An integrated environmental approach to investigate biomarker fluctuations in the blue mussel Mytilus edulis L. in the Vilaine estuary, France

Estuarine areas represent complex and highly changing environments at the interface between freshwater and marine aquatic ecosystems. Therefore, the aquatic organisms living in estuaries have to face highly variable environmental conditions. The aim of this work was to study the influence of environmental changes from either natural or anthropogenic origins on the physiological responses of Mytilus edulis. Mussels were collected in the Vilaine estuary during early summer because this season represents a critical period of active reproduction in mussels and of increased anthropogenic inputs from agricultural and boating activities into the estuary. The physiological status of the mussel M. edulis was evaluated through measurements of a suite of biomarkers related to: oxidative stress (catalase, malondialdehyde), detoxication (benzopyrene hydroxylase, carboxylesterase), neurotoxicity (acetylcholinesterase), reproductive cycle (vitelline, condition index, maturation stages), immunotoxicity (hemocyte concentration, granulocyte percentage, phagocytosis, reactive oxygen species production, oxidative burst), and general physiological stress (lysosomal stability). A selection of relevant organic contaminant (pesticides, (polycyclic aromatic hydrocarbons, polychlorobiphenyls) was measured as well as environmental parameters (water temperature, salinity, total suspended solids, turbidity, chlorophyll a, pheopigments) and mussel phycotoxin contamination. Two locations differently exposed to the plume of the Vilaine River were compared. Both temporal and inter-site variations of these biomarkers were studied. Our results show that reproduction cycle and environmental parameters such as temperature, organic ontaminants, and algal blooms could strongly influence the biomarker responses. These observations highlight the necessity to conduct integrated environmental approaches in order to better understand the causes of biomarker variations.     

Short-term exposure to sub-lethal doses of lindane affects developmental parameters in Chironomus riparius Meigen, but has no effect on larval glutathione-S-transferase activity

Chironomus riparius Meigen were exposed to 0, 0.01, 0.1, 0.5, 0.75 and 1.0 ppm lindane for 48 h as fourth instar larvae. Exposure had no effect on glutathione-S-transferase (GST) activity in larvae snap-frozen immediately following exposure. In contrast, exposure had longer-term consequences affecting developmental parameters. Concentrations above 0.5 ppm lindane affected larval behaviour, reduced adult body size and fecundity and delayed emergence times. The lack of significant change in GST activity when life history characters were affected by high concentrations of lindane, suggests that in C. riparius, GST is not a sensitive biomarker of pesticide exposure or effect.     

Accumulation and depuration of cyanobacterial toxin nodularin and biomarker responses in the mussel Mytilus edulis

Blue mussels (Mytilus edulis) were exposed to an extract made of natural cyanobacterial mixture containing toxic cyanobacterium Nodularia spumigena (70-110 microg nodularin l(-1), 24-h exposure followed by 144-h depuration period in clean water). Toxin concentration increased from initial 400 to 1100 mg kg(-1) after 24-h exposure, measured by liquid chromatography/mass spectrometry (LC/MS). Acetylcholinesterase activity (AChE), a biomarker of direct neurotoxic effects, showed inhibition after 12 and 24h exposure but returned to control level during the depuration period. Catalase (CAT) activity, an indicator of oxidative stress, showed significantly elevated levels in exposed mussels but only 72 h after the end of the exposure. No change in the activity of glutathione-S-transferase (GST) involved in conjugation reactions could be observed. A gradual yet incomplete elimination of nodularin (from 1100 to 600 mg kg(-1)) was observed during the depuration period, and the tissue levels were 30% lower in clean water after 24 h. The observed increase in oxidative stress indicated by elevated CAT activity is likely connected to detoxification reactions leading to the production of reactive oxygen species, including an apparent time lag in this specific enzymatic defence response. That no change in GST activity was observed suggests that this enzyme is not significantly involved in the detoxification process of nodularin-containing cyanobacterial extract in M. edulis.     

