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At least 163 records · Page 9Linked to original sources
PubMed1983

Absence of a complete block to polyspermy after fertilization of Mytilus galloprovincialis (mollusca, pelecypoda) oocytes.

Mytilus galloprovincialis oocytes undergo monospermic fertilizations (1 sperm nucleus/oocyte) over a wide range of sperm-oocyte ratios beyond which the number of penetrating sperm increases either linearly or exponentially over 10 min. Artificial activation of oocytes by KCl or the ionophore A 23187, up to the polar body extrusion stage, allows successful fertilizations upon a subsequent insemination. No organized and complete detachment of supernumerary oocyte-bound sperm is detected after fertilization. Reducing the external Na+ concentration promotes a higher rate of fertilizations. These results suggest that no complete block to polyspermy is established in this species but that a partial block, Na+ dependent, might be sufficient to ensure monospermic fertilizations under natural conditions.

Animals↗
PubMed1984

Concanavalin A induces germinal vesicle breakdown in Barnea candida (Mollusca, Pelecypoda) oocytes.

Treatment of Barnea candida oocytes with 5 micrograms/ml Con A or above elicits germinal vesicle breakdown (GVBD), the timing for this event being dose dependent. At 100 micrograms/ml, GVBD occurs within 20 to 30 min, a lag time corresponding to that observed after fertilization. Con A-induced GVBD requires the presence of 2 mM external calcium during all the treatment period while at 10 mM external Ca2+, the calcium-dependent period is slightly reduced. It is sensitive to low pH Na-acetate sea water, 50 microM trifluoperazine, 20 microM D-600 or 2,4-dinitrophenol, as well as to 10 micrograms/ml cytochalasin B. A straightforward interpretation of these data would be that Con A-induced maturation is sustained by an energy-requiring effector mechanism involving intracellular contractile proteins.

Animals↗
PubMed1988

Inhibition of dye-coupling in Patella (Mollusca) embryos by microinjection of antiserum against nephrops (Arthropoda) gap junctions.

Antiserum raised against Nephrops gap junctions was injected into single cells of the 2-, 4-, 8-, 16-, and 32-cell stage of the Patella vulgata embryos. The pattern of junctional communication by iontophoresis of Lucifer Yellow CH was tested at the 32-cell stage. The results show that the normal pattern of dye-coupling at the 32-cell stage is disrupted in greater than 65% of embryos previously injected with antisera. In contrast, less than 15% of embryos injected with preimmune serum exhibited disrupted patterns of dye-coupling. Up to the late 32-cell stage no effect of the antiserum on the pattern of cleavage was detected. This antiserum may provide a powerful tool to investigate the role of junctional communication in later stages of development of Patella embryos.

Animals↗
PubMed1985

The effect of the brain and dorsal bodies of Helisoma duryi (mollusca: pulmonata) on albumen gland synthetic activity in vitro.

Albumen gland explants from Helisoma duryi can be maintained in a liquid culture medium for at least 96 hr. This allows measurement of incorporation of [14C]glucose into newly synthesized polysaccharides both retained in the tissue and released into the medium. The albumen gland basal synthetic activity is much higher in reproductively active than in reproductively inactive snails (maintained in constant darkness, virgin, or without dorsal bodies). The presence of the whole brain or cerebral ganglia (with dorsal bodies) of reproductively active snails in the culture medium stimulates polysaccharide synthesis in albumen gland explants from snails in constant darkness. Addition of dorsal body homogenate to the culture medium stimulates polysaccharide synthesis in albumen gland explants from snails without dorsal bodies. These results show that an endocrine factor from the dorsal bodies and possibly a neuroendocrine factor(s) from the cerebral ganglia directly stimulate polysaccharide synthesis in the albumen gland.

Albumins↗
PubMed1994

Quantity of sporocysts and seasonality of two Rhipidocotyle species (Digenea: Bucephalidae) in Anodonta piscinalis (Mollusca: Bivalvia).

