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PubMed1975

Location of glycogen in spermatids and spermatozoa of the shipworm, Bankia australis (Teredinidae, Bivalvia, Mollusca).

The periodic acid-thiocarbohydrazide-silver proteinate technique and alpha-amylase digestion were used to locate glycogen in the spermatids and sperms of the bivalve Bankia australis. Glycogen was found in the middle piece and around the acrosome in spermatozoa, apparently randomly scattered throughout the cytoplasm of young spermatids, and in a cytoplasmic bead in old spermatids.

Acrosome↗
PubMed1982

Chiton integument: ultrastructure of the sensory hairs of Mopalia muscosa (Mollusca: Polyplacophora).

The dorsal integument of the girdle of the chiton Mopalia muscosa is covered by a chitinous cuticle about 0.1 mm in thickness. Within the cuticle are fusiform spicules composed of a central mass of pigment granules surrounded by a layer of calcium carbonate crystals. Tapered, curved chitinous hairs with a groove on the mesial surface pass through the cuticle and protrude above the surface. The spicules are produced by specialized groups of epidermal cells called spiniferous papillae and the hairs are produced by trichogenous papillae. Processes of pigment cells containing green granules are scattered among the cells of each type of papilla and among the common epidermal cells. The wall or cortex of each hair is composed of two layers. The cortex surrounds a central medulla that contains matrix material of low density and from 1 to 20 axial bundles of dendrites. The number of bundles within the medulla varies with the size of the hair. Each bundle contains from 1 to 25 dendrites ensheathed by processes of supporting cells. The dendrites and supporting sheath arise from epidermal cells of the central part of the papilla. At the base of each trichogenous papilla are several nerves that pass into the dermis. Two questions remain unresolved. The function of the hairs is unknown, and we have not determined whether the sensory cells are primary sensory neurons or secondary sensory cells.

Animals↗
PubMed1978

"Nodules" in the achiasmatic meiosis of Bithynia (Mollusca, Prosobranchia).

In spermatocytes of Bithynia leachi and B. tentaculata, synaptonemal complexes with nodules in an achiasmatic meiosis were demonstrated for the first time by means of the spreading technique. The number and position of the nodules are different in each species and are independent of the length of the chromosomes. Although no crossing over occurs in Bithynia chiasma-like terminal connections of the chromosomes are preserved in diakinesis by the presence of the nodules. --Enzymatic treatments revealed information regarding their composition of alkaline proteins, RNA and DNA. In all proteolytic digestions the nodules more of less retain their position in the central region, while they disappear immediately if SCs are exposed to DNase. On the basis of the results a model of the composition and the function of nodules can be developed considering the concept of a lampbrush-organization of the chromosomes in early meiotic prophase.

Animals↗
PubMed1982

Multiple forms of octopine dehydrogenase in Strombus luhuanus (mollusca, gastropoda, strombidae): genetic basis of polymorphism, properties of the enzymes, and relationship between the octopine dehydrogenase phenotype and the accumulation of anaerobic end products during exercise.

Octopine dehydrogenase (ODH) is electrophoretically polymorphic in the gastropod mollusk Strombus luhuanus. The frequencies of the six electrophoretic phenotypes in the Heron Island population, together with the molecular weight values of 38,000 obtained for each of the three forms of the enzyme, demonstrate that the monomeric enzyme is encoded by three codominant alleles at a single locus. The purified allozymes are indistinguishable in terms of Km values for substrates, product inhibition by octopine and NAD, pH optima, and substrate inhibition by pyruvate. No statistically significant correlations were found between the ODH phenotype and the maximum activities of ODH or alanopine dehydrogenase, the capacity for anaerobic muscle work, or the accumulation of octopine or strombine/alanopine during exercise. It would appear that the ODH allozymes may be functionally equivalent both in vitro and in vivo.

Alleles↗
PubMed1986

Purine nucleoside phosphorylase polymorphism in the genus Littorina (Prosobranchia: Mollusca).