Mussel transplantation and biomarkers as useful tools for assessing water quality in the NW Mediterranean

Mussels, coming from an aquaculture farm located in a clean open bay, were transplanted to several stations of the bays of Nice and Cannes (NW Mediterranean) including a reference site for one month at three periods. Several biomarkers: activities of glutathione S-transferase (GST; exposure to organics), of catalase (exposure to oxidative stress) and of acetylcholinesterase (inhibited by some pesticides) and the lipid peroxidation (thiobarbituric acid reactive substances: TBARS) were measured in transplanted mussels. Cd, Cu and Zn concentrations were also measured as well as their condition index. The results demonstrated some seasonal variations in GST and catalase activities with higher levels in June compared to October. The condition index was also higher in June than in October. Principal component analyses performed with the whole set of data allowed to separate stations or groups of stations according to their responses. The mussels from the harbour of Nice were characterized by high TBARS levels and catalase activity in October 1999 whereas in the harbour of Cannes, animals presented very high copper concentrations and GST activities in June 2000. At the reference site, mussels generally presented low enzymatic activities (except AChE activity) and peroxidation levels and low heavy metal concentrations.     

Response of multixenobiotic defence mechanism in Dreissena polymorpha exposed to environmental stress

Multixenobiotic defence mechanism (MXDM) has been recently described as a first line defence system in many aquatic organisms and it has raised attention for its potential as an early biomarker of exposure to environmental stress. In order to investigate the relevance of this biomarker in the freshwater zebra mussel Dreissena polymorpha, we examined its response to exposure and to cessation of exposure. For this purpose, depurated zebra mussels were transplanted to natural rivers or exposed to medium experimentally contaminated with fuel oil 2 in the laboratory. After the exposure period, mussels were submitted to depuration in clean water in the laboratory. The level of MXDM activity was assessed by the efflux method that allows a simple and fast measure of the rate of rhodamine B efflux. MXDM activity was induced following exposure and induction appears earlier after laboratory exposure (3 days) than after in the field exposure (3-14 days). The level of MXDM response could not be directly correlated to exposure dose in the laboratory and to isolated physicochemical parameters or AOX levels in the field. The behaviour of MXDM activity seems to reflect the occurrence of exposure to a global stress rather than to specific compounds. Our results highlighted the possibility to monitor MXDM response in the freshwater zebra mussel. In spite of the difficulty to interpret responses resulting from the lack of specificity of response, multixenobiotic defence mechanism displays qualities to represent a biomarker of general stress in freshwater ecosystems.     

Effects of increasing temperatures on biomarker responses and accumulation of hazardous substances in rope mussels (Mytilus galloprovincialis) from Bizerte lagoon

This study examined the influence of increasing temperatures in spring and summer on biochemical biomarkers in Mytilus galloprovincialis mussels sampled from Bizerte lagoon (northern Tunisia). Spatial and seasonal variations in a battery of seven biomarkers were analyzed in relation to environmental parameters (temperature, salinity, and pH), physiological status (condition and gonad indexes), stress on stress (SoS), and chemical contaminant levels (heavy metals, polycyclic aromatic hydrocarbons (PAHs), and PCBs) in digestive glands. Integrated biological response (IBR) was calculated using seven biomarkers (acetylcholinesterase (AChE), benzo[a]pyrene hydroxylase (BPH), multixenobiotic resistance (MXR), glutathione S-transferase (GST), catalase (CAT), malondialdehyde (MDA), and metallothioneins (MT). Seasonal variations in biological response were determined during a critical period between spring and summer at two sites, where chemical contamination varies by a factor of 2 for heavy metals and a factor 2.5 for PAHs. The analysis of a battery of biomarkers was combined with the measurement of physiological parameters at both sites, in order to quantify a maximum range of metabolic regulation with a temperature increase of 11 °C between May and August. According to our results, the MT, MDA, CAT, and AChE biomarkers showed the highest amplitude during the 11 °C rise, while the BPH, GST, and MXR biomarkers showed the lowest amplitude. Metabolic amplitude measured with the IBR at Menzel Abdelrahmen—the most severely contaminated station—revealed the highest metabolic stress in Bizerte lagoon in August, when temperatures were highest 29.1 °C. This high metabolic rate was quantified for each biomarker in the North African lagoon area and confirmed in August, when the highest IBR index values were obtained at the least contaminated site 2 (IBR = 9.6) and the most contaminated site 1 (IBR = 19.6). The combined effects of chemical contamination and increased salinity and temperatures in summer appear to induce a highest metabolic adaptation response and can therefore be used to determine thresholds of effectiveness and facilitate the interpretation of monitoring biomarkers. This approach, applied during substantial temperature increases at two sites with differing chemical contamination, is a first step toward determining an environmental assessment criteria (EAC) threshold in a North African lagoon.     

