Chamelea Gallina Research Articles

Allozymic analysis of some Mediterranean Veneridae (Mollusca: Bivalvia): preliminary notes on taxonomy and systematics of the family

An allozyme analysis on three species of Mediterranean Veneridae (Mollusca: Bivalvia): Callista chione (subfamily Pitarinae), Venus verrucosa (Venerinae) and Chamelea gallina (Chioninae) is presented. The results were compared with the previously obtained allozyme data on Tapes philippinarum, T. decussatus, Venerupis aurea and Paphia undulata (all pertaining to the subfamily Tapetinae). The newly analysed species showed remarkable departures from the Hardy–Weinberg proportions, as commonly observed in several populations of Bivalvia. The present analysis revealed a high level of relationship between C. gallina and Venus verrucosa and suggested that the genus Tapes, as presently defined, should be regarded as an unnatural taxon. The allozyme results are consistent with mitochondrial 16s ribosomal DNA and satellite DNAs analyses on the same species, with the only exception of Callista chione which seems to be basal to (UPGMA method) or even included (Neighbor-Joining method) in the Tapetinae cluster.

Bioavailability of Metals in Sediments of the Dogger Bank (Central North Sea): A Mesocosm Study

There are conflicting arguments surrounding the nature and origins of metal enrichment in sediments from the Dogger Bank (central North Sea) and much speculation as to its biological significance. To help resolve this controversy, a mesocosm approach was evaluated to test whether metal loadings in sediments from the Dogger Bank region display enhanced bioavailability, relative to reference sites off south-west England. This involved the combination of physicochemical characterization of sediments (including porewaters) with bioaccumulation studies, using sediment cores seeded with benthic organisms (bivalves Spisula solida and Venus striatula, the gastropod Turritella communis and the polychaete Melinna palmata).There was little evidence of As, Cu, Hg or Pb bioaccumulation from Dogger cores. In contrast, all species accumulated Cd; Ag concentrations rose by up to fourfold in most bioindicators; and Ni, Cr and Mn burdens also increased, occasionally by as much as 10-fold. Variable, but generally smaller increases in Fe and Zn were observed. Physiological variations in metal bioaccumulation processes, including the ability to regulate essential elements, were responsible for species differences in response—a feature which may contribute to uncertainty in the interpretation and comparison of biomonitoring data. Mesocosm results nevertheless complement earlier field reports of unexpectedly enriched levels of certain metals (notably Cd) in biota from this part of the central North Sea.Characterization of sediments provided some physicochemical explanations for enhanced metal uptake in biota and helped, partly, to define bioavailable and anthropogenic fractions. Thus, whilst total sediment-metal concentrations were not exceptional in Dogger samples, for some metals there was a significant proportion in non-refractory (readily extractable) form, together with relatively high concentrations in interstitial waters—both presumably available for assimilation. Normalization of sediment metals, with respect to grain size and Fe, indicated a homogeneous population of fines (<100μm) in this part of the central North Sea, in terms of anthropogenic influence. This was reflected in uniform bioaccumulation patterns, between sites, making it impossible to establish whether porewaters or sediment extracts were the better surrogates of bioavailable metal. However, both measures appear complementary, and invoke the greater lability of metals in Dogger sediments as the explanation for incidences of increased metal bioaccumulation. The combination of mesocosm exposure of biota and geochemical characterization of sediments, is not a substitute for large-scale survey but is suggested as a cost-effective means of investigating unusual episodes of metal uptake, particularly in areas where intensive field programmes are impractical. The approach may also be useful for screening the biological impact of sediments and wastes destined for disposal in the marine environment.

Differentiation of Clams from Fishing Areas as an Approximation to Coastal Quality Assessment

The quality assessment of fishing areas on the basis of the levels of heavy metals in clams ( Chamelea gallina) was attempted by using discriminant analysis. Five metals, Hg, Pb, Cd, Cu and Zn, were analyzed in the soft edible parts of clams from three fishing areas. The descriptive methods applied to data obtained do not show enough differences between sampling stations for management purposes. Only discriminant analysis is successful in the differentiation between all fishing areas. Through the first discriminant function, the group centroids are proposed as index of different source of clams. These values standardized are proposed as coastal quality index.

