Antioxidant responses in the nereidid Laeonereis acuta (Annelida, Polychaeta) after cadmium exposure

Toxicological effect of Parthenium hysterophorus and milk processing industry sludge on earthworms, Eisenia fetida

Production of large quantities of organic waste all over the world poses major environmental and disposal problems. The present study was conducted to explore the deleterious effects of Parthenium hysterophorus and milk processing industry sludge on the health of earthworm, Eisenia fetida. Earthworms were allowed to grow in the mixture of cow dung:Parthenium hysterophorus (75:25) and cow dung:milk processing industry sludge (60:40) for 60 days. The biochemical markers viz. superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and malondialdehyde (MDA) levels and histological changes in earthworm's intestine were assessed after 15, 30, 45, and 60 days of exposure. The results revealed increased MDA level, while SOD, CAT, and GPx activities showed variation in both treatments. Furthermore, histopathological changes revealed damage in the intestinal tissue in both treatments during all intervals. More severe effects were registered in P. hysterophorus treatment. Obtained results may contribute to the understanding of P. hysterophorus and milk processing industry sludge induced toxic effects on earthworms and to identify defense mechanism of Eisenia fetida.

Biochemical responses and DNA damage induced by herbicide QYR301 in earthworm (Eisenia fetida)

QYR301, a novel herbicidal inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD), has great potential for resistant weed control in paddy fields, but massive use of pesticides may result in toxicity to soil non-target organisms. Thus, this study was designed to assess subchronic toxicity of different doses of QYR301 in artificial soil (0, 0.1, 1.0, 2.5, and 5.0 mg kg^-1) to earthworms (Eisenia fetida) on days 7, 14, 21, and 28 after exposure, using biomarkers of reactive oxygen species (ROS) and malondialdehyde (MDA) contents, activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and glutathione-S-transferase (GST), and DNA damage. The ROS content significantly increased for all treatments on 7 and 14 days then decreased, and recovered to control level for 0.1 and 1.0 mg kg^-1 treatment on day 28. Concerning enzymes activities, QYR301 increased POD, SOD, and GST activities, but inhibited CAT activity. Except for POD activity, SOD, CAT, and GST activities of 0.1 mg kg^-1 group recovered to control level on day 28. Also, the MDA content of 0.1 mg kg^-1 group reached control level on day 28. However, DNA damage was observed for all treatments throughout the experiment and it increased with increasing doses and time except for 5.0 mg kg^-1 treatment on day 28. These results suggested that QYR301 induced excessive ROS production leading to oxidative stress in earthworms, which caused lipid membrane peroxidation and DNA damage ultimately. The findings could provide a theoretical foundation for assessing ecological damage of QYR301 to soils and a guide for future QYR301 applications.

Sub-lethal Responses of the Polychaete Armandia agilis in Whole-sediment Toxicity Testing

The present study assessed biochemical responses as sublethal endpoints in the polychaete Armandia agilis exposed to contaminated sediments to in order to assess its potential use as a test organism. Sediment samples from several locations at a dredging site were obtained and used in whole-sediment exposures. Samples were tested with A. agilis to determine the 10-day toxicity of the 100% sample and the enzymatic activity of catalase (CAT), glutathione-S-transferase (GST) and acetylcholinesterase (AChE) biochemical measurements made in whole-body homogenates of a subset of the surviving organisms. Biochemical responses reported in A. agilis were not statistically different from the reference site sediment, however, the integrated analysis demonstrated that contaminants bound to sediment samples influenced the sublethal effects.

The Chronic Effects of Copper and Cadmium on Life History Traits Across Cladocera Species: A Meta-analysis

The effect of sublethal concentrations of heavy metals on cladoceran growth and reproduction is a cornerstone of modern ecotoxicology. However, the literature contains assays across numerous concentrations, on numerous species and genotypes, and conditions are far from consistent. We undertook a systematic review of the sublethal effects of copper and cadmium concentrations on Cladocera spp. life history (reproduction, maturation age, and somatic growth rate). Using meta-analysis, we tested the hypothesis that the effects of increasing Cu and Cd concentrations on traits may vary by species. We also evaluated where possible whether the effect of metal concentrations on traits vary by water hardness, exposure duration, or whether the metals were delivered in aqueous solution or via food. We surveyed > 200 papers, resulting in a set of 32 experimental studies representing 446 trials where the results were presented compared with Daphnia magna-the most commonly assayed species. We found qualitatively similar effects of Cu and Cd on life history traits that included reduction in reproduction and somatic growth rate and delay of maturation. Cladocera species showed marked variations in their susceptibility to metals, and D. magna was found to be the least sensitive species to sublethal changes in reproduction. The effects were largely consistent for aqueous vs. dietary food. Water hardness, where data were available, had no detectable effect. Available data indicate that exposure duration had no effect on the toxicity of Cu but did for D. magna reproductive response to Cd. Our study highlights the importance of including species identity when considering toxicological testing and regulation development.

