A critical study of the histochemical lead method for localization of Mg-ATPase at cell boundaries

Cytochemical and biochemical demonstration of an ATPase in membranes of human peroxisomes

We demonstrated a neutral Mg-ATPase activity in human peroxisomal membranes. To establish the precise experimental conditions for detection of this ATPase, both cytochemical and biochemical characterizations were first carried out in liver peroxisomes from control and cipofibrate-treated rats. The results demonstrated an Mg-ATPase reaction in both normal and proliferated peroxisomes. The nucleotidase activity, with marked preference for ATP, was sensitive to the inhibitors N-ethylmaleimide and 7-chloro-4-nitro-benzo-2-oxadiazole (NBDCl). An ultrastructural cytochemical analysis was developed to evaluate the peroxisomal localization, which localized the reaction product to the peroxisomal membrane. These characteristics can help to differentiate the peroxisomal ATPase from the activity found in mitochondria and endoplasmic reticulum. The conditions established for detecting the rat peroxisomal ATPase were then applied to human peroxisomes isolated from liver and skin fibroblasts in culture. A similar Mg-ATPase activity was readily shown, both cytochemically and biochemically, in the membranes of human peroxisomes. These results, together with previous evidence, strongly support the presence of a specific ATPase in the human peroxisomal membrane. This ATPase may play a crucial role in peroxisome biogenesis.

Adenosinetriphosphatase (Mg-ATPase) activity in the plasma membrane of preimplantation mouse embryo as revealed by electron microscopy

The ultrastructural localization of Mg2+-ATPase activity was investigated in unfertilized eggs and in preimplantation mouse embryos. Enzyme activity was detected on the entire surface of unfertilized eggs and in one-cell embryos. From the two-cell stage up to the 12-cell embryo the reaction product was localized both at the exposed surface of the embryo and between blastomeres. At the late morula stage, activity was only present on the free surface of the peripheral cells outside the apical tight junctions. In the early blastocyst the membranar reaction was observed both on the outside membrane of the trophoblastic cells and on the inner surface facing the blastocoele, whereas in the late blastocyst the reaction remained unchanged on the outer surface of the embryo but was absent from the membranes bordering the blastocoele. These results are discussed with reference to the modification of the cell surface membrane during preimplantation development.

Adenosine triphosphate hydrolysis in rat dental tissues. A histochemical study to differentiate the enzymes involved

The purpose of this study was to try to differentiate histochemically between the various enzymes which may catalyze the hydrolysis of ATP in developing rat dental tissues. Freeze cut and freeze dried sections of molar and incisor teeth were incubated in lead capture-based media at pH 5.0, 7.2 or 9.4 with one of the following substrates: beta-glycerophosphate, AMP, ADP, ATP, AMP-PNP and tetrasodium pyrophosphate. To establish the enzymatic nature of the hydrolysis parallel sections were incubated after prior fixation in either formaldehyde or glutaraldehyde. By comparing the enzymatic stainings obtained with the various substrates and at the different pH:s, it was concluded that ATP can be visibly hydrolyzed in rat dental tissues by alkaline phosphatase (stratum intermedium, apical part of maturation ameloblasts, basal part of all ameloblasts, odontoblasts and subodontoblastic layer), specific ATPase (apical and basal parts of secretory ameloblasts) and ATP pyrophosphatase and/or adenylate cyclase (stratum intermedium, odontoblasts). Acid phosphatase, specific ADPase, 5'-nucleotidase, inorganic pyrophosphatase, 3':5'-cyclic-AMP-phosphodiesterase and adenylate kinase on the other hand, seem not to be engaged in the ATP hydrolysis to such a degree as to complicate the interpretation of the histochemical staining. The alkaline phosphatase part of the ATP hydrolysis appeared to be rather insensitive to aldehyde fixation, while the hydrolysis effected by specific ATPase and ATP pyrophosphatase and/or adenylate cyclase was extinguished after fixation with formaldehyde for 4 h or glutaraldehyde for 10 min.

