Adriana L. Goldemberg

Morphological and Histochemical Characterization of the Mucosa of the Digestive Tract in Engraulis anchoita (Hubbs and Marini, 1935)

The histomorphological aspects as well as the histochemical content and distribution of glycoproteins (GPs) in the mucosa of the digestive tract of the anchovy Engraulis anchoita were studied. The buccopharyngeal cavity is lined by a squamous stratified epithelium with mucous superficial cells; the oesophagus shows two zones, cranial with a squamous stratified epithelium with mucous superficial cells and caudal with a columnar secretory epithelium. Finally, the stomach presents both the cranial and pyloric portion lined with a simple columnar epithelium. Tubular branched glands, formed by a single type of glandular cell, located along the stomach, are more numerous in the cranial portion. The GPs were identified with (1) oxidizable vicinal diols; (2) sialic acids and some of their chain variants, C7 or C9; (3) sialic acid residues with O‐acyl substitution at C7 or C8; (4) carboxyl groups and (5) sulphate groups. Histochemical tests showed that the buccopharyngeal cavity presented the largest amount of the different types of mucosubstances. Epithelial secretory cells were found in the oesophagus, which synthesized a large quantity of sialosulphoglycoproteins likely to be related to a protective role. The surface epithelium of the stomach synthesizes and secretes acid and neutral GPs, probably related to the movement of fluids and to the absorption of easily digested substrates, respectively. Although great differences exist between different species, in E. anchoita as in other fish species, the wall of the digestive tract is composed of the four layers classically described for vertebrates. The GPs secreted by the epithelial cells are suggested to be important for the protection and inhibition of microorganisms. In additon, they are involved in enzymatic digestion of food, absorptive functions and lubrication of the alimentary tract.

The effect of fat deprivation on the allosteric inhibition by fluoride of the (Mg2+)-ATPase and (Na+ + K+)-ATPase from rat erythrocytes

Abstract It has been found that the ATPases (ATP phosphohydrolase, EC 3.6.1.3) from rat erythrocytes are inhibited by F − . Allosteric type of kinetics with n = −2.1 for the (Mg 2+ )-ATPase and −2.8 for the (Na + + K + )-ATPase have been obtained for the inhibition by F − . In animals fed fat-deficient diet the value of n for the (Mg 2+ )-ATPase changed from −2.1 to −1.4 and for the (Na + + K + )-ATPase from −2.7 to −1.5. When these animals were then fed fat-sufficient diet the value of n increased to the normal values. The possibility that changes in the unsaturated fatty acid composition of the erythrocyte membrane were responsible for the changes in the value of n is discussed.

Histology and histochemistry of the pharyngeal cavity and oesophagus of the silverside Odontesthes bonariensis (Cuvier and Valenciennes).

The histology of the pharyngeal cavity and oesophagus of the freshwater ‘silverside’Odontesthes bonariensis (Cuvier and Valenciennes) and the characteristics of their mucous cells were investigated. The histological characterization of its digestive wall revealed that the mucosa is thrown with longitudinal folds. The epithelium covering the folds was stratified with abundant mucous cells and gustative corpuscles, which are lacking in the oesophagus. The muscularis mucosa was absent. The submucosa presented the compactum stratum. The muscularis was organized in longitudinal and circular layers of muscular striated fibres. The serosa with a flat epithelium was located only in the oesophagus. Using histochemical procedures including methods for localization and characterization of glycoproteins (GPs), no differences were detected between the mucous cells contents of the pharyngeal cavity and those of the oesophagus. The mucous cells showed a weak periodic acid–Schiff (PAS) positive reaction in their content. The reactions for the differential analysis of sialic acids from GPs are feeble for periodic acid–Schiff at low temperature and low pH (PA*S) and KOH/PA*S and strong for periodic acid/borohydride/KOH/PAS (PA/Bh/KOH/PAS) and KOH/PA*/Bh/PAS revealing the scarce presence of C7 or C9 substituted and non‐substituted sialic acids and the abundance of C7, C8 substituted sialic acids, O‐acyl sugars and neutral sugars respectively. The results suggest that the pharyngeal cavity with the gustative corpuscles would induce the gastric secretion whereas the oesophagus is mainly involved in the transport of the food bolus to the stomach with the aid of abundant secretion of mucus. GPs secreted on the surface of the mucous cells, likely related to environmental conditions, would be involved in the lubrication, protection against abrasion and inhibition of microorganism proliferation.

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.