Seasonal and inter-annual variability of DNA integrity in mussels Mytilus galloprovincialis: A possible role for natural fluctuations of trace metal concentrations and oxidative biomarkers

The DNA strand fragmentation as analyzed by the Comet assay is a common biomarker widely used to assess the genotoxic potential of chemical pollutants in marine organisms. However, basal levels of DNA strand breaks can be influenced also by factors unrelated to chemical exposure, and a better knowledge on the natural variability of such response would thus be important to discriminate the effects of anthropogenic activities. In this respect, the aim of the present work was to characterize the fluctuations of DNA strand breaks in mussels, Mytilus galloprovincialis, seasonally sampled over a 3 year period from a reference site along the Adriatic coast. Parameters reflecting DNA integrity exhibited significant seasonal changes in mussels haemocytes, with considerable differences between various sampling years. Comparing such results with those previously obtained on the natural fluctuations of trace metal concentrations and oxidative stress biomarkers in mussels tissues, significant correlations were obtained between DNA strand breaks with levels of Ba, Cd, Cu, Hg, Ni, Se, activity of catalase and content of malondialdehyde. Although mechanisms remain to be demonstrated, the overall results of this work suggest the potential role of natural prooxidant factors in affecting the baseline levels of DNA integrity in mussels, and confirm that natural variability of such responses should be carefully considered when monitoring the impact of genotoxins in marine ecosystems.     

Comparative studies on the biokinetics of Cd, Cr, and Zn in the green mussel Perna viridis and the Manila clam Ruditapes philippinarum

A kinetic approach was employed to determine the rates of metal uptake (Cd, Cr and Zn) from the dissolved phase and the rate constants of metal depuration in the mussel Perna viridis and the clam Ruditapes philippinarum. The effects of ambient metal concentration, salinity, and body size on the metal influx rate were examined. A linear positive relationship was observed between the metal influx rate and the metal concentration in ambient seawater. There was some evidence that Zn uptake was regulated by the bivalves in response to an increase in ambient Zn concentration. The uptake rate constant was highest for Zn and lowest for Cr in both bivalves, and was higher in mussels than in clams. The metal influx rate decreased by 1.6-1.8 times for the three metals when the salinity was increased from 15 ppt to 30 ppt. However, the effect of salinity on Zn influx in mussels was not statistically significant. A negative relationship of Cd and Zn influx rates with tissue dry weight was also found in both bivalves. Cr uptake in mussels was not significantly correlated with body size, but its uptake in clams was significantly correlated with body size. Metal concentration in ambient seawater appeared to be the most determining factor on metal uptake from the dissolved phase in both bivalves. The efflux rate constants of the three metals were within the range of 0.01-0.03 d-1, and were comparable between the mussels and the clams. Using a simple bioenergetic-based kinetic model, it was shown that both dissolved uptake and food ingestion can contribute to metal accumulation in the bivalves. However, Zn accumulation in the clam R. philippinarum was dominated by uptake from food ingestion. Metal partitioning in ingested food was found to be critical in affecting the relative importance of metal uptake from the dissolved phase and food source, primarily because of the large variability of this parameter in natural environments.     

Impaired glutathione redox status is associated with decreased survival in two organophosphate-poisoned marine bivalves

