An integrated biomarker-based strategy for ecotoxicological evaluation of risk in environmental management

The potential role of cAMP as a pollution biomarker of terrestrial environments using the land snail Eobania vermiculata: correlation with lysosomal membrane stability

The present study investigates the role of the signal transduction molecule cAMP, and the lysosomal membrane stability (LMS), as biomarkers of terrestrial environmental pollution using the land snail Eobania vermiculata. Snails were exposed to different concentrations of heavy metals (Cd, Pb and Cu) and organic pollutants (chlorpyrifos, parathion-methyl and PAHs) in laboratory conditions for 25 days. In addition, snails were collected from various sites located at different distances away from two polluted areas in northern Greece (the road Agiou Dimitriou in Thessaloniki city and a lignite power station in the district of Kozani). The results of the current investigation showed significantly increased levels of cAMP in the digestive gland of snails, as well as decreased LMS values in all experimental groups compared to control animals. In support of our data, cAMP levels were significantly negatively correlated with the conventional biomarker LMS, thus encouraging the use of cAMP as a new potential stress index in terrestrial pollution biomonitoring studies.

Application of biomarkers to assess the condition of European Marine Sites

A series of European Marine Sites has been designated as Special Areas of Conservation (SAC) in England. The aim of this study was to develop a practical methodology to assess the condition of SACs by applying a suite of biomarkers. Biomarkers were applied to the blue mussel Mytilus edulis and the shore crab Carcinus maenas from the Fal and Helford SAC (Cornwall). Individual biomarkers provided useful diagnostic information on the activity of certain classes of contaminants and an integrated Biomarker Response Index (BRI) was used to achieve a more holistic understanding of the condition of the SAC. The BRI indicated that the general health of both organisms was impacted in the upper part of the SAC (Fal Estuary) which correlated well with known chemical hotspots and sources of contamination. The BRI allows a pragmatic way to prioritise SAC sites that may require further investigative studies.

Lysosomal enlargement and lysosomal membrane destabilisation in mussel digestive cells measured by an integrative index

Lysosomal responses (enlargement and membrane destabilisation) in mussel digestive cells are well-known environmental stress biomarkers in pollution effects monitoring in marine ecosystems. Presently, in laboratory and field studies, both responses were measured separately (in terms of lysosomal volume density--Vv--and labilisation period--LP) and combined (lysosomal response index--LRI) in order to contribute to their understanding and to develop an index useful for decisions makers. LRI integrates Vv and LP, which are not necessarily dependent lysosomal responses. It is unbiased and more sensitive than Vv and LP alone and diminishes background due to confounding factors. LRI provides a simple numerical index (consensus reference=0; critical threshold=1) directly related to the pollution impact degree. Moreover, LRI can be represented in a way that allows the interpretation of lysosomal responses, which is useful for environmental scientists.

Time-course study of the early lysosomal responses to pollutants in mussel digestive cells using acid phosphatase as lysosomal marker enzyme

Lysosomal biomarkers are early warning signals of the biological effects caused by environmental pollutants but the promptness of lysosomal responses to pollutants has not been investigated yet. This work is aimed to determine the response-time of digestive cell lysosomes in mussels exposed to metals and hydrocarbons. Mussels, Mytilus galloprovincialis, were exposed, under laboratory conditions to Cd and to the water-accommodated fraction of a lubricant oil. One mussel per experimental group was sacrificed and processed every hour from 0 h to 30 h. Changes in AcP activity, immunoreactivity and LMS test based on AcP histochemistry, discriminates significantly control and exposed mussels within 5 h exposure. The present results suggested that after 15-20 h exposure digestive cell loss might be accompanied by increased AcP activity (extralysosomal) without a parallel increase in the levels of immunoreactive AcP protein, especially after Cd-exposure. The reduced labilisation period of lysosomal membrane constitute a cost effective early warning signal that, however, is not necessarily correlated with the exposure time. The routine application of immunochemical techniques deserves more research efforts before its implementation although, these techniques are very valuable to understand and interpret correctly lysosomal responses to pollutants.

PAH biomarkers for human health risk assessment: a review of the state-of-the-art

Polycyclic aromatic hydrocarbons (PAH) are widely distributed in the environment, and some are carcinogenic to human beings. The study of biomarkers has helped clarify the nature and magnitude of the human health risks posed by such substances. This article provides a review of the state-of-the-art on PAH biomarkers for human health risk assessment and also discusses their applicability within the context of environmental management in Brazil. The article discusses the methodologies for determination of some biomarkers such as 1-hydroxypyrene and PAH-DNA adducts. Cytogenetic markers, frequency of chromosomal aberrations, and micronucleus induction were considered for the evaluation of cancer risk. The current stage of studies on validation of such biomarkers was also approached.

Utilization of the seagrass Posidonia oceanica to evaluate the spatial dispersion of metal contamination

Metal concentrations have been measured in blades of the endemic Mediterranean seagrass Posidonia oceanica, along transects from three different contaminant point sources (the former asbestos mine of Canari - Corsica, France; the chemical plant of Solvay/Rosignano - Livorno, Italy; and the industrial harbour of Porto-Torres - Sardinia, Italy). The aim of this study was to evaluate the spatial extent of the impact of these sources in terms of metal contamination. The results showed that metal contamination from the former mine of Canari (cobalt - Co, chromium - Cr and nickel - Ni) extends at least 5 km to the north and south. The impact of this mine, which closed in 1965, seems to be lingering still. Mercury (Hg) contamination in the Livorno location was difficult to evaluate due to the presence of others potential sources of mercury in the area (e.g. industrialized city of Livorno, natural cinnabar deposits, intense tectonic activity of the area). At any rate, mercury concentration decreased strongly with distance from the plant. Lead (Pb) contamination at the Porto-Torres harbour was very low and disappeared with distance from the harbour. However, as the Porto-Torres harbour does not appear as a substantial point source of Pb contamination and because of the ubiquitous characteristic of the Pb element, it is difficult to draw any general conclusions concerning this element. The results presented in this study demonstrated the usefulness of the seagrass P. oceanica as a tool for the evaluation of the spatial extent of metal contaminations from point sources and could, therefore, contribute to on-going efforts to manage coastal environments.

Genotoxicity of the herbicide formulation Roundup (glyphosate) in broad-snouted caiman (Caiman latirostris) evidenced by the Comet assay and the Micronucleus test

The genotoxicity of pesticides is an issue of worldwide concern. The present study was undertaken to evaluate the genotoxic potential of a widely used herbicide formulation, Roundup (glyphosate), in erythrocytes of broad-snouted caiman (Caiman latirostris) after in ovo exposure. Caiman embryos were exposed at early embryonic stage to different sub-lethal concentrations of Roundup (50, 100, 200, 300, 400, 500, 750, 1000, 1250 and 1750microg/egg). At time of hatching, blood samples were obtained from each animal and two short-term tests, the Comet assay and the Micronucleus (MN) test, were performed on erythrocytes to assess DNA damage. A significant increase in DNA damage was observed at a concentration of 500microg/egg or higher, compared to untreated control animals (p<0.05). Results from both the Comet assay and the MN test revealed a concentration-dependent effect. This study demonstrated adverse effects of Roundup on DNA of C. latirostris and confirmed that the Comet assay and the MN test applied on caiman erythrocytes are useful tools in determining potential genotoxicity of pesticides. The identification of sentinel species as well as sensitive biomarkers among the natural biota is imperative to thoroughly evaluate genetic damage, which has significant consequences for short- and long-term survival of the natural species.

