Sea Mussel Mytilus Galloprovincialis Research Articles

ЭНЕРГЕТИЧЕСКИЙ МЕТАБОЛИЗМ MYTILUS GALLOPROVINCIALIS В УСЛОВИЯХ НИЗКИХ PH МОРСКОЙ ВОДЫ

The problem of acidification of the World Ocean and predicting the consequences for its inhabitants is becoming more and more relevant every year. The effect of short-term pH fluctuations in coastal ecosystems on the physiology of calcifying organisms—bivalves—remains poorly understood. The energy metabolism of the Black Sea mussel Mytilus galloprovincialis was investigated for the marine environment in a wide pH range, from 8.2 to 6.65. Lowering the pH to 7.0–7.5 led to a 20–25 % reduction in oxygen consumption by molluscs. At lower pH (6.54–6.7), aerobic respiration sharply decreased by 85– 90 %, down to the minimum values (2.12–2.62 µgO2/g dry/h), and the organisms transitioned to anaerobic metabolism. The metabolic response of the mussels subjected to short-term pH changes (8.2→6.65→7.2) has been investigated. The oxygen consumption of molluscs exposed at the same pH of 7.2 depended on the direction of the change in pH. Thus, in the case of pH 6.65→7.2, the respiration intensity was 30 % higher compared to the values obtained under the acidification pH 8.2→7.2. The Black Sea mussel M. galloprovincialis is shown to have the capacity for survival in the marine environment characterized by the rapid fluctuations in pH that occur during the upwelling events in the coastal areas of the Black Sea.

ВЛИЯНИЕ НЕФТЯНЫХ УГЛЕВОДОРОДОВ НА БИОХИМИЧЕСКИЕ ПОКАЗАТЕЛИ ЧЕРНОМОРСКОЙ МИДИИ MYTILUS GALLOPROVINCIALIS

Almost all oil components are more or less toxic and have a toxic effect on aquatic organisms, and some groups of petroleum hydrocarbons (PH) can accumulate in organs and tissues and transmitted through food chains. Depending on the duration and scale of PH pollution, a wide range of responses can be observed – from physiological and biochemical, morphological, behavioral anomalies at organism level to structural and functional rearrangements in populations and communities. The study of the biochemical response in tissues of bivalve mollusks living in conditions of elevated PH concentrations in the experiment is necessary to understand the mechanisms of metabolism reorganization and adaptive reactions that occur in the body of hydrobionts when exposed to toxicants. The paper presents the results of a study of the PH effect on the parameters of the prooxidant-antioxidant system parameters (superoxide dismutase and catalase activities, level of lipid peroxidation and oxidized proteins) and amnotransferase activities (alanine aminotransferase and aspartate aminotransferase) in hepatopancreas of the Black Sea mussel Mytilus galloprovincialis in the acute toxicological experiment. The results of the experiment allowed to establish that PH at concentrations of 0.5 mg/l (10 MPC) and 1 mg/l (20 MPC) do not affect the activity of aminotransferases, but stimulate the development of oxidative stress by shifting the prooxidant-antioxidant balance towards the intensification of lipid peroxidation and protein oxidization; at the 1 mg/l concentration PH cause activation of superoxide dismutase and inhibition of catalase activity. Prooxidant-antioxidant system parameters demonstrate high sensitivity to PH and can be used along with other recommended parameters to assess the functional state of mollusks in conditions of oil environmental pollution.

ASSESSMENT OF THE BIOACCUMULATION OF MICROPLASTICS IN THE BLACK SEA MUSSEL Mytilus galloprovincialis L., 1819

The accumulation of microplastics in the world oceans is one of the main global problems of the modern world. The Black Sea is the main source of seafood for people from several countries, including Bulgaria. The pollution of the Black sea is a result of various factors, especially anthropogenic. The aim of this study was to determine the presence and accumulation of microplastics in the Black Sea mussel Mytilus galloprovincialis L., 1819, harvested from different locations along the northern Bulgarian Black Sea coast. Within each microplastic morphological group, three size classes were recognized: 100-200 μm, 25-100 μm, and ≤ 25 μm. Microplastics were found in the soft tissues of all studied specimens but in a different ratio of pellets, fibers and fragments. Generally, the pellets were the most often registered particles, followed by irregularly-shaped fragments, whereas fibers were less numerous. The dominant part of the isolated plastics are made of polyethylene (PE), and polyethylene terephthalate (PET). Our results pointed out serious pollution with plastic particles in the Bulgarian Black Sea aquatory, which in the future may seriously affect the health of the mussel population and also human health.