Biomonitoring organophosphate (OP) exposure in marine environments is generally achieved by the measurement of acetylcholinesterase activity in bivalves like mussels. However, there is evidence that indicates that oxidative stress may be implied in OP toxicity. The aim of this study was to evaluate the relationship between survival from the OP insecticide fenitrothion and glutathione levels in marine bivalves. Mussels (Mytilus galloprovincialis Lam.) and scallops (Flexopecten flexuosus Poli) were exposed, in a time to death test, to their LC85 of fenitrothion for 96 h. OP-poisoned mussels showed reduced (GSH) and oxidised (GSSG) glutathione depletion in the digestive gland, muscle and gills. Pectinid spats exposed to this insecticide presented GSH depletion in the digestive gland and mantle, and a reduction of the GSH/GSSG ratio in gills and mantle. Although survival curves were significantly different and mussels withstood twice as much fenitrothion as pectinid spats, muscular GSH/GSSG ratio was highly related to mortality in both species. We suggest that an impairment in the glutathione redox status could result in an induction of the cell death, either by apoptosis or necrosis, leading ultimately to the death of the organism. We conclude that whereas glutathione depletion can be used as a biomarker of exposure, the muscular GSH/GSSG ratio might be used as a biochemical marker of effect and individual susceptibility to mortality of marine bivalves exposed to fenitrothion or other pollutants that induce oxidative stress.     

Chemical and biomarker responses for site-specific quality assessment of the Lake Maggiore (Northern Italy)

Since the 1990s, the Lake Maggiore (Northern Italy) has been recognized as an aquatic environment contaminated by DDTs and other persistent organic pollutants, but to date just few studies were carried out to investigate the effects of pollution to aquatic organisms. The aim of this study was the application of a stepwise approach based on chemical data, a suite of biomarkers and the integration of their responses into a biomarker response index (BRI) to evaluate the site-specific quality assessment in different sampling stations of Lake Maggiore, one of the largest European lakes. We used as biological model the freshwater bivalve Zebra mussel (Dreissena polymorpha). Several hundred bivalve specimens were sampled on May 2011 from eight sampling sites located along the lake shoreline. We measured levels of DDTs, PCBs, HCHs, HCB, and PAHs accumulated in D. polymorpha soft tissues by GC/MSn, while the activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione S-transferase, as well as the lipid peroxidation and protein carbonyl content were evaluated in homogenates from native bivalves as oxidative stress indices. Moreover, DNA damage was investigated by the alkaline precipitation assay. Significant imbalances of enzymatic activity were found in mussels from most of the sampling sites, as well as notable increases of damage to macromolecules. Health status of mussels from Baveno was greatly affected by lake pollution, probably due to high levels of DDTs measured in this site, while a wide variability in biomarker responses was found in all the other stations. The application of a BRI allowed distinguishing impacts of pollution to bivalves, confirming mussels from Baveno as the most threatened and revealing that also the health status of bivalves from Suna, Brissago, Pallanza, and Laveno is affected. These evidences suggest the usefulness of a specific index to integrate all the biomarker endpoints in order to provide a correct environmental risk assessment.     

Effect of food level on the acute and chronic responses of daphnids to lindane

The toxic effects of lindane on the zooplankton communities may be strongly related to the population fitness, which is highly dependent on food availability. In order to test this hypothesis, acute (immobilisation) and chronic (life-history) responses of Daphnia longispina and Daphnia magna, reared at different food levels (low, normal, and high), were assessed in laboratorial exposures to several concentrations of lindane. A bifactorial design was employed (food level versus lindane concentration) for both species. Results showed that lindane was toxic to both D. magna and D. longispina, within a similar range. However, lindane toxicity to daphnids was dependent on food level, suggesting that the latter is an important factor to take into account when assessing the toxic effects of lindane on zooplankton communities.     

Combined effects of deltamethrin, temperature and salinity on oxidative stress biomarkers and acetylcholinesterase activity in the black tiger shrimp (Penaeus monodon)

This study aimed to investigate the interactions of two abiotic factors (temperature and salinity) and deltamethrin (pyrethroid pesticide) exposure on some oxidative stress biomarkers as well as on acetylcholinesterase activity (AChE) in hepatopancreas, gills and muscle of black tiger shrimp (Penaeus monodon). A combination of three temperatures (24, 29 and 34 °C), two salinities (15 and 25 ppt), and the absence or presence of 0.1 μg L⁻¹ deltamethrin was applied on shrimp during 4 d under laboratory conditions. Lipid peroxidation level (LPO) and glutathione S-transferase activity (GST) were not affected by combined effect of temperature, salinity and deltamethrin in any of the studied tissues. Deltamethrin impaired other tested oxidative stress biomarkers, i.e. total glutathione (tGSH), catalase (CAT), glutathione peroxidase (GPx). tGSH level significantly increased in hepatopancreas due to deltamethrin exposure mainly at 34 °C, while pesticide effects on tGSH and CAT activity in gills were influenced by both temperature and salinity. In addition, GPx activity in hepatopancreas decreased after deltamethrin treatment mainly at 24 °C. Finally, AChE in muscle was strongly inhibited by deltamethrin at all tested temperatures and salinities. These novel findings demonstrate that interactions between abiotic factors and a commonly used pesticide exposure should be taken into account when analyzing some widespread biomarkers in black tiger shrimp.     