Examination of eight Atlantic species of the genus Littorina by starch gel electrophoresis of purine nucleoside phosphorylase revealed extensive polymorphism within the L. saxatilis complex. In this group, four alleles have been identified. Heterozygotes are four banded, and thus, as in vertebrates, the enzyme is likely to be a trimer. Breeding experiments confirmed the genetic interpretation of the phenotype patterns. Where species of the saxatilis complex [L. saxatilis (=L. rudis), L. arcana, L. nigrolineata, L. neglecta] are sympatric, there are sometimes significant allele frequency differences between them. A fifth allele was present at a high frequency in L. obtusata and L. mariae, and L. littorea and L. neritoides each possessed unique alleles. A total of eight alleles was identified. Densitometric scanning of heterozygote patterns pointed to activity differences between alleles and also showed that, while the heterotrimeric bands were never less intense than the homotrimeric bands, the heterotrimeric bands were sometimes less intense than expected. It is not clear whether this represents nonrandom association of subunits, decreased stability of heterotrimers, or simply an artifact of the staining and quantifying process.

Animals↗
PubMed1989

The experimental receptivity of Helicella (Helicella) itala and Cepaea nemoralis (Mollusca, Helicidae) to larvae of Muellerius sp. and Neostrongylus linearis (Nematoda, Protostrongylidae) from chamois (Rupicapra rupicapra).

Two batches of Helicella (H.) itala (adult specimen) and two of Cepaea nemoralis (adult and young specimens) were experimentally infected with larvae I (L-I) of Muellerius sp. and Neostrongylus linearis obtained from the lungs and faeces of Rupicapra rupicapra. In assess larval development, the number and percentage of the total number of larvae (L-I + L-II - L-III) per mollusc were studied, together with the number and percentage of L-III per snail and the days on which the different larval stages were reached. The development of Muellerius sp. and N. linearis was greater in larvae from faeces. For both species of molluscs, the values for the percentages of the total number of larvae and L-III were higher in N. linearis than in Muellerius sp., but there were no notable differences in the days on which the various larval stages were reached. Both nematodes achieved a greater degree of development in young specimens of C. nemoralis than in adults. Whether the larvae came from faeces or the lungs, H. (H.) itala was a better intermediate host than C. nemoralis for Muellerius sp. and N. linearis.

Animals↗
PubMed1992

Fine structure of the blood-brain interface in the cuttlefish Sepia officinalis (Mollusca, Cephalopoda).

The blood-brain interface was studied in a cephalopod mollusc, the cuttlefish Sepia officinalis, by thin-section electron microscopy. Layers lining blood vessels in the optic and vertical lobes of the brain, counting from lumen outwards, include a layer of endothelial cells and associated basal lamina, a layer of pericytes and a second basal lamina, and perivascular glial cells. The distinction between endothelial cells and pericytes breaks down in small vessels. In the smallest microvessels, equivalent to capillaries, and in venous channels, and endothelial and pericyte layers are discontinuous, but a layer of glial cells is always interposed between blood and neural tissue, except where neurosecretory endings reach the second basal lamina. In microvessels in which cell membranes of the entire perivascular glial sheath could be followed, the glial layer was apparently 'seamless', not interrupted by an intercellular cleft, in ca 90% (27/30) of the profiles. Where a cleft did occur, it showed an elongated overlap zone between adjacent cells. The walls of venous channels are formed by lamellae of overlapping glial processes. In arterial vessels, the pericyte layer is thicker and more complete, with characteristic sinuous intercellular clefts. Arterioles are defined as vessels containing 'myofilaments' within pericytes, and arteries those in which the region of the second basal lamina is additionally expanded into a wide collagenous zone containing fibroblast-like cells and cell processes enclosing myofilaments. The 'glio-vascular channels' observed in Octopus brain are not a prominent feature of Sepia optic and vertical lobe. The organization of cell layers at the Sepia blood-brain interface suggests that it is designed to restrict permeability between blood and brain.

Animals↗