Determination of the antimicrobial activity of lactic acid bacteria isolated from the Black sea mussel Mytilus galloprovincialis Lamarck, 1819

The present study reports on the determination of the antimicrobial activity of lactic acid bacteria (LAB) isolated from the Black sea mussel Mytilus galloprovincialis Lamarck, 1819. The samples were collected in the period of August 2018 until March 2021. The BIOLOG system was used for microbiological determination. From the mussel M. galloprovincialis Lam. four species of LAB were isolated - Sporolactobacillus kofuensis, Lactobacillus sakei, Streptococcus gallolyticus ss gallolyticus and Lactibacillus brevis. The activity of the strains was determined against test cultures (Escherichia coli 3398, Staphylococus aureus 745, Bacillus subtilis 6633, Salmonella typhimurium 3591, Listeria monocytogens 863 Enterobacter aerogenes 3691, Aspergillus niger, Penicillium claviforme, Saccharomyces cerevisae, Candida albicans 8673 and Candida glabrata 72). Before the analysis for antimicrobial activity, the LAB were cultured in media with different concentrations of sugars - 2, 5 and 10%. The results showed that 4 strains S. kofuensis, L. sakei, S. gallolyticus ss gallolyticus and L. brevis cultured on glucose and oligosaccharides completely lost their activity in all studied variants. Therefore, some carbohydrates (glucose) and oligosaccharides induce the synthesis outside the cell of biologically active molecules, which can probably be attributed to peptides/proteins.

The role of microalgae of the genus prorocentrum in the Diet of mussels mytilus galloprovincialis (Lamarck, 1819) (Black Sea) in suspended culture

The aim of this work was to study the role of microalgae of the genus Prorocentrum in the diet of the Black Sea mussel Mytilus galloprovincialis. The work analyzed the qualitative and quantitative composition of dinophytes of the genus Prorocentrum: P. compressum, P. cordatum, P. micans, P. scutellum, P. pusillum, P. balticum, P. maximum, P. lima in three types of samples (phytoplankton, mussel stomachs and their bio-sediments). Differences in the species composition of microalgae are described for three types of samples. It was noted that P. cordatum and P. micans predominate in plankton in winter, P. balticum and P. cordatum - in spring, P. cordatum, P. micans, P. balticum and P. pussilum - in summer, and P. micans - in autumn. At the same time, P. compressum and P. micans dominate in stomachs throughout the year. P. compressum was found in bio-sediments throughout the year, reaching almost 100% of the total number of dinophytes of the genus Prorocentrum in April; P. micans prevailed in winter, summer and autumn; P. cordatum was dominant in February, March and May. Different types of microalgae of the genus Prorocentrum are expected to have different degrees of digestion.

Recovery of glucosamine and optimization of chitin extraction with acid and alkali process from shells of sea mussel Mytilus galloprovincialis in Greece

Mussel wastes include byproducts such as seed, barnacles fouling, broken shells, byssus threads, which are associated with serious environmental impacts on aquatic ecosystems. The objective of reducing wastes and to avoid environmental problems can be achieved by establishing alternative methods to valorize mussel wastes converting them into high value-added products. The present study aims to obtain by chemical methods the extraction of chitin and glucosamine from shells of Mytilus galloprovincialis. Chitin, which chemically is a linear polysaccharide of β (1→4) linked N-acetylglucosamine monomers, possesses multifunctional properties and is suitable for various applications mainly in pharmaceutical, biomedical food and packaging fields. Glucosamine (C6H13NO5) is an amino sugar (2-amino-2-deoxy-β-D-glucopyranose) and is a part of the structure of two polysaccharides, chitosan and chitin. Due to its high aqueous solubility and physical stability is used as a potential solid-dispersion carrier to improve the biopharmaceutical properties of drugs. The influence of temperature, solid/liquid ratio (g/ml), molarity of solutions and agitation on chitin production and acid hydrolysis of chitin was studied to achieve optimum output of chitin and glucosamine. Our results demonstrates that the production of glucosamine and chitin is greatly influenced by the experimental conditions. The best yield for glucosamine was obtained at a solid/liquid ratio of 1:15 at 60°C for 1 hour.