Effects of lindane on the photosynthetic apparatus of the cyanobacterium<Emphasis Type="Italic">anabaena</Emphasis>

INTENTION, GOAL, SCOPE, BACKGROUND: Cyanobacteria have the natural ability to degrade moderate amounts of organic pollutants. However, when pollutant concentration exceeds the level of tolerance, bleaching of the cells and death occur within 24 hours. Under stress conditions, cyanobacterial response includes the short-term adaptation of the photosynthetic apparatus to light quality, named state transitions. Moreover, prolonged stresses produce changes in the functional organization of phycobilisomes and in the core-complexes of both photosystems, which can result in large changes in the PS II fluorescence yield. The localization of ferredoxin-NADP+ reductase (FNR) at the ends of some peripheral rods of the cyanobacterial phycobilisomes, makes this protein a useful marker to check phycobilisome integrity. OBJECTIVE: The goal of this work is to improve the knowledge of the mechanism of action of a very potent pesticide, lindane (gamma-hexaclorociclohexane), in the cyanobacterium Anabaena sp., which can be considered a potential candidate for bioremediation of pesticides. We have studied the effect of lindane on the photosynthetic apparatus of Anabaena using fluorescence induction studies. As ferredoxin-NADP+ reductase plays a key role in the response to oxidative stress in several systems, changes in synthesis, degradation and activity of FNR were analyzed. Immunolocalization of this enzyme was used as a marker of phycobilisome integrity. The knowledge of the changes caused by lindane in the photosynthetic apparatus is essential for rational further design of genetically-modified cyanobacteria with improved biorremediation abilities. METHODS: Polyphasic chlorophyll a fluorescence rise measurements (OJIP) have been used to evaluate the vitality and stress adaptation of the nitrogen-fixing cyanobacterium Anabaena PCC 7119 in the presence of increasing concentrations of lindane. Effects of the pesticide on the ultrastructure have been investigated by electron microscopy, and FNR has been used as a marker of phycobilisome integrity. RESULTS AND DISCUSSION: Cultures of Anabaena sp. treated with moderate amounts of lindane showed a decrease in growth rate followed by a recovery after 72 hours of pesticide treatment. Concentrations of lindane below 5 ppm increased the photosynthetic performance and activity of the cells. Higher amounts of pesticide caused a decrease in these activities which seems to be due to a non-competitive inhibition of PS II. Active PS II units are converted into non-QA reducing, so called heat sink centers. Specific activity and amount of FNR in lindane-treated cells were similar to the values measured in control cultures. Release of FNR from the thylakoid after 48 hours of exposure to 5 ppm of lindane towards the cytoplasm was detected by immunogold labeling and electron microscopy. CONCLUSIONS: From these results, we conclude that the photosynthetic performance and activity of the cells are slightly increased in the presence of lindane up to 5 ppm. Moreover, in those conditions, lindane did not produce significant changes in the synthesis, degradation or activity of FNR. The high capability of Anabaena to tolerate lindane makes this cyanobacterium a good candidate for phytoremediation of polluted areas. RECOMMENDATION AND OUTLOOK: The results of this study show that cultures of Anabaena PCC 7119 tolerate lindane up to 5 ppm, without significant changes in the photosynthetic vitality index of the cells. However, a slight increase in phycobiliprotein synthesis is observed, which is related to total protein content. This change might be due to degradation of proteins less stable than phycobiliproteins. An identification of the proteins with altered expression pattern in the presence of the pesticide remains the subject of further work and will provide valuable information for the preparation of strains which are highly tolerant to lindane.     

