RESUMO

This study investigates the effects of different inorganic arsenic (As III) concentrations (0, 125, 500 and 1000 µg As/L) following two exposure times (7 and 14 days) on gills, digestive gland and muscle of scallop Aequipecten tehuelchus from Patagonia, Argentina. A biochemical approach was used to investigate oxidative stress-related parameters after different As concentrations and exposure times. Although the accumulation of As was of the same order of magnitude in all tissues, the results showed distinct tissue-specific oxidative responses to this metalloid. Furthermore, the variation in exposure time had no significant effect on As accumulation in any of the three tissues. In gills, despite no reactive oxygen and nitrogen species (RONS) were detected, there was an increase in catalase (CAT) activity and metallothionein (MT) levels. Conversely, digestive gland showed RONS production without a rise in CAT and glutathione S-transferases (GST) activities, but with an increase in MT levels. In muscle, RONS production and CAT activity kept constant or decreased, while MT levels remained unchanged. In addition, exposure time demonstrated its critical role in gills by influencing the response of CAT, GST and MT, particularly at high As concentrations, while exposure time did not affect the biochemical stress parameters in the digestive gland and muscle. Interestingly, neither concentration of As produced lipid damage, showing the effectiveness of the antioxidant mechanisms to avoid it. These results emphasize that A. tehuelchus exhibited no time-dependent effects in response to As exposure, while showing tissue-specific responses characterized by significant concentration-dependent effects of As. This study provides a comprehensive insight by considering the combined effects of time and concentration of a contaminant and distinguishing its effects on specific tissues, a dimension often overlooked in the existing literature. Subsequent studies should prioritize the analysis of additional contaminants in species with increased sensitivity.

Assuntos

Arsênio , Pectinidae , Poluentes Químicos da Água , Animais , Arsênio/análise , Argentina , Poluentes Químicos da Água/análise , Pectinidae/metabolismo , Estresse Oxidativo , Antioxidantes/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Brânquias/metabolismo , Catalase/metabolismo , Peroxidação de Lipídeos

RESUMO

The freshwater gastropod Pomacea canaliculata fulfills the ideal conditions of a bioindicator species since its digestive gland bioconcentrates elements toxic for human and ecosystems health. The aim of this work was to study the balance between production of free radicals and antioxidant defenses, and the generation of oxidative damage in the digestive gland of this mollusk after exposure (96 h) to three elements with differential affinities for functional biological groups: mercury (5.5 µg/L of Hg+2 as HgCl2), arsenic [500 µg/L of (AsO4)-3 as Na3AsO47H2O], or uranium [700 µg/L of (UO2)+2 as UO2(CH2COOH)2]. Bioconcentration factors of Hg, As, and U were 25, 23, and 53, respectively. Snails exhibited a sustained increase of reactive species (RS), and protein and lipid damage. Lipid radicals increased between 72 and 96 h, respectively, in snails exposed to U and Hg while this parameter changed early (24 h) in As- exposed snails. Snails showed protein damage, reaching maximum values at different endpoints. This redox disbalance was partially compensated by non-enzymatic antioxidant defenses α-tocopherol (α-T), ß-carotene (ß-C), uric acid, metallothionein (MTs). Snails consumed α-T and ß-C in an element-dependent manner. The digestive gland consumed rapidly uric acid and this molecule was not recovered at 96 h. Digestive gland showed a significant increase in MTs after elemental exposure at different endpoints. The enzymatic antioxidant defenses, represented by the catalase and glutathione-S-transferase activities, seems to be not necessary for the early stages of the oxidative process by metals. This work is the first attempt to elucidate cellular mechanisms involved in the tolerance of this gastropod to non-essential elements. The bioconcentration factors and changes in the oxidative status and damage confirm that this species can be used as a bioindicator species of metal pollution in freshwater bodies.