Recovery of glucosamine and optimization of chitin extraction with acid and alkali process from shells of sea mussel Mytilus galloprovincialis in Greece

Recovery of glucosamine and optimization of chitin extraction with acid and alkali process from shells of sea mussel Mytilus galloprovincialis in Greece

Operativnyy analiz stvorochnoy aktivnosti mollyuskov v avtomatizirovannykh sistemakh ekologicheskogo biomonitoringa

The article describes features of the operational analysis of valve activity of freshwater (Unio pictorum) and marine (Black Sea mussel Mytilus galloprovincialis) bivalve molluscs for created automated systems of bioelectronic environmental control. The studies used measuring data obtained from long-term field and laboratory experiments using instruments developed by the author. The assessment of the mollusc general behavioral characteristics expressed in the dynamics and amplitude of group valve activity as a response to various effects made it possible to determine typical behavioral response models of toxic effects in the aquatic control environment. For the operational analysis, the main statistical indicators are identified, which are used to create software algorithms for automatic decision-making of the environmental biomonitoring system. As these indicators are used first of all the group time-sliding estimates of the synchronism of mollusc reactions, the data of valve activity averaged in different time intervals and the gape level (group and individual). The existence of established models, specified calculated numerical indicators and their permissible limits will ensure the standardization of the approach to detection of toxic factors and further implementation of such biomonitoring systems at control points.

Assessment of recreational potential of Sevastopol bays using bioindication methods

Aim. Study of a group of biochemical parameters of the hepatopancreas and gills of the Black Sea mussel Mytilus galloprovincialis Lam. and the functional indicator of cardiac system adaptivity of mussels from Sevastopol bays with different levels of recreational and anthropogenic impact.Methods. Mussels were collected from four Sevastopol water areas (Kruglaya Bay, Kazachya Bay, Matyushenko Bay and Cape Khrustalnii) in autumn 2018. The bioindication methods used were based on application of functional (cardiac system adaptability) and biochemical indicators (antioxidant enzymes activity [AEA], aminotransferases, the alkaline phosphatase [AP], and products of the lipid peroxidation [LPO] and protein oxidation [PO]) of mussel tissues. The hydrochemical parameters of the investigated areas were determined.Results. The anthropogenic impact on a complex of biochemical indicators of mussels at the sampling sites was shown. At the same time, low values of mussel heart rate (HR) recovery time (Trec) (less than 60 min.) in all sampling sites demonstrated the efficiency of biochemical changes in mussels and the possible use of all tested bays as recreational areas.Conclusion. Results of the present research allow the characterization of the ecological status of these Sevastopol sea water areas and to make recommendations about their rational use. Matyushenko and Kazachya Bays are most suitable for beach recreation and recreational fishery. Kazachya Bay also has favourable conditions for the development of water sports. Kruglaya Bay and Cape Khrustalnii are less ecologically safe and require a series of actions to improve water quality.

