Cajaraville m p (3 risultati)

he present study has been performed to investigate the ultrastructure and subcellular distribution of several marker enzymes within the Golgi complex of digestive cells of the mussel, Mytilus galloprovincialis. This cell type is involved in the intracellular digestion of food and contains a well-developed lysosomal-vacuolar system and a characteristic cup-shaped Golgi complex. The number and degree of compaction of the tubulo-filamentous structures extending across the distended regions of the cisternae, the number of Golgi stacks per cell and the number of cisternae per stack vary with season and nutritional status of the animals. The degree of compaction of the tubulo-filamentous structures defines the cis- and trans-portions of the Golgi apparatus, the less compacted structures being associated with the cis-portion. Acid phosphatase and arylsulphatase activities are located within some tubules and vesicles in the trans-Golgi network and in some membrane-bounded organelles comprising the lysosomal-vacuolar system. The tubulo-filamentous structures of the dilated rims are reactive for arylsulphatase activity only when located in the trans-portion. Osmium impregnation techniques label all the cisternae of the Golgi complex. No nicotinamide adenine dinucleotide phosphatase activity is present in Golgi bodies or other associated structures in digestive cells. Thiamine pyrophosphatase activity only rarely occurs in some elongate tubules that are interpreted as belonging to trans-cisternae. 10 pp., 5 figs, 2 tabs, 4.…

8 pp., 4 figs, 4.

We examined the distribution and pattern of reactivity of a panel of 16 lectins in the digestive gland of the bivalve mollusc Mytilus galloprovincialis at the light-microscopic level. Various chemical treatments were applied in combination with lectins to differentiate between N- and O-linked oligosaccharides. Several control reactions were carried out, including replacement of lectins by buffer and incubation with their specific competitive inhibitors. Some lectins reacted selectively with particular cell types, thus revealing a cell-specific glycoconjugate distribution pattern which is possibly related to the metabolic role of each cell type in the digestive gland. Glycoconjugates containing glucosamine, mannose, and sulfated galactose were associated with the endolysosomal system of digestive cells. These glycoconjugates were also found in small vesicles randomly distributed in the cytoplasm of adipogranular cells in the connective tissue. However galactosamine residues appeared to be associated mainly with basophilic cells. Fucose residues did not exhibit a cell-specific distribution and appeared in small amounts homogeneously distributed throughout the digestive gland tissue. Conventional histochemical reactions for carbohydrate detection revealed moderate amounts of periodic-acid-Schiff-positive, neutral carbohydrates widely distributed in digestive and connective tissues. Among the acid carbohydrates, most cell types contained complex sulfated carbohydrates, but not carboxylated ones; this agreed well with the complete lack of sialic acid residues in all cell types studied, as observed by lectin histochemistry. 12 pp., 6 figs, 9 tabs, 4.…