Electron-cytochemical localization of alkaline phosphatase to G cells of Necturus maculosus antrum

Summary Electron-cytochemical localization of alkaline phosphatase activity was performed on G cells of Necturus maculosus antral mucosa. Alkaline phosphatase activity was localized to the nuclear membrane, the Golgi/endoplasmic reticulum, and the limiting membranes of G cell peptide-secretion vesicles. There was no specific localization of alkaline phosphatase activity to the plasma membrane. Treatment of the tissues with levamisole (an alkaline phosphatase inhibitor) did not markedly reduce the specific alkaline phosphatase activity. Specific lead deposition was reduced by removal of the substrate from the reaction mixture. The results from this study on N. maculosus G cells demonstrate that alkaline phosphatase activity can be found in a non-mammalian gastric endocrine cell and that specific activity was localized primarily to those intracellular structures involved with protein biosynthesis.     

Cytochemical demonstration of phosphatases in membrane-recycling structures of endodermal cells

We applied cytochemical procedures to demonstrate the presence of acid and alkaline phosphatase in the visceral yolk-sac endoderm of rats using frozen, aldehyde-fixed tissue with cerium as the capture agent. This procedure allowed more detailed topochemical localization than was possible using unfrozen tissue or with lead as the capture agent. Acid phosphatase was found to be present in lysosomes as well as in a small number of apical canaliculi, which are thought to be recycling structures of the cell membranes in endodermal cells. Reaction products of alkaline phosphatase were observed on the outer surface of apical, lateral, and basal cell membranes. In addition, some apical vacuoles contained alkaline phosphatase, and more apical canaliculi were positive for alkaline phosphatase than for acid phosphatase. However, most of the apical canaliculi were negative for both enzymes. It is suggested that acid and alkaline phosphatase are taken up by different numbers of apical canaliculi during the detachment of apical canaliculi from lysosomes and resorption vacuoles.     

The localization and properties of membrane adenosine triphosphatases in the guinea-pig placenta.

The distribution and properties of cytochemically demonstrable phosphatases in the near-term guinea-pig placenta were examined using a strontium capture technique for sodium- and potassium-dependent adenosine triphosphatase (Na+, K+-ATPase) and a lead capture technique for magnesium-dependent adenosine triphosphatase (Mg2+-ATPase). Localizations with the strontium technique in the presence of an alkaline phosphatase inhibitor were mainly on the syncytiotrophoblast plasma membranes; the reaction was potassium-dependent and ouabain-sensitive. Reaction product using the lead capture method was found on both trophoblast and endothelial cell plasma membranes and was independent of magnesium and insensitive to p-hydroxymercuribenzoate (POHMB), an inhibitor of membrane ATPases. However, a very large proportion of this reaction could be blocked by an alkaline phosphatase inhibitor. It is concluded that the strontium capture technique gave a reliable localization for Na+, K+-ATPase. However, the lead capture method mainly demonstrated alkaline phosphatase, and does not offer a useful approach to specific ATPase studies in this particular system.     

Fine structural localization of alkaline phosphatase in the fracture callus of the rat

Summary The fine structural localization of nonspecific alkaline phosphomonoesterase in the different cells constituting the fracture callus in the rat was studied by incubating sections of glutaraldehyde-fixed callus tissue of variable age in media containing -glycerophosphate and either lead or calcium ions. The specificity of the reactions were tested by exposing the tissues to inhibitors of alkaline phosphatase.The results showed presence of final product on the plasma membranes and associated structures (subplasmalemmal endocytotic vesicles) of fibroblasts, pre-osteoblasts, osteoblasts, and cartilaginous cells in the callus. With the calcium method, reaction product was demonstrated in vesicular elements of the Golgi apparatus in osteoblasts and chondrocytes. Precipitates indicating presence of alkaline phosphatase activity were also observed on the membranes bordering cytoplasmic projections and fragments of cytoplasm located adjacent to enzyme-containing cells. Furthermore, the globule-shaped bodies in the matrix (Bonucci-bodies) showed evidence of alkaline phosphatase activity.The evidence obtained supported the view that alkaline phosphatase plays a role in calcification. It is suggested that transfer of cellular alkaline phosphatase to the sites of initial calcification in the extracellular matrix occurs by way of pinched off vesicular fragments of the cytoplasm and plasma membrane of osteogenic enzyme-producing cells; these structures appear to move awy from their cells of origin to form the Bonucci bodies in the matrix.     

