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1.
Toxicon ; 203: 104-114, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34662628

ABSTRACT

We evaluated the accumulation of okadaic acid (OA), a diarrhetic toxin, and the antioxidant responses in the marine annelid Laeonereis acuta exposed to the benthic toxigenic dinoflagellate Prorocentrum cf. lima. Nontoxic Tetraselmis sp. was used as a control diet. Living cells of the two algae were supplied as food to animals kept in agar medium for 72 h. To assess the significance of the observed effects, our experimental design treated the algal species (diet), algal cell densities, and exposure time as fixed factors. Responses of the organisms were assessed through oxidative stress biomarkers (glutathione-S-transferase [GST], catalase [CAT], reduced glutathione [GSH] and lipid peroxidation [LPO]). Toxin accumulation was measured by LC-MS/MS in whole-body homogenates after 12, 24 and 72 h of exposure. Worms exposed to the toxigenic dinoflagellate gradually accumulated OA, with toxin levels directly related to the cell density of Prorocentrum cf. lima. Worms fed with Prorocentrum cf. lima exhibited decreased CAT activity, increased LPO levels - both interactively affected by algal species and time - and decreased GSH levels, which were interactively affected by algal species and cell density. Higher LPO levels, along with the inhibition of CAT and GSH, clearly indicated an oxidative stress situation in worms exposed to the toxigenic dinoflagellate. Laeonereis acuta accumulated moderate OA levels and may act as a vector of OA to food webs in estuarine areas under high Prorocentrum cf. lima abundance.


Subject(s)
Annelida , Dinoflagellida , Animals , Antioxidants , Chromatography, Liquid , Okadaic Acid/toxicity , Tandem Mass Spectrometry
2.
Aquat Toxicol ; 225: 105527, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32599436

ABSTRACT

A diverse range of chemicals are used in agriculture to increase food production on a large scale, and among them is the use of pesticides such as chlorothalonil, a broad-spectrum fungicide used in the control of foliar fungal diseases. This study aimed to elucidate the effects of chlorothalonil on biochemical biomarkers of oxidative stress in tissues of the fish Danio rerio. To achieve this, animals were exposed for 4 and 7 days, to nominal concentrations of chlorothalonil at 0 µg/L (DMSO, 0.001%), 0.1 µg/L and 10 µg/L, and after the exposure period, the tissues (gills and liver) were removed for biochemical analysis. Antioxidant capacity against peroxyl radicals (ACAP) and enzyme activities, such as superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and glutamate cysteine ligase (GCL), were evaluated in both tissues. In addition, the concentration of reactive oxygen species (ROS), reduced glutathione (GSH) and lipid peroxidation (LPO) levels were also analysed. A significant increase in ROS concentration, ACAP levels, GST and GCL activities and a significant reduction of LPO levels in gills exposed to the highest concentration were observed after 4 days. However, there was a significant reduction of ACAP and CAT activity, as well as a significant increase of GST activity and LPO levels in gills exposed to the lower concentration after 7 days. The liver was less affected, presenting a significant reduction in CAT activity and LPO levels after 4 days. However, a significant increase in SOD activity and LPO levels occurred after 7 days. These results indicate that chlorothalonil, after 4 days, caused activation of the antioxidant defence system in gills of animals exposed to the highest concentration. However, after 7 days, the lowest concentration of this compound caused oxidative stress in this same organ. Also, the results show that gills were more affected than the liver, probably because gills can be involved in chlorothalonil metabolisation. Therefore, it is possible that the liver could be exposed to lower chlorothalonil concentrations or less toxic metabolites due to the metabolism taking place in the gills.


Subject(s)
Antioxidants/metabolism , Fungicides, Industrial/toxicity , Nitriles/toxicity , Oxidative Stress/drug effects , Water Pollutants, Chemical/toxicity , Zebrafish/metabolism , Animals , Catalase/metabolism , Gills/drug effects , Gills/enzymology , Glutathione/metabolism , Glutathione Peroxidase/metabolism , Glutathione Transferase/metabolism , Lipid Peroxidation/drug effects , Peroxides/metabolism , Superoxide Dismutase/metabolism
3.
Aquat Toxicol ; 196: 1-8, 2018 Mar.
Article in English | MEDLINE | ID: mdl-29310040