Reproductive Cycleso Of the Razor Clam Ensis Siliqua and the Clam Venus Striatula off Vilamoura, Southern Portugal

Annual reproductive cycles of two commercially important bivalves, the razor clam Ensis siliqua and the clam Venus striatula were investigated. Specimens of both species were sampled monthly from a site off Vilamoura, south of Portugal, between June 1992 and May 1993. Gonadal development was monitored using standard histological methods. Observed gametogenic progression was categorized by six stages: (0) inactive; (I) early active gametogenesis; (II) late active gametogenesis; (HI) ripe; (IV) partially spawned; and (V) spent. Both males and females showed a synchronism in gonadal development. The gametogenesis in the razor clam began in December and by late April the gonads were characterized morphologically by an abundance of ripe eggs and sperm. Partially spawned individuals were first encountered in May. All were spent by July. The gametogenic activity in V. striatula began in the months of October/November and continued until March. Spawning occurred between April and early August. Both species reached maturity during the first year of life.

Characterization of a Highly Repeated DNA Family in Tapetinae Species (Mollusca Bivalvia: Veneridae)

A repetitive DNA family (phBglII400) was characterized in the clam species Tapes philippinarum (Veneridae Tapetinae). The tandemly repeated sequences are AT-rich and show a mainly pericentromeric localization, as most satellite DNAs do. Sequence analysis of phBglII400 DNA family showed a high level of intraspecific homogeneity. Furthermore a 200 bp subunit motif within the 400 bp monomer was apparent as well as the existence of two main "open reading frames" along the 400 bp sequence.In order to investigate the possible distribution of this DNA family among Veneridae, Southern blot analyses were performed on genomic DNAs of Tapes decussatus, Venerupis aurea and Paphia undulata (Tapetinae), Callista chione (Pitarinae), Chamelea gallina (Chioninae) and Venus verrucosa (Venerinae). The phBglII400 family has been found in two additional Tapetinae, namely V. aurea and P. undulata, but not in T. decussatus or other analyzed species. This pattern of sat-DNA distribution supports the high level of differentiation of T. decussatus observed in the previous gene-allozyme analysis. All of these suggest a better allocation of T. decussatus to a genus different from that of T. philippinarum.

Mutagenic activation of aromatic amines by molluscs as a biomarker of marine pollution

Mutagenic activation of arylamines by mollusc S9 fractions was evaluated as a biomarker for marine pollution. Two bivalve species were used as bioindicators, the common mussel (Mytilus edulis) and the striped venus (Chamelea gallina). A strain of Salmonella typhimurium overproducing O-acetyltransferase was used as indicator of mutagenicity. Mussels from an area of the North Atlantic Spanish zone that was exposed to an accidental crude oil spill were compared to bivalves from a reference area. C. gallina samples were from low polluted and highly polluted areas of the South Atlantic Spanish littoral. The promutagen 2-aminoanthracene (2-AA) was activated to mutagenic derivative(s) by S9 fractions from both C. gallina and M. edulis. Animals from contaminated sites showed higher arylamine activation capabilities than reference animals. This was further correlated with the mutagenic activities of corresponding cyclopentane-dichloromethane animal extracts. 2–AA activation by mollusc S9 was potentiated by α-naphthoflavone (ANF), known to inhibit PAH-inducible CYP1A cytochromes from vertebrates, but inhibited by methimazole (MZ), a substrate of the flavin monooxygenase (FMO) system. 2–AA–activating enzymes were mainly cytosolic; this localization clearly suggests that such activity could be attributed to soluble enzymes, different from the CYP1A or FMO systems. In conclusion, mutagenic activation of arylamines by mollusc S9, using as indicator a strain of Salmonella typhimurium that overproduces O-acetyltransferase, could be a reliable biomarker for marine pollution. Environ. Mol. Mutagen. 31:282–291, 1998 © 1998 Wiley-Liss, Inc.

Phylogenetic analysis of Veneridae (Bivalvia): comparison of molecular and palaeontological data.

An approximately 400-bp-long portion of the 16s rRNA gene sequence has been determined for the venerid clams Chamelea gallina (Chioninae), Dosinia lupinus (Dosiniinae), Pitar rudis, Callista chione (Pitarinae), Tapes decussatus, T. philippinarum, Venerupis (= Paphia) aurea (Tapetinae), and Venus verrucosa (Venerinae). Neighbor-joining and maximum parsimony trees support the results of traditional classification methods at the subfamily level but do not support the concept of a genus Tapes. The transversion divergence rate estimated on the basis of the palaeontological record for the C. gallina/V. verrucosa separation and for the Pitarinae is very close (0.14-0.16% per Myr, respectively) to that of ungulates and cetaceans, while the Tapetinae exhibit a much higher (0.36% per Myr) rate.