Geostatistical analysis of DNA damage in oysters, Crassostrea virginica, in Lavaca Bay, Texas

This study evaluated the health of the marine ecosystem in Lavaca Bay, Texas using the Eastern oyster (Crassostrea virginica) as the sentinel species. Lavaca Bay has a history of having gradients of concentrations of pollutants present with some areas containing concentrations high enough to pose a threat to marine ecosystem health. The Comet assay was used to evaluate for the presence of genotoxic response in oyster hematocytes. Bayesian geostatistical analysis was then used to determine if the DNA damage in oyster hematocytes was spatially oriented and to develop continuous surface maps of the risk of DNA damage in this sentinel species. Results indicated that proximity to industrial facilities increased the locational risk of genotoxicity in this species.

Biomarker responses in mussels, an integrated approach to biological effects measurements

Biological effects techniques have been used with the aim to further integrate biological effects measurements with chemical analysis and apply these methods to provide an assessment of mussel health status. Live native mussels were collected from selected coastal and estuarine sites around the British Isles, including the rivers Test, Thames, Tees, and Clyde, and Lunderston Bay. A suite of biological effects techniques was undertaken on these mussels, including whole organism responses (scope for growth), tissue responses (histopathology), and subcellular responses (lysosomal stability, multi-xenobiotic resistance [MXR], and Comet assay). In addition, whole mussel homogenates were used to measure organic (polycyclic aromatic hydrocarbons [PAH], polychlorinated biphenyls [PCB]) and metal concentrations. Overall the mussels collected from the Thames were in relatively poor health, based on histopathological markers, significantly higher DNA damage, and elevated expression of MXR detoxifying proteins. In contrast, the mussels collected from the River Test were in the best health, based on histopathological markers, respiration rate (SFG), and low frequency of DNA damage. In conclusion, the biological effects techniques were able to distinguish between relatively contaminated and clean environments, with the Thames mussels in worst health. Mussel tissue chemistry data were not able to explain the variations in biological response. Evidence indicates that the difference in the health of the mussels between the different sites was due to either effects of contaminants that were not measured, or the combined effects of mixture toxicity resulting in a threshold effect.

Integrated use of biomarkers and bioaccumulation data in Zebra mussel (Dreissena polymorpha) for site-specific quality assessment

One of the useful biological tools for environmental management is the measurement of biomarkers whose changes are related to the exposure to chemicals or environmental stress. Since these responses might vary with different contaminants or depending on the pollutant concentration reached in the organism, the support of bioaccumulation data is needed to prevent false conclusions. In this study, several persistent organic pollutants -- 23 polychlorinated biphenyl (PCB) congeners, 11 polycyclic aromatic hydrocarbons (PAHs), six dichlorodiphenyltricholroethane (DDT) relatives, hexachlorobenzene (HCB), chlorpyrifos and its oxidized metabolite -- and some herbicides (lindane and the isomers alpha, beta, delta; terbutilazine; alachlor; metolachlor) were measured in the soft tissues of the freshwater mollusc Zebra mussel (Dreissena polymorpha) from 25 sampling sites in the Italian portions of the sub-alpine great lakes along with the measure of ethoxyresorufin dealkylation (EROD) and acetylcholinesterase (AChE) activity. The linkage between bioaccumulation and biomarker data allowed us to create site-specific environmental quality indexes towards man-made chemicals. This classification highlighted three different degrees of xenobiotic contamination of the Italian sub-alpine great lakes: a high water quality in Lake Lugano with negligible pollutant levels and no effects on enzyme activities, an homogeneous poor quality for Lakes Garda, Iseo and Como, and the presence of some xenobiotic point-sources in Lake Maggiore, whose ecological status could be jeopardized, also due to the heavy DDT contamination revealed since 1996.

Development of an expert system for the integration of biomarker responses in mussels into an animal health index

Biomarkers on sentinel organisms are utilised worldwide in biomonitoring programs. However, the lack of effective interpretational capacity has hampered their uptake for use for assessment of risk in environmental management. The aim of the present study was to develop and test an objective decision-support or expert system capable of integrating biomarker results into a five-level health-status index. The expert system is based on a set of rules derived from available data on responses to natural and contaminant-induced stress of marine mussels. Integration of parameters includes: level of biological organization; biological significance; mutual interrelationship; and qualitative trends in a stress gradient. The system was tested on a set of biomarker data obtained from the field and subsequently validated with data from previous studies. The results demonstrate that the expert system can effectively quantify the biological effects of different levels of pollution. The system represents a simple tool for risk assessment of the harmful impact of contaminants by providing a clear indication of the degree of stress syndrome induced by pollutants in mussels.

Bioconcentration and phototoxicity of selected PAHs to marine mussel Mytilus galloprovincialis

This study assessed the sensitivity of Mytilus galloprovincialis (Mediterranean mussel) to UV-induced toxicity of pyrene, phenanthrene, fluoranthene and chrysene. Mussels were exposed to two different polyaromatic hydrocarbon (PAH) concentrations within the solubility limits for 7 days, after which the filtration rate and the blood cell stability of the mussels were determined to quantify the effects of PAHs. Mussel tissues were analysed at the end of the experiments to determine the degree of bioaccumulation of PAHs and in order to make quantitative body-burden/effect links. The differences between the tissue residue based effective concentration (TEC(20)/TEC(50)) values before and after ultraviolet (UV) exposure provided a measure of phototoxicity of the bioaccumulated PAHs. Out off the biomarkers applied, Neutral Red Retention (NRR) results showed that the most toxic compound is chrysene in the absence of UV. The NRR technique was found more sensitive compared to Fitration Rate (FR) technique. The toxicities of chrysene, phenanthrene and pyrene were enhanced by UV, while fluoranthene was toxic in the absence of UV lighting and its toxicity did not change by UV application.

Biochemical biomarkers in algae and marine pollution: a review

Environmental pollution by organic compounds and metals became extensive as mining and industrial activities increased in the 19th century and have intensified since then. Environmental pollutants originating from diverse anthropogenic sources have been known to possess adverse values capable of degrading the ecological integrity of marine environment. The consequences of anthropogenic contamination of marine environments have been ignored or poorly characterized with the possible exception of coastal and estuarine waters close to sewage outlets. Monitoring the impact of pollutants on aquatic life forms is challenging due to the differential sensitivities of organisms to a given pollutant, and the inability to assess the long-term effects of persistent pollutants on the ecosystem as they are bio-accumulated at higher trophic levels. Marine microalgae are particularly promising indicator species for organic and inorganic pollutants since they are typically the most abundant life forms in aquatic environments and occupy the base of the food chain. We review the effects of pollutants on the cellular biochemistry of microalgae and the biochemical mechanisms that microalgae use to detoxify or modify pollutants. In addition, we evaluate the potential uses of microalgae as bioindicator species as an early sentinel in polluted sites.