ABSTRACT

Chlorothalonil is an active biocide applied in antifouling paints, and also used as fungicide in agricultural activities with the purpose to protect plants from foliar and seed diseases. Thus, the aim of this study was to evaluate the effects of chlorothalonil exposure on biochemical biomarkers of oxidative metabolism as well as on cholinesterases in the estuarine polychaete Laeonereis acuta. Animals were exposed for 24 and 96 h to the following nominal concentrations of chlorothalonil: 0.1, 10.0 and 100.0 µg/L. The antioxidant capacity against peroxyl radicals (ACAP) and the activity of the enzymes catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), glutamate cysteine ligase (GCL), acetylcholinesterase (AChE) and propionylcholinesterase (PChE) were evaluated in whole-body tissue. In addition, the levels of reduced glutathione (GSH), lipid peroxidation (LPO), glycogen and lactate levels were also analyzed. A reduction in ACAP levels was observed in animals exposed to the higher chlorothalonil concentration, concomitantly with an induction of GST activity as well as diminution in GSH content in these animals. This disturbance in the redox state of animal tissues leads to an oxidative stress situation, resulting in an induction in LPO levels. It was also demonstrated that chlorothalonil exposure causes alteration in AChE activity, possibly related to damage to membrane lipids. These results demonstrated that chlorothalonil possesses harmful effects to estuarine animals and its use as antifouling biocide has to be carefully reconsidered in risk analysis studies.


Subject(s)
Fungicides, Industrial/toxicity , Nitriles/toxicity , Oxidative Stress/drug effects , Polychaeta/drug effects , Water Pollutants, Chemical/toxicity , Acetylcholinesterase/metabolism , Animals , Antioxidants/metabolism , Catalase/metabolism , Cholinesterases/metabolism , Glutathione/metabolism , Glutathione Peroxidase/metabolism , Glutathione Transferase/metabolism , Glycogen/analysis , Lactic Acid/analysis , Lipid Peroxidation/drug effects , Peroxides/metabolism , Polychaeta/metabolism , Spectrophotometry , Superoxide Dismutase/metabolism
4.
Ecotoxicol Environ Saf ; 135: 259-266, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27750093

ABSTRACT

Glyphosate based herbicides, including Roundup, are widely employed in agriculture and urban spaces. The objective of this study was to evaluate the toxicological effects of Roundup on the estuarine polychaeta Laeonereis acuta. Biomarkers of oxidative stress as well as acetylcholinesterase and propionilcholinesterase activities were analyzed. Firstly, the LC50 96h for L. acuta was established (8.19mg/L). After, the animals were exposed to two Roundup concentrations: 3.25mg/L (non-observed effect concentration - NOEC) and 5.35mg/L (LC10) for 24h and 96h. Oxygen consumption was determined and the animals were divided into three body regions (anterior, middle and posterior) for biochemical analysis. An inhibition of both cholinesterase isoforms were observed in animals exposed to both Roundup concentrations after 96h. A significant reactive oxygen species (ROS) reduction was observed in the posterior region of animals in both periods, while antioxidant capacity against peroxyl radicals (ACAP) was reduced in the posterior region of animals exposed for 24h. Considering the antioxidant defense system, both GSH levels and enzyme activities (catalase, superoxide dismutase, glutathione s-transferase, glutathione peroxidase and glutamate cysteine ligase) were not altered after exposure. Lipid peroxidation was reduced in all analyzed body regions in both Roundup concentrations after 24h. Animals exposed to the highest concentration presented a reduction in lipid peroxidation in the anterior region after 96h, while animals exposed to the lowest concentration presented a reduction in the middle region. Overall results indicate that Roundup exposure presents toxicity to L. acuta, causing a disruption in ROS and ACAP levels as well as affects the cholinergic system of this invertebrate species.


Subject(s)
Cholinesterase Inhibitors/pharmacology , Glycine/analogs & derivatives , Herbicides/toxicity , Oxidative Stress/drug effects , Polychaeta/drug effects , Acetylcholinesterase/drug effects , Animals , Antioxidants/pharmacology , Catalase/drug effects , Catalase/metabolism , Cholinesterases/drug effects , Glutathione Peroxidase/drug effects , Glutathione Transferase/drug effects , Glycine/toxicity , Lethal Dose 50 , Lipid Peroxidation/drug effects , Oxygen Consumption/drug effects , Peroxides/antagonists & inhibitors , Reactive Oxygen Species/analysis , Superoxide Dismutase/drug effects , Time Factors , Glyphosate
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