Enzyme histochemistry as a link between biochemistry and morphology

The presented paper describes the role of enzyme histochemistry in cell biological investigations. In the first chapter a general discussion has been given about enzyme histochemistry as a connecting link between biochemistry and morphology. The methods available for determination of enzymes in a particular cell or cell compartment have been reviewed. In this respect the characteristics of enzyme histochemistry have been discussed. Furthermore, attention has been paid to the possibilities and limitations of enzyme histochemistry. In chapter two a comparison has been made between histochemically judged and biochemically determined enzyme activities. Some fundamental differences between the biochemical and the histochemical approach in cell biological investigations are dealt with. To correlate histochemically and biochemically determined enzyme activities, a description has been given of the application of histochemical methods on isolated fractions and sucrose-ficoll gradients of these fractions. Several experimental results are described concerning the question whether a relation exists between histochemically and biochemically determined activities of respectively alkaline phosphatase, glucose-6-phosphatase, 5'-nucleotidase and 3ss-hydroxysteroid dehydrogenase. From these results the conclusion could be drawn that in general a good correlation exists between histochemically judged activity per volume (area X thickness) and biochemically determined activity per gram tissue. In chapter three the role of enzymes as markers of cellular particles and as parameters of metabolic pathways is described. Histochemical methods are available for most marker enzymes. Only activities of key enzymes can be regarded as parameters of metabolic pathways. The distribution in sucrose-ficoll gradients of enzymes, regarded as markers of mitochondria, lysosomes, endoplasmic reticulum and plasma membranes has been given. The changes occur ing under different experimental conditions for a number of marker enzymes in rat liver are described. Attention has been given to the contibution of enzyme histochemistry in the study of the heterogeneity of mitochondria, the dual localization of some (lysosomal) enzymes, the complexity of the microsomal fraction, the function of the Golgi apparatus and the heterogeneity and function of plasma membranes. Based on these results and on literature findings the possible role of some marker enzymes in cell metabolism has been discussed. In chapter four problems coherent with species and sex differences in enzyme activities are described. The interpretation of histochemical and biochemical results in view of these differences is discussed. Enzymes characteristic for a given cell type -3ss-hydroxysteroid dehydrogenase in steroid producing cells, ATP-ase in liver plasma membrane surrounding the bile canaliculi - do show less variations between species and sexes than enzymes not directly involved in specialized functions...

Ultrastructural localization and differentiation of membrane-bound ATP utilizing enzymes including adenyl cyclase in normal and psoriatic epidermis

The total membrane-bound ATP hydrolytic activity in human epidermis is due to the activities of at least three differently located enzymes, namely Mg++-activated ATPase, phosphomonoesterase and adenyl cyclase. Cytochemical studies on psoriatic epidermis with various inhibitory and stimulatory substances showed reduced activities of ATPase and phosphomonoesterase, and a lack of sensitivity of adenyl cyclase to specific stimulators such as isoproterenol and glucagon. Since no differences of basal adenyl cyclase activity were observed between normal and psoriatic human skin without stimulation, it seems likely that in psoriasis a latent defect of adenyl cyclase may exist, resulting in a deficient response of this enzyme to regulatory agents. In conclusion, the present study reveals that not a single enzyme but the entire membrane-bound nucleotide metabolism is altered in psoriatic keratinocytes, causing a disturbance of the membrane-bound energy utilization, similar to findings in proliferating tumour cells.

The localization of enzymes in fixed sections of soybean root nodules by electron microscopy

Attempts were made to localize the following enzymes within bacteroids and host tissue: reduced-NAD oxidoreductase, succinate oxidoreductase, adenosinetriphosphate phosphorylase, diaminobenzidineoxidase, and xylylene diamine oxidase. Diaminobenzidine (DAB) staining was localized within the mitochondrial membranes and within the bacteroid cytomembrane and associated vesicles, whereas dehydrogenase enzymes within the bacteroids were for the greater part mesosomal. Peroxidative reduction of DAB and xylylene diamine within the bacteroid nuclear regions occurred in the presence of catalase, to which the cytomembrane appeared to be impermeable. A cyanide-insensitive oxidase localized within the bacteroid mesosomes and nuclear regions was not affected by the addition of catalase, aminotriazole or pyruvate. Ca2+-stimulated ATP-phosphorylase was localized within the bacteroid cytomembrane, whereas a Mg2+-stimulated ATP-phosphorylase was localized within the host cell plasma membrane.