RESUMO

Changes in fatty acid (FA) composition can mean a mechanism of acclimation of Cyanobacteria to climate change. The objective of the present study was to evaluate the effects of increased temperature on M. aeruginosa cultures in terms of FA content, lipid damage, biomass and reactive oxygen species (ROS). Unicellular cultures were exposed to high (29 °C) and control (26 °C) temperature for 12 days. Differential sensitivity of ω3 FAs was observed after 2 days of exposure to elevated temperature (29 °C). Also, no significant differences in ROS content at different temperatures were observed although there was a significant decrease compared to the value at the start of the incubation. Thus, low FA peroxidation of selected ω6 PUFAs and potentially increased activation of antioxidant systems, resulting in lower lipid damage (on average 35%), could explain the strong acclimation to high temperature as shown by the increased growth rate (11%) compared to the control conditions. In high temperature conditions we found a retarded desaturation to 18:3ω3 and 18:4ω3 PUFAs which were 40% lower compared with control at the end of incubation. Overall, growth rate and omega-6 FA were increased at high temperature as a mechanism of successful acclimation. This is highly relevant for the ecological role of M. aeruginosa as food source for grazers. A reduced FA level can have serious implications for the flow of energy and thus the overall functioning of the ecosystem.

Assuntos

Adaptação Fisiológica , Ácidos Graxos/química , Temperatura Alta , Lipídeos/química , Microcystis/crescimento & desenvolvimento , Espécies Reativas de Oxigênio/metabolismo , Ecossistema , Microcystis/metabolismo

RESUMO

The studied hypothesis is that glyphosate (GLY) can affect the oxidative balance in the hydrophilic intracellular medium in non-target Chlorella vulgaris cells. Analytical GLY (5 µM) and a commercial product (RUP) (5 µM) supplementation, did not affect the growth profile. Neither in latent (Lag) nor in exponential (Exp) phase of development, there were significant differences in the cellular abundance, evaluated as cell number, after the supplementation with GLY or RUP. The ascorbyl (A•) content was significantly increased in the presence of GLY or RUP, in Lag and Exp phase of growth. No changes were observed in stationary (St) phase after supplementation with either GLY or RUP. Ascorbate (AH-) content was decreased by 30% in Exp phase of development the presence of RUP. In St phase of the development both, the administration of either GLY or RUP decreased the antioxidant content by 34 and 37%, respectively. The supplementation with GLY and RUP lead to a significant 5- and 10-fold increase in Exp phase, respectively in the A•/AH-content ratio, assessed as a damage/protection ratio in the hydrophilic fraction of the cells, as compared to controls. Neither GLY nor RUP affected the ratio in cells in St phase of development. The data presented here showed experimental evidence that suggested that oxidative balance in the hydrophilic environment is affected by GLY, even at the low to medium concentrations currently used. The effect seems as reversible either because of the magnitude of the herbicide-dependent damage or the antioxidant activity activated.

Assuntos

Chlorella vulgaris/efeitos dos fármacos , Glicina/análogos & derivados , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes , Ácido Ascórbico , Chlorella vulgaris/fisiologia , Glicina/toxicidade , Herbicidas/toxicidade , Oxirredução , Estresse Oxidativo , Glifosato

RESUMO

The health status of the commercial Tehuelche scallop Aequipecten tehuelchus from San Román and El Riacho in San José gulf (Patagonia, Argentina) was evaluated through biomarkers widely used in ecotoxicological applications. Natural levels of arsenic (As) and cadmium (Cd) were measured to determine their potential relationships with fluctuations of several oxidative stress biomarkers in the scallop. Oxidative biomarkers, such as catalase (CAT), glutathione S-transferase (GST), superoxide dismutase (SOD), metallothioneins (MT), reactive oxygen species (ROS), α-tocopherol (α-T), and lipid peroxidation (LPO) through thiobarbituric acid reactive substances (TBARS) and lipid radical (LR∙), were measured in gills, digestive gland, and muscle of Tehuelche scallop in winter (August 2015) and summer (January 2016). Levels of As and Cd and of most of the biomarkers (SOD, ROS, TBARS, and LR∙) showed strong seasonal variability in the three tissues. In general, the highest values were recorded in digestive gland. The Integrated Biomarker Response index indicated that the most stressed condition of A. tehuelchus was in summer in San Román. Additionally, the Integrated Biomarker Response index showed a strong relationship among tissues and As and Cd accumulation. This kind of approach could be used as an integrated tool to identify the health status of scallop A. tehuelchus from San José gulf.

