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PubMedDate not supplied

Biomarker responses in Macoma nasuta (Bivalvia) exposed to sediments from northern San Francisco Bay.

Our study investigates biomarker responses and survival of Macoma nasuta exposed to sediments collected from six locations in northern San Francisco Bay. Biomarkers analyzed were stress proteins (hsp70) in gill, mantle and digestive gland, lysosomal membrane damage and histopathologic lesions. Sediments and clam tissues were analyzed for a comprehensive suite of heavy metals and trace organic pollutants. Sediment grain size and organic carbon content were determined. Clams accumulated metals, polyaromatic hydrocarbons (PAHs) and organochlorine pesticides (aldrin and p,p(')-DDT and its metabolites p,p(')-DDD and p,p(')-DDE). Pearson and Spearman correlation analysis revealed that mortality, hsp70 in gill and histopathologic lesion scores in gonads, and lysosomal membrane damage were significantly correlated with tissue concentrations of DDT and/or its metabolites. Tissue concentrations of metals, in particular nickel, chromium, and copper, were associated with macrophage aggregates in digestive gland and germ cell necrosis. Cadmium was linked to mortality and lysosomal membrane damage.

Animals↗
PubMedDate not supplied

The influence of salinity on the heat-shock protein response of Potamocorbula amurensis (Bivalvia).

For biomarkers to be useful in assessing anthropogenic impacts in field studies involving aquatic organisms, they should not be affected by naturally occurring changes in environmental parameters such as salinity. This is especially important in estuarine environments and for relatively unspecific biomarkers like heat-shock proteins (hsps, stress proteins). In this study, the heat-shock protein response was measured in the euryhaline clam, Potamocorbula amurensis, after exposure to a range of salinities reflecting normal and extreme environmental conditions in Northern San Francisco Bay, California. The ability to raise cellular hsp70 levels in response to heat-shock was significantly impaired in P. amurensis collected from a low (0.5 ppt) salinity field site, and after 14 day exposure to low salinity in the laboratory.

Animals↗
PubMed2006

Metal sources to the Baltic clam Macoma balthica (Mollusca: Bivalvia) in the southern Baltic Sea (the Gulf of Gdansk).

Metal concentrations of Cu, Fe, Mn, Ni, Pb and Zn in an infaunal facultative deposit-feeding bivalve, the Baltic clam Macoma balthica, in the Gulf of Gdansk (southern Baltic Sea) were assessed and compared to selected concentrations of metals in the environment. Between October 1996 and September 1997, dissolved and easy extractable (by 1M HCl) metal fractions of total suspended particulate matter (TPM) in the overlying water and of surficial sediments (<63 microm) were measured monthly at five sublittoral sites in the Gulf of Gdansk, and accumulated tissue metal concentrations in M. balthica were determined simultaneously. The study highlights the importance of sediment geochemistry as a factor modifying ambient trace metal bioavailabilities. Surficial sediments appeared to contribute most to the accumulation of Cu and Pb in M. balthica, reflecting the high metal availability in the Gulf. Assimilation of Cu from sediments is controlled by Mn components possibly through an inhibitory effect of Mn oxyhydroxides, while Pb accumulation from sediments depends on the organic content of the sediment. A dual metal uptake pathway, with a suspended particulate-bound fraction and surficial sediments, was apparent for Mn and Zn. Partitioning of Mn in sediments was related to the concentration of labile Fe, with increased levels of Fe tending to inhibit the accumulation of Mn by the clam. Tissue accumulated Zn might have been altered by the clam's internal regulation, making Zn tissue concentrations, to some degree, independent of its environmental level. The principal source of Ni accumulated by the clams exists in the soluble phase.

Animals↗
PubMed2004

Desertification of Mediterranean rocky reefs caused by date-mussel, Lithophaga lithophaga (Mollusca: Bivalvia), fishery: effects on adult and juvenile abundance of a temperate fish.

Macroalgal beds in temperate rocky habitats provide shelter and food for many adult reef fishes and their juvenile stages. In the Mediterranean Sea, the fishery of the endolithic date-mussel Lithophaga lithophaga (which involves dismantling of rocky substrates inhabited by these bivalves) may cause formation of barrens in shallow rocky reefs. Preliminary data collected in SW Apulia (SE Italy) show that rocky reefs impacted by this destructive fishery display different distribution patterns of adult Coris julis (a common labrid fish in the Mediterranean basin), and lower abundance of juveniles. The ecological implications of date-mussel fishery for dynamics of fish populations and rocky-reef ecosystem functioning (e.g., nursery role) are discussed.

