Histochemical localization of alkaline and acid phosphatase activities in the skin ofMystus (Mystus) vittatus Bl. (Siluriformes)

Summary An attempt has been made to localize alkaline and acid phosphatase activities in the skin ofMystus vittatus by using histochemical techniques. The alkaline phosphatase activity is found in metabolically active cells such as basal columnar cells, mucous cells and polygonal support cells. The acid phosphatase activity is intense in the outermost squamous support cells and in the basal columnar cells. These activities have been correlated with some physiological functions of the epidermis.Acknowledgment. We are thankful to P. Vishwanatham, Government College, Mhow, and Dr R.S. Shrivastava, Holkar Science College, Indore, for providing laboratory facilities and to the Council of Scientific and Industrial Research, New Delhi, for a fellowship for M.S.     

Genetic analysis of the kinome and phosphatome in cancer

Protein phosphorylation is a well-characterized biochemical process for reversible regulation of protein activity. Protein kinases and protein phosphatases are the key complementary players in this process, and through their coordinated activity cell homeostasis is tightly controlled. If these enzymes display aberrant activity, cells may undergo unrestrained growth, thus giving rise to complex diseases such as cancer. The technological platform gathered during the Human Genome Project recently allowed the systematic identifi cation of the genetic alterations present in the kinase (the kinome) and the phosphatase (the phosphatome) gene families. These studies suggest that most if not all human tumors carry genetic alterations in at least one phosphatase or kinase gene. Here we integrate the biochemical knowledge on the properties of these molecules with the information collected through their systematic genetic analysis in cancer. We also analyze why the molecular profi ling of the kinome and phosphatome in individual cancers is revolutionizing basic and clinical oncology.Received 13 May 2005; received after revision 30 May 2005; accepted 22 June 2005     

Effect of the scorpion,Heterometrus fulvipes (C. Koch), venom on some enzyme systems in rat (albino) tissues

Summary Sublethal doses ofHeterometrus fulvipes venom decreased NADP-specific isocitrate dehydrogenase and malate dehydrogenase activity levels and increased NADP-specific glucose-6-phosphate dehydrogenase and alkaline phosphatase activity levels during a 48-h-period.Acknowledgments. D. V. thanks the Council of Scientific and Industrial Research, New Delhi, for awarding a Senior Research fellowship.     

Etude de la glucose-6-phosphatase dans la membrane chorioallantoïdienne traitée par des microsomes du foie

Summary In order to test the possibility for microsomes to multiply like viruses, microsomes of chick liver were inoculated on chorioallantoïc membranes. The glucose-6-phosphatase activity, an enzyme located in the liver microsomes, was determined in the treated membranes. The activity decreased during the first 24 h after inoculation. It reached, after 48 h, from two to six times the value attained after 24 h.A suspension of heated granules, or of heatedTétrahymèna géléii, though producing the same lesions of the membrane, did not increase the phosphatase activity of the microsome fraction after 48 h.The present results are compatible with the idea that liver microsomes multiply by autoduplication.     

Excretion of acid hydrolases during molting inPhilosamia ricini

Summary The level of the acid hydrolases -glucuronidase (EC 3.2.3.11), acid phosphatase (EC 3.1.3.2) and acid protease (EC 3.4.4) was studied during larval growth and molting inP. ricini. The level of activity of these enzymes remained low during larval growth; however, the level increased sharply at the time of molting and declined sharply thereafter in the newly ecdysed insect. Interestingly, the diminished activity of these enzymes was almost quantitatively recovered in the cast-off cuticle. The excretion of acid hydrolases through the cast-off cuticle has hitherto not been reported in insects during molting.     

Partial purification and characterization of acid phosphatase from sporulated oocysts ofEimeria tenella

Summary Acid phosphatase ofEimeria tenella oocysts (Peak II) was purified 77-fold with a recovery of 26% using protamine sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-200 gel filtration. This enzyme occurs in multiple forms as indicated by two peaks which can be separated by DEAE-cellulose chromatography and polyacrylamide gel electrophoresis. The partially purified enzyme has optimal activity at pH 4.5. With p-nitrophenyl phosphate the Km and V_max values for (Peak II) were 25 mM and 1.57 mol/min/mg protein, respectively. The enzyme (Peak II) ist strongly inhibited by Hg⁺⁺, Cu⁺⁺, iodoacetamide, fluoride and molybdate. Tartrate and other divalent metal ions have no effect on enzyme activity. The partially purified Peak II phosphatase is not a glycoprotein as it is not absorbed on concanavalin-A Sepharose and its treatment with bacterial neuraminidase does not alter its elution profile through DEAE cellulose.     

A possible genetic component of obesity in childhood. Observations on acid phosphatase polymorphism

Summary Phenotypes of acid phosphatase with low enzymatic activity (ACP₁ A and BA) are correlated with the highest degree of body mass increase observed in a sample of obese children. Since acid phosphatase probably functions as a flavin-mononucleotide phosphatase, differential modulation of flavo-enzyme activity and energy metabolism due to acid phosphatase genetic variability may explain the observed association.     