Induction of oxidative stress by chlorothalonil in the estuarine polychaete Laeonereis acuta

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.

Toxicological responses of Laeonereis acuta (Polychaeta, Nereididae) after acute, subchronic and chronic exposure to cadmium

The objective of this study was to analyze the toxicological responses of the estuarine polychaete Laeonereis acuta after acute (96h), subchronic (7 days) and chronic (14 days) exposure to cadmium (Cd). Concentrations of metallothioneins (MT), lipid peroxidation (LPO), total Cd and metal-rich granules (MRG) were evaluated. Seasonal variations of MT and LPO levels in the wild were also measured. Polychaetes were obtained in the Quequén estuary located southeast of Buenos Aires Province, Argentina. For the acute toxicity assay, individuals were exposed to 10; 30, 65; 310; 600; 1300; 2000; 4300; 8100; 16300µgCdL^-1, which included levels of environmental relevance and median lethal concentrations (LC₅₀) for related species of polychaete. Based on 96h LC₅₀ values, polychaetes were exposed to sublethal doses of Cd. The concentrations for both subchronic and chronic assays were: 10; 30; 65; 310; 600; 1300; 2000; 4300µgCdL^-1. The 96h LC₅₀ value was 8234.9µgL^-1, which was within the values reported for other species of polychaete, indicating a high tolerance to Cd. MT induction was not observed for any time exposure. In additoin, LPO levels showed no differences with respect to control levels, which indicated an absence of oxidative damage caused by Cd. However, the total Cd and MRG-Cd concentrations in L. acuta in all tested treatments showed significant differences with respect to control levels. L. acuta were able to accumulate Cd in their tissues in the form of granules which are the main mechanism of Cd detoxification.

Toxicological and biochemical responses of the earthworm Eisenia fetida to cyanobacteria toxins

Irrigation with eutrophic water containing cyanobacteria toxins poses a potential risk to soil animals. To evaluate ecotoxicological effect of microcystins (MCs) on earthworms, filter paper acute toxicity test, avoidance test and a 14-d artificial soil test were carried out. No acute toxicity was found in the filter paper test, and earthworms showed no avoidance response to MCs exposure. In the artificial soil test, Eisenia fetida were allowed to grow in presence or absence of MCs (0, 1, 10, 100, 1000 μg kg⁻¹ of soil) for 1, 7, and 14 d. Results showed that MCs could bioaccumulated in earthworm. A stimulatory effect on catalase and glutathione oxidase activities induced by MCs was found on day 1, and both of them were significantly inhibited at 100 and 1000 μg kg⁻¹ on days 14. The superoxide dismutase activity was relatively insensitive. Significant increase of malondialdehyde content and decrease of neutral red retention time were observed at 100 and 1000 μg kg⁻¹ on days 7 and 14. Our results suggest that MCs induces oxidative stress on earthworms, which leads to disruption of the antioxidant system and lipid peroxidation, as well as alterations in lysosomal membrane stability.

Effects of the herbicide Roundup on the polychaeta Laeonereis acuta: Cholinesterases and oxidative stress

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.

Propensity to metal accumulation and oxidative stress responses of two benthic species (Cerastoderma edule and Nephtys hombergii): are tolerance processes limiting their responsiveness?