Analysis of Variance↗
PubMed2004

Dreissena polymorpha (Bivalvia: Dreissenidae) in the Neva Estuary (eastern Gulf of Finland, Baltic Sea): is it a biofilter or source for pollution?

The zebra mussel Dreissena polymorpha, a ponto-caspian byssate bivalve, forms permanent dense populations along the shoreline in the northern part of the inner Neva Estuary. Its total biomass along a 17 km transect reached 4980 tons (mean 1060 g m(-2)) in 2000 and 6510 tons (mean 1385 g m(-2)) in 2001. Being persistent and abundant, the zebra mussel populations played an important role in benthic-pelagic coupling in inner Neva River Estuary. The D. polymorpha population released up to 514 kg day(-1) of dissolved inorganic phosphorus and was, therefore, a major source of bioavailable nutrients in the area. Mussel beds were also efficient biofilters and precipitate 15,020 kg day(-1) of particulate organic matter during the warm season. About 50% of precipitated matter had a relatively long retention time, being utilized within zebra mussel populations, while the rest was deposited as faeces and pseudofaeces and served as a source for organic pollution to the eastern Gulf of Finland.

Animals↗
PubMed2004

Abnormal features of Macoma balthica (Bivalvia) in the Baltic Sea: alerting symptoms of environmental adversity?

Recent studies of the Baltic clam Macoma balthica (L.) from the southern Baltic (the Gulf of Gdansk) have revealed striking morphological, histological and cytogenetic features. Strong deformation of the shell, including elongation of the posterior end and the appearance of an easily visible flexure in this part, has been recorded. The population contribution of the deformed blunt shelled ("irregular") clams ranged from 0% to 65% and tended to increase with depth. The morphologically "irregular" clams had higher accumulated tissue concentrations of trace metals (As, Ag, Cd, Pb, Cu and Zn), indicating a different metal handling ability. Adverse conditions in deeper water regions of the Gulf (e.g. hypoxia, hydrogen sulphide, elevated bioavailability of contaminants) have been suggested as inducers of the phenotypical changes (morphological deformation) in part of the population and, in parallel, of the specific physiological adaptations that result in higher metal accumulation in the "irregular" clams. Cytogenetic and histological analyses showed the presence of tumours in gill cells and digestive system of the affected clams, the prevalence of disseminated neoplasia ranging from 0% to 94% depending on the site. The disease was manifested by a modified karyotype (i.e. an abnormal number and morphology of chromosomes), a higher activity of nucleolar organizer regions (AgNORs), and tissue lesions (enlarged cells, actively proliferative with pleomorphic nuclei). Bottom sediments showed acute toxicity and have been proposed as a source of an initialising carcinogenic factor. However, none of the ecotoxicological studies provided was successful in the clear demonstration of a single (or multifactorial) agent that can account for the disseminated neoplasia.

Animals↗
PubMed2006

Phylogeny of venus clams (Bivalvia: Venerinae) as inferred from nuclear and mitochondrial gene sequences.

Venerinae (Heterodonta: Veneridae) is a diverse, commercially important, and cosmopolitan marine bivalve subfamily. Recent workers synonymized it with the subfamily Chioninae, due to their overall morphological similarity. The use of traditional shell-based characters alone, however, is questionable for resolving phylogenetic relationships of this group. A phylogenetic study was carried out, based on nucleotide sequences of the mitochondrial large ribosomal subunit (16S), cytochrome oxidase subunit I (COI), and the nuclear protein-coding gene histone 3, to investigate the relationships and circumscription of Venerinae and the phylogenetic pattern of characters in this group. This study consists of a total of 55 taxa: 13 venerine genera, 24 chionine taxa, and 18 taxa of other venerid subfamilies. We analyzed the alignments using a Bayesian approach using Markov Chain Monte Carlo tree sampling and maximum parsimony methods. The resulting phylogenetic hypothesis suggests that Chioninae and Venerinae are actually discrete taxa, but that the circumscription suffered from misplacement of some genera. Our analysis showed that the former chionine genera Chamelea and Clausinella should be placed in Venerinae, as sister taxa to Venus. We re-analyzed morphological and anatomical features in light of the molecular data to describe monophyletic entities. Features of the hinge and internal shell as well as the degree of siphonal fusion are identified as characters to morphologically distinguish the two subfamilies. Of the three genes used in this study, only COI (commonly used as "barcoding" gene) posed substantial problems in obtaining sequence data from older museum material.