Trace metals in the bivalve mollusc Chamelea gallina from the Atlantic coast of southern Spain

Trace metals in the bivalve mollusc Chamelea gallina from the Atlantic coast of southern Spain

Comparison of Cleanup Techniques for Simple Method for Analysis of Selected Organophosphorus Pesticide Residues in Molluscs

Abstract A simple method for determination of 5 organo phosphorus pesticides (dimethoate, chlorfenvin phos, chlorpyrifos, methidathion, and phosmet) in molluscs (Mytilus galloprovincialis and Venus gallina) was developed, with special attention to cleanup. Organophosphorus pesticides were extracted with acetonitrile-acetone (90 + 10, v/v) in a high-speed blender. Two cleanup procedures were used to defat extracts prior to injection into a gas chromatograph: liquid-liquid partition with acetoni trile-hexane and adsorption column chromatography with silica gel. The latter was more efficient for elimination of fat and fractionation of pesticides with different polarities. Limits of detection of the overall procedure including extraction and cleanup ranged from 0.2 to 1 ng/g. Quantitative recoveries for pesticide concentrations ranging from 1 to 10 000 ng/g were obtained.

Toxicity and bioconcentration of selected organophosphorus pesticides in Mytilus galloprovincialis and Venus gallina

A study on toxicity and bioconcentration of the organophosphorus pesticides dimethoate, methidathion, chlorfenvinphos, chlorpyrifos, and phosmet has been carried out for two species of mollusc (Mytilus galloprovincialis and Venus gallina). The LC50 (96-h) and NOLC (not observable lethal concentration) values were determined and some sublethal effects (the development of functional byssus for M. galloprovincialis and response speed at mechanical stimulation for both) were recorded at nominal pesticide concentrations of 1, 3.2, 5.6, 10, and 32 mg/L; and 56 mg/L only in M. galloprovincialis. Methidathion, chlorfenvinphos, and chlorpyrifos produced mortality and sublethal effects on M. galloprovincialis, but no effect was observed on V. gallina at the concentrations tested. Dimethoate and phosmet did not cause appreciable effects on either of the two species tested. Toxicity of the organophosphorus pesticides tested varied from moderate toxicity to no-effect (in acute tests), depending on the compound and organism that was tested.

Resistance of bivalves to anoxia as a response to pollution-induced environmental stress

The effect of environmental pollution stress factors on anoxic survival time was established in three bivalve molluscs ( Mytilus edulis, Scapharca inaequivalvis and Venus gallina). In order to study relationships with energy status of the cell and ATP turnover rates the accumulation of fermentative end-products and changes in the glycogen, the adenylate phosphate and the phosphoarginine pool were also estimated. The response among the different species was not consistent. In contrast to Scapharca inaequivalvis, in Mytilus edulis and Venus gallina, accumulated cadmium reduced the tolerance to anoxic conditions. In Mytilus edulis this was accompanied with enhanced metabolic activity indicating a higher anaerobic ATP utilization rate. Additional evidence from literature shows that the anoxic survival response of mussels is a simple method to judge whether environmental variables might have perturbing effects on cellular processes which lead to reduced fitness.

Conversion of phosphoenolpyruvate in venus gallina and scapharca inaequivalvis at anoxia stress—I. time dependency

1. 1. The origin of carbon incorporated in succinate in the first 12 hr of environmental anoxia was studied in two bivalve species of the Northern Adriatic Sea. 2. 2. Posterior adductor muscles were excised after various periods of exposure to anoxic seawater and incubated under nitrogen in the presence of metabolic inhibitors (aminooxyacetate, iodoacetate, 3-mercaptopicolinate) and UL- 14C substrates, in order to examine the redirection of glycolytic flux from pyruvate kinase to phosphoenolpyruvate carboxykinase. 3. 3. Changes in the levels of key metabolites and the distribution of radiolabeled glucose and aspartate indicate that PEP-carboxykinase did not participate in anaerobic metabolism of these species for at least the initial 12 hr of anaerobiosis.