Assuntos

Bioacumulação/efeitos dos fármacos , Monitoramento Ambiental/métodos , Estresse Oxidativo/efeitos dos fármacos , Pectinidae/efeitos dos fármacos , Poluentes Químicos da Água/análise , Animais , Argentina , Biomarcadores/metabolismo , Brânquias/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Músculos/metabolismo , Pectinidae/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Alimentos Marinhos/análise , Estações do Ano , Poluentes Químicos da Água/metabolismo

RESUMO

The aim of this study was to evaluate the effects of short-term (hours) exposure to solar UV radiation (UVR, 280-400 nm) on the physiology of Microcystis aeruginosa. Three solar radiation treatments were implemented: (i) PAR (PAR, 400-700 nm), (ii) TUVA (PAR + UVAR, 315-700 nm) and (iii) TUVR (PAR + UVAR + UVBR, 280-700 nm). Differential responses of antioxidant enzymes and the reactive oxygen species (ROS) production to UVR were observed. Antioxidant enzymes were more active at high UVR doses. However, different responses were observed depending on the exposure to UVAR or UVBR and the dose level. No effects were observed on the biomass, ROS production or increased activity of superoxide dismutase (SOD) and catalase (CAT) compared to the control when UVR + PAR doses were lower than 9875 kJ m-2. For intermediate doses, UVR + PAR doses between 9875 and 10 275 kJ m-2, oxidative stress increased while resistance was imparted through SOD and CAT in the cells exposed to UVAR. Despite the increased antioxidant activity, biomass decrease and photosynthesis inhibition were observed, but no effects were observed with added exposure to UVBR. At the highest doses (UVR + PAR higher than 10 275 kJ m-2), the solar UVR caused decreased photosynthesis and biomass with only activation of CAT by UVBR and SOD and CAT by UVAR. In addition, for such doses, a significant decrease of microcystins (MCs, measured as MC-LR equivalents) was observed as a consequence of UVAR. This study facilitates our understanding of the SOD and CAT protection according to UVAR and UVBR doses and cellular damage and reinforces the importance of UVR as an environmental stressor. In addition, our results support the hypothesized antioxidant function of MCs.

Assuntos

Toxinas Bacterianas/biossíntese , Microcystis/metabolismo , Microcystis/efeitos da radiação , Raios Ultravioleta , Toxinas Bacterianas/química , Catalase/metabolismo , Microcystis/enzimologia , Superóxido Dismutase/metabolismo

RESUMO

Alcohol hangover (AH) is the pathophysiological state after a binge-like drinking. We have previously demonstrated that AH induced bioenergetics impairments in a total fresh mitochondrial fraction in brain cortex and cerebellum. The aim of this work was to determine free radical production and antioxidant systems in non-synaptic mitochondria and synaptosomes in control and hangover animals. Superoxide production was not modified in non-synaptic mitochondria while a 17.5% increase was observed in synaptosomes. A similar response was observed for cardiolipin content as no changes were evidenced in non-synaptic mitochondria while a 55% decrease in cardiolipin content was found in synaptosomes. Hydrogen peroxide production was 3-fold increased in non-synaptic mitochondria and 4-fold increased in synaptosomes. In the presence of deprenyl, synaptosomal H2O2 production was 67% decreased in the AH condition. Hydrogen peroxide generation was not affected by deprenyl addition in non-synaptic mitochondria from AH mice. MAO activity was 57% increased in non-synaptic mitochondria and 3-fold increased in synaptosomes. Catalase activity was 40% and 50% decreased in non-synaptic mitochondria and synaptosomes, respectively. Superoxide dismutase was 60% decreased in non-synaptic mitochondria and 80% increased in synaptosomal fractions. On the other hand, GSH (glutathione) content was 43% and 17% decreased in synaptosomes and cytosol. GSH-related enzymes were mostly affected in synaptosomes fractions by AH condition. Acetylcholinesterase activity in synaptosomes was 11% increased due to AH. The present work reveals that AH provokes an imbalance in the cellular redox homeostasis mainly affecting mitochondria present in synaptic terminals.