Response to environmental salinity of Na+–K+ATPase activity in individual gills of the euryhaline crab Cyrtograpsus angulatus

Abstract The occurrence, localization and response to environmental salinity changes of Na + –K + ATPase activity were studied in each of the individual gills 4–8 of the euryhaline crab Cyrtograpsus angulatus from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina). Na + –K + ATPase activity appeared to be differentially sensitive to environmental salinity among gills. Upon an abrupt change to low salinity, a differential response of Na + –K + ATPase activity occurred in each individual gill which could suggest a differential role of this enzyme in ion transport process in the different gills of C. angulatus . With the exception of gill 8, a short-term increase of Na + –K + ATPase specific activity was observed in posterior gills, which is similar to adaptative variations of this activity described in other euryhaline crabs. However, and conversely to that described in other hyperregulating crabs, the highest increase of activity occurred in anterior gills 4 by 1 day after the change to dilute media which could suggest also a role for these gills in ion transport processes in C. angulatus . The fact that variations of Na + –K + ATPase activity in anterior and posterior gills were concomitant with the transition to hyperregulation indicate that this enzyme could be a component of the branchial ionoregulatory mechanisms at the biochemical level in this crab. The results suggest a differential participation of branchial Na + –K + ATPase activity in ionoregulatory mechanisms of C. angulatus . The possible existence of functional differences as well as distinct regulation mechanisms operating in individual gills is discussed.

Branchial carbonic anhydrase (CA) of gills of Chasmagnathus granulata (Crustacea Decapoda)

The occurrence, localization and response to environmental salinity of carbonic anhydrase (CA) activity were studied in all of the gills of the euryhaline crab Chasmagnathus granulata from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina). CA activity in all gills appeared to be dependent on salinity. The pattern of distribution of CA activity among gills was different upon transition of C. granulata from osmoionoconformity (more uniform distribution) to hyperregulation (highest activity in posterior gills 6-8). Upon abrupt salinity change a differential response of CA activity occurred among gills which could suggest a differential role of CA in ion transport process in different gills of this crab. Furthermore, CA activity in anterior and posterior gills was found in cytosolic and microsomal fractions, although highest activity appeared to be membrane-associated. Both pools of CA were also strongly influenced by salinity and very sensitive to sulfonamide acetazolamide. The results suggest a differential participation of branchial CA in ionoregulatory mechanisms of C. granulata.

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.

Acid phosphatase activity in pre- and post-spawning hake (Merluccius hubbsi)

1. The specific activity of muscle acid phosphatase (E.C. 3.1.3.1.) in pre- and post-spawning hake was investigated. 2. Specific activity values, 0.54 in pre-spawning hakes and 1.64 in post-spawning fish, have been obtained. 3. Using a histochemical test, acid phosphatase has been localized mainly in the connective tissue. The strongest reaction has been observed in post-spawning hake. 4. The increase of the lysosomal activity in the connective tissue may be related to the changes found in the muscle texture associated with spawning.

The Mucosa of the Digestive Tract in Micropogonias furnieri: A Light and Electron Microscope Approach

The histomorphological aspects as well as the histochemical content and distribution of glycoproteins (GPs) in the mucosa of the digestive tract of the white croaker Micropogonias furnieri were studied. The buccopharyngeal cavity and the esophagous showed a squamous stratified epithelium with mucous cells. The stomach presented three portions: cardias, fundus and pylorus. Tubular glands formed by a single type of gland cell were located along the cardias and fundus. Histochemical tests showed that the buccopharyngeal cavity and the esophagous presented the largest amount of the different types of mucosubstances. Both organs showed abundant secretory mucous cells that synthesize large quantities of neutral, sulphated and sialylated GPs. The surface epithelium in the cardias and fundus synthesized and secreted scarce sialylated and neutral GPs whereas the secretions of the apical surface were abundant. The pylorus secreted large amounts of neutral as well as sulphated and sialylated GPs. Gland cells secreted neutral GPs. The ultrastructural features of the gut cells were quite similar to those of other teleosts. The buccopharyngeal cavity and the esophagous surface epithelial cells, identified by their superficial localization, were characterized by cytoplasmic vesicles of different size. Abundant goblet cells with secretory mucous granules were also present. Gastric glands in the stomach contained just one form of cell with a fine structure similar to cells that secrete pepsinogen.

Allosteric transitions and membrane-bound ATPase from rat tissues: The effect of fat deprivation on the allosteric inhibition by fluoride

Abstract In rats red a fat-sufficient diet, ATPases (ATP phosphohydrolase, EC 3.6.1.3) from heart, kidney and brain microsomes showed allosteric kinetics for the inhibition by F − , with values of n = −2.0 . In rats fed a far-free diet, the values of n for the ATPases changed from −2.0 to −1.0 in heart and kidney microsomes. When these animals were then fed a fat-sufficient diet the values of n reached the control values. In brain microsomal ATPases no modification of the values of n were found between both groups of animals. The regulatory properties of the membrane on bound ATPases are discussed.