Influence of Sediment Grain Size on the Burrowing of Bivalves: Correlation with Distribution and Stratigraphic Persistence of Selected Neogene Clams

Burrowing ability of 21 species of clams from Oregon, New Jersey, and Scotland was determined in each sieved sediment ranging from fine gravel to mud in half phi increments. A burrowing rate index (BRI), which normalizes burrowing time for specimen mass, was calculated for each species in each sediment. Skewness and kurtosis of the profile of average BRI's across the range of grain sizes was used to categorize species as substrate generalists, substrate sensitive, or substrate specialists. Substrate generalists (Anadara ovalis, Mercenaria mercenaria, Astarte sulcata, Venerupis decussata, Venus striatula, Venus casina, Mya arenaria] burrowed slowly into a wide range of grain sizes

Comparison and Evaluation of Different Microbiological Quality Criteria for Shellfish and Shellfish-Growing Waters

The objective of this study is to compare different microbiological criteria based on the control of shellfish-growing waters and shellfish flesh, to assess the microbiological quality of the shellfish harvested in a marine zone affected by discharges of a moderately polluted river. Two species of shellfish grown in Mediterranean countries, cockles (Cardium edule) and striped venus (Chamelea gallina) were chosen to carry out this study. A total of 55 samples of diellfish and sea water were collected over the four seasons of the year. According to the results obtained, the US, EEC and Spanish criteria, based on the level of faecal coliforms in shellfish flesh, guaranteed appropriately their safety for human consumption, but among the criteria based on the level of Escherichia coli, only the Australian criterion has been shown to be totally safe, this microorganism being the best indicator of the presence of Vibrio parahaemolyticus and Salmonella. For the criteria based on the analysis of indicators in seawater, the indicators which relate to the age of faecal pollution, such as spores of clostridium sulfite reducer and faecal streptococci are the best indexes of the presence of pathogens in shellfish. Furthermore, criteria that establish the percentage of water samples that fulfill the microbiological level specified, or log-normal distributions of indicators such as total coliforms, faecal coliforms and E. coli, are better than mean counts.

Relationship Between Indicators of Fecal Pollution in Shellfish-growing Water and the Occurrence of Human Pathogenic Microorganisms in Shellfish

The suitability and efficiency of fecal indicators of pollution to determine the quality of shellfish-growing waters were studied in the estuary of Guadalhorce river (Málaga, Spain). A direct relationship between the concentration of indicator microorganisms in shellfish-growing waters and that of pathogens in shellfish (Cardium edule and Chamelea gallina) has not been established. However, in this study the log-normal distribution of the concentration of sulfite-reducer Clostridium spores, fecal streptococci, and coliphages showed a significant relationship with the detection of Salmonella, Vibrio parahaemolyticus, and Aeromonas hydrophila, respectively.

Metal, mutagenicity, and biochemical studies on bivalve molluscs from Spanish coasts.

Three species of marine bivalve molluscs (Chamelea gallina, Ruditapes decussatus, and Crassostrea gigas) have been studied in order to evaluate the levels of pollution on the South Atlantic Spanish littoral. Several transition metals (Cu, As, Cd, Sn, Hg, Pb) were determined as a general index of total contamination. Animals from putative contaminated areas exhibited higher metal contents than those from cleaner waters. C. gigas showed 5-20-fold higher total metal content than the other two species. The mutagenicity of ethanolic extracts was assayed by using both the His reversion and the Ara forward mutation tests. Mollusc tissues from the three species did not contain genotoxins active on TA98 (frameshift mutations) or TA100 (mainly G:C base-pair substitutions), but did contain direct-acting genotoxins of a polar nature and oxidative type. This was based on the following observations: 1) mammalian metabolic activation was not required for mutagenicity, 2) mutagens were eluted with the polar fraction from XAD-2 columns, and 3) mutagenic responses were observed with Salmonella typhimurium TA102 (A:T base-pair substitutions; sensitive to oxidative damages) and Escherichia coli catalase-deficient (AraR forward mutations) strains. No relevant differences were found in the mutagenicity of mollusc extracts from areas with different pollution levels. Otherwise, our data suggest that, in general, animals living in contaminated environments had fewer genotoxins of oxidative type than those from less polluted areas. Such a result might be explained by the observation of increased levels of a number of detoxifying and antioxidant enzymes, such as glutathione-S-transferase, glutathione-peroxidase, catalase, and superoxide dismutase. Thus, contaminated animals seem to be better protected against the oxidative damages induced by metals, in agreement with their lower malondialdehyde levels. To what extent the responsible mutagenic compounds are of endogenous origins, or "Nature's pesticides" (the major toxic chemicals ingested by phytoplankton filter-feeders), and/or the result of human activities remains to be determined.