Assuntos

Transtornos do Sistema Nervoso Induzidos por Álcool/metabolismo , Córtex Cerebral/patologia , Radicais Livres/metabolismo , Mitocôndrias/metabolismo , Terminações Pré-Sinápticas/metabolismo , Acetilcolinesterase/metabolismo , Animais , Cardiolipinas/metabolismo , Metabolismo Energético , Etanol/toxicidade , Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Masculino , Potencial da Membrana Mitocondrial , Camundongos , Oxirredução , Terminações Pré-Sinápticas/patologia , Superóxidos/metabolismo , Sinaptossomos/metabolismo

RESUMO

Microcystis are known for their potential ability to synthesize toxins, mainly microcystins (MCs). In order to evaluate the effects of temperature on chlorophyll a (Chl a), growth, physiological responses and toxin production of a native Microcystis aeruginosa, we exposed the cells to low (23°C) and high (29°C) temperature in addition to a 26°C control treatment. Exponential growth rate was significantly higher at 29°C compared to 23°C and control, reaching 0.43, 0.32 and 0.33day(-)(1) respectively. In addition, there was a delay of the start of exponential growth at 23°C. However, the intracellular concentration of Chl a decreased significantly due to temperature change. A significant increase in intracellular ROS was observed in coincidence with the activation of enzymatic antioxidant catalase (CAT) during the first two days of exposure to 23° and 29°C in comparison to the control experiment, decreasing thereafter to nearly initial values. Five MCs were determined by LC-MS/MS analysis. In the experiments, the highest MC concentration, 205fg [Leu(1)] MC-LR.cell(-1) expressed as MC-LR equivalent was measured in the beginning of the experiment and subsequently declined to 160fg.cell(-1) on day 2 and 70fg.cell(-1) on day 4 in cells exposed to 29°C. The same trend was observed for all other MCs except for the least abundant MC-LR which showed a continuous increase during exposure time. Our results suggest a high ability of M. aeruginosa to perceive ROS and to rapidly initiate antioxidant defenses with a differential response on MC production.

Assuntos

Antioxidantes/metabolismo , Proteínas de Bactérias/metabolismo , Catalase/metabolismo , Microcistinas/metabolismo , Microcystis/enzimologia , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Temperatura , Adaptação Fisiológica , Biomassa , Clorofila/metabolismo , Clorofila A , Cromatografia Líquida , Microcystis/crescimento & desenvolvimento , Espectrometria de Massas em Tandem , Fatores de Tempo

RESUMO

The Natural Protected Area San Antonio bay is of particular importance for its congregation of migratory shorebirds and it has been declared one of the Western Hemisphere Shorebird Reserve Network International site (WHSRN). Present study represents the first assessment of variation on oxidative stress biomarkers in male crab Neohelice granulata from San Antonio bay (Río Negro, Argentina) under field conditions, associated mainly to metal contamination coming from passive mining wastes. Three sites were sampled once every three months from November 2012 to August 2013 within this sea inlet (Pile, Fishery and Port) and a control site at the southeast of the bay (Punta Perdices). Accumulation of Ni, Zn, Cr and Al varied only with seasons although without a constant trend, meanwhile Cd, Cu and Pb also varied among sites being highest in Pile and Port. Biochemical results indicated that variations in catalase activity was only site specific being maximum in Pile; meanwhile lipid radical, α-tocopherol and metallothioneins were only seasonal specific being higher in autumn and winter. Seasonal variation was also found for total thioles, being the content higher in summer and autumn than in winter. Correlation analysis revealed that malondialdehyde and α-tocopherol have a positive association with Al and negative with Ni, meanwhile GST has a positive association with Fe. Crabs from the closest area to the waste pile did not exhibit a differentiated oxidative pressure despite the higher accumulation of metals. It is possible that crabs from contaminated areas have developed a tolerance to metals, indicating a strong ecotoxicological selective pressure. More studies are needed to assess whether there is a transfer of metals through the food chain.

Assuntos

Braquiúros/efeitos dos fármacos , Metais/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Argentina , Baías , Braquiúros/metabolismo , Monitoramento Ambiental/métodos , Resíduos Industriais , Masculino , Metais/análise , Mineração , Estresse Oxidativo/efeitos dos fármacos , Estações do Ano , Poluentes Químicos da Água/análise