The chronic exposure of benthic organisms to metals in sediments can lead to the development of tolerance mechanisms, thus diminishing their responsiveness. This study aims to evaluate the accumulation profiles of V, Cr, Co, Ni, As, Cd, Pb and Hg and antioxidant system responses of two benthic organisms (Cerastoderma edule, Bivalvia; Nephtys hombergii, Polychaeta). This approach will provide clarifications about the ability of each species to signalise metal contamination. Organisms of both species were collected at the Tagus estuary, in two sites with distinct contamination degrees (ALC, slightly contaminated; BAR, highly contaminated). Accordingly, C. edule accumulated higher concentrations of As, Pb and Hg at BAR compared to ALC. However, antioxidant responses of C. edule were almost unaltered at BAR and no peroxidative damage occurred, suggesting adjustment mechanisms to the presence of metals. In contrast, N. hombergii showed a minor propensity to metal accumulation, only signalising spatial differences for As and Pb and accumulating lower concentrations of metals than C. edule. The differences in metal accumulation observed between species might be due to their distinctive foraging behaviour and/or the ability of N. hombergii to minimise the metal uptake. Despite that, the accumulation of As and Pb was on the basis of the polychaete antioxidant defences inhibition at BAR, including CAT, SOD, GR and GPx. The integrated biomarker response index (IBRv2) confirmed that N. hombergii was more affected by metal exposure than C. edule. In the light of current findings, in field-based studies, the information of C. edule as a bioindicator should be complemented by that provided by another benthic species, since tolerance mechanisms to metals can hinder a correct diagnosis of sediment contamination and of the system's health. Overall, the present study contributed to improve the lack of fundamental knowledge of two widespread and common estuarine species, providing insights of the metal accumulation profiles under a scenario of chronic contamination. Finally, this work provided useful information that can be applied in the interpretation of future environmental monitoring studies.

Impact of Parthenium weeds on earthworms (Eudrilus eugeniae) during vermicomposting

The aim of this work is to evaluate the effect of Parthenium-mediated compost on Eudrilus eugeniae during the process of vermicomposting. Nine different concentrations of Parthenium hysterophorus and cow dung mixtures were used to assess toxicity. The earthworms' growth, fecundity and antioxidant enzyme levels were analysed every 15 days. The antioxidant activities of enzymes [superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)], considered as biomarkers, indicate the biochemical and oxidative stresses due to the toxin from Parthenium weeds. The earthworms' growth, biomass gain, cocoon production and antioxidant enzymes were in a low level in a high concentration of P. hysterophorus (without cow dung). The results clearly indicated that appropriate mixing of P. hysterophorus quantity is an essential factor for the survival of earthworms without causing any harm.

Dietary fucoidan enhance the non-specific immune response and disease resistance in African catfish, Clarias gariepinus, immunosuppressed by cadmium chloride

Fucoidan is sulfated polysaccharide extracted from seaweed brown algae. This study was designed to evaluate the immunomodulatory effects and disease resistance of dietary fucoidan on catfish, Clarias gariepinus, immunosuppressed by cadmium. Three hundred and sixty African catfish, C. gariepinus, was allocated into six equal groups. The first group served as a control. Groups (F1 and F2) were fed on fucoidan supplemented ration at concentrations of 4 and 6g/kg diet respectively for 21 days. Groups (Cd, CdF1 and CdF2) were subjected throughout the experiment to a sub-lethal concentration of 5ppm cadmium chloride solution and groups (CdF1 and CdF2) were fed on a ration supplemented with fucoidan. Macrophages oxidative burst, phagocytic activity percentages and lymphocytes transformation index were a significant increase in the fucoidan-treated groups (F1 and F2), while serum lysozyme, nitric oxide and bactericidal activity were enhanced only in group (F2) when compared with controls. These parameters as well as absolute lymphocyte count and survival rate were significantly increased in group (CdF2) when compared with cadmium chloride immunosuppressed group (Cd). It could be concluded that the fucoidan can be used as immunostimulant for the farmed African catfish, C. gariepinus as it can improve its resistance to immunosuppressive stressful conditions.

Acute and chronic toxic effects of Pb²⁺ on polychaete Perinereis aibuhitensis: morphological changes and responses of the antioxidant system

Perinereis aibuhitensis was used to assess adverse biological effects caused by acute and chronic Pb²⁺ exposure in artificial seawater under controlled laboratory conditions. In 96-hr acute toxicity experiments, the morphological changes showed a positive time/dose-dependent tendency, and the 96-hr LC₅₀ value of Pb²⁺ was 686.41 mg/L. The responses of enzymatic and non-enzymatic antioxidants in tissues including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), malondialdehyde (MDA) and the content of total soluble protein (TSP), were investigated on days 1, 4, 7 and 10 after Pb²⁺ exposure under chronic toxicity testing. Results showed that the activation of the antioxidant system in P. aibuhitensis depended on the Pb²⁺ concentration and the duration of exposure time. Specifically, POD and SOD activities were induced on the first day of the exposure and decreased to the control level on day 10 after exposure. Therefore, these two indexes could be used to indicate oxidative stress associated with P. aibuhitensis exposure to Pb²⁺.

