The effects of aroclor 1254 and petrochemical pollutants on cytochrome P450 from the digestive gland microsomes of four species of mediterranean molluscs

The Mediterranean limpet Patella caerulea (Gastropoda, Mollusca) to assess marine ecotoxicological risk: a case study of Tunisian coasts contaminated by metals

Participants in the coastal socio-economy of the Mediterranean Sea, such as industries, aquaculture, urban populations, conglomerates, and tourists, create intense anthropogenic pressures on marine ecosystems (such as the release of trace metals). This raises concerns about their impact on the surrounding environment and on marine organisms, including those collected for human consumption. This study introduces the possibility of using Patella caerulea (Linnaeus 1758), indigenous to the Mediterranean Sea, as a biosentinel of marine pollution. This study proposes coupling environmental (bioaccumulation) and toxicological (redox homeostasis) measures of bioavailability with genetic variability (COI mtDNA) assessments. Concentrations of six trace metals (cadmium, copper, iron, lead, nickel, and zinc) were measured in surface seawater and in P. caerulea individuals collected from four coastal stations on the Tunisian coast where different levels of metal contamination have occurred. The quantified biomarkers involved the determination of antioxidant defense enzymes, catalase (CAT), glutathione peroxidase (GPX), superoxide dismutase (SOD), and the measurement of lipid peroxidation indicated by malondialdehyde (MDA) levels. Our study identified critical levels of metal contamination among locations in the Gulf of Gabes. Concomitantly, the induction of antioxidant biomarkers (especially SOD and GPX) was observed, highlighting the potential of P. caerulea to acclimate to stressful pollution conditions. Molecular analysis of COI (mtDNA) revealed low discrimination between the four P. caerulea populations, highlighting the role of marine currents in the Mediterranean Sea in the dispersal and passive transportation of limpet larvae, allowing an exchange of individuals among physically separated, P. caerulea populations.

A review of the empirical literature on the use of limpets Patella spp. (Mollusca: Gastropoda) as bioindicators of environmental quality

The need to carry out monitoring programs for environmental pollution of coastal ecosystems makes it necessary to increase the number of indicator species in order to have a wide range of suitable organisms for most of the possible toxic substances and ways of exposure. With the purpose of analyzing the suitability of limpets (Patella spp.) for their use in biomonitoring programs, a literature review was performed on 88 cases found in the Web of Science online platform. The capacity of limpets to accumulate metals and hydrocarbons has been examined in several field studies. In most cases there is a clear relationship between body content of a pollutant in soft tissues of limpets and the corresponding environmental level. Likewise, different responses to pollutants have been reported in limpets, including induction of DNA damage, induction of metallothioneins, oxidative stress, decrease of Neutral Red retention or variations in heart rate. Regarding the study of changes in community structure, an uneven response to disturbances (e.g. oil spills, wastewater discharge) by species of the genus Patella has been documented. Moreover, generally limpets respond to pollutants similarly to, or even more effectively than, mussels; therefore, their inclusion as sentinel organisms in regional monitoring plans seems appropriate.

In vivo indirect measurement of cytochrome P450-associated activities in freshwater gastropod molluscs

The cytochrome P450 (CYP) system is widely distributed across phyla and plays a key role in the metabolism of xenobiotic compounds. However, most studies on CYP system were developed on vertebrates and among invertebrates, gastropod molluscs are rarely used. In this context, ethoxycoumarin-O-deethylase (ECOD), ethoxyresorufin-O-deethylase (EROD), and pentoxyresorufin-O-dealkylase (PROD) activities, which are indirect measurements of CYP system, were characterized in two freshwater gastropod molluscs, Potamopyrgus antipodarum, and Valvata piscinalis, to ascertain their potential interest as biomarkers of exposure to chemicals. Activities were measured using an in vivo non lethal method based on the measurement of formed product (resorufin or hydroxycoumarin). This in vivo assay allowed to measure the three activities in P. antipodarum and two of them (ECOD and PROD) in V. piscinalis. The detection of activities and the optimization of experimental design were carried out first and allowed to measure the selected activities for one individual. The modulation of the detected activities was secondly assessed using a polycyclic aromatic hydrocarbon (Benzo(a)pyrene). Based on this non destructive measurement, effect of BaP exposure could be detected on ECOD and EROD activity in P. antipodarum, as well on PROD activity of V. piscinalis after 96 h of exposure. Such an in vivo assay must be further developed to be valuably used to screen the exposure of gastropod species to CYP inducer chemicals and its consequences in terms of fitness of the organisms and of the population.