Translational responses of Mytilus galloprovincialis to environmental pollution: integrating the responses to oxidative stress and other biomarker responses into a general stress index

Heavy metals are commonly associated with the generation of reactive oxygen species (ROS), which may cause oxidative damage to several cellular macromolecules and organelles. In an attempt to correlate biomarker responses to oxidative stress, caged mussels (Mytilus galloprovincialis) were exposed for 30 days in a relatively clean site and two areas (Stations 1 and 2) unevenly polluted by heavy metals in Gulf of Patras (Greece). Three periods of caging were: one in winter, the second in spring, and the third in autumn. Heavy metal content was determined in digestive glands of the exposed mussels as a measure of metal pollution, metallothionein content as an adaptive and detoxifying index, lysosomal membrane stability as a biomarker of general stress, superoxide radical production and lipid peroxidation as indicators of oxidative stress, and micronucleus frequency in gill cells as an index of chromosomal damage. Considering that protein-synthesizing machinery is one of the candidate targets for ROS, the in vivo activity of ribosomes in digestive glands was also tested. Compared with the reference samples, mussels transplanted to Station 1 showed increased levels of heavy metals and metallothionein in digestive glands, lower lysosomal membrane stability, higher values in oxidative stress indices, reduced activity of ribosomes, and increased chromosomal damage in gill cells. In addition, run-off ribosomes isolated from mussels transplanted to Station 1 were less efficient at initiating protein synthesis in a cell-free system than those from mussels in the reference site. Mussels transplanted to Station 2 exhibited similar but less pronounced responses. Statistical analysis revealed a strong positive correlation of ribosomal activity with lysosomal membrane stability, as well as a significant negative correlation with the oxidative stress indices, metallothionein content, micronucleus frequency, and the digestive gland content in Cr, Cu and Mn. Integration of all the measured biomarker responses into one general "stress index" demonstrated a clear distinction between the sampling sites, allowing classification along a pollution gradient (reference site<Station 2<Station 1), independently from the season. Moreover, this analysis allowed us to compare responses between sampling campaigns and showed that the biomarker responses show best integration in winter. It was also evident that climatic or metabolic changes could modulate bioavailability of pollutants and priming of cellular defence processes.

Toxic effects of DDT and methyl mercury on the hepatocytes from Hoplias malabaricus

Here, we examined the impact of dichlorodiphenyltrichloroethane (DDT) and monomethyl mercury (MeHg) on the redox milieu and survival of hepatocytes from Hoplias malabaricus (traíra). After isolation and attachment of cells, we established one control and four treatments: DDT (50nM of DDT), MeHg I (0.25microM of MeHg), MeHg II (2.5microM of MeHg) and DDT * MeHg I (combination of 50nM of DDT and 0.25microM of MeHg). After four days the exposed hepatocytes presented significantly increased damage in lipids (all treatments), proteins (DDT * MeHg I and MeHg II) and reduced cell viability (all treatments). Also the antioxidant enzymes catalase, glucose-6-phosphate dehydrogenase (G6PDH), glutathione reductase and superoxide dismutase were affected. The current data showed that despite of some protective responses, the increased disturbs on membrane lipids and proteins, increased hydrogen peroxide levels, and decreased glutathione concentration and cell viability strongly indicate oxidative stress as the reason of hepatotoxicity due to DDT and MeHg exposure. In addition, DDT and MeHg together had greater effect than alone when G6PDH and glutathione-S-transferase activities and lipids damage were considered. These findings are indicative of hepatotoxicity occurring at realistic concentrations of DDT and MeHg found in Amazonian fish tissues.

Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10microg Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed.

Use of highly sensitive sublethal stress responses in the social amoeba Dictyostelium discoideum for an assessment of freshwater quality

In this work, the sensitivity of a battery of tests on the social amoeba Dictyostelium discoideum has been assessed within a freshwater toxicity study. The results obtained from the evaluation of survival and replication rate of D. discoideum were compared to those derived with a series of widely used tests for freshwater toxicity assessment, i. e. bioassays using Vibrio fischeri, Daphnia magna and Pseudokirchneriella subcapitata. The effects on sublethal endpoints, i.e. lysosomal membrane stability (LMS) and endocytotic rate, were analysed in conjunction with high-level endpoints to verify the potential to make a typical bioassay more sensitive. The field ecotoxicological investigation employing D. discoideum is part of a monitoring study assessing environmental quality of the Bormida River (Italy), subjected until recently to a chronic industrial pollution. The survey was carried out at several stations (upstream and downstream of a chemical factory outlet) in two different periods. In 2002, the results of chemical analyses performed on river water indicated no contamination. The ecotoxicological data obtained in this period showed that no evidence of biological effects was observed using V. fischeri and D. magna bioassays. In spite of the previous classical acute toxicity tests, significant differences in cell viability of D. discoideum were found. By analysing the effects measured on LMS and endocytotic rate, more relevant changes were observed for these sublethal stress biomarkers compared to survival. The chronic toxicity data showed significant changes in cell growth both of P. subcapitata and D. discoideum. Nevertheless, more sensitive and rapid responses were obtained when assessing the effects of exposure on D. discoideum. The chemical and ecotoxicological data obtained in 2006 indicated a full recovery of the quality of the river water (neither contamination nor toxicity found). Altogether, the results reported in this study underline that the use of a battery of biomarkers in conjunction with high-level endpoints may help follow the pollutant-induced stress syndrome in the organisms from early sublethal effects to starting mortality.

Cholinesterase activities in the scallop Pecten jacobaeus: characterization and effects of exposure to aquatic contaminants

Nearshore marine environments of industrialized countries are increasingly threatened by anthropogenic pollution. It is therefore a priority task to investigate the sensitivity of new ecotoxicological warning signals of the occurrence and effects of aquatic pollutants. The main aims of the present study were: 1) to characterize the biochemical properties of ChEs in tissues of the bivalve Pecten jacobaeus, using different specific substrates and selective inhibitors; 2) to measure sensitivity of ChE activities to in vitro exposure to the OPs azamethiphos and DFP and to the heavy metals cadmium and zinc. Our final aim was to carry out a preliminary evaluation of the suitability of ChEs measurement in tissues of the scallop for monitoring marine environmental quality and neurotoxic compounds contamination in the Mediterranean Sea. Responses to specific inhibitors have suggested that ChEs in adductor muscle share many characteristics with vertebrate acetylcholinesterase. Dose-dependent inhibition of ChE was observed in response to in vitro exposure to environmental contaminants such as cadmium and azamethiphos. Sensitivity to zinc and DFP was lower. ChEs in P. jacobaeus might therefore have potential as a sensitive biomarker for monitoring marine pollution. Results of the present study will be useful to focus further experiment of exposure to pollutants under in vivo conditions.

CAPSULE

Cholinesterase activities in scallop Pecten jacobaeus were observed to be sensitive to contaminants in vitro and may therefore have potential as biomarkers for monitoring water pollution.