Zonation in the digestive tract of Eisenia fetida: implications in biomarker measurements for toxicity assessment

Eisenia fetida is a model species for soil health assessment and different biomarkers that detect either the presence of bioavailable contaminants or their biological effect have been developed. These parameters are performed in a target tissue or whole earthworm, without considering the marked zonation in histological organisation, enzyme activities and gene expression pattern existing along the body. Thus, the present work was aimed at (a) characterising the morphofunctional heterogeneity along the digestive tract of E. fetida in tissue morphology and turnover, lysosomal enzyme markers (β-glucuronidase, β-GUS; hexosaminidase, HEX), lipofuscin contents (LPF) and metallothionein (MT) and catalase (CAT) gene expression; and (b) determining whether the responsiveness to Cd exposure varies among tissues and along the digestive tract. HEX and β-GUS exhibited a heterogeneous distribution pattern along and across the digestive tract and Cd exposure caused a marked decrease of HEX and an increase of β-GUS activity. Likewise, the significant decrease of cell turnover and the induction of MT transcription were was zone-dependent. Therefore, in was concluded that the consideration of the zonation when applying biomarker for toxicity assessment would reduce the intrinsic variability that results from overlooking the marked morphofunctional heterogeneity that exists in annelids along their body axis.

Biochemical responses of ecological importance in males of the austral South America amphipod Hyalella curvispina Shoemaker, 1942 exposed to waterborne cadmium and copper

The use of physiological parameters as sensitive indicators of toxic stress from exposure to different pollutants is an important issue to be studied. Hyalella curvispina is a Neotropical amphipod often used in ecotoxicological evaluations. This work aimed to quantify biochemical responses of ecological importance in H. curvispina males under stress exposure to sublethal concentrations of waterborne copper (Cu) and cadmium (Cd); in order to obtain basic physiological data as indicators of early effect on this species, on track to its standardization. In order to evaluate the physiological, biochemical and energetic status of the exposed animals, the following endpoints were selected: content of glycogen, total proteins, total lipids, triglycerides, glycerol, arginine, arginine phosphate, levels of lipid peroxidation (TBARS), and Na(+)/K(+)ATPase, catalase (CAT) and superoxide dismutase (SOD) activities. Our results show that the concentrations of Cu (135 and 175 µg/L) and Cd (6.5 and 10.5 µg/L) tested altered most of the biochemical variables measured (glycogen, total proteins, total lipids, triglycerides, arginine phosphate, TBARS, and SOD and Na(+)/K(+)ATPase activities). In addition, neither the levels of glycerol and arginine nor CAT activity were affected by exposure to either metal. Energy metabolism was similarly affected both by exposure to Cu and exposure to Cd. The results obtained show the existence of an energy imbalance associated with oxidative damage, suggesting a comprehensive response. This work represents a first contribution of the evaluation of the effect of two heavy metals in some parameters of oxidative stress and energy metabolism of H. curvispina males. The results indicate these parameters can provide a sensitive criterion for the assessment of early ecotoxicological effects of Cu and Cd in laboratory assays, on a native species representative of the zoobenthic and epiphytic communities of South America.

Biochemical responses of earthworm Eisenia fetida exposed to cadmium-contaminated soil with long duration

The biochemical responses of the earthworms, Eisenia fetida, exposed to a series of Cd concentrations (0.00, 1.25, 2.50, 5.00 and 10.00 mg Cd(2+) kg(-1) soil) for up to 8 weeks were investigated, aiming to evaluate the sublethal effects of Cd with long exposure and to explore the potential for applying these responses as biomarkers to indicate the Cd-contaminated soil. The following biochemical parameters were determined: cytochrome P450 (CYP) contents and activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-s-transferase (GST). Cadmium concentrations in all earthworms were apparently accumulated in 4 weeks, and showed minor changes in weeks 6-8 compared to the first 4 weeks. CYP presented a significant elevation in 2-4 weeks and a decline in 6-8 weeks in each treated group. The activities of SOD and CAT showed an obvious increase with exposure of 6-8 weeks while their levels were not affected in 4 weeks in each treated group. GST activity revealed significant activation starting from week 4. This study confirmed the significance of applying a suite of biomarkers rather than a selective choice to assess the impact of pollutants on organisms. It also indicated that the observed effects were more dependent upon exposure duration than dose.