Animals↗
PubMed2002

Field and laboratory studies of Ophryoglena sp. (Ciliata: Ophryoglenidae) infection in zebra mussels, Dreissena polymorpha (Bivalvia: Dreissenidae).

This study, conducted in the Dnieper-Bug Canal in Belarus, is the first to monitor the seasonal (June-November) dynamics of infection with the parasitic ciliate Ophryoglena sp. in a zebra mussel (Dreissena polymorpha) population. Mean population prevalence and intensity of infection varied, respectively, from 11 to 62% and from 0.9 to 24.1 ciliates/mussel. Mean prevalence was highly correlated with mussel length in mussels <20 mm (R(2)=0.97) and was lower in larger mussels. Mean infection intensity in mussels 1-25 mm long was similarly correlated with their size (R=0.98), reached a maximum in the 20-25 mm size-class, and then sharply decreased, thus providing evidence, albeit limited, that high intensity of infection might be lethal. Transinfection of zebra mussels by Ophryoglena sp. was achieved in the laboratory-a first for a protozoan parasite of D. polymorpha; from an initial complete lack of infection, mean prevalence and intensity rose, respectively, to 86.7% and 8.3 ciliates/mussel.

Animals↗
PubMed2003

Lysosomal membrane stability, phagocytosis and tolerance to emersion in the mussel Perna viridis (Bivalvia: Mytilidae) following exposure to acute, sublethal, copper.

The mytilid mussel Perna viridis is distributed throughout the Indo-Pacific region and is potentially a suitable candidate for biological effects (biomarker) monitoring in the subtropics. A suite of cytological and physiological responses to acute (48-72 h) copper exposures of 50-200 microgl(-1) were assessed in order to determine the suitability of P. viridis for marine pollution monitoring. Copper elicited significant destabilisation of the haemocyte lysosomal membranes and also impaired phagocytosis. Survival during emersion following exposure to copper was not related to the experimental copper exposures suggesting that higher metal concentrations may be required to interfere with anaerobic enzymes responsible for suppression of metabolism. Based on this preliminary study, cytological biomarkers evaluated in the haemocytes extracted from P. viridis should prove an effective non-destructive means of assessing metal pollution throughout the mussels subtropical range.

Animals↗
PubMedDate not supplied

Phagocytosis associated chemiluminescence of hemocytes in Mytilus edulis (Bivalvia).

The respiratory burst associated with phagocytosis by Mytilus edulis hemocytes was investigated by measurement of luminol-dependent chemiluminescence (LDCL). After experimental parameters (number of cells, quantity of stimulus) were determined, the biochemical mechanisms involved in the chemiluminescent process were investigated using inhibitors of oxygen radicals and enzymes. In particular, catechol-like phenols suggested the involvement of NADPH-oxidase and peroxidase in oxidative metabolism of mussel hemocytes. The variability of LDCL response observed among individuals and separated hemocyte subpopulations strongly suggests a variable immunocapacity depending on hemogram composition. Using a specific monoclonal antibody to discriminate different hemocyte types, the eosinophilic granulocytes appeared to exhibit the highest LDCL activity.

Animals↗
PubMed2001

Environmental toxicity assessment in the Paraná river delta (Argentina): simultaneous evaluation of selected pollutants and mortality rates of Corbicula fluminea (Bivalvia) early juveniles.