RESUMO

In this study, we assessed in gills of native ribbed mussels Aulacomya atra atra from three sites within Nuevo Gulf (Northern Patagonia) several biomarkers such as reactive oxygen species (ROS), lipid radicals (LR), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and metallothionein (MT). Furthermore, concentrations of main trace metals (Fe, Al, Zn, Cu, Cd and Pb) were quantified in mussel tissue. Results showed significant induction of SOD, GST, MT and MDA, as well as, higher concentration of Fe, Al and Cd in winter than in summer. The high MDA content measured in mussels from Folías Wreck seemed to be caused by the very high levels of Fe that would come from the corrosion of the vessel. Mussels from the control site Punta Cuevas presented the lowest levels of Cd and the highest of Al in winter. Despite positive correlations were found between Al and GST and MT, no spatial differentiation was detected in those biomarkers. On the other hand, MT was only related to Al been most likely influenced by environmental variables than by the trace metals. It has to be highlighted that the relationship detected among water temperature, nutrients and antioxidant responses in gills is probably related to the fact that this tissue is in direct contact with water and it is sensitive to its fluctuations. Taking into account that mussel gill is a tissue actively proliferating and the first target of contaminants present in water, so that changes in its antioxidant system can provide an earlier warning signal than in other tissues.

Assuntos

Biomarcadores/análise , Monitoramento Ambiental , Brânquias/química , Mytilidae/química , Estresse Fisiológico , Animais , Antioxidantes/análise , Argentina , Catalase/análise , Feminino , Brânquias/enzimologia , Glutationa Transferase/análise , Masculino , Malondialdeído/análise , Metalotioneína/análise , Mytilidae/enzimologia , Espécies Reativas de Oxigênio/análise , Estações do Ano , Superóxido Dismutase/análise , Oligoelementos/análise

RESUMO

Electron paramagnetic resonance (EPR) spectroscopy detects the presence of radicals of biological interest, such as ascorbyl radical (A(•)) and lipid radicals. A(•) is easily detectable by EPR even in aqueous solution at room-temperature. Under oxidative conditions leading to changes in total ascorbate (AH(-)) content, the A(•)/AH(-) ratio could be used to estimate early oxidative stress in the hydrophilic milieu. This methodology was applied to a wide range of aquatic systems including algae, sea urchin, limpets, bivalves and fish, under physiological and oxidative stress conditions as well. The A(•)/AH(-) ratio reflected the state of one part of the oxidative defense system and provided an early and simple diagnosis of environmental stressing conditions. Oxidative damage to lipids was assessed by the EPR-sensitive adduct formation that correlates well with cell membrane damage with no interference from other biological compounds. Probe instability, tissue metabolism, and lack of spin specificity are drawback factors for employing EPR for in vivo determination of free radicals. However, the dependability of this technique, mostly by combining it with other biochemical strategies, enhances the value of these procedures as contributors to the knowledge of oxidative condition in aquatic organisms.

Assuntos

Ácido Desidroascórbico/análogos & derivados , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Peroxidação de Lipídeos , Estresse Oxidativo/fisiologia , Animais , Organismos Aquáticos/metabolismo , Ácido Desidroascórbico/isolamento & purificação , Radicais Livres/isolamento & purificação , Oxirredução

RESUMO

Seasonal and spatial variability of trace metal concentrations and of a battery of antioxidant parameters were evaluated in digestive gland of the ribbed mussel Aulacomya atra atra. Fe, Al and Cu accumulated in tissue exhibited maximum values in winter, coinciding partially with the highest labile concentrations of Fe and Cu in sediment. Metals, as other pollutants, are known to influence the oxidative status of organisms and antioxidant enzymes have been often proposed as biomarkers of contaminant effects. Seasonal variations of trace metals did not appear to influence those of biochemical parameters, which generally showed an opposite trend with higher enzymatic activities in summer when trace metal concentrations were lower. Organisms from Punta Cuevas (control site) showed higher induction of reactive oxygen species production than those from both considered impacted sites, suggesting the possibility of some biochemical adaptation in organisms or a higher modulation of environmental and physiological factors on antioxidant responses than levels of trace metals. This study, which is the first in the area in this matter, showed that seasonal variations of potential biomarkers should be incorporated into interpretation of long-term biomonitoring studies in this marine coastal ecosystem.

Assuntos

Bivalves/química , Metais/análise , Poluentes Químicos da Água/análise , Animais , Argentina , Bivalves/metabolismo , Monitoramento Ambiental , Metais/metabolismo , Estações do Ano , Poluentes Químicos da Água/metabolismo

RESUMO

Recently, a number of synthetic drugs used in a variety of therapeutic indications have been reported to have antiaging effects. Among them, Dimethylaminoethanol (DMAE), an anologue of dietylaminoethanol, is a precursor of choline, which in turn allows the brain to optimize the production of acetylcholine that is a primary neurotransmitter involved in learning and memory. The data presented here includes new information on the ability of the compound to scavenge specific free radicals, assessed by Electron Spectroscopic Resonance (EPR), to further analyze the role of DMAE as an antioxidant. DMAE ability to directly react with hydroxyl, ascorbyl and lipid radicals was tested employing in vitro assays, and related to the supplemented dose of the compound.