ANTIBACTERIAL ACTIVITY OF DIFFERENT EXTRACTS OF BLACK MUSSEL (MYTILUS GALLOPROVINCIALIS) FROM THE BLACK SEA, BULGARIA

Background: Over the past decade, there has been a growing interest in sea bivalves, which are an inexpensive and easily accessible source of high-quality proteins, lipids and secondary metabolites with antimicrobial and anti-fungal potential. Farmed Black Sea mussel (M. galloprovincialis) are promising objects for the study of their antimicrobial potential. Purpose: The aim of this work is to determine the antibacterial activity of different extracts from the Black Sea mussel Mytilus galloprovincialis tissues by using the disc diffusion method with cultures of Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae. Material/Methods: Extraction of mussel tissues was done with different solvents: ethyl acetate (100%), methanol (100%), glycerol:water (50%, 1:1 v/v), ethanol (50%), acetone (70%), hot water. Antimicrobial activities of these extracts from Mytilus galloprovincialis was assessed by the disc-diffusion method. Results: Testing antibacterial activity of black mussels revealed that ethyl acetate extract showed the highest activity against Еscherichia coli (13 mm) and Klebsiella pneumoniae (11 mm) and no activity against Staphilococcus aureus. The glycerol: water extract showed growth inhibition effect against Staphylococcus aureus (11 mm) and Escherichia coli (10 mm), but no effect against Klebsiella pneumoniae. Conclusions: The preliminary information presented in this study showed that the Black Sea farmed mussel could be an interesting source of antibacterial compounds. The glycerol-water extracts of Mytilus galloprovincialis had low antimicrobial activities against Staphylococcus aureus and more important against Escherichia coli.

Таксономічна структура прибережного угруповання обростання, що формується чорноморською мiдiєю Mytilus galloprovincialis

Peculiarities of the taxonomic structure of the coastal fouling community formed by the bivalve mollusk Mytilus galloprovincialis Lamarck, 1819 on the underwater surface of solid substrates located in the Odessa Bay of the Black Sea have been revealed. The qualitative composition, degree of occurrence, size characteristics and features of quantitative development of invertebrates of this community were determined. As part of the fouling community, 65 species of invertebrates belonging to 61 genera, 47 families, 22 orders, 10 classes and 6 types were identified. It was found that among the large taxa of the community Cnidaria, Annelida, Bryozoa, Arthropoda, Mollusca, Chordata, the most numerous species was the Arthropod type. Annelida and Mollusca accounted for one-fifth and one-fourth of all species. The other three types of invertebrates were represented by one or two species. A characteristic feature of the taxonomic structure of the community was that in most cases, each identified genus was represented by only one species, which in specific conditions was the most environmentally plastic representative of it. It is shown that the species structure of the fouling community was characterized by evident dominance of its edificator M. galloprovincialis. The maximum abundance of this species in the community was 11960 sp.·m-2, and biomass – 10328,6 g·m-2. In addition, 12 other invertebrates with 100 % occurrence were key-species of the community. These species, together with those with occurrence of more than 75 %, belonged to the characteristic species of the community. A total of 22 such species were identified. Among other invertebrates, 5 species (P = 50–75 %) were permanent, 8 species (P = 25–50 %) were rare, and 30 species (P <25 %) were random. The most of the organisms in the coastal fouling community of the Odessa Bay are eurybiont species was established. The presence in the fouling community invasive species of bivalve mollusks Arcuatula senhousia (Benson, 1842), which is systematically very close to the Black Sea mussel Mytilus galloprovincialis, was revealed. Due to its opportunistic properties, this mollusk poses a certain threat to the existence of settlements of aboriginal species of bivalve mollusks. The coastal fouling community formed by the Black Sea mussel has a certain degree of stability, as the same species of invertebrates remain characteristic of its taxonomic structure for 40 years.

Стан кісткової тканини курчат-бройлерів за використання у раціоні кормових добавок, виготовлених із морських гідробіонтів