Lysosomes and autophagy in aquatic animals

The lysosomal-autophagic system appears to be a common target for many environmental pollutants, as lysosomes accumulate many toxic metals and organic xenobiotics, which perturb normal function and damage the lysosomal membrane. In fact, autophagic reactions frequently involving reduced lysosomal membrane integrity or stability appear to be effective generic indicators of cellular well-being in eukaryotes: in social amoebae (slime mold), mollusks and fish, autophagy/membrane destabilization is correlated with many stress and toxicological responses and pathological reactions. Prognostic use of adverse lysosomal and autophagic reactions to environmental pollutants can be used for predicting cellular dysfunction and health in aquatic animals, such as shellfish and fish, which are extensively used as sensitive bioindicators in monitoring ecosystem health; and also represent a significant food resource for at least 20% of the global human population. Explanatory frameworks for prediction of pollutant impact on health have been derived encompassing a conceptual mechanistic model linking lysosomal damage and autophagic dysfunction with injury to cells and tissues. Methods are described for tracking in vivo autophagy of fluorescently labeled cytoplasmic proteins, measuring degradation of radiolabeled intracellular proteins and morphometric measurement of lysosomal/cytoplasmic volume ratio. Additional methods for the determination of lysosomal membrane stability in lower animals are also described, which can be applied to frozen tissue sections, protozoans and isolated cells in vivo. Experimental and simulated results have also indicated that nutritional deprivation (analogous in marine mussels to caloric restriction)-induced autophagy has a protective function against toxic effects mediated by reactive oxygen species (ROS). Finally, coupled measurement of lysosomal-autophagic reactions and simulation modelling is proposed as a practical toolbox for predicting toxic environmental risk.

Effects of sublethal Zn++ and Cd ++ concentrations on filtration rate, absorption efficiency and scope for growth in Donax trunculus (Bivalvia; Donacidae)

Physiological parameters (filtration rate measured as clearance rate; absorption efficiency measured as Conover index) and energy balance [scope for growth (SFG)] where determined under Zn++ (essential metal) and Cd++ (nonessential metal) at different concentration levels and timing. The toxic effect observed on Donax trunculus was higher for Cd++ than for Zn++ in almost all the parameters studied. The SFG is proposed as an integrated environmental biomarker to be used like a tool with others from different organization levels to obtain a more comprehensive vision of the ecological consequences of pollutants.

Application of a biomarker battery for the evaluation of the sublethal effects of pollutants in the earthworm Eisenia andrei

We applied a battery of biomarkers in the earthworm Eisenia andrei to assess the pollutant-induced stress syndrome. Earthworms were exposed to sublethal concentrations of copper (1-10 microM) and benzo[a]pyrene (0.01-10 microM) as models of inorganic and organic pollutants for 1, 3 and 7 days. Four potential biomarkers of stress were measured: lysosomal membrane stability of coelomocytes, lysosomal accumulation of lipofuscin in chloragogenous tissue and of neutral lipids in coelomatic cells, plasma membrane Ca2+-ATPase activity in the intestinal epithelium; metallothionein content was also evaluated as a biomarker of exposure. Significant changes were observed in the parameters measured in earthworms exposed to both contaminants. Certain biomarkers, such as lysosomal membrane stability and Ca2+-ATPase activity, that showed a decreasing trend with increasing pollutant concentration and time of exposure, proved to be particularly suitable to describe the evolution of a stress syndrome from its early phase to the development of pathological conditions. On the other hand, contaminant-induced changes in lysosomal lipofuscin and neutral lipid accumulation showed a bell-shaped trend, indicating that these biomarkers are able to follow the development of pollutant-induced stress syndrome as far as an equilibrium in the cell functions is maintained; therefore, they are particularly useful to describe mild stress conditions.

Autophagic and lysosomal reactions to stress in the hepatopancreas of blue mussels

The aim of this investigation was to test the reactions of the hepatopancreatic digestive cells of blue mussels (Mytilus edulis and Mytilus galloprovincialis) to a variety of environmental stressors. These stressors included anoxia, hyperthermia, polycyclic aromatic hydrocarbons, copper and a combination of copper+nutritional deprivation. Paraquat was used as an experimental generator of reactive oxygen species (ROS). All of these stressors induced adverse reactions in the lysosomal system of the digestive cells and many also induced autophagy. Changes induced by anoxia and hyperthermia were reversible, whereas autophagic reactions caused by PAHs were incomplete resulting in swelling and accumulation of lipid and phospholipid in the autolysosomes. The lysosomotropic drug chloroquine, an inducer of incomplete autophagy, enhanced the toxicity of phenanthrene but was not itself toxic at the experimental concentration used. Nutritional deprivation-induced autophagy had a protective effect on lysosomal stability in mussels exposed to copper. These findings complement previous findings and support a mechanistic model for lysosomal responses to free radicals and reactive oxygen (ROS, reactive oxygen species) which are generated by normal metabolism and often enhanced by stress and toxic xenobiotics and metals. The protective role of autophagy induced by nutritional deprivation against oxidative stress can be explained by this model, where autophagy boosts "cellular housekeeping" through enhanced removal of ROS-damaged proteins and organelles minimising formation of harmful stress/age pigment (lipofuscin). Finally, we discuss the possibility of low level triggering of autophagy in mussels by fluctuating environmental regimes providing a mechanism for tolerance to environmental stress.

DNA damage, acetylcholinesterase activity and lysosomal stability in native and transplanted mussels (Mytilus edulis) in areas close to coastal chemical dumping sites in Denmark

Biomarkers of genotoxicity (DNA damage, measured as tail moment in the Comet assay), neurotoxicity (acetylcholinesterase inhibition, AChE) and general stress (lysosomal membrane stability, LMS) were studied in native and transplanted blue mussels (Mytilus edulis) in coastal areas of western Denmark potentially affected by anthropogenic pollution originating from chemical dumping sites. The results indicate responses to pollution in all the biomarkers applied at the suspected areas, but the results were not consistent. Seasonal fluctuations in exposure situations at the study sites make interpretation of chemical pollution complex, as seen especially in the variability in results on DNA damage, and also in regard to AChE activity. These investigations further stress the importance of understanding the effects of natural factors (salinity, temperature, water levels, rain and storm events) in correct interpretation of the biomarker data obtained. In addition, adaptation of populations to local contamination may play a role in some of the response patterns observed.