Assuntos

Antioxidantes/farmacologia , Deanol/farmacologia , Sequestradores de Radicais Livres/farmacologia , Animais , Antioxidantes/administração & dosagem , Deanol/administração & dosagem , Ácido Desidroascórbico/análogos & derivados , Ácido Desidroascórbico/metabolismo , Relação Dose-Resposta a Droga , Espectroscopia de Ressonância de Spin Eletrônica , Sequestradores de Radicais Livres/administração & dosagem , Radicais Livres/metabolismo , Radical Hidroxila/metabolismo , Microssomos Hepáticos/metabolismo , Ratos

RESUMO

The occurrence of biomarker variations linked to environmental factors makes it difficult to distinguish the effect of pollution. In an attempt to evaluate spatial and seasonal effects of environmental parameters on biomarker responses, mussels Mytilus edulis chilensis coming from an aquaculture farm were transplanted to several points within Ushuaia Bay (Beagle Channel) for 6 weeks in summer and winter. Activities of superoxide dismutase, catalase, glutathione-S-transferase and levels of lipid peroxidation were measured in gills and digestive gland. Cu, Zn, Fe, Cd and Pb concentrations were also assessed. Results indicated a significant effect of seasons on biological responses as well as in metal bioaccumulation showing the influence of natural factors such as dissolved oxygen, temperature and food availability. The interdependence of those environmental factors is important for the homeostasis of thermoconformers, especially regarding their oxidative metabolism and should also be taken into consideration to distinguish natural from pollution-induced variations.

Assuntos

Biomarcadores/metabolismo , Mytilus edulis/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Aquicultura , Catalase/metabolismo , Monitoramento Ambiental , Glutationa Transferase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Mytilus edulis/metabolismo , Estações do Ano , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/metabolismo , Poluição Química da Água/estatística & dados numéricos

RESUMO

We studied the seasonal variation on aerobic metabolism and the response of oxidative stress parameters in the digestive glands of the subpolar limpet Nacella (P.) magellanica. Sampling was carried out from July (winter) 2002 to July 2003 in Beagle Channel, Tierra del Fuego, Argentina. Whole animal respiration rates increased in early spring as the animals spawned and remained elevated throughout summer and fall (winter: 0.09+/-0.02 micromol O2 h-1 g-1; summer: 0.31+/-0.06 micromol O2 h-1 g-1). Oxidative stress was assessed at the hydrophilic level as the ascorbyl radical content/ascorbate content ratio (A./AH-). The A./AH- ratio showed minimum values in winter (3.7+/-0.2 10(-5)AU) and increased in summer (18+/-5 10(-5) AU). A similar pattern was observed for lipid radical content (122+/-29 pmol mg-1 fresh mass [FW] in winter and 314+/-45 pmol mg-1 FW in summer), iron content (0.99+/-0.07 and 2.7+/-0.6 nmol mg-1 FW in winter and summer, respectively) and catalase activity (2.9+/-0.2 and 7+/-1 U mg-1 FW in winter and summer, respectively). Since nitrogen derived radicals are thought to be critically involved in oxidative metabolism in cells, nitric oxide content was measured and a significant difference in the content of the Fe-MGD-NO adduct in digestive glands from winter and summer animals was observed. Together, the data indicate that both oxygen and nitrogen radical generation rates in N. (P.) magellanica are strongly dependent on season.

Assuntos

Sistema Digestório/metabolismo , Gastrópodes/metabolismo , Estresse Oxidativo , Animais , Antioxidantes/metabolismo , Peso Corporal , Catalase/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Enzimas/metabolismo , Radicais Livres/metabolismo , Gastrópodes/fisiologia , Peroxidação de Lipídeos , Oxigênio/metabolismo , Estações do Ano