Sublethal effect of silver and chromium in the green mussel Perna viridis with reference to alterations in oxygen uptake, filtration rate and membrane bound ATPase system as biomarkers

Perna viridis is an ideal animal for studying the impairment caused by the effects of heavy metals that are often detected in coastal areas. Preliminary bioassay tests revealed that the lethal (LC(100)), median lethal (LC(50)) and sublethal (LC(0)) concentration of silver and chromium to P. viridis were 6.5, 4.0, 2.0 mg l(-1) and 4.5, 2.5, 1.0 mg l(-1), respectively. Toxic effect of silver and chromium was evaluated in the green mussel P. viridis, with reference to oxygen consumption, filtration rate and ATPase system in laboratory experiments. These parameters were selected as the end point of sublethal stress. Oxygen consumption and filtration rates were calculated as a measure of decline in the dissolved oxygen level and algal concentration (feed) in the aquaria water, respectively. Silver and chromium affects both oxygen consumption and filtration rate significantly (P<0.01) at 96 h when compared to control. The activity of ATPases system in the gills, hepatopancreas, ovary and muscle of mussels were inhibited by silver and chromium indicating that metals exerted significant toxic effect. The inhibition of Na(+)K(+) ATPase, Ca(2+) ATPase and Mg(2+) ATPase in the mussels were significant (P<0.05) for silver and highly significant (P<0.01) for chromium, which indicates that chromium was more toxic to mussels when compared to silver. The assessment of oxygen consumption, filtration and ATPases system can thus be used as a valid biomarker in aquatic ecotoxicology studies.     

Adaptation to osmotic stress provides protection against ammonium nitrate in Pelophylax perezi embryos

The negative effects of pollution on amphibians are especially high when animals are additionally stressed by other environmental factors such as water salinity. However, the stress provoked by salinity may vary among populations because of adaptation processes. We tested the combined effect of a common fertilizer, ammonium nitrate (0-90.3 mg N-NO₃NH₄/L), and water salinity (0-2‰) on embryos of two Pelophylax perezi populations from ponds with different salinity concentrations. Embryos exposed to the fertilizer were up to 17% smaller than controls. Survival rates of embryos exposed to a single stressor were always below 10%. The exposure to both stressors concurrently increased mortality rate (>95%) of embryos from freshwater. Since the fertilizer was lethal only when individuals were stressed by the salinity, it did not cause lethal effects on embryos naturally adapted to saline environments. Our results underscore the importance of testing multiple stressors when analyzing amphibian sensitivity to environmental pollution.     

Cellular energy allocation in zebra mussels exposed along a pollution gradient: linking cellular effects to higher levels of biological organization

Organisms exposed to suboptimal environments incur a cost of dealing with stress in terms of metabolic resources. The total amount of energy available for maintenance, growth and reproduction, based on the biochemical analysis of the energy budget, may provide a sensitive measure of stress in an organism. While the concept is clear, linking cellular or biochemical responses to the individual and population or community level remains difficult. The aim of this study was to validate, under field conditions, using cellular energy budgets [i.e. changes in glycogen-, lipid- and protein-content and mitochondrial electron transport system (ETS)] as an ecologically relevant measurement of stress by comparing these responses to physiological and organismal endpoints. Therefore, a 28-day in situ bioassay with zebra mussels (Dreissena polymorpha) was performed in an effluent-dominated stream. Five locations were selected along the pollution gradient and compared with a nearby (reference) site. Cellular Energy Allocation (CEA) served as a biomarker of cellular energetics, while Scope for Growth (SFG) indicated effects on a physiological level and Tissue Condition Index and wet tissue weight/dry tissue weight ratio were used as endpoints of organismal effects. Results indicated that energy budgets at a cellular level of biological organization provided the fastest and most sensitive response and energy budgets are a relevant currency to extrapolate cellular effects to higher levels of biological organization within the exposed mussels.     

