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Marine benthic invertebrates are frequently exposed to fluctuating oxygen levels resulting in hypoxia-reoxygenation (H/R) stress in the intertidal, estuarine and shallow coastal habitats. H/R stress can strongly affect the organisms' physiological performance due to the negative shifts in bioenergetics and redox balance. H/R stress commonly leads to the depletion of energy substrates and accumulation of anaerobic end products, but the effects of H/R stress on the homeostasis of the intermediate nitrogenous compounds are not well understood. We studied the effects of the short-term and long-term hypoxia (1 and 6 days, respectively) and subsequent reoxygenation on the metabolite profiles of free amino acids (FAAs), as well as the intermediates of the urea cycle and purine metabolism in two species of hypoxia-tolerant intertidal bivalves, the blue mussels Mytilus edulis and the Pacific oysters Crassostrea gigas. Accumulation of succinate was assessed to determine the role of anaerobiosis in the metabolic responses to H/R stress. Our study showed that the more hypoxia-tolerant of the two studied species (C. gigas) had lower rate of succinate accumulation during hypoxia (indicating stronger metabolic rate suppression) and was better able to maintain the homeostasis of nitrogenous intermediates during H/R stress compared with the less hypoxia-tolerant M. edulis. Furthermore, analysis of the metabolite profiles indicate that the oysters maintain high levels of cytoprotective compounds (such as taurine and GABA), accumulate lower levels of potential prooxidants (such as succinate and hypoxanthine) and experience less damage to oxidation-prone thiol-containing amino acids such as cysteine, homocysteine and methionine during hypoxia and reoxygenation compared with the blue mussels. This study indicates a potentially important role of intermediate metabolite homeostasis in the tolerance to prolonged hypoxia and H/R stress in marine organisms and opens avenue for further testing of this hypothesis in a broader comparative framework., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Pharmaceutical and personal care products (PPCPs) are the environmental pollutants of growing concern. The aim of this study was to indicate the effects of typical PPCPs on the marsh frog Pelophylax ridibundus. We treated male frogs with waterborne ibuprofen (IBU, 250ng·L -1 ), triclosan (TCS, 500ng·L -1 ), or estrone (E1, 100ng·L -1 ) for 14days. Common vulnerability of the frogs was detected from dramatic decrease of Zn, total and metalated metallothionein (MT) concentrations, Zn/Cu ratio, the elevation of activity of glutathione-S-transferase, cathepsin D and DNA instability in the liver, the depletion of cholinesterase in the brain and cortisol in the blood plasma in all exposures. Nevertheless, lipofuscin concentration in the liver was always decreased. The groups were best distinguished by cytochrome P450 (CYP450) activity determined by ELISA. The exposure to IBU caused lesser damage, but elevated the levels of oxyradicals and glutathione (GSH and GSSG) and lysosomal membrane instability. Exposures to TCS and E1 provoked the endocrine disturbance (increased levels of vitellogenin and thyrotropin in blood plasma), decreased lactate dehydrogenase activity and increased level of pyruvate in the liver. TCS caused the increase of GSSG by 7.3 times and lactate levels. Only E1 lead to decrease of deiodinase activity in the liver, activation of CYP450 and caspase-3 and efflux of cathepsin D from lysosomes. Spectrophotometric and ELISA assays of MTs and CYP450 gave distinct results in E1-group. Broad disruption of the hormonal pathways caused by E1 could be of concern for the health status of frogs in their habitats., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Estuarine organisms including mollusks are exposed to periodic oxygen deficiency (hypoxia) that leads to a decrease in intracellular pH and accumulation of bicarbonate (HCO3(-)). These changes can affect cellular bioenergetics; however, their effects on mitochondria of estuarine mollusks are not well understood. We determined the interactive effects of bicarbonate (0-10mM) and pH (7.2 and 6.5) on mitochondrial oxygen consumption (ṀO2), membrane potential (Δψ) and production of reactive oxygen species (ROS) in two common estuarine bivalves - hard clams Mercenaria mercenaria, and bay scallops Argopecten irradians. In both species, elevated HCO3(-) levels suppressed ADP-stimulated (state 3) ṀO2 but had little effect on the resting (state 4) respiration. These effects were not mediated by the soluble adenylyl cyclase or cyclic AMP. Effects of the low pH (6.5) on mitochondrial traits were species-specific and depended on the substrate oxidized by the mitochondria. Mild acidosis (pH6.5) had minimal effects on ṀO2 and Δψ of the bivalve mitochondria oxidizing pyruvate but led to increased rates of ROS production in clams (ROS production could not be measured in scallops). In succinate-respiring mitochondria of clams, mild acidosis suppressed ṀO2 and increased mitochondrial coupling, while in scallop mitochondria the effects of low pH were opposite. Suppression of mitochondrial oxidative phosphorylation by bicarbonate and/or acidosis may contribute to the metabolic rate depression during shell closure or environmental hypoxia/hypercapnia. These findings have implications for understanding the physiological mechanisms involved in regulation of mitochondrial bioenergetics during hypoxia exposure in estuarine bivalves., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Despite numerous studies suggesting a dramatic decline of amphibians, the biochemical mechanisms of adaptation in these animals to polluted environment are poorly studied. The aim of this study was to elucidate the ability to release cobalt (Co) and zinc (Zn) from their nanoscale complexes (NCs) derived from the polymeric substance of N-vinylpyrrolidone (PS) in the liver of amphibian (Rana ridibunda). Frog males were subjected to 14days exposure to waterborne Co(2+) (50μg/L), Zn(2+) (100μg/L), as well as corresponding concentrations of Co-NC, Zn-NC or PS. Main attention was paid to MT's interrelations with indices of stress and toxicity. Only Co(2+) and Zn(2+) caused elevation of the correspondent metal in MTs. Co(2+) caused down-regulation of cathepsin D activity, while Zn(2+), Zn-NC and the PS up-regulated this activity. Zn(2+) provoked 1.6 times increase of metal-bounded form of the MT (MT-Me), while all other exposures caused the elevation of the ratio of MT total protein concentration (MT-SH) and concentrations of the MT-Me and/or immunoreactive (MTi) form (up to ~10 times) accompanied by a decrease in the levels of oxyradicals. The increased DNA fragmentation and down-regulation of caspase-3 activity in relation to the redox state of glutathione and/or lactate/pyruvate were shown at all exposures. These data indicate the vulnerability of the redox state of cellular thiols and inability to release Co and Zn from NCs in frog's liver., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The environmental safety of pharmaceutical and personal care products (PPCPs) requires a crucial examination. The aim of this study was to evaluate the responses of biomarkers of stress and toxicity in freshwater mussels to the effect of commonly found PPCPs in wastewater. We treated male mussels Unio tumidus, from an undisturbed site with ibuprofen (IBU, 250 ng L(-1)), triclosan (TCS, 500 ng L(-1)), or estrone (E1, 100 ng L(-1)) for 14 days. Untreated mussels from this site (C) and mussels inhabiting a polluted area (P) were also examined after a similar time of being kept in the laboratory. The consequences of chronic exposure of the mussels in the P-group were reflected in elevated concentrations of oxyradicals (1.4 times), oxidized glutathione (4.3 times), lipofuscin (2.2 times), and DNA-strand breaks in the digestive gland (DG) in comparison to the C-group, higher levels of caspase-3 activity in the DG, and vitellogenin-like proteins in gonads among all studied groups. Exposed mussels demonstrated some common responses with mussels in the P-group: elevated levels of lactate/pyruvate ratio, lipofuscin (IBU and E1), DNA fragmentation (TCS and E1), and caspase-3 activity (TCS and E1). Exposed to PPCPs mussels also showed elevation of ethoxyresorufin-O-deethylase and/or glutathione-S-transferase activity in the DG and a decrease in lysosomal stability in hemocytes (TCS and E1). The TCS group was distinguished by having the highest level of DNA-fragmentation and the lowest concentrations of total glutathione, oxyradicals, lipofuscin, pyruvate, and lactate, reflecting total metabolic depression. These results show that selected PPCPs at low concentrations alter a variety of physiological processes in this animal model system., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The main goal of this study was to evaluate the ability of fish Carassius auratus tissues to release cobalt (Co) and zinc (Zn) cations present in the applied Co- and Zn-containing nanoscale composites (NCs). Male fish was subjected to 14day long action of Co- and Zn-NCs, as well as of Co(2+) and Zn(2+) or polymeric substance (PS) used for the NC preparation and derived from the vinylpyrrolidone. 