Comparison of the effects of pollution on the marine bivalve Donax trunculus in the vicinity of polluted sites with specimens from a clean reference site (Mediterranean Sea)

The physiological and biochemical characteristics of tissue samples of the marine mussel, Donax trunculus, from an oil-polluted site (Qiryat Yam) and from a site adjacent to an industrial factory (Frutarom) producing polyvinyl chloride (PVC) were compared with samples from a clean reference site (Akko). All sites were located along the sandy shores of the Israeli Mediterranean Sea. The mussels from the oil-polluted site showed increased activity of the system of active transport of organic anions (SATOA) in the gills and the renocardial organ and also of the multixenobiotic resistance transporter (MXR) in the gills. In contrast, samples collected near the PVC factory showed a decrease in SATOA activity and no increase in the activity of MXR in the gills. Specimens from the reference site demonstrated a redox state of equilibrium between energy production and utilization, while in Donax from both the oil polluted and the PVC-polluted sites, the mitochondrial redox state reflected intensive consumption of energy. No significant changes were found in the activity of reduced glutathione s-transferase (GST) in the cytosolic fraction of the digestive gland of Donax collected from any of the three sites. The data demonstrate a differential increase in the anti-chemical defense systems and an intensification of energy metabolism in the mussels exposed to pollution.

Components of the cytochrome P450-dependent monooxygenase system and 'NADPH-independent benzo[a]pyrene hydroxylase' activity in a wide range of marine invertebrate species

Levels of components of the cytochrome P450 (CYP)-dependent monooxygenase system were characterised in microsomes of major biotransformation tissues, or whole bodies, of 33 species from six phyla of aquatic invertebrates. The phylogenetic distribution of benzo[a]pyrene hydroxylase (BPH) activity in the absence of added NADPH (so-called 'NADPH-independent BPH activity') and presence of NADPH was also examined. Microsomal protein yield was higher in individual tissues than whole tissues. The main components (total CYP and cytochrome b5; NADPH-dependent cytochrome c (CYP) reductase, NADH-dependent cytochrome c reductase and NADH-dependent ferricyanide (b5) reductase activities) were found in most species of the Porifera, Cnidaria, Mollusca, Polychaeta, Crustacea and Echinodermata examined. The so-called '418-peak' of the carbon-monoxide difference spectrum of reduced microsomes was found in all species, indicating the wide distribution of this protein. Total CYP levels (pmol mg(-1) protein; mean+/-SEM) were similar in molluscs (50+/-7), crustaceans (61+/-11) and echinoderms (56+/-9), with the exception of high levels (223-266) in two crustacean species. NADPH-dependent BPH activity (pmol min(-1) mg(-1) protein) was found in 32 species, being lowest in Porifera and Cnidaria (3-4), intermediate in Mollusca (7.8+/-1.3), and highest in Crustacea (25+/-4) and Echinodermata (15+/-4). NADPH-independent BPH activity was evident in 13 out of 15 molluscan species examined, with the addition of NADPH either stimulating (8 species) or inhibiting (5 species) the activity. NADPH-independent BPH activity was also seen in two poriferan species and indicated in three crustacean species, suggesting that the phenomenon is not solely restricted to the Mollusca.

Esterase activities in the bivalve mollusc Adamussium colbecki as a biomarker for pollution monitoring in the Antarctic marine environment

Marine environments are continuously being threatened by a large number of xenobiotics from anthropogenic sources. Even in sparsely populated and relatively pristine areas, such as Antarctica, hazardous chemicals can pose a serious environmental problem. The main aims of the present study were to (1) validate and optimize an analytical technique utilizing a microtitre-plate photometer to ascertain background levels of esterase activities in the Antarctic bivalve Adamussium colbecki, (2) carry out in situ monitoring of esterase activities to assess any potential environmental impacts of the Italian Scientific Antarctic Base "Terra Nova Bay" on the surrounding marine area. Results showed the presence of organophosphorous-sensitive cholinesterase (ChE) and carboxylesterase (CbE) activities in the gills of A. colbecki and optimal assay conditions were comparable with those found for bivalve species from temperate areas. A higher sensitivity of ChE versus acetylthiocholine activity in A. colbecki to chlorpyrifos compared to species from temperate areas may also be inferred. The in situ study indicated no differences in the environmental quality of the three study sites located around the Italian Base.