The copepod Tigriopus: a promising marine model organism for ecotoxicology and environmental genomics

There is an increasing body of evidence to support the significant role of invertebrates in assessing impacts of environmental contaminants on marine ecosystems. Therefore, in recent years massive efforts have been directed to identify viable and ecologically relevant invertebrate toxicity testing models. Tigriopus, a harpacticoid copepod has a number of promising characteristics which make it a candidate worth consideration in such efforts. Tigriopus and other copepods are widely distributed and ecologically important organisms. Their position in marine food chains is very prominent, especially with regard to the transfer of energy. Copepods also play an important role in the transportation of aquatic pollutants across the food chains. In recent years there has been a phenomenal increase in the knowledge base of Tigriopus spp., particularly in the areas of their ecology, geophylogeny, genomics and their behavioural, biochemical and molecular responses following exposure to environmental stressors and chemicals. Sequences of a number of important marker genes have been studied in various Tigriopus spp., notably T. californicus and T. japonicus. These genes belong to normal biophysiological functions (e.g. electron transport system enzymes) as well as stress and toxic chemical exposure responses (heat shock protein 20, glutathione reductase, glutathione S-transferase). Recently, 40,740 expressed sequenced tags (ESTs) from T. japonicus, have been sequenced and of them, 5,673 ESTs showed significant hits (E-value, >1.0E-05) to the red flour beetle Tribolium genome database. Metals and organic pollutants such as antifouling agents, pesticides, polycyclic aromatic hydrocarbons (PAH) and polychrlorinated biphenyls (PCB) have shown reproducible biological responses when tested in Tigriopus spp. Promising results have been obtained when Tigriopus was used for assessment of risk associated with exposure to endocrine-disrupting chemicals (EDCs). Application of environmental gene expression techniques has allowed evaluation of transcriptional changes in T. japonicus with the ultimate aim of understanding the mechanisms of action of environmental stressors. Through a better understanding of toxicological mechanisms, ecotoxicologists may use this ecologically relevant species in risk assessment studies in marine systems. The combination of uses as a whole-animal bioassay and gene expression studies indicate that Tigriopus may serve as an excellent tool to evaluate the impacts of marine pollution throughout the coastal region. The purpose of this review is to illustrate the potential of using Tigriopus to fulfill the niche as an important invertebrate marine model organism for ecotoxicology and environmental genomics. In addition, the knowledge gaps and areas for further studies have also been discussed.

The potential of proteomics for providing new insights into environmental impacts on human health

The effects of environmental chemicals have traditionally been detected by monitoring biomarkers of exposure or biomarkers of effect. Proteomics, the study of the complete profile of proteins in a given cell, tissue or biological system, is a new approach using a set of high-throughput methodologies with a wide dynamic range that makes possible the discovery of novel biomarkers. This article reviews the application of two-dimensional electrophoresis and mass-spectrometry methods to environmental toxicology. Emphasis is placed on the protein-expression signature approach and on identifying redox-based post-translational protein modifications. The methodological links between studies in sentinel organisms and humans are explored. Significant limitations and challenges are placed on this approach by the shortage of genome sequence data necessary for protein identification and the growing requirement for more stringent study design. Proteomics will continue to be an important toolkit to help address the growing environmental threat posed by nanoparticles and endocrine disrupting agents.

Lysosomal responses and metallothionein induction in the blue mussel Mytilus edulis from the south-west coast of Iceland

It has recently been emphasized that high levels of inorganic and organic micropollutants (particularly organometals, POPs and PAHs) may be present in coastal waters at high latitudes, stressing the need to evaluate the effects of contaminants on marine organisms from sub-arctic zones. With this aim, specimens of the blue mussel Mytilus edulis were sampled in polluted and reference areas along the south-west coast of Iceland in July 2004. Samples were collected from the intertidal zone at three sites in Reykjavik harbour which are differently exposed to contaminants, and at three reference coastal sites, two located along the Reykjanes Peninsula and the third one on the northern part of Hvalfjordur fiord. Lipofuscin content, neutral lipid accumulation and lysosomal enlargement were evaluated in digestive cells from cryostat sections of the mussel hepatopancreas, and quantified by automated image analysis. Metallothionein induction was also determined in the same tissue. Results indicate that mussels from the inner part of Reykjavik harbour, which is the most sheltered and most influenced by extensive shipping traffic, were the worst affected, with the highest values in neutral lipids, lipofuscin and lysosomal swelling. At the other two harbour sites, mussels exhibited lower values, similar to those observed in organisms collected in Hvalfjordur fiord and in bay of Osar. Mussels from Kuagerdi had the lowest values.

Oxidative stress in the clam Ruditapes decussatus (Linnaeus, 1758) in relation to polycyclic aromatic hydrocarbon body burden

Seasonal variation of antioxidant enzymes activities (superoxide dismutase, catalase, and glutathione peroxidases) and lipid peroxidation (LPO) were studied in the clam Ruditapes decussatus in relation to body burdens of polycyclic aromatic hydrocarbons (PAHs). Clams were sampled in eight sites from the Ria Formosa lagoon. PAH concentrations were seasonally rather than spatially dependent, being higher in summer (August). Antioxidant enzymes activities and LPO levels in the clam digestive gland were also seasonally dependent. Antioxidant enzymes presented distinct seasonal variations: Mit SOD (superoxide dismutase activity measured in the mitochondrial fraction) was induced in the summer and down-regulated in winter and spring, while Cyt SOD activity (measured in the cytosolic fraction) was highest in autumn and lower in the summer. Neither Mit nor Cyt SOD were related to the clam PAH body burden, suggesting that cells are using other antioxidant systems to eliminate oxyradicals. Catalase (CAT), however, was induced in spring and down-regulated in summer, the inverse of the PAH concentrations in clam tissues. CAT induction in spring appears to be related to the excess of oxyradicals arising from the metabolic activity associated with the reproductive cycle. Conversely, the decrease in CAT activity in the summer may be related to the high water temperatures reached in the Ria Formosa (up to 30 degrees C). Glutathione peroxidases (total fraction - T-GPx and dependent on selenium - Se-GPx) presented a similar seasonal pattern, and were negatively related to PAH concentrations, which may indicate a precarious state of the clams, associated with PAH toxicity. Similarly, LPO was also inversely correlated to the PAH concentrations indicating that increases in PAH concentrations were not causing membrane oxidative damage in R. decussatus digestive gland. The results suggest that antioxidant enzymes in R. decussatus digestive gland are strongly affected by seasonal factors stressing the need of other experiments to clarify the PAHs effect on this clam species.

Towards a validation of a cellular biomarker suite in native and transplanted zebra mussels: a 2-year integrative field study of seasonal and pollution-induced variations

Two of the questions raised in the validation process of biomarkers are their relevance in the identification and discrimination of environmental perturbations, and the influence of seasonal factors on these biological endpoints. Determining the advantages and restrictions associated with the use of native or transplanted animals and comparing their responses is also needed. To obtain this information, a 2-year integrative field study was conducted in the vicinity of a nuclear power plant in northeastern France. A station was located in the reservoir receiving the cooling waters of the plant, and two other sites were studied 2 km upstream and 5 km downstream from the reservoir's discharge in the Moselle river. Elevated temperatures, copper contamination and a 1.4-fold-concentration factor of dissolved salts affected water quality of the reservoir. Native and transplanted zebra mussels (Dreissena polymorpha) were collected monthly and their digestive glands were processed for histochemical determinations of the lysosomal and peroxisomal systems and of the lipofuscin and neutral lipid contents. The responses were quantified using automated image analysis and stereology. Apart from neutral lipid contents, there were no systematic seasonal patterns in mussel populations or from 1 year to another. Principal Component Analyses showed a general higher discrimination potential of biological responses in transplanted organisms compared to native ones. They also pointed out the relationships between the cellular and physiological markers and abiotic factors. The present multiple biomarker integrative approach in transplanted D. polymorpha brings promising elements in their validation process as relevant biomonitoring tools.

Do nanoparticles present ecotoxicological risks for the health of the aquatic environment?

