Invasive species versus pollutants: Potential of Limnoperna fortunei to degrade glyphosate-based commercial formulations.

The intensive use of glyphosate in industrial agriculture may lead to freshwater contamination, encouraging studies of its toxic effect on non-target aquatic organisms. Glyphosate-based commercial formulations contain adjuvants, making them even more toxic than the active ingredient (a.i.) itself. The golden mussel Limnoperna fortunei is a freshwater invasive species which has been found to increase glyphosate dissipation in water and to accelerate eutrophication. The aim of this study is to evaluate the capability of L. fortunei to reduce the concentration of glyphosate in two commercial formulations, Roundup Max® and Glifosato Atanor®. Results were compared with the decay of the a.i. alone and in presence of mussels. Evasive response and toxicity tests were performed in a first set of trials to analyze the response of L. fortunei exposed to Roundup Max® and Glifosato Atanor®. Subsequently, we conducted a 21-day degradation experiment in 2.6-L microcosms applying the following treatments: 6 mg L-1 of technical-grade glyphosate (G), Glifosato Atanor® (A), Roundup Max® (R), 20 mussels in dechlorinated tap water (M), and the combination of mussels and herbicide either in the technical-grade (MG) or formulated form (MA and MR) (all by triplicate). Samples were collected at days 0, 1, 7, 14 and 21. No significant differences in glyphosate decay were found between treatments with mussels (MG: 2.03 ± 0.40 mg L-1; MA: 1.60 ± 0.32 mg L-1; MR: 1.81 ± 0.21 mg L-1), between glyphosate as a.i. and the commercial formulations, and between the commercial formulations, suggesting that the adjuvants did not affect the degrading potential of L. fortunei. In addition to the acceleration of glyphosate dissipation in water, there was an increase in the concentration of dissolved nutrients in water (N-NH4+ and P-PO43-) even higher than that caused by the filtering activity of the mussels, probably resulting from stress or from the degradation of glyphosate and adjuvants. We believe that a larger bioavailability of these nutrients due to glyphosate metabolization mediated by mussels would accelerate eutrophication processes in natural water bodies. The approach used here, where L. fortunei was exposed to two commercial formulations actually used in agricultural practices, sheds light on the potential impact of glyphosate decay on water bodies invaded by this species.

Acute Toxicity of [Formula: see text], [Formula: see text], and [Formula: see text] to the Golden Mussel Limnoperna fortunei (Dunker 1857).

In this study we test the sensitivity of three sizes of golden mussel (Limnoperna fortunei), an introduced species in Argentina, to a 96-h exposure to [Formula: see text], [Formula: see text], and [Formula: see text]. We also analysed the relative sensitivity of L. fortunei compared to other freshwater bivalve equivalent sensitivity data. The ANOVA results showed that both factors, heavy metal and size, had significant effects (p = 0.0013 and p = 0.0091, respectively) on the mortality of the golden mussel. Tukey's test showed significant differences for [Formula: see text] treatment and the smallest size class (7 mm [Formula: see text]). The relative sensitivity analysis showed that [Formula: see text] values for the smallest size class of L. fortunei exposed to [Formula: see text] and [Formula: see text] were in the low range, with values of 11.40 mg/L and 12.65 mg/L, respectively. In the case of [Formula: see text] (1.66 mg/L), its [Formula: see text] was in the medium-low range of the freshwater bivalve sensitivity distribution.

Protein expression profiles in Bathymodiolus azoricus exposed to cadmium.

Proteomic changes in the "gill-bacteria complex" of the hydrothermal vent mussel B. azoricus exposed to cadmium in pressurized chambers ((Incubateurs Pressurises pour l'Observation en Culture d'Animaux Marins Profonds - IPOCAMP) were analyzed and compared with the non-exposed control group. 2-D Fluorescence Difference Gel Electrophoresis (2D-DIGE) showed that less than 1.5% of the proteome of mussels and symbiotic bacteria were affected by a short-term (24 h) Cd exposure. Twelve proteins of the more abundant differentially expressed proteins of which six were up-regulated and six were down-regulated were excised, digested and identified by mass spectrometry. The identified proteins included structural proteins (actin/actin like proteins), metabolic proteins (calreticulin/calnexin, peptidyl-prolyl cis-trans isomerase, aminotransferase class-III, electron transfer flavoprotein, proteasome, alpha-subunit and carbonic anhydrase) and stress response proteins (chaperone protein htpG, selenium-binding protein and glutathione transferases). All differently expressed proteins are tightly connected to Cd exposure and are affected by oxidative stress. It was also demonstrated that B. azoricus was well adapted to Cd contamination therefore B. azoricus from hydrothermal vent areas may be considered a good bioindicator.