Fine structural localization of alkaline phosphatase in the granular pneumonocytes of hamster lung.

The fine structural localization of nonspecific alkaline phosphatase was studied in the granular pneumonocytes (type II alveolar epithelial cells) of hamster lung by incubating sections of glutaraldehyde-fixed tissues in a medium containing lead ions and sodium beta-glycerophosphate or alpha-naphthyl acid phosphate. The specificity of the reaction was tested by exposing the sections to inhibitors of alkaline phosphatase. The results showed that alkaline phosphatase activity was present in the inclusion bodies of granular pneumonocytes. The enzyme reaction was strong in the membrane lining the inclusion bodies and a weaker reaction was generally detectable in the inclusion contents. Although only a proportion of the inclusion bodies showed enzyme activity, there was no obvious correlation between the reactivity of the inclusions and their intracellular position or size. The other organelles were unreactive. The finding of alkaline phosphatase activity within the inclusion bodies of granular pneumonocytes is an enigma as these organelles are generally considered to be lyosomes.     

The localization and properties of membrane adenosine triphosphatases in the guinea-pig placenta

Summary The distribution and properties of cytochemically demonstrable phosphatases in the near-term guinea-pig placenta were examined using a strontium capture technique for sodium- and potassium-dependent adenosine triphosphatase (Na⁺, K⁺-ATPase) and a lead capture technique for magnesium-dependent adenosine triphosphatase (Mg²⁺-ATPase).Localizations with the strontium technique in the presence of an alkaline phosphatase inhibitor were mainly on the syncytiotrophoblast plasma membranes; the reaction was potassium-dependent and ouabain-sensitive. Reaction product using the lead capture method was found on both trophoblast and endothelial cell plasma membranes and was independent of magnesium and insensitive to p-hydroxymercuribenzoate (POHMB), an inhibitor of membrane ATPases. However, a very large proportion of this reaction could be blocked by an alkaline phosphatase inhibitor.It is concluded that the strontium capture technique gave a reliable localization for Na⁺, K⁺-ATPase. However, the lead capture method mainly demonstrated alkaline phosphatase, and does not offer a useful approach to specific ATPase studies in this particular system.     

Pyridoxal 5'-phosphate: a possible physiological substrate for alkaline phosphatase in human neutrophils

The intracellular localization of pyridoxal phosphatase activity was demonstrated in human neutrophils by electron microscope cytochemistry. Under alkaline conditions, an enzyme active against pyridoxal phosphate was localized to a cytoplasmic granule population, the phosphasome. These granules have previously been shown by electron microscope cytochemical techniques and by subcellular fractionation to be rich in alkaline phosphatase. Under acidic conditions, a phosphatase activity against pyridoxal phosphate was localized to intracellular multilamellar bodies resembling secondary lysosomes. These were quite distinct from the primary, secondary and phosphasome granules and this unique localization corresponds to that previously demonstrated (tertiary granules) by subcellular fractionation studies of these cells. The similarity in the enzyme reaction requirements of alkaline pyridoxal phosphatase and alkaline phosphatase, and their localization to the same subcellular organelle, suggests that pyridoxal phosphate may be a physiological substrate for human neutrophil alkaline phosphatase.     