The prevalence of Rhipidocotyle campanula in Lake Kuivasjärvi, northern Finland, was 5.7% (n = 1486) during 1989. The prevalences of R. campanula and R. fennica in Lake Saravesi, central Finland, during 1987 to 1989 were 1.0 and 33.2% (n = 1157), respectively. No clear seasonality in prevalence was found in either species, although miracidia of these digeneans are present only in late summer and autumn. The proportion of infected clams in which the gonad was full of sporocyst tubules was on average 90% for R. campanula and 30% for R. fennica. Clams with only few sporocyst tubules in their gonad were observed most frequently in spring. Old; empty sporocyst ribbons of R. fennica first appeared in the clams during August after the beginning of the cercarial emergence and disappeared slowly thereafter. However, in both species viable sporocyst ribbons with early developmental stages of cercariae were found throughout the year. The emergence of R. fennica cercariae began during July and continued throughout September in Lake Saravesi. The duration of cercariae emergence was found to be up to 72 days in the laboratory. R. campanula cerariae in the northern Lake Kuivasjärvi emerged from mid-June until mid-August.

Animals↗
PubMed1978

Fine structure of muscle insertions on the larval shell and operculum of the nudibranch Phestilla sibogae (Mollusca: Gastropoda) before and during metamorphosis.

In Phestilla, the attachment of the larval body to shell and operculum occurs at muscle insertion sites. Attachment zones are specialized areas of squamous epithelium wherein the cells contain structures considered to be cytoplasmic anchors. The anchors are intracellular organelles consisting of apical and basal hemidesmosomal plaques connected by bundles of tonofilaments which traverse the cells. Muscle-to-epithelium and epithelium-to-shell adhesion is probably due to an extracellular cement. At metamorphosis, both shell and operculum are lost. Electron microscopic investigation of shell and opercular attachment sites during metamorphosis has demonstrated that apical hemidesmosomes lose their integrity and tonofilament bundles pull away from the apical plasmalemma of the epithelial cells as the cells lose contact with the shell or operculum.

Animals↗
PubMed1989

Cross-reactivity of IgE antibodies to caddis fly with arthropoda and mollusca.

We investigated the possibility that subjects with IgE antibodies to an inhalant insect allergen, such as caddis fly, might also have antibodies to cross-reacting carbohydrate determinants (CCDs). IgE antibodies to cross-reacting allergens in caddis flies, mussels, oysters, shrimps, crabs, honeybee, and yellow jacket venoms were determined by RAST, RAST inhibition, and immunoblot studies with sera from three different sources: (1) sera of patients with well-defined inhalant atopy to caddis fly, (2) sera with IgE anti-CCD antibodies from subjects without known exposure to caddis fly, and (3) hyperimmune antisera with IgG anti-CCD antibodies raised as a result of immunization of rabbits with grass-pollen extract, buckwheat glycoprotein, or with honeybee venom. Sera from groups 2 and 3 reacted with Sepharose-coupled caddis fly extract in a RAST-type assay and elicited virtually identical patterns on immunoblots of caddis fly extract separated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereas the sera from group 1 atopic patients did not react with CCD-rich material. However, indications for other types of cross-reacting antibodies were detected. The IgE antibodies of one of the patients studied (who was allergic not only to caddis fly but also to shellfish) were found to detect a cross-reacting homologous protein in extracts of mussel, oyster, shrimp, crab, honeybee, and yellow jacket venom. Preliminary results suggest that this cross-reacting 13 kd protein, the most prominent caddis fly allergen, is an invertebrate hemoglobin (erythrocruorin)-like molecule. These studies suggest the possibility that patients sensitized by exposure to caddis fly antigens could develop allergic reactions during their first exposure to shellfish or to their first bee sting.

Adult↗
PubMed1994

The effects of semi-purified diets on growth and condition of Sepia officinalis L. (Mollusca: Cephalopoda).

The effects of five different surimi diets (fish myofibrillar protein concentrate) on growth and condition of Sepia officinalis were evaluated in terms of individual growth using different morphometric and biochemical parameters. A casein supplemented surimi diet produced significant growth (instantaneous growth rate 0.4-0.8% body weight). The digestive gland-to-body weight ratio increased and the cuttlebone-to-body weight ratio decreased significantly in relation to instantaneous growth rate. The RNA content of mantle muscle increased significantly, while the DNA content of mantle muscle did not change in relation to instantaneous growth rate. Mantle muscle protein content was depleted in cuttlefish with instantaneous growth rate < or = 0. No compensatory food consumption, food conversion or growth was observed for cuttlefish fed surimi diets after refeeding them with a natural diet (thawed raw shrimp). Digestive gland and cuttlebone-to-body weight ratios, and RNA content in mantle muscle could be used as short-term indicators of instantaneous growth rate and condition of cuttlefish. Mantle muscle protein content could be used as a long-term indicator.

Animals↗