Oxidative stress in Laeonereis acuta (Polychaeta, Nereididae): environmental and seasonal effects

Laeonereis acuta was seasonally collected in an industrially polluted site (P) and in an unpolluted site (UP) at the Patos Lagoon estuary (southern Brazil). Glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) activity (U/mg protein) was determined in five groups of worms from each site. Metallothionein (MT – lmol GSH/g ww) and lipid peroxides content (LPO – nmoles of cumene hydroperoxide/g ww) were also measured. Annual mean values for CAT (UP ¼ 3:7 _ 0:3; P ¼ 5:7 _ 0:6), GST (UP ¼ 0:034 _ 0:003; P ¼ 0:045 _ 0:004) and MT (UP ¼ 0:15 _ 0:02; P ¼ 0:23 _ 0:03) were higher ðp 0:05Þ in the LPO content was observed in worms from the different sites or collected in different seasons. These results indicate that worms from the polluted site showed higher antioxidant responses than those from the unpolluted site, sufficient to prevent oxidative damage in terms of LPO

Physiological and antioxidant enzyme responses to acute and chronic exposure of Laeonereis acuta (Polychaeta, Nereididae) to copper

Chronic (14 days) and acute (48 h) copper effects on the antioxidant defense system and some physiological variables of Laeonereis acuta (Polychaeta, Nereididae) were evaluated. In both assays, two nominal copper concentrations (chronic: C1 = 31.25 and C2 = 62.50 Ag/l; acute: A1 = 250 and A2 = 500 Ag/l) and one control group (Cc and Ac=0 Ag/l) were tested. End points analyzed were antioxidant enzyme activity (catalase, CAT; superoxide dismutase, SOD; and glutathione Stransferase, GST), oxygen consumption, metahemoglobin concentration, and lipid peroxidation (LPO). In the chronic assay, CAT activity was significantly higher in worms exposed to both concentrations of copper tested (C1 = 3.36F0.07 U CAT/mg protein; C2 = 4.06 0.32 U CAT/mg protein) than in control worms (Cc = 2.16F0.39 U CAT/mg protein). SOD activity was also increased in the two copper-exposed groups (C1 = 16.85F4.22 U SOD/mg protein; C2 = 38.19F4.31 U SOD/ mg protein) than in control group (Cc = 3.54F0.46 U SOD/mg protein). However, GST activity was increased only in worms exposed to the higher copper concentration (C2 = 0.022F9.10 _ 4 U GST/mg protein) when compared to the other groups tested (Cc = 0.012F3.10 _ 3 U GST/mg protein; C1 = 0.016F9.10 _ 4 U GST/mg protein). None of the physiological variables analyzed (oxygen consumption, metahemoglobin concentration, and lipid peroxidation) was affected by chronic copper exposure. In the acute assay, only GST activity was induced in worms exposed to copper. This induction was observed only in the A1 group (0.027F2.10 _ 3 U GST/mg protein) when compared to Ac (0.017F2.10 _ 3 U GST/mg protein) or A2 (0.016F7.10 _ 4 U GST/mg protein) groups. On the other hand, lipid peroxidation was higher in A2 (481.9F49.2 nmol CHP/g ww) than in control worms (Ac = 337.9F25.0 nmol CHP/g ww). Oxygen consumption was higher in worms acutely exposed to the lower copper concentration tested (A1 = 0.27F0.04 mg O2/g ww/h) than in the higher concentration (A2 = 0.14F0.01 mg O2/g ww/h). Changes in the swimming behavior of copperexposed animals in both assays and edemas in the body wall of worms acutely exposed to copper were also observed. Results suggest that copper exposure favors reactive oxygen species generation and that enzymatic defense system is induced under chronic exposure, preventing oxygen consumption changes and lipid peroxidation and metahemoglobin formation. However, in acutely exposed worms, in spite of a transient peak of GST activity, no induction of antioxidant enzymes occurs, leading to morphological and physiological changes

Current and Future Perspectives Using Biomarkers to Assess Pollution in Aquatic Ecosystems