Ultrastructural localization of alkaline phosphatase in the hypertrophic chondrocyte of the frog

Summary The ultrastructural localization of alkaline phosphatase was studied in the hypertrophic chondrocyte of the frog (Rana temporaria) by incubating sections of glutaraldehyde fixed tissue in a medium containing sodium glycerophosphate and calcium chloride. Control specimens were incubated in substrate free medium.Alkaline phosphatase (orthophosphoric monoester phosphohydrolase) is a hight molecular weight glycoprotein that hydrolyses phosphorylated metabolites much as acid phosphatase does except that its action is optimal at an alkaline pH.The results of this investigation showed that alkaline phosphatase activity was present within the cytoplasm and around the plasma membrane of frog hypertrophic chondrocytes. Although only a small proportion of frog hypertrophic chondrocytes demonstrated enzyme activity, there was evidence that this was concentrated within Golgi lamellae and vesicles leaving other organelles unreactive. The finding of alkaline phosphatase activity within Golgi lamellae of hypertrophic chondrocytes is regarded as unusual although positive reactions within chondrocyte lysosomes have previously been reported (Doty and Schofield, 1976).     

Phosphatase activity in Amoeba proteus at pH 9.0

In the free-living amoeba Amoeba proteus (strain B), after PAAG disk-electrophoresis of the homogenate supernatant, at using 1-naphthyl phosphate as a substrate and pH 9.0, three forms of phosphatase activity were revealed; they were arbitrarily called "fast", "intermediate", and "slow" phosphatases. The fast phosphatase has been established to be a fraction of lysosomal acid phosphatase that preserves some low activity at alkaline pH. The question as to which particular class the intermediate phosphatase belongs to has remained unanswered: it can be both acid phosphatase and protein tyrosine phosphatase (PTP). Based on data of inhibitor analysis, large substrate specificity, results of experiments with reactivation by Zn ions after inactivation with EDTA, other than in the fast and intermediate phosphatases localization in the amoeba cell, it is concluded that only slow phosphatase can be classified as alkaline phosphatase (EC 3.1.3.1).     

Alkaline phosphatase in human lymphocytes. II. A method for ultracytochemical detection of alkaline phosphatase in lymphocytes

For the ultracytochemical identification of alkaline phosphatase in lymphocytes gained from the peripheral blood of healthy individuals a sensitive method is described which allows the low enzyme activity of these cells to be determined. This was possible because the authors succeeded in stabilizing lead ions in the alkaline medium by forming a complex directly between tris-(hydroxymethyl) aminomethan and lead (II) citrate. AP localized ultrachemically in lymphocytes in particular formations similar to phosphasomes of neutrophilic granulocytes. In those lymphocytes stimulated by lipopolysaccharides a high enzyme activity could be observed and, in addition to phosphasomes, the product of response can also be found in canal-like structures of the endoplasmatic reticulum. These findings contribute to clarify the ultrastructural localization of alkaline phosphatase in lymphocytes and may be regarded as an aid in discovering the importance of the enzyme in the biology of lymphocytes or in its activation, respectively.     

A highly sensitive assay method for human placental alkaline phosphatase involving a monoclonal antibody bound to a paper disk

A monoclonal antibody which is specific for human placental alkaline phosphatase and does not cross-react at all with intestinal alkaline phosphatase was prepared, and a procedure for the determination of placental alkaline phosphatase activity in serum was developed involving this monoclonal antibody bound to a paper disk. The minimum amount of placental alkaline phosphatase detectable by this method is 0.0025 King-Armstrong unit. Good correlation with the heat-treatment method was obtained. Therefore this proposed method can be used as a routine clinical test for the determination of serum placental alkaline phosphatase.     

Plasma membrane localization of alkaline phosphatase in HeLa cells.