Cytochromes P450 in liver of the turtle Chrysemys picta picta and the induction and partial purification of CYP1A-like proteins

Cytochromes P450 (CYP) in hepatic microsomes from the turtle Chrysemys picta picta and their response to inducers were examined. Freshly caught turtles had one protein (59 kDa) detected in western blot with monoclonal antibody 1-12-3 to scup CYP1A. That same band and a second band were detected with polyclonal anti-mouse Cyp1a1. Polyclonal anti-scup P450B (putative CYP2B) recognized three bands and anti-scup P450A (putative CYP3A), one band. TCB (3,3',4,4'-tetrachlorobiphenyl) at 5 mg kg-1 injected once induced EROD activity 3-fold. Repeated high-dose injections of TCB, 2,3,3',4,4'-pentachlorobiphenyl, Aroclor 1254 or beta-naphthoflavone induced CYP1A 20-fold and P450B-related proteins 2-3-fold. Rates of ethoxy- (EROD) methoxy- (MROD) and pentoxyresorufin O-dealkylases and benzo[a]pyrene (B[a]P) hydroxylase (AHH) were induced by these treatments, and were correlated with putative CYP1A content. Phenobarbital slightly elevated only MROD activity. Ethoxycoumarin (EC) O-deethylase rates were high, 1.6-2.2 nmol min-1 mg-1 in control and treated turtles, suggesting that EC is not a turtle CYP1A substrate. Highly induced EROD rates were 0.06 nmol min-1 mg-1, while AHH rates exceeded 4 nmol min-1 mg-1, suggesting that C. picta picta CYP1A may prefer PAH substrates. Induction of AHH was reflected in the formation of metabolites 3-OH-, 9-OH- and 7-OH-BP and BP-7,8-dihydrodiol (DHD). BP-4,5-DHD was not detected. Chromatographic procedures resolved the 59 kDa putative CYP1A from the second protein recognized by anti-Cyp1a1. The 59-kDa protein was also specifically and highly immunopurified by Mab 1-12-3. Thus, several CYP including two CYP1A-related proteins are expressed in turtle liver. Multiple CYP1A genes in reptiles may provide an insight into the origin of divergence in the CYP1A subfamily. Induction of a CYP1A may be a useful indicator of exposure to Ah receptor agonists in turtles.

The suitability of gastropods as biomarkers: Induction of ethoxy-, pentoxy- and benzoxyresorufin-O-dealkylase in limnetic gastropods via aroclor 1254

The measurement and induction of mixed function oxyigenases (MFOs) of limnetic gastropods were investigated to estimate their suitability as biomarkers. A determination of MFO activities was performed through the measurement of ethoxyresorufin-O-dealkylase (EROD), pentoxy-(PROD) and benzoxyresorufin-O-dealkylase-activity (BROD). Optimal measuring conditions of these activities were investigated in preparations of the digestive gland of 4 species of limnetic gastropods. Results indicate that MFO-activity inhibiting substances are accumulating in the microsomal pellet, the fraction commonly used for the measurement of MFO-activities. Therefore, the fraction used for induction studies was the postmitochondrial supernatant (PMS). EROD, PROD, and BROD activity of Planorbis planorbis and Planorbis carinatus were measured after a treatment with Aroclor 1254 for 1-17 days. Maximal induction of EROD and PROD were 6 and 10 times the value in the control group of P. carinatus, respectively induction in P. planorbis was lower. BROD-activity could not been measured in P. planorbis. In P. carinatus, BROD-activity increased to a maximum of 2 times after treatment with Aroclor 1254. The level of induction of EROD-activity is comparable to results described in analog studies with fish.