Lysosomal Membrane Stability in Hemocytes and Micronuclei in Gills of Perumytilus purpuratus Lamarck 1819 (Bivalvia: Mytilidae) Exposed to Copper.

The aim of this study was to determine the cytotoxic and genotoxic effects of copper on the bivalve Perumytilus purpuratus. The individuals were exposed to three copper concentrations: 1, 30 and 45 µg L-1 for 24, 48 and 96 h. Lysosomal membrane stability in hemocytes was determined through the neutral red retention time (NRRT) and micronucleus (MN) frequency tests in hemocytes and gills. The results show that the NRRT decreased significantly at 30 µg L-1 after 48 h of exposure. The frequency of MN was significantly greater in gills after 24 h in all concentrations tested. Copper is cytotoxic from 30 µg L-1 and genotoxic from 1 µg L-1. The use of these biomarkers of effects in P. purpuratus is proposed as an early warning tool for monitoring in environmental assessment of coastal ecosystems impacted by mining activities.

Biochemical responses of the golden mussel Limnoperna fortunei under dietary glyphosate exposure.

The aim of this study was to analyze the biochemical alterations in the golden mussel Limnoperna fortunei under dietary glyphosate exposure. Mussels were fed during 4 weeks with the green algae Scenedesmus vacuolatus previously exposed to a commercial formulation of glyphosate (6 mg L-1 active principle) with the addition of alkyl aryl polyglycol ether surfactant. After 1, 7, 14, 21 and 28 days of dietary exposure, glutathione-S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), acetylcholinesterase (AChE), carboxylesterases (CES) and alkaline phosphatase (ALP) activities, glutathione (GSH) content and damage to lipids and proteins levels were analyzed. A significant increase (72%) in the GST activity and a significant decrease (26%) in the CES activity in the mussels fed on glyphosate exposed algae for 28 days were observed. The ALP activity was significantly increased at 21 and 28 days of dietary exposure (48% and 72%, respectively). GSH content and CAT, SOD and AchE activities did not show any differences between the exposed and non exposed bivalves. No oxidative damage to lipids and proteins, measured as TBARS and carbonyl content respectively, was observed in response to glyphosate dietary exposure. The decrease in the CES activity and the increases in GST and ALP activities observed in L. fortunei indicate that dietary exposure to glyphosate provokes metabolic alterations, related with detoxification mechanisms.

Quantification of heat shock protein 70 and acetylcholinesterase over a time course suggests environmental adaptation in a foundational molluscan species.

Waterways in urban areas often act as repositories for sewage, industrial waste, and environmental contaminants. In response, inhabitants of these watersheds undergo physiological adaptations specific to their respective environments. Effects of these stressors can be assayed by quantification of various well-documented biomarkers in sentinel species such as the Atlantic Ribbed mussel, Geukensia demissa, a native to the Bronx River Estuary, Bronx, NY, USA. Heat shock protein 70 (Hsp70) is a universally expressed biomarker for an array of environmental stressors including toxins and low dissolved oxygen. To better understand the mechanisms by which organisms tolerate their contaminated environments, we monitored the constitutive and heat shock-induced levels of two proteins: Hsp70 and acetylcholinesterase (AChE) in natural populations of G. demissa from differentially impacted sites: the Bronx River and Greenwich Cove estuaries. We show that G. demissa from the Bronx River exhibits a higher level of constitutive Hsp70, and launches a more rapid and robust heat shock response than does its Greenwich Cove counterpart. In addition, AChE levels are recovered more quickly in Bronx River mussels. Based on response pattern investigations from heat stress as well as constitutive expression, we suggest that the Hsp70/AChE chaperone/client relationship exemplifies the unique adaptive mechanisms utilized by organisms in order to tolerate environmentally impacted habitats. Results from this study offer important insights from an ecological perspective into the molecular and cellular basis of stress response and provide valuable information regarding adaptation to the increased demands of challenging environments.