The purpose of the work was to determine the content of Calcium and Phosphorus in bone tissue, as well as the tibia strength index of broiler chickens under using two feed additives made from the waste of primary processing of marine hydrobionts in the diet. The experiment was carried out on “Ross 308” cross broilers, which were divided into 5 groups: 1 control and 4 experimental. Each additive was fed in two ways: by replacing 7% of the diet weight and adding 7% to it. Chickens of the control group were fed only the basic diet (BD), balanced by basic nutrients. Chickens of experimental groups from 20 to 42 days old were additionally fed the feed additives. Chickens D-1 and D-2 groups consumed a mineral feed additive (MFA), D-3 and D-4 groups received a protein-mineral feed additive (PMFA). Moreover, broilers of D-1 and D-3 groups by feed weight received 93% of BD and 7% of MFA and PMFA respectively, D-2 and D-4 groups in addition to BD (100%) received 7% respectively of MFA and PMFA. MFA is milled leaves of the Black Sea Mussel (Mytilus galloprovincialis) and seawater. PMFA contained milled leaves of large and the body of small mussels, waste from the primary processing of red algae Phyllophora nervosa and seawater. As a material for research was considered the chickens’ tibia of of 42 days old. The concentration of total Calcium and inorganic Phosphorus was determined in the middle part of the tibia using a UV mini-1240 SHIMADZU spectrophotometer (Japan) and a set of reagents NPP Filisit-Diagnostika (Ukraine). The bone cross-sectional area was determined by scanning prior to testing with processing in the Compass-3D graphics program. The mechanical parameters of the bones were determined on an FM-1000 testing machine under the action of a double-support bend. The use of feed additives contributed to an increase in the content of Calcium and Phosphorus in the bone tissue of broiler chickens and, accordingly, the strength of the tibia. The Phosphorus content increase took place to a greater extent than Calcium, which caused a decrease in the Calcium-Phosphorus ratio. The content of Calcium and Phosphorus in the bone tissue, as well as the strength of the tibia of the chickens increased due to diet enrichment with feed additives, and not its partial replacement.

DEPENDENCE OF THE PHENOTYPES OF THE MYTILUS GALLOPROVINCIALIS (LAMARCK, 1819) ON THE DEPTH OF GROUND IN THE ODESA BAY OF THE BLACK SEA

Introduction. The Black Sea mussel Mytilus galloprovincialis (Lamarck, 1819) is one of the dominant species of macrozoobenthos and fouling of the Black Sea. It occurs on rocks and stones, on shell, sand and muddy ground, in fouling of metal and concrete hydraulic structures. The species is represented by three phenotypes which have their own specific biological and ecological characteristics. The aim of the work is to analyze the distribution of various phenotypes of the Black Sea mussel over the depths and soils in the area of the Odesa Bay. Methods. The material was mussels, collected in October 2013 p. in the north-western region of the Odesa Bay near the Big Fountain Cape. In two transects 739 specimens of mollusks (12 samples). were collected and processed according to standard methods. Research results and conclusions. Mussel phenotypes Fa, Fb, Fc have been identified in the Odesa Bay. On the shell-sandy soil, mussels were predominant in the mussel phenotype – the average of 1397 ind./m2, in mussel phenotype mussels Fа – 1644,0 g/m2. On the stony ground, the mammalian phenotype Fс – 3400 ind./m2 and 1550.9 g/m2 on average were characterized by a larger number and biomass. The proportion of mussels of the phenotype Fа in the total number varied from 4.8 % (depth – 1 m) to 53.9 % (6 m); in biomass – from 4.7 % (1 m) to 5.8 % (6 m); the share of Fb in the total number was 21.1 % (6 m) – 52.2 % (3 m); in biomass 22.0 % (6 m) – 58.0 % (3 m); the share of Fс varied from 25.0% (6 m) to 52.4 % (1 m); in biomass – from 25.5 % (6 m) to 53.6 % (1 m).

Predation by the gull Larus crassirostris on benthic invertebrates: First report of avian predation on the abalone Haliotis discus hannai

AbstractWe conducted field surveys to study avian predation on invertebrates inhabiting the intertidal and shallow subtidal zones in Otsuchi Bay on the Sanriku Coast. The black‐tailed gull Larus crassirostris was the most frequently observed avian predator, and we observed the gull actively foraging on benthic invertebrates at the study site. In particular, we found frequent predation activities by the black‐tailed gull on the abalone Haliotis discus hannnai. The abalone accounted for 56.3% of the total amount of the prey remains, and the sea urchin Strongylocentrotus intermedius and mussel Mytilus galloprovincialis were also major components of the prey remains and accounted for 14.6% and 11.8% of the total number, respectively. While the gull preys on the abalone over a wide size range (27.0–105.7 mm shell length), smaller size class abalone individuals (<40 mm shell length) were dominant in prey remains compared to the live abalone surveyed in the surrounding habitats. Among four time periods in a day, predation rate on the abalone was highest in the late afternoon. Predation rate on the abalone was higher on rising tides than falling tides, although no clear relationship was confirmed between the predation rate and the tidal height. The predation by the black‐tailed gull might have large impacts on the shallow rocky reef ecosystem.

