Alicia Mabel García

Mucous Cells in Micropogonias furnieri gills: Histochemistry and Ultrastructure

The characteristics of the mucous cells located in the gills of the fish Micropogonias furnieri were investigated. Using histochemical procedures that included methods for localization and characterization of glycoproteins (GPs), no differences were detected between the mucous cell contents of the primary and secondary lamellae. The GPs were identified with (a) oxidizable vecinal diols; (b) sialic acids and some of their chain variants, C7 or C9; (c) carboxyl groups and (d) sulphate groups. The electron microscope showed large mucous globules of different electro densities from mucous cells located deep in the epithelium between the other epithelial cells; the release of mucus by exocytosis was observed. GPs secreted on the surface of the mucous cells was suggested to be important for the lubrication, protection and inhibition of micro‐organisms. It is possibility that GPs could have similar roles in Micropogonias furnieri gills.

Ultrastructure and histochemical study of glycoconjugates in the gills of the white croaker (Micropogonias furnieri).

The ultrastructure of the primary and secondary lamellae of gills was investigated in a marine teleost, the white croaker. The following cells were identified and briefly described: pavement cells, mucous cells, mitochondria‐rich cells and rodlet cells. These cell types are present throughout the length of the lamellae. They are studied by means of a series of carbohydrate histochemical methods, including lectin procedures. Neutral sugars and substituted sialic acid were detected by means of periodic acid–borohydride reduction–saponification–periodic acid Schiff reaction (PA/Bh/KOH/PAS), saponification–selective periodic acid Schiff reaction (KOH/PA*S) and saponification–selective periodic acid–borohydride reduction–periodic acid Schiff reaction (KOH/PA*/Bh/PAS) histochemical techniques. A battery of seven lectins was used to study binding on tissue sections at the light microscopic level to characterize glycoconjugates in gills. The reaction to Canavalia ensiformis agglutinin (Con‐A), Triticum vulgaris agglutinin (WGA), and Ricinus cummunis agglutinin‐1 (RCA‐1) was weak in pavement cells; unlike Con‐A, the reaction to WGA and RCA‐1 was more intense in mucous cells. Arachis hypogaea agglutinin (PNA) lectin showed a strong reaction in mucous cells. Ulex europaens agglutinin‐1 (UEA‐1) lectin was negative in all cell types. The lectin pattern was similar for both primary and secondary lamellae, except for PNA reaction, which was weak in the pavement cells of the secondary lamella and negative in the pavement cells of the primary lamella.

Lectin histochemical aspects of the ovarian lamellae epithelium of Genypterus blacodes (Schneider, 1801)

The composition and distribution of the glycoconjugates (GCs) secreted by the epithelium of ovarian lamellae with reference to the reproductive biology of Genypterus blacodes (Schneider, 1801) through lectin hi stochemistry is here discussed. In this species, the epithelial cells that line the ovarian cavity presented sharp morphological variations along the reproductive cycle related to the mucus secretion that accompanies oocyte ma turation. During sp awning season, residues of mannose and N-acetylglucosamine were detected in the glycocalyx of those cells using lectinhistochemistry. N- acetylgalactosamine and fucose were also observed in the same zone. The greatest variations in the lectinhistochemical pattern were found in the apical cytoplasm composition in comparison to the basal zone of the cells. The results of the present study were discussed by comparing their possible functional implications.

Allosteric transition of erythrocyte alkaline phosphatase from duchenne muscular dystrophy (DMD) patients and duchenne muscular dystrophy carriers (Homo sapiens)

1. The kinetic properties of the p-nitrophenylphosphatase (EC 3.1.3.1) from erythrocytes was investigated in DMD-patients and DMD-carriers. 2. A different allosteric behaviour in the p-nitrophenylphosphatase from DMD-patients and DMD-carriers compared to controls is supported by the following findings: (a) values of n altered in F- inhibition of (K+)-activated p-nitrophenylphosphatase with Hill coefficients -1.5, -2.2 and -3.1; (b) heterotropic effect of increased concentration of Mg2+ on F- inhibition which is reverted by K+ in DMD-carriers and in control, but not in DMD-patients. 3. Evidence is presented showing that in DMD-patients and in DMD-carriers the interaction membrane-enzyme is different from the corresponding controls.

4-Nitrophenylalkaline phosphatase inhibition in muscular dystrophy

The allosteric behaviour of 4-nitrophenylphosphatase from membrane erythrocytes was investigated in Duchenne muscular dystrophy (DMD) patients, in female carriers and in healthy controls. Cooperative type kinetics with a Hill coefficient of -2.19, -1.71 and -1.54 has been obtained from the inhibition by fluoride in controls, female carriers and Duchenne patients, respectively. Our observation supports the previously described membrane abnormalities in DMD erythrocytes and may extend then to female carriers.