Effect of sulfide, osmotic, and thermal stresses on taurine transporter mRNA levels in the gills of the hydrothermal vent-specific mussel Bathymodiolus septemdierum.

Hydrothermal vent environmental conditions are characterized by high sulfide concentrations, fluctuating osmolality, and irregular temperature elevations caused by vent effluents. These parameters represent potential stressors for organisms that inhabit the area around hydrothermal vents. Here, we aimed to obtain a better understanding of the adaptation mechanisms of marine species to hydrothermal vent environments. Specifically, we examined the effect of sulfide, osmolality, and thermal stress on the expression of taurine transporter (TAUT) mRNA in the gill of the deep-sea mussel Bathymodiolus septemdierum, which is a dominant species around hydrothermal vent sites. We analyzed TAUT mRNA levels by quantitative real-time polymerase chain reaction (PCR) in the gill of mussels exposed to sulfide (0.1 or 1mg/L Na2S·9H2O), hyper- (115% seawater) and hypo- (97.5%, 95.5%, and 85% seawater) osmotic conditions, and thermal stresses (12°C and 20°C) for 24 and 48h. The results showed that mussels exposed to relatively low levels of sulfide (0.1mg/L) and moderate heat stress (12°C) exhibited higher TAUT mRNA levels than the control. Although hyper- and hypo-osmotic stress did not significantly change TAUT mRNA levels, slight induction was observed in mussels exposed to low osmolality. Our results indicate that TAUT is involved in the coping mechanism of mussels to various hydrothermal vent stresses.

Evidence for intraspecific endocrine disruption of Geukensia demissa (Atlantic ribbed mussel) in an urban watershed.

Populations undergo physiological adaptations in response to environmental stressors. Our 5-year bio-monitoring study of the Bronx River Estuary demonstrates comparatively low dissolved oxygen concentrations in this urbanized watershed. Additionally, our current results establish altered hormonal levels, resulting from endocrine disruption, in Geukensia demissa (Atlantic ribbed mussel) from the Bronx River Estuary. No studies have yet investigated a correlation between low dissolved oxygen and endocrine disruption in field-collected bivalves. Testosterone, estradiol, and progesterone levels were collected from male and female mussels in the oxygen depleted Bronx River and well-oxygenated Greenwich Cove. Bronx River mussels exhibited higher testosterone levels and lower estradiol levels than Greenwich Cove mussels. The resulting abnormal hormonal ratio seems to indicate that environmental conditions in the Bronx River facilitate an allosteric inhibition of the cytochrome P450 aromatase enzyme, which aids conversion of testosterone to estradiol. Low progesterone levels suggest that Bronx River mussels are experiencing a delay in sexual maturation, and morphometric data show a stalling of shell and tissue growth. To confirm that the mussels collected from both sites are the same species, the universal mitochondrial cytochrome c oxidase subunit I gene was analyzed, through DNA barcoding. Minimal sequential heterogeneity confirmed the mussels are the same species. Such findings suggest intraspecific divergence in various endocrine processes, resulting from environmentally induced stress.

Antioxidant defense responses in Mytella guyanensis (Lamarck, 1819) exposed to an experimental diesel oil spill in Paranaguá Bay (Paraná, Brazil).

We evaluated the effects of diesel oil on the bivalve Mytella guyanensis using biomarkers of oxidative stress (glutathione S-transferase, glutathione peroxidase, and reduced glutathione) after an experimental in situ spill in a mangrove area in southern Brazil. A linear model was developed for the Multiple Before-After Control-Impact (MBACI) experimental design to assess the significance of biological responses. Control and impacted sites were sampled seven and two days before as well as two and seven days after the spill. With the exception of a late response of reduced glutathione (GSH) levels on day seven, none of the biomarkers were significantly altered by the impact. This result was attributed to the high environmental variability of the experimental sites combined with a low sensitivity of Mytella guyanensis to diesel oil at short time-scales. The high resistance of M. guyanensis suggests that its antioxidant response is triggered only after a medium- to long-term exposure to contaminants.