Toxicological and biochemical responses of the earthworm Lumbricus rubellus to pyrene, a non-carcinogenic polycyclic aromatic hydrocarbon

The effects of the polycyclic aromatic hydrocarbon (PAH) pyrene on earthworms were investigated in contact and soil tests. In addition to measuring toxic effects on survival and reproduction, Ethoxyresorufin-o-deethylase (EROD) activity and catalase activity were also studied as possible biomarkers of toxic stress. The survival data indicated that LC₅₀ values were 0.0068 mg/ml for the contact test, and 283 mg/kg in the soil test. Cocoon production rate was significantly reduced compared to controls at 160, 640 and 2560 mg/kg in the soil test. No EROD activity could be detected in preliminary studies using control and exposed animals from the contact test, so this assay was not used to the soil test. Catalase activity was shown to be significantly lower at 640 mg/kg in the soil test compared to all other treatments and the control. When compared to toxicological data for other soil invertebrates, Lumbricus rubellus has an intermediate sensitivity in respects of survival and a lower sensitivity for reproductive effects, although the soil used in this study had a higher organic content than previous studies, meaning that the sensitivity of this species may be underestimated in comparison to previous published data for other soil invertebrates.     

Effect of lindane on antibody response to typhoid vaccine in weanling rats

The immunosuppressive effect of lindane was assessed in weanling rats over a period of 5 weeks. Agglutinin titres against S. typhi 'O' and 'H', S. paratyphi 'AH' and 'BR' antigens were determined following TAB vaccination in control and lindane-fed animals. The titres attained in non-treated controls were higher significantly than those in treated animals indicating a suppressive effect of lindane on humoral immune responses.     

Temperature enhanced effects of chlorine exposure on the health status of the sentinel organism Mytilus galloprovincialis

It now is widely recognised that the global temperature is rising, a phenomenon which could alter the effects of pollution on wildlife. In order to assess the role of temperature and exposure to chlorine due to cooling water discharges, a battery of metabolic, oxidative stress and histological parameters were evaluated in Mytilus galloprovincialis after 15 and 30 days at 15 °C and at two increased temperatures (+5 and +10 °C). Diverse gill pathologies such as haemolymphatic sinus dilatation, an increased number of mucocytes and granulocytes as well as a lower number of cilia were observed after 30 days exposure at higher temperatures. Protein, amino acid, triglyceride and fatty acid levels decreased when the temperature increased, as a consequence of higher energetic demand. Similarly, acetylcholinesterase, catalase and glutathione S-transferase activities showed an inhibition at higher temperatures, although gill lipid peroxidation levels remained unaffected. Our results suggest that increased temperatures induce deterioration in the health status of the mussels and in their defensive capacity against a polluted environment.     

New evidences for old biomarkers: effects of several xenobiotics on EROD and AChE activities in Zebra mussel (Dreissena polymorpha)

The biomarker approach is widely used both in vertebrates and invertebrates for environmental biomonitoring, because it can supply an integrated response for multi-xenobiotics contamination. However, the use of biomarkers requires the identification of every possible variation that can influence the biochemical response, because ecosystems are generally subject to a mixture of pollutants, which can create additive, opposite or competitive effects. In recent years, there has been considerable interest in the use of biomarkers within marine bivalves, while very few data are available for freshwater molluscs. The aim of this research was to investigate changes on EROD and AChE activities in the freshwater bivalve Zebra mussel (Dreissena polymorpha) exposed to different pollutants (Arochlor 1260, CB 153 and 126, pp'DDT, chlorpyrifos, carbaryl) at laboratory conditions, in order to standardize the analytical procedures and to highlight eventual interferences on enzyme activities. Chemical concentrations in the mussel soft tissues were analyzed by GC/MS-MS. Main results showed a significant induction of EROD activity when mussels were exposed to 100 ng/l of PCB mixture of Arochlor 1260 and dioxin-like CB 126, but this congener showed also a clear competitive inhibition after 48 h of exposure. Surprisingly, pp'DDT determined a significant decrease of basal EROD activity after only 24 h of exposure, even if it was not possible to discriminate between the effect of the parent compound and that of its metabolites (DDD, DDE). We also found an interaction between the organophosphate insecticide chlorpyrifos, which does not directly decrease the AChE activity, and terbutilazine. This herbicide increased the biotransformation of the organophosphate compound to its oxidized metabolite (oxon), a much stronger AChE inhibitor. The possible use of the oxime Pyridine-2-Aldoxime Methochloride (2-PAM) to bring back the catalytic activity to basal levels was also demonstrated.