Effect of fly ash on biochemical responses and DNA damage in earthworm, Dichogaster curgensis

Fly ash is receiving alarming attention due to its hazardous nature, widespread usage, and the manner of disposal; leading to environmental deterioration. We carried out bio-monitoring and risk assessment of fly ash in earthworms as a model system. Dichogaster curgensis were allowed to grow in presence or absence of fly ash (0-40%, w/w) for 1, 7, and 14 d. The biochemical markers viz. catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione S-transferase (GST), and malondialdehyde (MDA) level were measured. The comet and neutral red retention assays were performed on earthworm coelomocytes to assess genetic damages and lysosomal membrane stability. The results revealed increased activities of SOD, GPx, GST, and MDA level in a dose-response manner while GR activity was decreased with increasing concentrations of fly ash. No obvious trend was observed in the CAT activity and fly ash concentration. Lysosomal membrane destabilization was noted in the earthworms exposed to 5% and more fly ash concentration in a dose and time dependent manner. The comet assay demonstrated that the fly ash induced DNA damage and DNA-protein crosslinks in earthworm coelomocytes.

Toxicity assessment of simulated urban runoff containing polycyclic musks and cadmium in Carassius auratus using oxidative stress biomarkers

The objective of this study was to assess potential toxic effects of simulated urban runoff on Carassius auratus using oxidative stress biomarkers. The activity of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the content of malondialdehyde (MDA) in the liver of C. auratus were analyzed after a 7-, 14- and 21-day exposure to simulated urban runoff containing galaxolide (HHCB) and cadmium (Cd). The results showed that the activity of antioxidant enzymes and the content of MDA increased significantly exposed to the simulated urban runoff containing HHCB alone or mixture of HHCB and Cd. The activity of the investigated enzymes and the content of MDA then returned to the blank level over a longer period of exposure. The oxidative stress could be obviously caused in the liver of C. auratus under the experimental conditions. This could provide useful information for toxic risk assessment of urban runoff.

Effects of multigenerational cadmium exposure of insects (Spodoptera exigua larvae) on anti-oxidant response in haemolymph and developmental parameters

Biochemical and organismal indices of metal tolerance were studied in Spodoptera exigua exposed to a cadmium-contaminated diet for one or many (33 or 61) generations. Reduced and oxidised glutathione, protein thiols, total anti-oxidant capacity level, glutathione transferase activity, and Cd accumulation were assayed in the haemolymph of the last instar larvae. The cadmium concentration in the whole larval body as well as larval survival, larval duration time and last instar body weight were also measured. Elevated cadmium concentration in the whole body, higher mortality and longer duration of the larval stage in one-generation exposed insects in comparison with those exposed for many generations suggest that metal tolerance builds over time. For the larvae from multigeneration metal treatment, the higher cadmium concentration in larval haemolymph positively correlated with glutathione oxidation and total anti-oxidant capacity. One-generation exposed insects had lower metal concentration in haemolymph than did 33-generation exposed insects.

The polychaete, Perinereis nuntia ESTs and its use to uncover potential biomarker genes for molecular ecotoxicological studies

The polychaete, Perinereis nuntia, has been used as an indicator species to assess the environmental condition of benthic communities in coastal marine environments. Recently, high-throughput sequencing technology has been proven to be a useful method for analyzing expressed sequence tags (ESTs) in non-model species. Thus, we have obtained extensive cDNA information by the pyrosequencing method, to utilize the polychaete species as a test organism for sediment quality monitoring studies. From the total RNA of P. nuntia, cDNA was reversely synthesized and randomly sequenced using a GS-FLX sequencer. In the assembly stage 1, 40,379 transcripts (13,666 contigs and 26,713 singletons) were acquired and showed 47% hitting rate compared with the GenBank non-redundant (NR) amino acid sequence database using BLASTX. After the stage-2 assembly, 21,657 transcripts were identified and showed 28% hitting rate. Finally, we obtained 6 064 unigenes that corresponded to the GenBank NR amino acid sequence database using BLASTX. Of the transcripts obtained in this species, we found a number of stress- and cell defense-related genes (e.g. heat shock protein family, antioxidant-related genes, cytochrome P450 genes) that are potentially useful for sediment monitoring at the molecular level, indicating that the pyrosequencing method is an effective approach to uncover gene families of potential biomarker genes simultaneously, and thus make transcriptomic studies possible. To confirm the usefulness of those potential biomarker genes, we analyzed the comparative profiling of P. nuntia mRNA transcripts between the samples collected from the polychaete aquaculture farm and the southern coast field of South Korea. In this paper, we summarize the expressed cDNA information of P. nuntia and discussed its potential use in environmental genomics and ecotoxicological studies for uncovering the potential molecular mechanisms of environmental stresses and chemical toxicity to the indicator species, P. nuntia in marine sediments.