Acute Toxicity of the Lampricide 4-Nitro-3-(trifluoromethyl)phenol to the Mussel (Obovaria subrotunda), Its Host (Percina maculata), and a Surrogate Mussel Species (Obovaria olivaria).

The risk of lampricide applications (such as 4-nitro-3-[trifluoromethyl]phenol [TFM]) to nontarget fauna continues to be a concern within the Great Lakes Fishery Commission Sea Lamprey Control Program, especially among imperiled aquatic species-such as native freshwater mussels. The Grand River (Ohio, USA) is routinely treated for larval sea lampreys (Petromyzon marinus), and this river contains populations of the federally threatened mussel Obovaria subrotunda. Given this spatial overlap, information on the sensitivity of O. subrotunda to TFM is needed. Our objectives were to assess the toxicity of TFM to (1) adult Obovaria olivaria (a surrogate for O. subrotunda), (2) glochidial larvae of O. olivaria and O. subrotunda, (3) juveniles of O. olivaria and O. subrotunda, and (4) adult Percina maculata (host for O. subrotunda glochidia). In acute toxicity tests, TFM was not toxic to glochidia and adult mussels at exposure concentrations that exceed typical treatment rates. Although significant dose-response relationships were observed in hosts and juveniles, survival was ≥95% (Percina maculata), ≥93% (O. olivaria), and ≥74% (O. subrotunda) at typical treatment rates. However, the steep slope of these dose-response relationships indicates that an approximately 20% difference in the treatment level can result in nearly an order of magnitude difference in survival. Collectively, these data indicate that routine sea lamprey control operations are unlikely to acutely affect these species or their host. However, given that many mussel species are long-lived (30-100 years), the risks posed by lampricide treatments in the Great Lakes would be further informed by research on the potential long-term effects of lampricides on imperiled species. Environ Toxicol Chem 2024;43:1423-1430. Published 2024. This article is a U.S. Government work and is in the public domain in the USA.

Integrated transcriptomic and metabolomic approaches reveal molecular response and potential biomarkers of the deep-sea mussel Gigantidas platifrons to copper exposure.

Metal pollution caused by deep-sea mining activities has potential detrimental effects on deep-sea ecosystems. However, our knowledge of how deep-sea organisms respond to this pollution is limited, given the challenges of remoteness and technology. To address this, we conducted a toxicity experiment by using deep-sea mussel Gigantidas platifrons as model animals and exposing them to different copper (Cu) concentrations (50 and 500 µg/L) for 7 days. Transcriptomics and LC-MS-based metabolomics methods were employed to characterize the profiles of transcription and metabolism in deep-sea mussels exposed to Cu. Transcriptomic results suggested that Cu toxicity significantly affected the immune response, apoptosis, and signaling processes in G. platifrons. Metabolomic results demonstrated that Cu exposure disrupted its carbohydrate metabolism, anaerobic metabolism and amino acid metabolism. By integrating both sets of results, transcriptomic and metabolomic, we find that Cu exposure significantly disrupts the metabolic pathway of protein digestion and absorption in G. platifrons. Furthermore, several key genes (e.g., heat shock protein 70 and baculoviral IAP repeat-containing protein 2/3) and metabolites (e.g., alanine and succinate) were identified as potential molecular biomarkers for deep-sea mussel's responses to Cu toxicity. This study contributes novel insight for assessing the potential effects of deep-sea mining activities on deep-sea organisms.

Evaluation of biochemical markers in the golden mussel Limnoperna fortunei exposed to glyphosate acid in outdoor microcosms.