Water and sediment samples were collected in the lower Paraná delta at four sites with different levels of exposure to pollution to evaluate the anthropogenic impact through chemical analyses and mortality bioassays. Individual polychlorinated biphenyls, chlorinated pesticides, aliphatic hydrocarbons, polycyclic aromatic hydrocarbons, and heavy metals were measured in waters, porewaters and sediments. The same three phases were also subjected to toxicity assays with straight-hinged juveniles of Corbicula fluminea. Concentrations of several pollutants were above levels recommended for the protection of aquatic life: in waters, Zn, Cu and Cr were 1.6-4.9 times higher, whereas in the sediments Cr was 1.8-3.6, and benzo(a)pyrene was 2.8-5.6 times higher. Pollutant concentrations followed a clear geographic pattern with highest values in the densely populated area of the Reconquista and Luján rivers, lower levels in the San Antonio, and lowest loadings in the remote Paraná de las Palmas. This gradient was adequately matched by the pattern of mortality rates of C. fluminea early juveniles, which were highest in the Reconquista-Luján (40-93%) and lowest (and not significantly different from the control) in the Paraná (3.3-23%). Mortality rates also increased from surface waters (3.3-53%), to porewaters (12-73%), to sediments (23-93%). Although toxicity was probably mainly due to dissolved contaminants, agreement between chemical and biological evidence of pollution was best for the sediment compartment, whereas porewater and surface water showed a higher degree of variability.

Animals↗
PubMed2006

Study on sequences of ribosomal DNA internal transcribed spacers of clams belonging to the Veneridae family (Mollusca: Bivalvia).

The first and second internal transcribed spacer (ITS1 and ITS2) regions of the ribosomal DNA from four species, Meretrix meretrix L., Cyclina sinensis G., Mercenaria mercenaria L., and Protothaca jedoensis L., belonging to the family Veneridae were amplified by PCR and sequenced. The size of the ITS1 PCR amplification product ranged from 663 bp to 978 bp, with GC contents ranging from 60.78% to 64.97%. The size of the ITS1 sequence ranged from 585 bp to 900 bp, which is the largest range reported thus far in bivalve species, with GC contents ranging from 61.03% to 65.62%. The size of the ITS2 PCR amplification product ranged from 513 bp to 644 bp, with GC contents ranging from 61.29% to 62.73%. The size of the ITS2 sequence ranged from 281 bp to 412 bp, with GC contents ranging from 65.21% to 67.87%. Extensive sequence variation and obvious length polymorphisms were noted for both regions in these species, and sequence similarity of ITS2 was higher than that of ITS1 across species. The complete sequences of 5.8S ribosomal RNA gene were obtained by assembling ITS1 and ITS2 sequences, and the sequence length in all species was 157 bp. The phylogenetic tree of Veneridae clams was reconstructed using ITS2-containing partial sequences of both 5.8S and 28S ribosomal DNA as markers and the corresponding sequence information in Arctica islandica as the outgroup. Tree topologies indicated that P. jedoensis shared a close relationship with M. mercenaria and C. sinensis, a distant relationship with other species.

Animals↗
PubMed2003

Two Corbicula (Corbiculidae: Bivalvia) mitochondrial lineages are widely distributed in Asian freshwater environment.

We investigated the biogeography of Asian Corbicula using mitochondrial gene sequence variation for Corbicula members sampled from 24 localities of eight Asian regions. A total of 210 individuals were genetically characterized by examining sequence variations of a 614 bp fragment of the mitochondrial cytochrome oxidase I (COI) gene. Phylogenetic analyses of the COI dataset revealed that Corbicula members are subdivided into two well-supported clades: estuarine and freshwater. A robust dichotomy between the Japanese/Korean (Corbicula japonica) and Chinese (Corbicula fluminalis) estuarine forms was evident, suggesting that these two regional populations represent a deep phylogeographic split. Our mitochondrial gene tree showed that among the freshwater members, two Corbicula mitochondrial lineages are the most common, having attained extensive geographic distribution in the Asian freshwater environment. While the present study provides significant biogeographic information on Asian Corbicula, a comprehensive phylogenetic study by cross-referencing the mitochondrial-based Corbicula phylogeny with nuclear gene data is required to fully understand the evolutionary origin(s) of triploidy/clonality in this genus.

Animals↗
PubMed2003

Free amino acids in the clam Macoma balthica L. (Bivalvia, Mollusca) from brackish waters of the southern Baltic Sea.