The localization of alkaline phosphatase in HeLa cells was examined by electron microscopic histochemistry and subcellular fractionation techniques. Two monophenotypic sublines of HeLa cells which respectively produced Regan and non-Regan isoenzymes of alkaline phosphatase were used for this study. The electron microscopic histochemical results showed that in both sublines the major location of alkaline phosphatase is in the plasma membrane. The enzyme reaction was occasionally observed in some of the dense body lysosomes. This result was supported by data obtained from a subcellular fractionation study which showed that the microsomal fraction rich in plasma membrane fragments had the highest activity of alkaline phosphatase. The distribution of this enzyme among the subcellular fractions closely paralleled that of the 5'-nucleotidase, a plasma membrane marker enzyme. Characterization of the alkaline phosphatase present in each subcellular fraction showed identical enzyme properties, which suggests that a single isoenzyme exists among fractions obtained from each cell line. The results, therefore, confirm the reports suggesting that plasma membrane is the major site of alkaline phosphatase localization in HeLa cells. The absence of any enzyme reaction in the perimitochondrial space in these cultured tumor cells also indicates that the mitochondrial localization of the Regan isoenzyme reported in ovarian cancer may not be a common phenomenon in Regan-producing cancer cells.     

Alkaline and Acid Phosphatase Demonstration in Human Bone and Cartilage: Effects of Fixation Interval and Methacrylate Embedments

Human bone and cartilage specimens were evaluated for acid and alkaline phosphatase localization following varying fixation periods for fresh or frozen tissue. Formalin fixations of up to 183 hr were followed by embedment in methyl methacrylate; frozen tissue was examined either without fixation or following fixation for up to 1 hr and subsequent glycol or methyl methacrylate embedding. The humeral epiphysis of a young patient with osteogenic sarcoma showed optimum acid and alkaline phosphatase localization following fixation for periods up to 15 hr and embedding in methyl methacrylate. Frozen costochondral junction from a newborn with osteogenesis imperfecta type II showed optimum acid and alkaline phosphatase localization following 30 min fixation in formalin and embedding in methyl methacrylate or after 5 min fixation and embedding in glycol methacrylate.     

Alkaline and acid phosphatase demonstration in human bone and cartilage: effects of fixation interval and methacrylate embedments

Human bone and cartilage specimens were evaluated for acid and alkaline phosphatase localization following varying fixation periods for fresh or frozen tissue. Formalin fixations of up to 183 hr were followed by embedment in methyl methacrylate; frozen tissue was examined either without fixation or following fixation for up to 1 hr and subsequent glycol or methyl methacrylate embedding. The humeral epiphysis of a young patient with osteogenic sarcoma showed optimum acid and alkaline phosphatase localization following fixation for periods up to 15 hr and embedding in methyl methacrylate. Frozen costochondral junction from a newborn with osteogenesis imperfecta type II showed optimum acid and alkaline phosphatase localization following 30 min fixation in formalin and embedding in methyl methacrylate or after 5 min fixation and embedding in glycol methacrylate.     

Localization of Acid and Alkaline Phosphatases in Staphylococcus aureus

The localization of acid and alkaline phosphatases in Staphylococcus aureus was studied by fractionation of cells after treatment with the L-11 enzyme and by electron microscopic histochemistry. The two enzyme activities were located in distinctly different positions at the surface of the cells. Acid phosphatase appeared to be localized around the cell membrane of the bacteria, because the enzyme was recovered exclusively in the membrane fraction and because deposition of lead phosphate was detected by electron microscopic histochemistry on the inner surface of the cell membrane of intact bacteria and spheroplasts. The highest specific activity of alkaline phosphatase was also associated with the membrane fraction. However, on electron microscopic histochemistry of intact cells, the deposition of lead phosphate was only seen on the outer surface of the cell wall.     

A new direct lead technique for histochemical demonstration of alkaline phosphatase activity.

A lead method for demonstrating alkaline phosphatase is described. The method is based on direct precipitation of lead as lead phosphatase at pH 9.5, the pH optimum of the enzyme. Stable incubation medium was achieved by using tartrate, instead of maleate, as chelating for lead. The method was found to be suitable for visualization of alkaline phosphatase in different types of tissues.     