In this study, the impact of technical grade glyphosate acid on Limnoperna fortunei was assessed employing outdoor microcosms treated with nominal glyphosate concentrations of 1, 3 and 6 mg L(-1). At the end of the experiment (26 days), catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), acetylcholinesterase (AChE), carboxylesterases (CES) and alkaline phosphatase (ALP) activities, and lipid peroxidation levels were analyzed. GST and ALP activities and lipid peroxidation levels showed a significant increase with respect to controls in the mussels exposed to glyphosate (up to 90, 500 and 69 percent, respectively). CES and SOD activities showed a significant decrease in glyphosate exposed bivalves with respect to controls (up to 48 and 37 percent, respectively). CAT and AChE did not show differences between exposed and no exposed bivalves. The increase in lipid peroxidation levels and the decrease in SOD and CES activities observed in L. fortunei indicate that glyphosate had adverse effects on the metabolism of this bivalve. The results of the present study also indicate that a "multibiomarker approach" provides a more precise knowledge of the impact of glyphosate on L. fortunei.

[Adaptation of the cholinergic system of Crenomytilus grayanus (Bivalvia, Mytilidae) to the impact of natural and anthropogenic conditions].

The effects of environmental conditions on cholinesterase activity and kinetic parameters of substrate hydrolysis in the hemolymph of the mussel Crenomytilus grayanus were studied. Under seasonal upwellings, the cholinergic system efficiency is provided for by a wide range of efficient concentrations of the substrate, i.e., under such conditions the mussels at the molecular level have a quantitative adaptation strategy of the enzyme. In mussels from the stationary upwelling zone (at a steady low temperature of water) for efficiency of the cholinergic system, the quantitative strategy of enzyme adaptation is realized. In mussels from a highly contaminated site, irreversible damages to the cholinergic process were observed. The affinity of the substrate to the enzyme is highly informative and an appropriate biomarker for the load level and the adaptation capacity of the organism. The affinity of the substrate to the enzyme is recommended as a new biomarker.

Biochemical and metabolic responses of the deep-sea mussel Bathymodiolus platifrons to cadmium and copper exposure.

Greater interest in commercial deep-sea mining has been accompanied by mounting environmental concerns, including metal contamination resulting from mining activities. However, little is known about the toxic effects of metal exposure on deep-sea life. Given its ability to accumulate metals from the surrounding environment, its wide distribution at both vents and seeps, and its high abundance, the deep-sea mussel Bathymodiolus platifrons could serve as an ideal model to investigate the toxicological responses of deep-sea organisms to metal exposure. Here, we evaluated metal accumulation, traditional metal-related biomarkers, namely acid phosphatase (ACP), alkaline phosphatase (AKP), superoxide dismutase, catalase, reduced glutathione, metallothioneins, and malondialdehyde, as well as metabolic profiles in the gills of B. platifrons after a 7-day exposure to copper (100 µg/L), cadmium (500 µg/L), or copper-plus-cadmium treatments (100 µg/L Cu and 500 µg/L Cd). Metal exposure concentrations selected in this study can be found in deep-sea hydrothermal environments. Metal exposure resulted in significant metal accumulation in the gills of the mussel, indicating that B. platifrons has promise for use as an indicator of deep-sea metal pollution levels. Traditional biomarkers (AKP, ACP, and measured antioxidants) revealed cellular injury and oxidative stress in mussels following metal exposure. Metabolic responses in the three treatment groups indicated that metal exposure perturbed osmoregulation, energy metabolism, and nucleotide metabolism in mussels, in a response marked by differentially altered levels of amino acids, hypotaurine, betaine, succinate, glucose 6-phosphate, fructose 6-phosphate, guanosine, guanosine 5'-monophosphate, and inosine. Nevertheless, several uniquely altered metabolites were found in each treatment exposure group, suggesting dissimilar modes of toxicity between the two metal types. In the Cd-exposed group, the monosaccharide D-allose, which is involved in suppressing mitochondrial ROS production, was downregulated, a response consistent with oxidative stress in Cd-exposed B. platifrons. In the Cu-exposed group, the detected alterations in dopamine, dopamine-related, and serotonin-related metabolites together suggest disturbed neurotransmission in Cu-exposed B. platifrons. In the Cu-plus-Cd group, we detected a decline in fatty acid levels, implying that exposure to both metals jointly exerted a negative influence on the physiological functioning of the mussel. To the best of our knowledge, this is the first study to investigate changes in metabolite profiles in Bathymodiolus mussels exposed to metal. The findings reported here advance our understanding of the adverse impact of metal exposure on deep-sea life and can inform deep-sea mining assessments through the use of multiple biomarkers.