50μg∙L(-1) of Co and 100μg∙L(-1) of Zn were applied either as a salt or a nanocomposite. Both Co and Co-NC increased (3.1 and 2.3 times, respectively) concentration of total Co, metallothionein-related Co (3.7 and 6.6 times, respectively) and thiols (by 71 and 95%, respectively), and caspase-3 activity (2.2 and 3.7 times, respectively) in the fish liver. At the same time, Co and Co-NC decreased glutathione level (1.8 and 1.9 times, respectively) and activated vitellogenesis (5.1 and 9.9 times, respectively) in the fish liver. Both Zn and Zn-NC increased markedly concentrations of metallothionein-related Zn (2.4 and 2.9 times, respectively) and Cu (2.8 and 3.2 times, respectively), and decreased metallothionein-related thiol (2.5 and 4.2 times, respectively), oxyradical (by 30.4 and 44.2%, respectively), and caspase-3 (3.0 and 5.3 times, respectively) levels in the fish liver. These peculiarities are common for metal and metal-NC and witness a release of metal from NS in fish organism. The differences in the levels of DNA strand breaks, biotransformation enzymes and total Zn levels in the liver were dependent on the kind of exposure., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The aim of this study was to evaluate population-related peculiarities of the adaptive responses of Carassius auratus gibelio. In order to do this, male specimens from polluted (B) and clean (Z) sites were exposed to commercial pesticides thiocarbamate Tatoo (9.1 μg·L(-1)and 91 μg·L(-1)) or tetrazine Apollo (2 μg·L(-1) and 10 μg·L(-1)) during fourteen days. The control fish from site B was distinguished by weakness of antioxidant defence (measured from superoxide dismutase and catalase activities, redox index of glutathione (GSH), superoxide anion (O(2)) and lipid peroxidation levels), imbalance of the concentrations of protein metallothionein (MT-SH) and MT-related metals (MT-Me) and neurotoxicity. Differences in glutathione-S-transferase activity in the liver and vitellogenin-like proteins in the serum were also showed between B and Z control groups. Common effects of pesticides were related to a decrease in GSH, an increase in O(2) production, ethoxyresorufin O-deethylase activity and hepatosomatic index. Apollo provoked particular elevation of MT-SH/MT-Me ratio. Population-related difference in the response was the activation of antioxidant defence in fish from site B and its inhibition in fish from site Z. The genotoxic effect of exposures was more expressed in fish from site B. Principal component analysis combine all exposed groups from site Z and control group from site B in one set, and separated each exposed group from site B. The main distinguishing index of each population selected by classification and regression tree analysis was MT-SH., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The aim of this study was to compare the effect of pro-oxidants copper (Cu(2+), 0.005 and 0.050mg L(-1)) or manganese (Mn(2+), 0.17 and 1.7mg L(-1)) on Carassius auratus gibelio from polluted (B) and unpolluted (Z) sites after exposure for fourteen days. Fish from site B showed high levels of lipid peroxidation (TBARS concentration), lower levels of metallothionein (MT)-related metal, total glutathione (GSH), its redox index, superoxide dismutase (Cu,Zn- and Mn-SOD), glutathione-S-transferase (GST) and cholinesterase (ChE) activities and also higher MT-related thiol concentration in the liver and gills. A common effect of exposure was related to genotoxicity, a decrease in GSH and an increase in microsomal ethoxyresorufin O-deethylase activity in the liver. However, the systems of oxidative stress and biotransformation were more efficient in fish from the polluted site, while the responsivity of MTs in this fish was impaired. Principle Component Analysis separated the subgroups from the unpolluted site and fish loaded by lesser concentrations of metals on the one side, and fish from the polluted site jointly with fish exposed to higher concentrations of metals on the other side. The main distinguishing indices of sites and exposures selected by classification and regression tree (CART) analysis were MT characteristics and genotoxicity., (Copyright © 2011 Elsevier Inc. All rights reserved.)