Age determination and shell growth of Chamelea gallina (Bivalvia: Veneridae) in the western Mediterranean

Age determination and shell growth of Chamelea gallina (Bivalvia: Veneridae) in the western Mediterranean

Accumulation and Depuration of Pathogenic and Indicator Microorganisms by the bivalve mollusc, Chamelea gallina L, Under Controlled Laboratory Conditions

The comparative accumulation and depuration processes for several microorganisms (Escherichia coli, Salmonella typhimurium, Vibrio parahaemolyticus, Aeromonas hydrophila, Streptococcus faecalis, Staphylococcus aureus, and MS-2 coliphage) by the striped venus, Chamelea gallina, under controlled laboratory conditions were studied. Microorganisms accumulated rapidly in bivalves during the first 6 h, with accumulation rates between 3.2 to 360.5 organisms/h depending on the type of microorganism. The relative patterns and rates of elimination of the microorganisms suggest that they are eliminated from shellfish in two different ways. One is of a mechanical nature that results in microbial elimination during the first 12 h. The other elimination mechanism depends upon the microbial species and their accumulated number. All microorganisms tested were eliminated completely by the molluscs after 3 d of depuration, except MS-2 bacteriophages. Results indicate that MS-2 coliphages may be a more reliable indicator of the microbial depuration efficiency by the shellfish under laboratory conditions than E. coli.

Differential survival of Venus gallina and Scapharca inaequivalvis during anoxic stress: Covalent modification of phosphofructokinase and glycogen phosphorylase during anoxia

Biochemical mechanisms underlying anaerobiosis were assessed in two Mediterranean bivalve species, Scapharca inaequivalvis and Venus gallina, with widely differing tolerances for oxygen lack. These species displayed LT50 values for anoxic survival at 17–18°C of 17 and 4 d, respectively. Succinate and alanine were the major products of 24 h anaerobic metabolism in both species but only S. inaequivalvis further metabolized succinate to propionate. Both species reduced metabolic rate while anoxic but metabolic arrest was more pronounced in S. inaequivalvis. Calculated ATP turnover rate (MATP) during exposure to N2-bubbled seawater was only 4.51% of the aerobic rate in S. inaequivalvis but was 12.68% in V. gallina. To counteract a greater load of acid end products, V. gallina foot showed a significantly greater buffering capacity, 23.38±0.20 slykes, compared to 19.6±0.79 slykes in S. inaequivalvis. The two species also differed distinctly in the enzymatic regulation of anaerobiosis. In V. gallina anoxia exposure caused only a small change in PFK kinetic parameters (a decrease in Ka AMP) and had no effect on glycogen phosphorylase. By contrast, S. inaequivalvis foot showed a strong modification of enzyme properties in anoxia. The percentage of glycogen phosphorylase in the a form dropped significantly only in S. inaequivalvis. Other changes included alterations in the properties of PFK leading to a less active enzyme form in anoxia. Compared to the aerobic enzyme form, PFK from anoxic foot showed a reduced affinity for fructose-6-P (Km increased 2.4-fold), greater inhibition by ATP (I50 decreased 6.8-fold), and an increase in sensitivity to AMP activation (Ka decreased by 50%). These enzyme changes appear to be key to a glycolytic rate depression during anaerobiosis in S. inaequivalvis foot muscle.

Enzymic synthesis of HexNAc-containing disaccharide glycosides

The following disaccharide glycosides were obtained from the appropriate donor and acceptor glycosides by employing glycosidases from the mollusc Chamelea gallina as catalysts: a- d-Gal pNAc-(1 → 3)- a- d-Gal p-OMe ( N-acetyl- a- d-galactosaminidase), β- d-Gal pNAc-(1 → 3)-β- d-Gal p-OMe, β- d-Glc pNAc-(1 → 3)-β- d- Gal p-OMe, and β- d-Glc pNAc-(1 → 6)- a- d-Man p-OMe ( N-acetyl-β- d-hexosaminidase). The regioselectivity of the N-acetyl-β- d-hexosaminidase-catalysed reactions depended on the anomeric configuration of the acceptor. Thus, a- d-Gal p-OMe gave β- d-Glc pNAc-(1 → 6)- a- d-Gal p-OMe almost exclusively, whereas β- d-Galp-OMe gave β- d-Glc pNAc-(1 → 3)-β- d-Gal p-OMe and β- d-Glc pNAc-(1 → 6)-β- d-Gal p-OMe in almost equal amounts. The isolation of the products by chromatography was straightforward.