Sub-lethal effects of cadmium on the antioxidant defence system of the hydrothermal vent mussel Bathymodiolus azoricus.

The mussel Bathymodiolus azoricus is one of the most abundant species in the Mid-Atlantic Ridge hydrothermal vents and is continually exposed to the high-temperature venting fluids containing high metal concentrations and enriched in sulphides and methane, which constitute a potential toxic environment for marine species. The aim of this study was to assess the effects of a sub-lethal Cd concentration on the antioxidant defence system of this mussel. B. azoricus were collected at Menez Gwen vent site (37 degrees 51'N, 32 degrees 31'W) and exposed to Cd (50 microg l(-1)) during 24 days, followed by a depuration period of six days. A battery of stress related biomarkers including antioxidant enzymes (superoxide dismutase-SOD, catalase-CAT; glutathione peroxidases-GPx), metallothioneins (MT), lipid peroxidation (LPO) and total oxyradical scavenging capacity (TOSC) were measured in the gills and mantle of B. azoricus. Cd was accumulated linearly during the exposure period in both tissues and no significant elimination occurred after the 6 days of depuration. Antioxidant enzymes activities were significantly higher in the gills. Cyt-SOD, T-GPx and Se-GPx were induced during the experiment but this was also observed in control organisms. Mit-SOD and CAT activities remained relatively unchanged. MT levels increased linearly in the gills of exposed mussels in the first 18 days of exposure. No significant differences were observed between LPO levels of control and exposed mussels. TOSC levels remained unchanged in control and exposed mussels. This suggests that although Cd is being accumulated in the tissues of exposed mussels, MT defence system is enough to detoxify the effect of Cd accumulated in the tissues. Furthermore, other factors besides the presence of Cd are influencing the antioxidant defence system in B. azoricus.

Biochemical biomarkers and metals in Perna perna mussels from mariculture zones of Santa Catarina, Brazil.

The activity of cholinesterase (ChE), glutathione-S transferase (GST), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH) and catalase (CAT) was evaluated in the gill and digestive glands of the Perna perna mussel transplanted to three non-contaminated mariculture zones under the influence of distinct physical-chemical characteristics. Differences among sites for ChE, GST and CAT activities in gill, as well as ChE, GST and G6PDH activity in digestive gland of mussels, were found and possibly related to differences in physicochemical characteristics of the sites and/or biological status of the mussels. Mussels that were transplanted to another, more urbanized site (Ponta do Lessa) with similar physicochemical characteristics to one of the farming sites (Sambaqui), was also chosen to evaluate biomarker responses to pollution. Activities of ChE, GST and GR in the digestive glands and CAT in the gills were higher in the polluted site. GR was the only biomarker to be unaltered in different farming sites, but induced in the pollution site. The trace metal concentrations in the mussels were low and unlikely to cause the changes observed in the biomarker levels. The present study strongly suggests that monitoring programs should compare sites with similar physicochemical characteristics when using a complementary biomarker approach. In addition, the baselines for the biomarkers and metal used in the present study can serve as a reference for the monitoring of these mariculture zones in future monitoring programs employing P. perna.

[Effect of copper ions on spatial density of NO-synthase-positive cells in the intestine of the mussel Crenomytilus grayanus (Mollusca: Bivalvia: Mytilidae) a histochemical study].

By the histochemical method of detection of NADPH-diaphorase (NADPH-d) (EC 1.6.99.1) the state of nitroxidergic enteric nervous system of the mussel Crenomytilus grayanus was studied under conditions of an increased copper concentration in water. Under the action of copper ions the density of distribution of NADPH-d-positive cells has been established to be changed as compared with control throughout 28 days. A sharp rise of proportion of the labeled cells and their enzyme activity was noted after one day of the experiment. The labeled bipolar cells were of dark blue color and were located within the epithelium. There were revealed numerous nerve fibers penetrating the intestinal epithelium throughout its entire length as well as bipolar nerve cells in epithelium of the minor typhlosole and of crystalline style sac; in control molluscs the NADPH-d-positive cells in these parts were absent. After 7 days the difference between control and experimental decreased and remained at this level after 14 days, while after 21 days of exposition the proportion of labeled cells in the experimental mussels was lower than in control, but increased again after 28 days. It is suggested that nitric oxide is an important protective factor of the intestinal epithelium of the mussel C. grayanus and participates in adaptation of this mollusc to action of the elevated concentration of copper ions in water.