Nanotechnology is a major innovative scientific and economic growth area, which may present a variety of hazards for environmental and human health. The surface properties and very small size of nanoparticles and nanotubes provide surfaces that may bind and transport toxic chemical pollutants, as well as possibly being toxic in their own right by generating reactive radicals. There is a wealth of evidence for the harmful effects of nanoscale combustion-derived particulates (ultrafines), which when inhaled can cause a number of pulmonary pathologies in mammals and humans. However, release of manufactured nanoparticles into the aquatic environment is largely an unknown. This review addresses the possible hazards associated with nanomaterials and harmful effects that may result from exposure of aquatic animals to nanoparticles. Possible nanoparticle association with naturally occurring colloids and particles is considered together with how this could affect their bioavailability and uptake into cells and organisms. Uptake by endocytotic routes are identified as probable major mechanisms of entry into cells; potentially leading to various types of toxic cell injury. The higher level consequences for damage to animal health, ecological risk and possible food chain risks for humans are also considered based on known behaviours and toxicities for inhaled and ingested nanoparticles in the terrestrial environment. It is concluded that a precautionary approach is required with individual evaluation of new nanomaterials for risk to the health of the environment. Although current toxicity testing protocols should be generally applicable to identify harmful effects associated with nanoparticles, research into new methods is required to address the special properties of nanomaterials.

Evaluation of the global protein synthesis in Mytilus galloprovincialis in marine pollution monitoring: seasonal variability and correlations with other biomarkers

Protein synthesis down-regulation is a life-saving mechanism for many organisms exposed to xenobiotics that threaten normal life. The present study was designed to assess the spatial and seasonal variability of global protein synthesis, determined in the microsomal fraction of digestive glands from caged Mytilus galloprovincialis mussels exposed for 30 days in a relatively clean region and two unevenly polluted areas (Stations 1 and 2) along the Gulf of Patras (Greece). The in vivo activity of translating ribosomes was evaluated by analyzing the translating ribosomes, polysome content, which may serve as an indicator of the efficiency of the protein-synthesizing machinery. To correlate with classical biomonitoring strategies, various biomarkers were measured in digestive glands, including metallothionein content, heavy-metal content, and lysosomal membrane stability. In parallel, gill cells were examined for micronucleus frequency. Metal ion concentrations were also estimated in the surrounding waters as a measure of metal exposure. Substantially lower polysome content was recorded in caged mussels collected from Station 1, in particular during the winter and spring sampling. As verified by chemical analysis of the seawater and measurement of other biomarkers, Station 1 was more contaminated than Station 2. Polysome content was found negatively correlated with metallothionein levels, micronucleus frequency and cytosolic Cu and Hg in all seasons. In addition, negative correlations were obtained between polysome content and lysosomal membrane stability in winter and spring. A progressive increase in polysomes was observed from winter to autumn, in particular in samples from Station 1. A non-uniform trend was detected in 80S ribosomal monosomes, whereas the seasonal changes in ribosomal subunits were opposite to those found in polysome content. Comparisons between seasonal and local site-specific influences on polysome content provides evidence that winter and spring are the most appropriate sampling seasons for application of translation activity as a possible biomarker in biomonitoring studies.

Genotoxic risk identification of soil contamination at a major industrialized city in northeast China by a combination of in vitro and in vivo bioassays

The present study evaluated the genotoxicity of field soils in the Tianjin area, one of the most industrialized contaminated areas in northeast China. The genotoxicity of organic extracts of 41 soils was assayed by an in vitro SOS/ umu bioassay with Salmonella typhimurium TA 1535/pSK 1002. From the 41 soil samples, 11 samples were selected to confirm the genotoxic effect by in vivo single-cell gel electrophoresis (comet assay) using earthworms (Eisenia fetida). The results obtained demonstrated that, in the in vitro assay, genotoxicity expressed as induction ratios (IR) ranged from 1.00 to 4.60, and in the in vivo assay, the genotoxicity expressed as tail moment (TM) varied from 14.6 to 57.8 microm. All samples with high genotoxicity assessed by the SOS/umu bioassay possessed significantly high genotoxic effects in the comet assay, and there was a correlation (R2 = 0.736, p < 0.05) between IR and TM in both bioassays. It is concluded that soils in the Tianjin area were seriously contaminated by organic genotoxicants and higher levels of genotoxic effects existed in soils in the urban area of Tianjin as well as in areas near the coastal towns in the northeast part of the city. It can be concluded that a combination of in vivo and in vitro bioassays as a powerful and efficient genotoxicity-assessing tool could facilitate the assessment of genotoxic risk at a regional scale.

Proteomics as a route to identification of toxicity targets in environmental toxicology

Ecotoxicology describes a three-way relationship between ecosystems, chemical pollutants and living organisms. It is predicated on the fact that chemical pollution can exert toxic effects on organisms at the individual and population levels. These toxic effects may provide important information to supplement chemical analysis of environmental samples and aid in assessing the environmental quality of specific ecosystems. Traditionally, effects have been detected by means of biomarkers which, of necessity, were often molecules or processes known to be affected by pollutants. Proteomics provides a means of achieving high-throughput analysis of effects on protein populations and sub-populations with the potential to identify novel biomarkers. This review summarises the main approaches currently used in this area and assesses the potential of proteomics for identification of novel toxicity targets.

Linkage of biomarkers along levels of biological complexity in juvenile and adult diazinon fed terrestrial isopod (Porcellio scaber, Isopoda, Crustacea)

In parallel laboratory experiments, we determined the effect of a typical representative of organophosphorous pesticides, diazinon, on AChE activity, lipid, protein and glycogen content, weight change, feeding activity and mortality of juvenile and adult terrestrial isopods Porcellio scaber (Isopoda, Crustacea). Organophosphorous pesticides (OP) are among the most extensively used pesticides, which have replaced organochlorine pesticides. OPs inhibit the enzyme acetylcholinesterase (AChE), resulting in neurotoxicity. They have more widespread effects on non-target organisms than do organochlorine pesticides. The aim of this study was to link effect of diazinon on target enzyme to energy reserves and to integrated biomarker responses in juvenile and adult P. scaber. The non-observed effect concentration (NOEC) for AChE activity after diazinon exposure in two weeks toxicity study with isopods was below 5 microg/g diazinon. There was a good agreement between concentrations at which AChE and survival were affected (10 microg/g diazinon in juveniles, 100 microg/g diazinon in adults). We revealed a link among AChE activity, protein content and mortality. Glycogen and lipid content, feeding activity and weight change were not affected in two weeks diazinon exposure up to 100 microg/g diazinon. Juveniles were affected at concentrations that were an order of magnitude lower than those provoking similar effects on adults. Recommendations are made for future toxicity studies with terrestrial isopods.

Autophagy: role in surviving environmental stress

This conceptual paper addresses the role of lysosomal autophagy in cellular defence against oxidative stress. A hypothesis is proposed that autophagic removal of oxidatively damaged organelles and proteins provides a second tier of defence against oxidative stress. Age pigment or lipofuscin is a product of oxidative attack on proteins and lipids and can accumulate in lysosomes, where it can generate reactive oxygen species (ROS) and inhibit lysosomal function, resulting in autophagic failure. It is further hypothesised that repeated triggering of augmented autophagy can protectively minimise lipofuscin generation; and that animals living in fluctuating environments, where autophagy is repeatedly stimulated by natural stressors, will be generically more tolerant of pollutant stress. Data for resistance to pollutant stress is presented, together with evidence for a correlation between lysosomal stability and macrobenthic diversity. Finally, we speculate that organisms making up functional ecological assemblages in fluctuating environments, where up-regulation of autophagy should provide a selective advantage, may be pre-selected to be tolerant of pollutant-induced oxidative stress.