Sediment-quality assessment using the polychaete Arenicola marina: contamination, bioavailability, and toxicity

The sediment quality of Cádiz Bay, Las Palmas de Gran Canaria (LPGC) Port, Santander Bay, Algeciras Bay, and Huelva Estuary (Spain) was evaluated by analysing a battery of biochemical biomarkers-activities of biotranformation enzymes ethoxyresorufin O-deethylase [EROD], dibenzylflourescein dealkylase [DBF], and glutathione S-transferase [GST]; activity of antioxidant enzyme glutathione reductase [GR]; and lipid peroxidation [LPO]-in the polychaete Arenicola marina after laboratory sediment exposure. Huelva Estuary polychaetes showed significantly (p < 0.05) enhanced LPO, GST, and EROD activities compared with control lugworms related to metals and presumably polychlorinated biphenyls. EROD activity significant (p < 0.05) induction was associated polycyclic aromatic hydrocarbons after Santander Bay sediment exposure. Nickel appeared to significantly (p < 0.05) induce GR activity and LPO in LPGC Port sediment-exposed organisms. DBF activity significantly (p < 0.05) increased in polychaetes exposed to sediments from sewage-contaminated areas. A. marina was sensitive at the biochemical level. Integration of sediment characterization and biomarker results allowed the identification of polluted sites as well as the cause of possible sediment toxicity.

Accumulation, biotransformation, and biochemical responses after exposure to arsenite and arsenate in the estuarine polychaete Laeonereis acuta (Nereididae)

INTRODUCTION

This study aimed to analyze antioxidant responses and oxidative damage induced by two inorganic forms of arsenic (As; As(III) and As(V)) in an estuarine polychaete species, Laeonereis acuta (Nereididae). The capacity of arsenic biotransformation was also evaluated through the methylation process considering the activity of a key enzyme involved in the metabolization process.

MATERIALS AND METHODS

Worms were exposed to 50 μg (As(III) or As(V))/l during 2 or 7 days, plus a control group. Endpoints analyzed included concentration of reactive oxygen species (ROS), activities of antioxidant enzymes such as glutathione reductase (GR), total glutathione-S-transferase (GST), and omega isoform (GST Ω), glucose-6-phosphate deshydrogenase (G6PDH), levels of the antioxidant glutathione (GSH), and lipid peroxides concentration (TBARS).

RESULTS AND DISCUSSION

Results showed: (1) GR inhibition after 2-day exposure to both As forms (p < 0.05); (2) GST Ω inhibition after 7-day exposure to As(III) paralleled by an increase in total GST activity (p < 0.05); (3) augmented G6PDH activity after 7-day exposure to both As forms (p < 0.05); (4) no differences in terms of ROS and TBARS; and (5) inhibition of GST Ω activity in As(III) exposed worms, which was concomitant with a lowering of mono- and dymethylated arsenic species.

CONCLUSION

These results confirm the reactivity of some biochemical variables of L. acuta to As and indicates its importance as a sentinel species in estuarine regions with presence of arsenic.

Response of glutathione S-transferase (GST) genes to cadmium exposure in the marine pollution indicator worm, Perinereis nuntia

Glutathione S-transferase (GST) is a phase II enzyme that functions as a detoxicant by catalyzing the conjugation of reduced glutathione with a variety of xenobiotics via cysteine thiol. Molecular genetic approaches using gene biomarkers show substantial relevance as sensitive biomarkers for the indication of pollution levels. In order to use GSTs as molecular biomarkers for marine pollution monitoring, we cloned and sequenced the full-length cDNA of seven GST genes from the marine polychaete Perinereis nuntia. The deduced amino acid sequence of Pn-GSTs showed a high similarity to those of other species that clustered into the same clades in a phylogenetic analysis. In addition, to evaluate Pn-GSTs as useful biomarkers on effects after cadmium (Cd) exposure, we exposed sublethal concentrations of Cd (5, 50, and 500 μg/L) to P. nuntia, and they showed relatively different but significantly increases, depending on exposure time and Cd concentrations. Particularly, Pn-GST-omega and Pn-GST-sigma genes were highly sensitive with a clear dose-dependent manner on mRNA expression. The total GST activities also have significantly increased levels at higher concentrations of Cd exposure. These results indicate that Pn-GSTs play important roles in Cd-induced oxidative stress in terms of the physiological changes relating to metabolism and cell protection, and those genes would have great potential as molecular biomarkers to monitor marine environmental health.

