Bivalvia: A class in the phylum MOLLUSCA comprised of mussels; clams; OYSTERS; COCKLES; and SCALLOPS. They are characterized by a bilaterally symmetrical hinged shell and a muscular foot used for burrowing and anchoring.Mytilidae: A family of marine MUSSELS in the class BIVALVIA.Mollusca: A phylum of the kingdom Metazoa. Mollusca have soft, unsegmented bodies with an anterior head, a dorsal visceral mass, and a ventral foot. Most are encased in a protective calcareous shell. It includes the classes GASTROPODA; BIVALVIA; CEPHALOPODA; Aplacophora; Scaphopoda; Polyplacophora; and Monoplacophora.Pectinidae: A large family of mollusks in the class BIVALVIA, known commonly as scallops. They possess flat, almost circular shells and are found in all seas from shallow water to great depths.Unionidae: A family of freshwater mussels in the class BIVALVIA. They differ from ZEBRA MUSSELS in that they are larger and posses a larval stage called glochidia, which requires attachment to the GILLS or fins of particular species of FISHES.Gills: Paired respiratory organs of fishes and some amphibians that are analogous to lungs. They are richly supplied with blood vessels by which oxygen and carbon dioxide are exchanged directly with the environment.Perna: A genus of freshwater mussel in the family MYTILIDAE, class BIVALVIA. It is found in tropical and warm temperate coastal waters. Most species have green in their shells.Symbiosis: The relationship between two different species of organisms that are interdependent; each gains benefits from the other or a relationship between different species where both of the organisms in question benefit from the presence of the other.Rivers: Large natural streams of FRESH WATER formed by converging tributaries and which empty into a body of water (lake or ocean).Atlantic OceanDNA, Mitochondrial: Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.RNA, Ribosomal, 16S: Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.DNA, Ribosomal: DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA.Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.Fresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.Acari: A large, subclass of arachnids comprising the MITES and TICKS, including parasites of plants, animals, and humans, as well as several important disease vectors.Corbicula: A genus of freshwater clams, in the family Corbiculidae, class BIVALVIA. It originated in Asia but was introduced in North America and is now found throughout the United States.Spisula: A genus of surf clams in the family Mactridae, class BIVALVIA. They are often used in EMBRYOLOGY research.Echinostomatidae: A family of flukes (TREMATODA) characterized by a collar of spines at their anterior end. The body is elongated and is covered with spines, and the two suckers are usually close together. (Noble et al., Parasitology: the Biology of Animal Parasites, 6th ed, p183)Karyotyping: Mapping of the KARYOTYPE of a cell.In Situ Hybridization, Fluorescence: A type of IN SITU HYBRIDIZATION in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei.Heterochromatin: The portion of chromosome material that remains condensed and is transcriptionally inactive during INTERPHASE.Spermatozoa: Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility.Axoneme: A bundle of MICROTUBULES and MICROTUBULE-ASSOCIATED PROTEINS forming the core of each CILIUM or FLAGELLUM. In most eukaryotic cilia or flagella, an axoneme shaft has 20 microtubules arranged in nine doublets and two singlets.Sperm Tail: The posterior filiform portion of the spermatozoon (SPERMATOZOA) that provides sperm motility.Sperm Motility: Movement characteristics of SPERMATOZOA in a fresh specimen. It is measured as the percentage of sperms that are moving, and as the percentage of sperms with productive flagellar motion such as rapid, linear, and forward progression.Mytilus: A genus of marine mussels in the family MYTILIDAE, class BIVALVIA. The species MYTILUS EDULIS is the highly edible common mussel.Mytilus edulis: A species of mussel in the genus MYTILUS, family MYTILIDAE, class BIVALVIA, known as the common mussel. It has a bluish-black shell and is highly edible.Marine Biology: The study of the origin, structure, development, growth, function, genetics, and reproduction of organisms which inhabit the OCEANS AND SEAS.Muscle Proteins: The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.