Soil screening for identifying ecological risk stressors using a battery of in vitro cell bioassays

Soil screening could be a process of identifying and defining areas, contaminants, and condition at the sites that warrant further attention for developing ecological risk assessments. In present work, a total of 41 surface soil samples from Tianjin, China were sampled and the soil organic extracts were evaluated using a battery of in vitro cell bioassays. The battery included ethoxyresorfin O-deethylase (EROD) with H4IIE rat hepatoma cells bioassay for Aryl hydrocarbon (Ah) receptor (Ah-agonists) effects, the SOS/umu bioassay for genotoxic effects, and human estrogen receptor recombinant yeast bioassay for estrogenic effects. The results have showed that total estrogenic effects in these soil samples was measured to be between 0.1 and 14.2ng EEQkg(-1) soil (d.w.); Ah-agonists effects assayed by EROD bioassay varied from 2.8ng TEQkg(-1) soil (d.w.) to 42.6ng TEQkg(-1) soil (d.w.), and the amounts of soil weight required for the extracts to lead positive result (IR 2.0) in the SOS/umu bioassay were between 3.9 and 31.3mg (d.w.) per well. In addition, the geographic distributions of Ah-agonists effects and genotoxic effects in Tianjin area exhibited a strong positive correlation with each other. However, the distribution of estrogenic effects with high levels in northwest Tianjin was markedly different from that of Ah-agonists effects, where the high levels were distributed in the urban of Tianjin, as well as coastal towns. It has been concluded that the toxicity assessment of surface soil using a battery of in vitro cell bioassays could provided meaningful information regarding characterization procedure in ecological risk assessment.

Pathological reactions and recovery of hepatopancreatic digestive cells from the marine snail Littorina littorea following exposure to a polycyclic aromatic hydrocarbon

The aim of this study was to investigate the cellular pathological responses of hepatopancreatic digestive cells from the periwinkle Littorina littorea exposed to the polycyclic aromatic hydrocarbon (PAH) fluoranthene and to ascertain whether any injurious effects were reversible within the experimental time scale. A secondary objective was to establish the relationship of the various reactions to animal health status, using lysosomal stability as an index of well-being. Exposure of snails to a concentration of 335 microgl(-1) (1.7 microM) fluoranthene (seawater renewed and spiked daily with fluoranthene) for 5 days resulted in a reduction in lysosomal stability (neutral red retention) and endocytosis; and an increase in smooth endoplasmic reticulum (ER) and 7-ethoxycoumarin-o-deethylase (ECOD; measured as cyano-ECOD) activity measured in isolated live digestive cells. Exposed snails treated with clean seawater for a further 8 days resulted in a return to control levels of lysosomal stability, ECOD and ER; endocytosis showed only a partial recovery. Multi-variate and uni-variate analysis showed that there were strong correlations between the various cellular biomarker responses. These findings are interpretable within the current framework of molluscan biomarker responses to PAHs. Principal component analysis was used to derive the first principal component for endocytosis, ER and ECOD reactions and these were plotted against lysosomal stability as a measure of cellular well-being. The resulting significant regression represents the mapping of the individual biomarkers within health status space for a gradient of fluoranthene toxicity. From this analysis, we concluded that endocytosis is an indicator of healthy snails while proliferation of ER and to a lesser extent induced ECOD are indicative of dysfunction and reduced health. Finally, the results indicate that stress induced by chronic exposure to a PAH is reversible.

Field application of a set of cellular biomarkers in the digestive gland of the freshwater snail Radix peregra (Gastropoda, Pulmonata)

An active biomonitoring study was performed in the vicinity of two pulp and paper mill effluents (PPMEs) released in two different streams in northeastern France. Freshwater gastropods, Radix peregra (=Lymnaea peregra or Lymnaea pereger), were transplanted for 0, 3, 14 and 21 days at two to three sites located upstream and downstream from the mill discharge points in both rivers. Lysosomal and peroxisomal systems, as well as lipofuscin and neutral lipids, were tested using histochemical methods on cryostat sections of digestive gland tissues, and stereological data were obtained by image analysis. Evidence of structural changes in the lysosomal system was found in animals exposed to both effluents, comprising general stress responses such as enlarged and more numerous lysosomes; and also possible specific pluri-phasic effects. Modifications of the lysosomal and cytoplasmic contents of lipid-related materials were also described, namely enhanced lipofuscin deposit and neutral lipid depletion. The peroxisomal proliferation in exposed snails seems to show its implication in oxidative stress detoxication, without preventing higher lipoperoxidation, as indicated by the increased amounts of digestive lipofuscin. Structural changes of the lysosomal and peroxisomal systems, digestive lipofuscin and neutral lipid contents have potential for use as early cellular biomarkers in Radix peregra exposed to environmental stressors, which deserve further investigations.

Environmental prognostics: an integrated model supporting lysosomal stress responses as predictive biomarkers of animal health status

The potential prognostic use of lysosomal reactions to environmental pollutants is explored in relation to predicting animal health in marine mussels, based on diagnostic biomarker data. Cellular lysosomes are already known to accumulate many metals and organic xenobiotics and the lysosomal accumulation of the carcinogenic polycyclic aromatic hydrocarbon 3-methylcholanthrene (3-MC) is demonstrated here in the hepatopancreatic digestive cells and ovarian oocytes of the blue mussel. Lysosomal membrane integrity or stability appears to be a generic indicator of cellular well-being in eukaryotes; and in bivalve molluscs it is correlated with total oxygen and nitrogen radical scavenging capacity (TOSC), protein synthesis, scope for growth and larval viability; and inversely correlated with DNA damage (micronuclei), as well as lysosomal swelling (volume density), lipidosis and lipofuscinosis, which are all characteristic of failed or incomplete autophagy. Integration of multiple biomarker data is achieved using multivariate statistics and then mapped onto "health status space" by using lysosomal membrane stability as a measure of cellular well-being. This is viewed as a crucial step towards the derivation of explanatory frameworks for prediction of pollutant impact on animal health; and has facilitated the development of a conceptual mechanistic model linking lysosomal damage and autophagic dysfunction with injury to cells, tissues and the whole animal. This model has also complemented the creation and use of a cell-based bioenergetic computational model of molluscan hepatopancreatic cells that simulates lysosomal and cellular reactions to pollutants. More speculatively, the use of coupled empirical measurements of biomarker reactions and modelling is proposed as a practical approach to the development of an operational toolbox for predicting the health of the environment.