Mixture toxicity assessment of cadmium and benzo[a]pyrene in the sea worm Hediste diversicolor

In the present study, Hediste diversicolor biotransformation and anti-oxidant responses to acute exposure to cadmium (Cd) and to the polycyclic aromatic hydrocarbons benzo[a]pyrene (B[a]P) were investigated. Worms were submitted to 0.2, 0.4 and 1 microM of each contaminant and to their mixture during a period of test of 48h. Following biological responses were measured: (1) NADPH cytochrome c reductase (NADPH cyt c) activity, as phase I biotransformation parameter; (2) gluthathione-S-transferase (GST) activity as a phase II conjugation enzyme, (3) catalase activity as anti-oxidant response and (4) malondialdehyde accumulation (MDA) as lipid peroxydation marker. The cholinergic system was evaluated using the acetylcholinesterase activity (AChE). Exposure to the mixture resulted in low dose level additive effects on the investigated biomarkers. However, worms exposed to 1 microM of the single compounds and to their mixture exhibited the highest MDA accumulation and the lowest enzymatic biomarkers activities suggesting severe toxicological effects. These data should be carefully considered in view of the biological effects of mixture pollutants and particularly in marine sediment ecosystems.

Evaluation of enzymatic biomarkers and lipoperoxidation level in Hediste diversicolor exposed to copper and benzo[a]pyrene

This study aims to evaluate the effects of exposure to copper, benzo[a]pyrene, and to their mixture on enzymatic and lipid peroxidation biomarkers in Hediste diversicolor. Worms were submitted to 1 microM of both single compounds and to their mixture during a period of test of 12, 24, 36, and 48 h. The biomarkers selected in this work were the activities of cytochrome P450-dependent NADPH cytochrome c reductase (NADPH red) as phase I enzyme, glutathione-S-transferase (GST) as phase II enzyme, and the acetylcholinesterase (AChE) activity as neurotoxicity marker. Oxidative stress was evaluated using catalase activity (CAT) and malondialdehyde accumulation (MDA). The NADPH red activity was not significantly affected by copper exposure; it shows a drastic increase in both B[a]P and mixture-exposed organisms. GST activities were significant in B[a]P-exposed worms only after 36 h, and in animals exposed to the mixture after 12 and 48 h. The ACHE activity was inhibited only in B[a]P-exposed worms.

Pollution biomarkers in two estuarine invertebrates, Nereis diversicolor and Scrobicularia plana, from a Marsh ecosystem in SW Spain

The polychaete worm Nereis diversicolor and the clam Scrobicularia plana were collected from several sites, affected by different types of contamination, in a littoral enclosure in the SW Spain (Caño Sancti-Petri and Rio San Pedro). N. diversicolor was present in 6 sampling sites whereas S. plana in 4 of them. The aim of our study was to relate several pollution biomarkers to chemical sources (metals and organic pollutants e.g. PCB, PAH) in these species, thereby confirming their adequacy as sentinels for this habitat. The biomarkers surveyed in the two invertebrates were the activities of the antioxidant enzyme catalase (CAT), the phase II detoxifying enzyme glutathione S-transferase (GST) and the neurotoxicity marker acetylcholinesterase (AChE). Metallothionein (MT) levels were measured as a biomarker of exposure to metals. The results suggested a different response in the two sediment-dwelling organisms, the sediment-eating polychaete and the water-filtering clam, probably as a consequence of different contamination exposures. The results also suggested that samples from the "Caño Sancti-Petri" were exposed to biologically active compounds that altered some of their biochemical responses. Of all the biomarkers tested, AChE was the most sensitive one and N. diversicolor the potentially most robust sentinel in this ecosystem. In this low to moderately polluted environment, the biochemical approach better reflected temporal trends than site-related differences although it was also able to detect punctual chemical insults.