Fluorimetric multiparameter cell assay at the single cell level fabricated by optical tweezers. (1/906)

A fluorimetric multi-parameter cell sensor at the single cell level is presented which makes it possible to observe the physiological behavior of different cell lines, different physiological parameters, and statistical data at the same time. Different cell types were immobilized at predefined positions with high accuracy using optical tweezers and adhesion promoting surface layers. The process is applicable to both adherent and non-adherent cells. Coating of the immobilization area with mussel adhesive protein was shown to be essential for the process. Intracellular proton and calcium concentrations in different cell classes were simultaneously imaged and the specific activation of T lymphocytes was demonstrated. This method should be especially useful for drug screening due to the small sample volume and high information density.  (+info)

Tumor-like lesions in the mantle of the mussel Modiolus difficilis from the Sea of Japan. (2/906)

Two inner growths in the mantle beneath the epithelium were found in 1 of 1000 mussels Modiolus difficilis from Amursky Bay, Sea of Japan, within the city precincts of Vladivostok. Both growths were about 2000 microns in maximal diameter in section and elevated slightly above the mantle surface. The mantle epithelium near the growths formed deep invaginations, and clusters of mucous cells were numerous beneath the epithelium. Histological and histochemical methods were employed. Two different kinds of growth were revealed. The off-white growth consisted of cells with thin granular or vesicular cytoplasm containing glucosaminoglycans, proteins and a small amount of neutral polysaccharides. Growth cells were pure white in color after treatment of preparations with 1% H2SO4 and differed markedly from the mantle cells. The yellow growth consisted of large granular cells with neutral polysaccharides and proteins. Although growths were composed of different kinds of cells, they seemed to be derived from subepithelial mucous cells. This was supported by histological and histochemical staining reactions of some tumor and mantle epithelial cells. Mitotic indices (MI) of growths and subepithelial mucous cells were zero, MI of ciliated mantle epithelium reached 0.07%. The lesions were areas of strongly altered mucous cells of mantle epithelium and were non-neoplastic.  (+info)

Heart action of the freshwater bivalve Anodonta anatina during activity. (3/906)

1. Heart action of Anodonta anatina (L.) was investigated by recording the electrocardiogram (ECG), heart impedance, and ventricular and pericardial cavity pressure during different aspects of the normal behaviour. The contribution of mechanical and nervous mechanisms in controlling changes in heart action is discussed. 2. Pressure recordings were generally more reliable than the other methods and it is suggested that pericardial pressure pulses indicate the stroke volume output of the ventricle. 3. During spontaneous periods of prolonged shell closure there was an initial small increase in heart activity followed by a large reduction in both heart rate and systolic pressure, indicating that total heart output was considerably reduced. When the shell reopened, heart rate increased very rapidly with an initial overshoot of the normal level; systolic pressure increased more slowly with no overshoot. 4. These major changes in heart activity appear to be associated with respiratory changes and are controlled largely by the nervous regulatory system, but some minor rhythmic variations in the amplitude of heart beat are probably caused by mechanical factors. 5. Characteristic patterns of change in heart action were recorded during burrowing. These appear to result from haemodynamic changes associated with the muscular movements of the digging cycle. Control of the heart by the nervous regulatory system is apparently of much greater importance in relation to respiratory control than in relation to the haemodynamic functioning of the fluid-muscle system in locomotion.  (+info)

Dynein is required for spindle assembly in cytoplasmic extracts of Spisula solidissima oocytes. (4/906)

Meiosis I spindle assembly is induced in lysate-extract mixtures prepared from clam (Spisula solidissima) oocytes. Unactivated lysate prepared from unactivated oocytes contain nuclei (germinal vesicles, GVs) which house condensed chromosomes. Treatment of unactivated lysate with clarified activated extract prepared from oocytes induced to complete meiosis by treatment with KCl induces GV breakdown (GVBD) and assembly of monopolar, bipolar, and multipolar aster-chromosome complexes. The process of in vitro meiosis I spindle assembly involves the assembly of microtubule asters and the association of these asters with the surfaces of the GVs, followed by GVBD and spindle assembly. Monoclonal antibody m74-1, known to react specifically with the N terminus of the intermediate chain of cytoplasmic dynein, recognizes Spisula oocyte dynein and inhibits in vitro meiosis I spindle assembly. Control antibody has no affect on spindle assembly. A similar inhibitory effect on spindle assembly was observed in the presence of orthovanadate, a known inhibitor of dynein ATPase activity. Neither m74-1 nor orthovanadate has any obvious affect on GVBD or aster formation. We propose that dynein function is required for the association of chromosomes with astral microtubules during in vitro meiosis I spindle assembly in these lysate-extract mixtures. However, we conclude that dynein function is not required for centrosome assembly and maturation or for centrosome-dependent aster formation.  (+info)

Ca2+ is required for phosphorylation of clam p82/CPEB in vitro: implications for dual and independent roles of MAP and Cdc2 kinases. (5/906)

