NDPase Activity Research Articles

Schistosoma mansoni and Haematoloechus medioplexus: Nucleosidediphosphatase localization in tegument

The distribution of nucleosidediphosphatase (EC 3.6.1.6) activity in the teguments of two trematodes, Haematoloechus medioplexus and Schistosoma mansoni, was determined by cytochemical methods. Enzyme activity was observed associated with the apical plasma membrane of the tegument of H. medioplexus and with the plasma membranes of the tegumental invaginations of S. mansoni. The NDPase activity is dependent on the presence on Mn 2+ ions. In addition to its ability to hydrolyze a number of nucleoside diphosphates, the tegument of H. medioplexus hydrolyzed a number of nucleoside triphosphates. The tegumental invaginations of S. mansoni represented sites where a wider variety of phosphate esters, including nucleoside mono- and triphosphates, thiamine pyrophosphate, and sodium glycerophosphate, were hydrolyzed. The hydrolysis of these latter compounds was not dependent on the presence of Mn 2+ ions, possibly indicating at least two enzyme systems associated with the tegument of S. mansoni. It is speculated that areas displaying NDPase activity represent sites of transport over which ions and molecules cross the tegument. No NDPase activity was associated with the teguments of two trematodes that reportedly display little or no ability for tegumental transport, Megalodiscus temperatus and Gorgoderina attenuata.

Nucleoside diphosphatase and thiamine pyrophosphatase activities in the endoplasmic reticulum and golgi apparatus.

The effects of pH, fixatives and divalent ions on nucleoside diphosphatase (NDPase) and thiamine pyrophosphatase (TPPase) activities in the endoplasmic reticulum (ER) and Golgi apparatus (GA) were examined in adult and neonatal hepatocytes and other cell types in the rat. In liver cells TPPase and NDPase both have a similar localization in the rough ER, nuclear envelope and smooth ER but differ in their pH optima; TPPase is most active at pH 8, NDPase at pH 7. TPPase in the GA, unlike its counterpart in the ER, is most active at neutral pH. High levels of NDPase activity are present in the GA of neurons, epididymis and other cells, but not in hepatocytes. TPPase in the ER, but not the GA, is stimulated by the addition of adenosine triphosphate to the medium. These observations show that different conditions are required to demonstrate ER and GA diphosphatase activities. Whether separate enzymes or multiple configurations of a single protein are responsible for these activities cannot be determined by staining procedures.

Immunochemical studies of detergent-soluble nucleoside phosphatases in rat liver plasma membranes

1. 1. Antiserum against plasma membranes was prepared in rabbits. 2. 2. Freshly isolated membranes were solubilized in a mixture of Lubrol W and sodium deoxycholate. By immunoelectrophoretic analysis of the extracts 18 distinct antigens were identified. 3. 3. Histochemical staining procedures were applied to the immunoelectrophoresis plates. NMPase (5′-nucleotidase, 5′-ribonucleotide phosphohydrolase, EC 3.1.3.5) activity was found in two precipitates with the same electrophoretic mobility. 6 antigens had both NTPase (nucleoside triphosphatase, nucleoside triphosphate phosphohydrolase) and NDPase (nucleoside diphosphatase, nucleoside diphosphate phosphohydrolase, EC 3.1.3.5) activity on adenosine, uridine, inosine, guanosine and cytidine phosphates. 4. 4. Nucleoside phosphatase activities in membranes, in detergent extracts of membranes and in antigen-antibody precipitates were also determined in test tube assays. The assays confirmed the results obtained in agarose plates, by showing that the 6 precipitates hydrolysed both ATP and ADP. 5. 5. These results, together with inhibition experiments, support the assumption that an apyrase-like activity (EC 3.6.1.5) exists in liver plasma membranes.

Modulation in nucleoside diphosphatase activity of mammotrophic cells of the rat adenohypophysis during secretion.

The modulations in nucleoside diphosphatase (NDPase) activity which occur during protein secretion have been investigated in mammotrophic hormone-producing cells (MT) of the female rat adenohypophysis. Pituitaries were fixed by perfusion or immersion in glutaraldehyde, and nonfrozen sections were incubated for NDPase. Tissue was examined from lactating and estrogen-treated animals in which mammotrophic hormone secretion (MTH) is high and from postlactating rats in which secretion of MTH is suppressed. In all experimental groups, NDPase reaction product was found: ( a) in Golgi cisternae, ( b) around forming and mature secretion granules, ( c) in pericapillary and intercellular spaces and ( d) along the outer surface of endothelial and MT cell membranes. The staining intensity of both the intracellular and extracellular sites paralleled the level of MTH secretion; it was greatest after estrogen treatment, moderate during lactation and minimal in the postlactating animal. In animals given estrogen, the Golgi apparatus was increased in size and up to six successive cisternae along the concave Golgi face were filled with reaction product in virtually every cell. In postlactating animals, the Golgi apparatus was small, and there was only patchy staining of a few cisternae in some cells. From its location and fluctuations with secretion, it seems likely that NDPase activity may be associated with the condensation and/or discharge of secretory granules.

PHOSPHATASE HISTOCHEMISTRY OF FELINE CERVICAL SPINAL CORD AFTER BRACHIAL PLEXECTOMY

A reticulum is demonstrable in perikaryon and dendrites of feline motoneurons by application of a histochemical technic for TPPase and NDPase activities. At the level of light microscopy this reticulum is separable from the basophil network of Nissl except that, in dendrites especially, lamellae derived from both structures appear, occasionally, to be in continuity or even identical. During axonal reaction the TPPase-, NDPase-positive reticulum recedes from the perinuclear area, especially opposite the axon, and migrates to the periphery. These changes, well-developed in the 15 to 30 day postoperative period, are followed by a restitution toward the normal appearance about 46 to 60 days after neurectomy. Regeneration of the reticulum appears to occur from both the cytoplasmic and nuclear membrane sides of the cytoplasm. The alternations encountered resemble those reported by earlier workers who applied classical technics for the Golgi apparatus to chromatolytic neurons. The network demonstrated by the enzyme histochemical method is equated with the Golgi organelle. Lysosomes, identified in Gomori acid phosphatase preparations, increase in numbers in chromatolytic neurons. In addition to the perikaryon, dendrites show a conspicuous increase in lysosomal content. This phenomenon is discussed. Possible developmental relations between lysosomes and other cell constituents are also discussed. Evidence, suggestive of a discharge of TPPAse- and NDPase-positive lamellae and lysosomes into axons during chromatolysis, is described. In TPPase and NDPase preparations there is a striking increase in glial activity in the anterior and posterior horns following plexectomy.