The possibility of detecting aquatic pollution problems to take corrective decisions is intimately related to the organization levels of the living matter. Measurements at the biochemical or physiological levels detect more quickly and specifically the presence of several toxic compounds, allowing its utilization in a prospective way, until that deleterious effect reaches higher organization levels. The detection of environmental ‘‘hot spots’’ needs general nonspecific biomarkers if no previous information about the presence of specific pollutants exist. Since several xenobiotics can modify directly or indirectly the balance between pro-oxidant and antioxidant concentration, the determination of oxidative stress (DNA damage, protein oxidation, lipid peroxidation) in aquatic species is commonly used as a nonspecific biomarker. On the other hand, acetylcholinesterase activity or determination of metallothionein concentration (or expression) represents specific biomarkers that indicate the presence of anticholinesterasic compounds (organophosphorus pesticides or neurotoxins, for instance) and metals, respectively. The fact that animal populations inhabiting polluted areas can express responses qualitatively and quantitatively different from those of reference areas has lead to the ‘‘pollution induced community tolerance’’ approach that seems to be a valuable tool to compare toxicological responses of different aquatic populations

Scientometric analysis of Latin American environmental studies

The objective analysis of scientific production is analysed by scientometric methods that measure the development and progress in science through the analysis of productivity and impact of the scientific production in different universities, countries, research groups, etc. In this context, the aim of present study was to analyse scientific literature in the field of environmental studies that apply biomarkers in Latin America. The selected period of analysis was from 1999 to 2008. Brazil was the country that presented the highest number of published articles (872), followed by Mexico (559), Argentina (368) and Chile (232). The analysis of the h index showed that the four Latin American countries with higher scientific productivity presented lower values when compared with countries outside this region, meaning that the establishment of collaborative studies could be one of the strategies to improve Latin American visibility in environmental studies

Histological and morphological alterations induced by copper exposure in Laeonereis acuta (Polychaeta, Nereididae)

Laeonereis acuta (Polychaeta, Nereididae) was collected in an unpolluted (UP) and an polluted (P) site at the Patos Lagoon estuary (Southern Brazil) and maintained under control conditions (UPC and PC, respectively) or exposed to waterborne copper (UPCu and PCu; 500 lg Cu/l), for 48 h. Four groups (aaUPC, aaPC, aaUPCu, and aaPCu) were also pre-exposed for 48 h to ascorbic acid (aa; 0.1 mM) before copper exposure. Histological and morphological alterations, as well as oxygen consumption changes were evaluated. Independently of the sampling site and the pre-exposure to the ascorbic acid, morphological abnormalities were evident in more than 80% of worms exposed to copper. Conspicuous histological changes (coeloma obliteration, cuticle separation from the epidermis, and absence of dorsal vessel) were also observed. In addition, PCu worms showed loss of the digestive epithelium and coiling behavior. Similar oxygen consumption values were observed in control and copper exposed worms

Oxidative stress responses in two populations of Laeonereis acuta (Polychaeta, Nereididae) after acute and chronic exposure to copper

Acute (4 days) and chronic (14 days) effects of copper were evaluated on the antioxidant defenses of Laeonereis acuta (Polychaeta) collected in unpolluted (UP) and polluted (P) sites. In the acute assay (125 and 250 lg Cu/l) superoxide dismutase (SOD) and glutathione Stransferase (GST) activities did not change, whereas catalase (CAT) increased in worms from both the sites. Lipid peroxidation was higher in copper exposed worms from the P site. In the chronic assay (62.5 lg Cu/l) polychaetes from the P site showed enhanced activities of SOD, GST and CAT and higher contents of metallothionein-like proteins and sulfhydrils compared to worms from UP. Differences in responses between polychaetes from UP and P sites suggest that organisms from the polluted site, P, are more susceptible to oxidative stress conditions. _ 2004 Elsevier Ltd. All rights reserved

Biomarkers of exposure and effect in the Brazilian flounder Paralichthys orbignyanus (Teleostei: Paralichthyidae) from the Patos Lagoon estuary (Southern Brazil).