Fourteen acidic and neutral free amino acids (FAA) were investigated in soft tissue of Macoma balthica from different depth zones of the Gulf of Gdansk (Baltic Sea) over a full seasonal cycle. The dry weight of the bivalves and physico-chemical parameters of overlying bottom water and surface sediments were measured simultaneously at each site. In the brackish waters of the Baltic, the main pool of FAA is composed of Ala, Gln, Arg, Gly and Orn which represent approximately 80% of the total. Compared to the full saline environments, the composition of FAA in the clams from the Baltic differs substantially. The differences can be attributed to the lower salinity of the Baltic. In the Baltic, Gly appears to play a most important role in regulating intracellular osmolarity in the clams, a function performed primarily by Tau in Atlantic and North Sea populations. Spatio-temporal variations of the FAA are affected by biotic and environmental parameters; their respective influence differs with the amino acids. The concentration of Arg depends on its uptake from the external medium. However, its level might be temporarily modified by stress-induced metabolic transformation (e.g. hydrolysis to Orn) caused by changes in the ambient environment. The concentration of Ala increases with depth, probably because of physiological adaptations of the animal to diminishing oxygen concentration through anaerobic glucose catabolism. Biosynthesis of Ala, similarly to Gln, in the shallower zone is generally related to the physiological state of an organism. The concentration of Gly is most likely regulated by internal mechanisms driven by gonadal development and reproduction.

Alanine↗
PubMed2001

Pernin: a novel, self-aggregating haemolymph protein from the New Zealand green-lipped mussel, Perna canaliculus (Bivalvia: Mytilidae).

A protein, designated pernin, found in the New Zealand green-lipped mussel, comprises almost all of the protein in cell-free haemolymph. It occurs as large, aggregate structures of several hundred units resembling small virus-like particles. Pernin is a non-pigmented, glycosylated protein, composed of 497 amino acids, which has an estimated molecular mass of 60 kDa. It is exceptionally rich in histidine (13.7%) and aspartic acid (12.3%), amino acids both known to participate in the binding of divalent metal cations. In addition, pernin has serine protease inhibitor activity, likely due to a sequence of eight N-terminal amino acid residues, separated from the remainder of the protein via a histidine-aspartate spacer. The pernin monomer comprises three regions of obvious sequence duplication. These make up approximately 95% of the pernin molecule and have sequences clearly homologous to the active-site domain of Cu-Zn SODs (superoxide dismutases). Despite several of the metal ion co-ordinating histidine residues being retained, pernin contains no Cu or Zn. It is, however, associated with Fe with an apparent stoichiometry of 1 atom of Fe to 6 molecules of pernin. Since pernin has no demonstrable SOD activity, these SOD-derived sequences presumably have been modified for another function.

Amino Acid Sequence↗
PubMed1998

Dynamic changes of the microtubule system corresponding to the unequal and spiral cleavage modes in the embryo of the zebra mussel, Dreissena polymorpha (Mollusca, Bivalvia).

Unequal cleavage requires a highly organised cytoskeleton. We investigated the localisation of both tubulins and microtubular arrays in Dreissena eggs during and after fertilisation using confocal laser scanning microscopy. Freshly spawned eggs are arrested in metaphase I. A maternal pool of gamma-tubulin is found mainly in the centre of the asters of the meiotic spindle. The paternal pool of gamma-tubulin, present in the fertilising sperm, could not be traced within the egg, but a microtubule-organising centre forms near the male pronucleus at anaphase II. Male and female pronuclei grow as they migrate in the wake of their aster and rendezvous. First cleavage is unequal and starts without pronuclear fusion. At metaphase the two equal-sized asters span the entire egg in a symmetrical arrangement. At late metaphase the spindle shifts along its longitudinal axis into an eccentric position and the peripheral aster takes on an umbrella-like appearance, whereas the central aster remains spherical. The cleavage furrow becomes determined in the circumferential overlap of the asters. The inequality at second cleavage, however, is due to the unequal size of the asters. The third cleavage spindle also has asymmetrical asters and spindle shift was only observed in the D-cell. The spiral character is a result of an asymmetrical organisation of the larger, vegetal aster. Our results show that the arrangement of the gamma-tubulin clusters and of microtubules changes and develops during early development of Dreissena in a way that can explain the axis-generating asymmetries in cell pattern and the spiral sense of cleavage. The major cytological characters expected to direct pattern formation in this phase of development are: size, position, and symmetry or asymmetry of both spindle and asters.

Animals↗