Molecular Identification, Characterization, and Expression Analysis of a Metallothionein Gene from Septifer virgatus.

This study provides a preliminary characterization of a metallothionein (MT) gene in Septifer virgatus and highlights its potential use in biomonitoring. The full-length SvMT cDNA and the complete sequence of the SvMT gene were identified using reverse transcriptase PCR coupled with the rapid amplification of cDNA ends and the primer walking method. The SvMT cDNA encodes a protein of 72 amino acids having nine classical Cys-X-Cys motifs. Moreover, the deduced amino acids contained the conserved motif (Cys-x-Cys-x(3)-Cys-Thr-Gly-x(3)-Cys-x-Cys-x(3)-Cys-x-Cys-Lys) of MT family 2. Its molecular mass and isoelectric point were estimated to be 7.01 kDa and 7.00, respectively. BLAST-based searching indicated that SvMT shared 81.0% amino acid sequence identity with Mytilus edulis MT-20-II. The SvMT gene has three coding exons and two introns. After exposure to 1 mg/L cadmium chloride, the expression of SvMT increased 15-fold by 3 days (d), with a maximum expression of 27-fold by 5 d compared with the pre-exposure level. After exposure to 2 mg/L zinc chloride, the expression of SvMT increased 2.5-fold by 3 d and 4.7-fold by 5 d compared with the pre-exposure level. A significant increase in the expression level of SvMT mRNA was observed after the exposure of S. virgatus to the combination of 0.003 mg/L cadmium chloride and 0.2 mg/L zinc chloride compared with the pre-exposure level. Our work indicates that the SvMT gene is associated with stress responses and could be a potential biomarker for marine pollution.

Biotransformation and antioxidant enzymes of Limnoperna fortunei detect site impact in watercourses of Córdoba, Argentina.

The golden mussel Limnoperna fortunei was used as a biomonitor of environmental pollution in the Suquía River basin around Córdoba City (Argentina). The sampling sites along the river were chosen according to their increasing levels of pollutants (e.g. heavy metals) as well as biological oxygen demand (BOD) and chemical oxygen demand (COD). A water quality index (WQI) was constructed from the interaction of several normalized factors that affect the aquatic environment, such as the mentioned pollutants and physico-chemical characteristics of the sampling sites. Activity changes of biotransformation enzyme glutathione S-transferase (GST) and the antioxidant enzymes glutathione peroxidase (GPx), glutathione reductase (GR) and catalase (CAT), after exposure to pollutants, served as biomarkers. Membrane bound GST and antioxidant enzymes responded at the most polluted sampling site within 1 day showing increased activities lasting for 4 days. Further sampling was restricted due to no survival of the animals. Antioxidant enzymes GPx, GR and CAT were sensitive responding to the different pollution scenarios, showing good correlation to the chemical characterization.

Mytilidae as model organisms in the marine ecotoxicology of pharmaceuticals - A review.

Growing production and consumption of pharmaceuticals is a global problem. Due to insufficient data on the concentration and distribution of pharmaceuticals in the marine environment, there are no appropriate legal regulations concerning their emission. In order to understand all aspects of the fate of pharmaceuticals in the marine environment and their effect on marine biota, it is necessary to find the most appropriate model organism for this purpose. This paper presents an overview of the ecotoxicological studies of pharmaceuticals, regarding the assessment of Mytilidae as suitable organisms for biomonitoring programs and toxicity tests. The use of mussels in the monitoring of pharmaceuticals allows the observation of changes in the concentration and distribution of these compounds. This in turn gives valuable information on the amount of pharmaceutical pollutants released into the environment in different areas. In this context, information necessary for the assessment of risks related to pharmaceuticals in the marine environment are provided based on what effective management procedures can be developed. However, the accumulation capacity of individual Mytilidae species, the bioavailability of pharmaceuticals and their biological effects should be further scrutinized.