Biomarkers of exposure (liver metallothionein-like proteins content and catalase and glutathione S-transferase activities) and effect (liver lipoperoxidation and blood cell DNA damage) of contaminants were analyzed in the Brazilian flounder Paralichthys orbignyanus from the Patos Lagoon estuary (Southern Brazil). Flounders were collected for a year in two sites: ‘‘Coroa do Boi’’ (polluted site) and ‘‘Saco do Justino’’ (non-polluted site). Results indicated that micronucleated cells frequency was the best biomarker to distinguish flounders from the two sites. Taken together, data from DNA damage analyses (micronucleus test and comet assay) indicated that flounders from the non-polluted site efficiently repaired the DNA breaks, contrary to those from the polluted site, which probably had their DNA repair system inhibited or exhausted. Furthermore, data from enzyme activities (catalase and GST) and lipid peroxidation indicated that flounders from the polluted site were under oxidative stress in summer and autumn

Microcystin-induced oxidative stress in Laeonereis acuta (Polychaeta, Nereididae)

Oxidative stress induced by microcystins was evaluated in an estuarine worm, Laeonereis acuta (Nereididae).Ten organisms were exposed to lyophilized cells of a toxic Microcystis aeruginosa strain RST9501 ( 2 lg/mL microcystins, MC); 10 were exposed to lyophilized cells of a nontoxic Aphanotece sp. strain RSMan92 and 10 were maintained without cyanobacterial cells. Exposure time was 48 h. The enzymatic antioxidant defenses, as well as the oxidative damage, were analyzed. Toxic and nontoxic cyanobacteria lowered catalase activity with no changes in glutathione reductase and glutathione-S-transferase activities. This may have led to toxin intracellular accumulation, which should favor oxidative stress generation,observed by the high lipid peroxide and DNA–protein crosslink levels in the group exposed to MC

Application of public-domain statistical analysis software for evaluation and comparison of comet assay data

A novel approach for statistical analysis of comet assay data (i.e.: tail moment) is proposed, employing public-domain statistical software, the R system. The analytical strategy takes into account that the distribution of comet assay data, like the tail moment, is usually skewed and do not follow a normal distribution. Probability distributions used to model comet assay data included: the Weibull, the exponential, the logistic, the normal, the log normal and log-logistic distribution. In this approach it was also considered that heterogeneity observed among experimental units is a random feature of the comet assay data. This statistical model can be characterized with a location parameter mij, a scale parameter r and a between experimental units variability parameter θ. In the logarithmic scale, the parameter mij depends additively on treatment and random effects, as follows: log(mij) = a0 + a1xij + bi, where exp(a0) represents approximately the mean value of the control group, exp(a1) can be interpreted as the relative risk of damage with respect to the control group, xij is an indicator of experimental group and exp(bi) is the individual risk effects assume to follows a Gamma distribution with mean 1 and variance θ. Model selection is based on Akaike’s information criteria (AIC). Real data coming from comet analysis of blood samples taken from the flounder Paralichtys orbignyanus (Teleostei: Paralichtyidae) and from samples of cells suspension obtained from the estuarine polychaeta Laeonereis acuta (Nereididae) were employed. This statistical approach showed that the comet assay data should be analyzed under a modeling framework that take into account the important features of these measurements. Model selection and heterogeneity between experimental units play central points in the analysis of these data

Antioxidant mechanisms of the nereidid (anelida: polychaeta) to cope with environmental hydrogen peroxide

Hydrogen peroxide (H2O2) is a naturally occurring prooxidant molecule, and its effects in the macroinvertebrate infauna were previously observed. The existence of a gradient of antioxidant enzymes activity (catalase [CAT], glutathione peroxidase [GPx], suéroxide dismutase [SOD], and glutathione-S-transferase [GST] and/or oxidative demage along the body of the estuarine polychaeta Laeonereis acuta (Polychaeta, Nereididae) was analyzed after exposure to H2O2. Because this species secretes conspicuous amounts of mucus, its capability in degrading H2O2 was studied. The results suggest that L. acuta deal with the generation of oxidative stress with different strategies along the body. In the posterior region, higher CAT and SOD activities ensure the degradation of inductors of lipid peroxidation such as H2O2 and superoxide anion (O2.-). The higher GST activity in anterior region aids to conjugate lipid peroxides products. In the middle region, the lack of high CAT, SOD, or GST activities correlates with the higher lipid hydroperoxide levels found after H2O2 exposure. Ten days of exposure to H2O2 also induced oxidative stress (lipid peroxidation and DNA damage) in the whole animal paralleled by a lack of CAT induction. The mucus production contributes substantially to H2O2 degradation, suggesting that bacteria that grow in this secretion provide this capabiblity