During early development gene expression is controlled principally at the translational level. Oocytes of the surf clam Spisula solidissima contain large stockpiles of maternal mRNAs which are translationally dormant or masked until meiotic maturation. Fertilisation of the oocyte leads to rapid polysomal recruitment of the abundant cyclin and ribonucleotide reductase mRNAs at about the time they undergo cytoplasmic polyadenylation. Clam p82, a 3' UTR RNA-binding protein, and a member of the CPEB (cytoplasmic polyadenylation element binding protein) family, functions as a translational masking factor in oocytes and as a polyadenylation factor in fertilised eggs. In meiotically maturing clam oocytes, p82/CPEB is rapidly phosphorylated on multiple residues to a 92-kDa apparent size, prior to its degradation during the first cell cleavage. Here we examine the protein kinase(s) that phosphorylates clam p82/CPEB using a clam oocyte activation cell-free system that responds to elevated pH, mirroring the pH rise that accompanies fertilisation. We show that p82/CPEB phosphorylation requires Ca2+ (<100 microM) in addition to raised pH. Examination of the calcium dependency combined with the use of specific inhibitors implicates the combined and independent actions of cdc2 and MAP kinases in p82/CPEB phosphorylation. Calcium is necessary for both the activation and the maintenance of MAP kinase, whose activity is transient in vitro, as in vivo. While cdc2 kinase plays a role in the maintenance of MAP kinase activity, it is not required for the activation of MAP kinase. We propose a model of clam p82/CPEB phosphorylation in which MAP kinase initially phosphorylates clam p82/CPEB, at a minor subset of sites that does not alter its migration, and cdc2 kinase is necessary for the second wave of phosphorylation that results in the large mobility size shift of clam p82/CPEB. The possible roles of phosphorylation for the function and regulation of p82/CPEB are discussed.  (+info)

Actin filament-membrane attachment: are membrane particles involved? (6/906)

The association of actin filaments with membranes is an important feature in the motility of nonmuscle cells. We investigated the role of membrane particles in the attachment of actin filaments to membranes in those systems in which the attachment site can be identified. Freeze fractures through the end-on attachment site of the acrosomal filament bundles in Mytilus (mussel) and Limulus (horseshoe crab) sperm and the attachment site of the microvillar filament bundles in the brush border of intestinal epithelial cells were examined. There are no particles on the P face of the membrane at these sites in the sperm systems and generally none at these sites in microvilli. In microvilli, the actin filaments are also attached along their lengths to the membrane by bridges. When the isolated brush border is incubated in high concentrations of Mg++ (15 mM), the actin filaments form paracrystals and, as a result, the bridges are in register (330 A period). Under these conditions, alignment of the particles on the P face of the membrane into circumferential bands also occurs. However, these bands are generally separated by 800-900 A, indicating that all the bridges cannot be directly attached to membrane particles. Thus membrane particles are not directly involved in the attachment of actin filaments to membranes.  (+info)

Interspecies transfer of female mitochondrial DNA is coupled with role-reversals and departure from neutrality in the mussel Mytilus trossulus. (7/906)

Mussels of the genus Mytilus have distinct and highly diverged male and female mitochondrial DNA (mtDNA) genomes with separate routes of inheritance. Previous studies of European populations of Mytilus trossulus demonstrated that 33% of males are heteroplasmic for a second mtDNA genome of increased length and that hybridization with Mytilus edulis does not block mtDNA introgression, in contrast to reports for American populations. Here, we demonstrate that the female mtDNA type of M. edulis has replaced the resident female mtDNA type of European M. trossulus. This is supported by COIII sequence data indicating that the female mtDNA of European M. trossulus is very similar to that of M. edulis and that in phylogenetic trees, the mtDNAs of these two species cluster together but separately from American M. trossulus sequences, the latter not being disturbed by introgressive hybridization. We also provide evidence that the mtDNA genome of increased length found in heteroplasmic males of European M. trossulus derives from a recent partition of an introgressed M. edulis female type into the male route of transmission. Neutrality tests reveal that European populations of M. trossulus display an excess of replacement polymorphism within the female mtDNA type with respect to conspecific American populations, as well as a significant excess of rare variants, of a similar magnitude to those previously reported for the invading European M. edulis mtDNA. Results are consistent with a nearly neutral model of molecular evolution and suggest that selection acting on European M. trossulus mtDNA is largely independent of the nuclear genetic background.  (+info)

Mytilus mitochondrial DNA contains a functional gene for a tRNASer(UCN) with a dihydrouridine arm-replacement loop and a pseudo-tRNASer(UCN) gene. (8/906)

