), glutathione reductase (GR), and glucose-6-phosphate dehydrogenase (G6PDH). Among the parameters assessed, EDS at the sublethal concentration in subchronic exposure caused significant changes in liver somatic indices as well as induction of the phase I biotransformation system and oxidative stress in juvenile common carp (Cyprinus carpio). Thus, it is seen that the use of biochemical biomarkers of environmental contamination in this study proved to be an extremely important tool for detecting the adverse effects of xenobiotics in the aquatic environment, even at low concentration.

Photochemical degradation increases polycyclic aromatic hydrocarbon (PAH) toxicity to the grouper Epinephelus marginatus as assessed by multiple biomarkers.

The effects of halogen-light-irradiated and non-irradiated PAHs on the grouper Epinephelus marginatus were assessed through biomarkers including morphometric parameters, liver histopathology, biliary PAH concentration, genetic alterations, and enzyme activity modulation. E. marginatus juveniles were divided into three groups: control (C), non-irradiated PAHs (PAHs1), and irradiated PAHs (PAHs2). Test groups were exposed for 14 days to a 0.5 ppm PAH solution in the semi-static system. After this period, fish were anesthetized with benzocaine (2%) and peripheric blood was collected by caudal puncture. Blood smears were prepared and stained with propidium iodide. Fish livers were collected, fixed in McDowell's solution, embedded in paraplast, thin-sectioned, and stained with hematoxylin-eosin (H&E). For biochemical analyses including superoxide dismutase, catalase, and glutathione S-transferase activities, fish livers were collected and preserved in liquid nitrogen. Water samples were analyzed using gas chromatography-mass spectrometry (GC-MS) and bile synchronous fluorescence spectroscopy. Fish in the PAHs2 group had micronuclei (MN) in blood cells, as well as significant differences in nuclear morphology (NMA). Significant morphological alterations were observed in the livers from fish exposed to PAHs as well as inhibition of the catalase activity. Our results show that irradiation altered the bioavailability of PAHs, especially benzanthracene, which has great impact in aquatic ecosystems. Among the consequences of physical and chemical changes to PAHs, we observed a significant increase in NMA and MN incidence in E. marginatus erythrocytes, indicating the potential initiation of mutagenic and carcinogenic processes.