Fine structural localization of acid and alkaline phosphatase activities in the absorbing cells of the duodenum of rodents

Summary The morphology of the absorbing cells of the duodenal villi in the mouse, the rat, the hamster and the guinea-pig is described. The polymorphism of the dense bodies is pointed out. The fine localization of acid and alkaline phosphatase is investigated and compared. In all the species, acid phosphatase activity is observed in the dense bodies, Golgi vesicles and rare smooth endoplasmic profiles. Alkaline phosphatase is localized on the microvilli, Golgi apparatus, some smooth endoplasmic cisternae and numerous dense bodies. The presence of an alkaline phosphatase reaction in the dense bodies, probably lysosomes, of the absorbing cells is discussed. It is assumed that this enzyme follows a catabolic pathway and is finally degraded in the lysosomes.Abbreviations used AlPase alkaline phosphatase - AcPase acid phosphatase This work was done thanks to the contract C.E.N./A.I.E.A. N 347/RB and thanks to grants from the Fonds de la Recherche scientifique fondamentale collective.     

A new fluorescence method for alkaline phosphatase histochemistry.

We have developed a new fluorescence method for the histochemical localization of alkaline phosphatase activity. Calcium phosphate deposited at the sites of alkaline phosphatase activity in a Gomori-type reaction are identified by calcium binding fluorochromes. The calcium binding fluorochromes calcein, calcein blue, and xylenol orange were investigated, with each fluorochrome being included in the alkaline phosphatase incubating medium and used in a single-step procedure. Alkaline phosphatase activity was studied in freeze-substituted, resin-embedded human liver and jejunal biopsies, and each fluorochrome produced intense fluorescence of different colors at sites of alkaline phosphatase activity. Calcein, calcein blue, and xylenol orange produced green, blue, and red fluorescence, respectively. Sites of enzyme activity were accurately localized without evidence of diffusion, and there was an absence of non-enzyme-catalyzed binding of any of the fluorochromes to tissue. This fluorescence method, which is particularly suited to investigating the localization and distribution of the activity of different enzymes in the same section, was used to investigate the distribution and co-localization of alkaline phosphatase and aminopeptidase M in human liver and jejunum.     

Cytochemical markers of bladder carcinogenesis

Summary Enzyme cytochemical and immunocytochemical techniques at the light and electron microscope levels were used to study the distribution of potential markers of chemical transformation in rodent bladders. In rat tumours induced byin vivo treatment with methylnitrosourea, alkaline phosphatase localization was normal on the external surface of the plasma membranes of some cells but abnormal in others where reaction product was seen only on intracellular membranes. 5-Nucleotidase localization was abnormal in all cells, being seen on endoplasmic reticulum and nuclear membranes only, while in normal bladders only ectoenzyme localization was seen. Heterogeneity of alkaline phosphatase and 5-nucleotidase localization was seen on the plasma membranes of these tumours after 15 days in organ culture. Some cells produced enzyme and others did not; in other cells only parts of the membrane reacted heavily, while other regions were negative.In transformed cell cultures and tumours of mouse bladder derived byin vitro treatment of explants with dimethylbenz (a) anthracene, a bimodal pattern of alkaline phosphatase localization was seen. Cells had either normal ectoenzyme reaction product or abnormal intracellular membrane reaction product. 5-Nucleotidase and ADPase were lost after transformation while cAMP-phosphodiesterase was retained as an ectoenzyme. Mg.ATPase and a cAMP-independent, calcium-insensitive protein phosphatase were induced in transformed cell cultures. An epithelial antigen was detected in the cytoplasm of both normal and transformed cells associated with reticular cytoplasmic ground substance, plasma membrane vesicles and cytoskeletal elements.     

Properties of alkaline phosphatase in crude homogenates of human diploid fibroblasts

The kinetic properties of the "constitutive" and the "induced" alkaline phosphatase in diploid fibroblasts are compared with those of the enzymes in crude tissue homogenates. Both the constitutive as the induced enzyme have properties comparable with those of the liver-bone-kidney group. The induced alkaline phosphatase clearly differs from the "constitutive" alkaline phosphatase concerning the effect of high concentrations of L-phenylalanine and the effect of Mg2+ ions. The induced alkaline phosphatase seems to be identical with the enzyme in liver, but the constitutive alkaline phosphatase could not be identified.