Genetic Changeability by Loci COI mtDNA for Different Coloring of Shell Phenotypes of Black Sea Mussel Mytilus galloprovincialis Lam. (Mollusca: Bivalvia: Mytilidae)

The variability of the nucleotide sequences of the fragment of the COI gene of the female genome was studied in four phenotypic groups of the Black Sea mollusk Mytilus galloprovincialis. It was shown that the parameters of genomic diversity (the number of haplotypes, haplotypic and nucleotide diversity, and the number of nucleotide substitutions, including pairwise ones) in mussels with dark shell color are significantly higher than in individuals with light color phenotypes. The revealed differences are related to the peculiarities of ecological preferences of mussels with dark and light shells.

Biotic links in the fouling community of Odessa Bay (Black Sea)

This paper reveals the character of the biotic links between the various organisms that compose the fouling community of Odessa Bay (Black Sea). The fouling community of solid substrates is formed by 62 species of invertebrates and 12 species of macrophytes. The edificator species of the community is the Black Sea mussel Mytilus galloprovincialis Lamarck, 1819. The environment-forming role of the mussel, which is represents the core of the corresponding consortia, was examined. The leading role of sessile organisms in the formation of a superorganismic structure that significantly modifies the properties of the environment was revealed. Together with the mussel, this structure is formed by the bivalve mollusc Mytilaster lineatus (Gmelin, 1791) and the barnacle crustacean Amphibalanus improvisus (Darwin, 1854). The proportion of sessile organisms accounts for 24.6% of the total number of species in the community. In this case, they significantly dominate in relative abundance and biomass (78.9% and 98.8%, respectively). The mussels during the process of growth form complexly organized druses, which are peculiar three-dimensional formations, consisting of mussels of different sizes, fastened together with a substrate by an entire network of strong byssus threads. These formations increase the level of heterogeneity of the substrate and increase the variety of available habitats for other animals. The aggregate of these druses is a kind of sedimentary trap in which particles of nutritive detritus accumulate. The availability of accessible habitats, convenient shelters and food reserves attracts various species of invertebrates to the community. Around the core of the consortia a cluster of organisms formed associated with edificator species. An important role is played by trophic links between different mobile organisms and the phyto-component of the community. The ability of the Black Sea mussel to condition the environment, creating favourable conditions for the development of other organisms, characterizes it as an autogenic ecosystem engineer. Trophic and mediopathic links between the organisms that compose the fouling community go beyond it and extend to the inhabitants of the pelagic environment.

The interaction between algal viruses and the mussel Mytilus galloprovincialis Lamarck, 1819 (Bivalvia: Mytilidae) in experiments

The utilization (possible assimilation and concentration in organs) of 99% of algal viruses from the water by the Black Sea mussel Mytilus galloprovincialis was confirmed experimentally. This index depends on the duration of the experiment, the complexity of the morphology of the virus, the age (size) of the mussels, and the presence of a nonindicatory microalga, which allows the experimental conditions to be close to natural and is conducive to the agglutination of viruses in pseudofeces and their enhanced utilization by mussels. It was found that some algal viruses concentrated by filter-feeding mussels return to the environment in the feces and are transported to the bottom (where they can be used by benthivores) or diffuse back into the pelagic zone. The results indicate that mussels have a role in the circulation of marine viruses, utilizing and transferring them from the pelagic to the benthic biotope.