A 2500-nucleotide pair (ntp) sequence of F-type mitochondrial (mt) DNA of the Pacific Rim mussel Mytilus californianus (class Bivalvia, phylum Mollusca) that contains two complete (ND2 and ND3) and two partial (COI and COIII) protein genes and nine tRNA genes is presented. Seven of the encoded tRNAs (Ala, Arg, His, Met(AUA), Pro, Ser(UCN), and Trp) have the potential to fold into the orthodox four-armed tRNA secondary structure, while two [tRNASer(AGN) and a second tRNASer(UCN)] will fold only into tRNAs with a dihydrouridine (DHU) arm-replacement loop. Comparison of these mt-tRNA gene sequences with previously published, corresponding M. edulis F-type mtDNA indicates that similarity between the four-armed tRNASer(UCN) genes is only 63.8% compared with an average of 92.1% (range 86.2-98. 5%) for the remaining eight tRNA genes. Northern blot analysis indicated that mature tRNAs encoded by the DHU arm-replacement loop-containing tRNASer(UCN), tRNASer(AGN), tRNAMet(AUA), tRNATrp, and tRNAPro genes occur in M. californianus mitochondria, strengthening the view that all of these genes are functional. However, Northern blot and 5' RACE (rapid amplification of cDNA ends) analyses indicated that the four-armed tRNASer(UCN) gene is transcribed into a stable RNA that includes the downstream COI sequence and is not processed into a mature tRNA. On the basis of these observations the M. californianus and M. edulis four-armed tRNASer(UCN) sequences are interpreted as pseudo-tRNASer(UCN) genes.  (+info)

  • On becoming cemented: evolutionary relationships among the genera in the freshwater bivalve family Etheriidae (Bivalvia: Unionoida). (
  • This is a list of the marine Mollusca Bivalvia recorded from Ireland. (
  • Biomonitoring study of an estuarine coastal ecosystem, the Sacca di Goro lagoon, using Ruditapes philippinarum (Mollusca: Bivalvia). (
  • Tropical deep-water lucinids (Mollusca: Bivalvia) from the Indo-Pacific: essentially unknown, but diverse and occasionally gigantic. (
  • 1989. Ultrastructural characteristics of spermatogenesis in Pecten maximus (Mollusca, Bivalvia). (
  • 1995. Estudo ultraestrutural da espermatogenese de Donax striatus Linnaeus (Mollusca, Bivalvia) do litoral norte do Brasil. (
  • 1989. Ultrastructural and cytochemical study of spermatogenesis in Scorbicularia plana (Mollusca, Bivalvia). (
  • Beninger, P.G., Le Pennec, M. and Salaun, M. (1988) New observations of the gills of Placopecten magellanicus (Mollusca: Bivalvia), and implications for nutrition. (
  • Observations on the symbiosis with zooxanthellae among the tridacnidae (Mollusca, Bivalvia). (
  • Identifying robust proxies of gonad maturation for the protandrous Hermaphrodite Tridacna maxima (Roding, 1798, bivalvia) from individual to population scale. (
  • In the Bivalvia, a model system for macroevolution and macroecology, this taxonomic trend is accompanied by a decline in the number of functional groups and an increase in the evenness of taxa distributed among those groups, with maximum functional evenness (FE) in polar waters of both hemispheres. (
  • Beninger PG, Dufour SC (1996) Mucocyte distribution and relationship to particle transport on the pseudolamellibranch gill of Crassostrea virginica (Bivalvia: Ostreidae). (
  • This symposium was convened to commemorate the work of C. M. Yonge, who throughout his long career was a master theorist who sought to integrate many originally disjunct observations on morphology and morphological functions in the Bivalvia. (
  • Testing alternative hypotheses of Neotrigonia (Bivalvia: Trigonioida) Phylogenetic relationships using Cytochrome c Oxidase Subunit 1 DNA sequences. (
  • Comparative morphometrics of the acrosomes of the sperms of "externally" and "internally" fertilizing sperms of the shipworms (Teredinidae,Bivalvia,Mollusca). (
  • Abnormal features of Macoma balthica (Bivalvia) in the Baltic Sea: alerting symptoms of environmental adversity? (
  • Electrophoretic studies on Sphaerium novaezelandiae Deshayes and Pisidium hodgkini (Suter) (Bivalvia: Sphaeriidae) Sphaerium novaezelandiae and Pisidium hodgkini (24 and 72 individuals respectively) differ in the enzymes esterase, phosphoglucose isomerase and amylase. (
  • Diversity and trans-arctic invasion history of mitochondrial lineages in the North Atlantic Macoma baltica complex (Bivalvia: Tellinidae). (