RESUMO

The aim of this work was to study the oxidative profile of digestive glands of two limpets species (Nacella (Patinigera) magellanica and Nacella (Patinigera) deaurata) exposed to different environmental conditions. The intertidal population of N. (P.) magellanica is subjected to a wide variety of stresses not experienced by N. (P.) deaurata. Although a typical electron paramagnetic resonance (EPR) spectrum of ascorbyl radical in digestive gland from both limpets was observed, neither ascorbyl radical content nor the ascorbyl radical content/ascorbate content ratio was significantly different, suggesting that the difference in the environmental conditions did not appear to be responsible for developing alterations in the oxidative status of both organisms at the hydrophilic level (e.g. cytosol). Lipid peroxidation in the digestive glands was estimated, both as the content of thiobarbituric acid reactive substances (TBARS) and as the content of lipid radicals assessed by EPR, in both organisms. TBARS and lipid radical content were 34.8 and 36.5%, respectively, lower in N. (P.) magellanica as compared to N. (P.) deaurata. On the other hand, total iron content and the rate of generation of superoxide anion were 47.9 and 51.4%, respectively, lower in N. (P.) magellanica as compared to N. (P.) deaurata. The activity of catalase and superoxide dismutase (SOD) was 35.3 and 128.6% higher in N. (P.) magellanica as compared to N. (P.) deaurata, respectively. No significant differences were determined between the digestive glands of both molluscs regarding the content of total thiols. alpha-Tocopherol and beta-carotene content were significantly lower in N. (P.) magellanica as compared to N. (P.) deaurata. A distinctive EPR signal for the adduct Fe--MGD--NO (g = 2.03 and a(N) = 12.5 G) was detected in the homogenates of digestive glands of both limpets. A significant difference in the content of the Fe-MGD-NO adduct in digestive glands from N. (P.) magellanica and N. (P.) deaurata (491 +/- 137 and 839 +/- 63 pmol/g FW, respectively) was observed. Taken as a whole, the data presented here indicated that coping with environmental stressing conditions requires a complex adjustment of the physiological metabolic pathways to ensure survival by minimizing intracellular damage. It is likely that N. (P.) magellanica has a particular evolutionary adaptation to extreme environmental conditions by keeping iron content low and antioxidant activities high.

Assuntos

Ácido Desidroascórbico/análogos & derivados , Sistema Digestório/metabolismo , Meio Ambiente , Estresse Oxidativo/fisiologia , Caramujos/metabolismo , Caramujos/fisiologia , Análise de Variância , Animais , Argentina , Catalase/metabolismo , Ácido Desidroascórbico/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres/metabolismo , Ferro/metabolismo , Metabolismo dos Lipídeos , Peroxidação de Lipídeos/fisiologia , Óxido Nítrico/metabolismo , Água do Mar , Superóxido Dismutase/metabolismo , Superóxidos/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , alfa-Tocoferol/metabolismo , beta Caroteno/metabolismo

RESUMO

The aim of the present study was to characterize the effect of oxidative stress on iron reduction rates in biological systems. The tested oxidative stress conditions included acute iron overload in rats, UV-B irradiation in algae cultures and leaves, and paraquat treatment and aging in soybean embryonic axes upon imbibition. Treatment of rats with iron-dextran resembles hemochromatosis secondary to iron loading anemias and high oral iron intake. A significant increase was detected in both iron deposits in liver cells and microsomal iron content after 4 h of a single dose of iron-dextran, however, the iron reduction rate was not affected in the presence of either NADPH or NADH as cofactor. In vivo iron reduction rate in Chlorella vulgaris cells was not significantly different in log and stationary phases. Exposure of the cultures to UV-B doses of O.8 and 4.4 kJ/m2 increased iron reduction rate by intact cells from 6 (control) to 32 and 64 nmol/lO(9) cell.min, respectively. UV-B exposure of soybean leaves lead to a significant increase in leakage of electrolytes probably due to membrane damage, however, iron reduction rates were not significantly different in control and irradiated leaves. Soybean embryonic axes incubated in the presence of paraquat or axes from aged seeds showed a significant decrease in fresh weight of the axes after 30 h of development. Moreover, the consistent increase in iron reduction rates measured in control axes during the imbibition period was inhibited either in the presence of paraquat or with aged embryonic axes. The data presented here suggest that iron reduction does not seem a universal early index of oxidative damage in biological systems, in spite of its crucial role in oxidative metabolism.

Assuntos

Ratos , Animais , Técnicas In Vitro , Ferro/metabolismo , Estresse Oxidativo/fisiologia , Ferro/efeitos da radiação , Ratos Wistar