Fat soluble vitamins and fatty acid composition of wild Black sea mussel, rapana and shrimp

Abstract Many studies suggest that marine molluscs are one of the most important dietary sources of fat soluble vitamins (E, D3 and A) and essential fatty acids (FA). The most commercially important species from the Bulgarian Black Sea are the Black mussel, rapana and shrimp. There is scarce information in the scientific literature about fat soluble vitamins and FA composition of these Black Sea molluscs. The aims of the present study are to determine and compare fat soluble vitamins content as well as relative daily intake, FA composition and atherogenic index (IA), thrombogenicity index (IT) and flesh-lipid quality index (FLQ) in wild Black Sea mussel (Mytilus galloprovincialis), rapana (Rapana venosa) and shrimp (Crangon crangon). Fat soluble vitamins were analysed simultaneously using RP-HPLC system. The FA profile was analysed by GC-MS. All of the analysed samples presented significant amounts of vitamin E, followed by vitamin A and D3. Black Sea molluscs are excellent sources of fat soluble vitamins, especially for vitamin D3 - one survey provides more than 100% of the RDI established in Bulgaria. The FA composition of total lipids showed significant differences and the present study revealed that SFA content was significantly higher than MUFA (p<0.001) and PUFA (p<0.001) (SFA>PUFA>MUFA) in shrimp and mussel whereas rapana showed opposite trends (PUFA>SFA>MUFA). The omega6/omega3 and PUFA/SFA ratios of the analysed species were greater than the FAO/WHO recommendations.

Evaluation of artificially-weathered standard fuel oil toxicity by marine invertebrate embryogenesis bioassays

Weathering of petroleum spilled in the marine environment may not only change its physical and chemical properties but also its effects on the marine ecosystem. The objective of this study was to evaluate the toxicity of the water-accommodated fraction (WAF) obtained from a standard fuel oil following an environmentally realistic simulated weathering process for a period of 80d. Experimental flasks with 40gL−1 of fuel oil were incubated at 18°C with a 14hlight:10hdark photoperiod and a photosynthetically active radiation (PAR) intensity of 70μEm−2s−1. Samples were taken at four weathering periods: 24h, 7, 21 and 80d. WAF toxicity was tested using the sea urchin (Paracentrotus lividus) and mussel (Mytilus galloprovincialis) embryo–larval bioassays and the aromatic hydrocarbons levels (AH) in the WAF were measured by gas chromatography/mass spectrometry. In contrast with the classic assumption of toxicity decrease with oil weathering, the present study shows a progressive increase in WAF toxicity with weathering, being the EC50 after 80d eightfold lower than the EC50 at day1, whereas AH concentration slightly decreased. In the long term, inoculation of WAF with bacteria from a hydrocarbon chronically-polluted harbor slightly reduced toxicity. The differences in toxicity between fresh and weathered fuels could not be explained on the basis of the total AH content and the formation of oxidized derivatives is suggested to explain this toxicity increase.

Filamin isoforms in molluscan smooth muscle

The role of filamin in molluscan catch muscles is unknown. In this work three proteins isolated from the posterior adductor muscle of the sea mussel Mytilus galloprovincialis were identified by MALDI-TOF/TOF MS as homologous to mammalian filamin. They were named FLN-270, FLN-230 and FLN-105, according to their apparent molecular weight determined by SDS-PAGE: 270kDa, 230kDa and 105kDa, respectively. Both FLN-270 and FLN-230 contain the C-terminal dimerization domain and the N-terminal actin-binding domain typical of filamins. These findings, together with the data from peptide mass fingerprints, indicate that FLN-270 and FLN-230 are different isoforms of mussel filamin, with FLN-230 being the predominant isoform in the mussel catch muscle. De novo sequencing data revealed structural differences between both filamin isoforms at the rod 2 segment, the one responsible for the interaction of filamin with the most of its binding partners. FLN270 but not FLN230 was phosphorylated in vitro by cAMP-dependent protein kinase. As for the FLN-105, it would be an N-terminal proteolytic fragment generated from the FLN-270 isoform or a C-terminally truncated variant of filamin. On the other hand, a 45-kDa protein that copurifies with mussel catch muscle filamins was identified as the mussel calponin-like protein. The fact that this protein coelutes with the FLN-270 isoform from a gel filtration chromatography suggests a specific interaction between both proteins.