The potential of ecotoxicoproteomics in environmental monitoring: biomarker profiling in mussel plasma using ProteinChip array technology

New global technologies, allowing simultaneous analysis of thousands of genes, proteins, and metabolites (so-called "omics" technologies), are being adopted rapidly by industry, academia, and regulatory agencies. This study evaluated the potential of proteomics in ecotoxicological research (i.e., ecotoxicoproteomics). Filter-feeding mussels (Mytilus edulis) were exposed continuously for 3 wk to oil, or oil spiked with alkylphenols and extra polycyclic aromatic hydrocarbons. The influence of chronic exposure on mussel plasma protein expression was investigated utilizing ProteinChip array technology in combination with surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI TOF MS). Results indicated that exposure to spiked oil had a more significant effect on protein expression in mussels than oil alone. In total, 83 mass peaks (intact or modified proteins/peptides) were significantly altered by spiked oil, while 49 were altered by oil. In exposed organisms, the majority of peaks were upregulated compared to controls (i.e., 69% in oil and 71% in spiked oil). Some peaks (32 in total) were affected by both treatments; however, the degree of response was higher in the spiked oil group for 25 of the 32 commonly affected features. Additionally, certain peaks revealed exposure- or gender-specific responses. Multivariate analysis with regression tree-based methods detected protein patterns associated with exposure that correctly classified masked samples with 90-95% accuracy. Similarly, 92% of females and 85% of males were correctly classified (independent of exposure). Results indicate that proteomics have the potential to make a valuable contribution to environmental monitoring and risk assessment.

Biomarker responses in flounder (Platichthys flesus) and mussel (Mytilus edulis) in the Klaipeda-Būtinge area (Baltic Sea)

During the EU project BEEP a battery of biomarkers was applied in flounder (Platichthys flesus) and the blue mussel (Mytilus edulis) collected at three locations off the Lithuanian coast (Baltic Sea) in June and September 2001 and 2002. The elevated biomarker responses in specimens sampled in September 2001 were apparently related to the extensive dredging activities in the Klaipeda port area and subsequent dumping of contaminated sediments. High concentrations of organic pollutants (organochlorines and PBDEs) were also measured in the tissues of both indicator species. In addition, response levels of genotoxicity, cytotoxicity, immunotoxicity as well as concentrations of PAH metabolites in the bile of flounder showed elevations in 2002 after an oil spill in the Būtinge oil terminal in November 2001. In flounder, biomarker measurements 10 months after the spill indicated recovery processes but in mussels a high level of genotoxicity could still be observed 22 months later. The present study illustrates the usefulness of the multi-biomarker approach in the detection of biological effects of pollution in this region of the Baltic Sea.

Use of the land snail Helix aspersa as sentinel organism for monitoring ecotoxicologic effects of urban pollution: an integrated approach

Atmospheric pollution from vehicular traffic is a matter of growing interest, often leading to temporary restrictions in urban areas. Although guidelines indicate limits for several parameters, the real toxicologic impacts remain largely unexplored in field conditions. In this study our aim was to validate an ecotoxicologic approach to evaluate both bioaccumulation and toxicologic effects caused by airborne pollutants. Specimens of the land snail Helix aspersa were caged in five sites in the urban area of Ancona, Italy. After 4 weeks, trace metals (cadmium, chromium, copper, iron, manganese, nickel, lead, and zinc) and polycyclic aromatic hydrocarbons (PAHs) were measured and these data integrated with the analyses of molecular and biochemical responses. Such biomarkers reflected the induction of detoxification pathways or the onset of cellular toxicity caused by pollutants. Biomarkers that correlated with contaminant accumulation included levels of metallothioneins, activity of biotransformation enzymes (ethoxyresorufin O-deethylase, ethoxycoumarin O-deethylase), and peroxisomal proliferation. More general responses were investigated as oxidative stress variations, including efficiency of antioxidant defenses (catalase, glutathione reductase, glutathione S-transferases, glutathione peroxidases, and total glutathione) and total oxyradical scavenging capacity toward peroxyl and hydroxyl radicals, onset of cellular damages (i.e., lysosomal destabilization), and loss of DNA integrity. Results revealed a marked accumulation of metals and PAHs in digestive tissues of organisms maintained in more traffic-congested sites. The contemporary appearance of several alterations confirmed the cellular reactivity of these chemicals with toxicologic effects of potential concern for human health. The overall results of this exploratory study suggest the utility of H. aspersa as a sentinel organism for biomonitoring the biologic impact of atmospheric pollution in urban areas. Key words: atmospheric pollutants, bioindicators, biomarkers, DNA integrity, lysosomes, metallothioneins, oxidative stress, peroxisomes, polycyclic aromatic hydrocarbons, trace metals.

Protein carbonyls: novel biomarkers of exposure to oxidative stress-inducing pesticides in freshwater fish Channa punctata (Bloch)

It has been established in mammalian system including humans that direct damage to proteins or chemical modification of amino acids in proteins during oxidative stress can give rise to protein carbonyls. Protein carbonyl induction, as a biomarker of oxidative stress was used in laboratory studies to assess the toxic effects of pesticides in freshwater fish, Channa punctata (Bloch), exposed to deltamethrin, endosulfan and paraquat. Protein carbonyls were measured in gills, kidney and liver. Significant (P<0.05-0.001) increase in protein carbonyls was observed in response to single 48h exposure to various pesticides in all the tissues. The time kinetics study involving deltamethrin (0.75μg/L) also showed a significant (P<0.05-0.001) induction of protein carbonyls in all the organs. The induction was significant (P<0.05-0.001) in all the durations of exposure (12h, 96h, 7 days, 14 days, 28 days). However, relatively pronounced induction was observed during shorter duration of exposure. The findings of the present investigation showed that deltamethrin had the maximum oxidative stress-inducing potential among the three pesticides used and gills are the most sensitive organs prone to oxidative damage. It is suggested that measurement of carbonyl groups may provide a convenient technique for detecting and quantifying oxidative modification of proteins during oxidative stress. The induction of protein carbonyl in fish was identified as a potentially useful biomarker of oxidative stress that warrants its application in the field investigations.

Lysosomal enlargement in digestive cells of mussels exposed to cadmium, benzo[a]pyrene and their combination

Digestive cell lysosomes in mussels are known to respond to individual organic chemicals and metals after experimental exposure under laboratory conditions but reports dealing with the response to mixtures of pollutants are scarce. The aim of the present investigation was to compare the lysosomal responses elicited by exposure to a model organic chemical compound (benzo(a)pyrene, B[a]P), a model toxic metal (Cd) and their combination (B[a]P+Cd) under controlled laboratory conditions. Dimethylsulfoxide (DMSO) was used as vehicle to dissolve organic chemicals into seawater. Control mussels were either kept untreated in clean seawater or treated with DMSO. Digestive glands were excised on Day 21. beta-Glucuronidase activity was demonstrated in 8 mum cryotome sections. Lysosomal volume, surface and numerical densities (Vv, Sv and Nv), and surface-to-volume ratio (S/V) were quantified by image analysis. Lysosomal enlargement was evident in digestive cells of mussels exposed to either Cd, B[a]P or B[a]P+Cd. Such enlargement was more marked after exposure to B[a]P+Cd than to B[a]P, but did not reach the levels recorded after Cd exposure. It seems therefore that the presence of B[a]P reduced to some extent the effects of Cd on digestive cell lysosomes in mussels.