Evidence for the metabolism of phospholipids and triacylglycerols in humanAscaris lumbricoides

Summary HumanAscaris lumbricoides has the necessary mechanism for the biosynthesis and degradation of phospholipids and triacylglycerols, as in most other species. Piperazine decreases the level of triacylglycerols of this parasite by stimulating the activity of lipase and partially inhibiting the activity of phosphatidate phosphatase.Acknowledgments. Thanks are due to the University of Kerala for facilities provided, Dr T. Ramasarma of the I.I. Sc., Bangalore for help in the labelling studies, Dr. G. D. Cain of the University of Iowa for valuable comments and Dr P. Vijayagopal of ANU for the gift of CDP-choline.     

The in vitro characterization of the inhibition of mouse brain protein kinase-C by retinoids and their receptors

Summary The mechanism of the in vitro inhibition of Ca²⁺-, phosphatidylserine-dependent protein kinase C (PK-C)² by the purifiedholo (ligand-saturated) forms of cellular retinol-binding protein (cRBP) and cellular retinoic acid-binding protein (cRABP) was studied. We report here that i) the PK-C-inhibitory action ofholo-cRBP andholo-cRABP is due to their respective ligands, all-trans-retinol and all-trans-retinoic acid; ii) the reduced phosphorylation of theholo-retinoid-binding proteins and brain cytosolic proteins is not the result of a retinoid-induced soluble phosphatase or protease activity; iii) retinoids reduce PK-C affinity for calcium and phosphatidylserine in vitro; and iv) the structure-function activity of the retinoids and the specific interaction of these effect of retinoids on plasma membrane-associated PK-C activity pays a significant role in defining the early epigenetic aspects of PK-C-dependent tumor promotion and may be a physiological mechanism by which retinoids induce terminal differentiation in cell types that do not express soluble retinoid-binding proteins.We would like to thank Dr L.M. De Luca (NIH, USA) for his contribution of retinylphosphate, Dr H.N. Bhagavan (Hoffmann-La Roche) for his contribution of the arotinoids, and Merrill-Dow Corp. for their contribution of difluoromethylornithine. This work was supported by NIH Grants CA-34968, CA-07175, CA-22484, and CA-09020.     

Diagnostic alleles and systematics in termite species of the genusReticulitermes in europe

Summary It was possible to separate species and complexes of species in theReticulitermes genus of Western Europe using esterase 3 and acid phosphatase 2.     

Wirkung von Actinomycin auf das Enzymmuster der Rattenniere während der Entwicklung

Summary Actinomycin D causes a marked increase of alkaline phosphatase activity in the zona subcorticalis of the developing rat kidney. The effect is more pronounced in female than in male animals. Acid phosphatase activity increases in males only.     

Phosphomonoesterases in the 2 sexes of the root-knot nematode,Meloidogyne lucknowica Singh, 1969

Summary The 2 phosphomonoesterases of the root-knot nematode were colorimetrically determined. Alkaline phosphatase activity was observed to be lower than the acid phosphatase activity. Sex related trends were clearly seen in the enzyme levels of the 2 sexes of thenematode. Alkaline phosphatase level differed 28.76%, while acid phosphatase level differed 60.36% in the 2 sexes.The authors are grateful to the Council of Science and Technology U.P. for the grant of a Research Scheme for these studies.     

The chromosomal location of phosphatase isozymes of the wheat endosperm

Summary The 7 phosphatase isozymes found in the endosperm of hexaploid wheat (Triticum aestivum L.) are related to chromosomes of homoeology group 4. At least 4 loci are related to phosphatase isozymes.Acknowledgments: The authors thank Dr B. Cifuentes, P. González and E. Wiltshire for technical assistance.     

Phosphoprotein phosphatase activity of bovine intestinal alkaline phosphatase

The phosphoprotein phosphatase activity of a commercial preparation of bovine intestinal alkaline phosphatase (EC 3.1.3.1) was examined using phosvitin and dentine phosphoprotein as substrates. Over 90% and 70% of the phosphorus from dentine phosphoprotein and phosvitin were hydrolyzed in 2 h. The optimum pH of the enzyme for the dephosphorylation of phosvitin and dentine phosphoprotein was nearly 6. No protein phosphatase activity was observed when the alkaline phosphatases from bovine liver and pulp were investigated.     

Effect of prenatal and neonatal pantothenic acid deficiency on rat intestinal phosphatases

Alkaline phosphatase activity was increased in the distal part of the small intestine of pantothenic acid deficient neonatal rats, while acid phosphatase activity was slightly increased and protein concentration was decreased throughout the small intestine. The growth and maturation of the distal part of the small intestine were retarded more severely than in the proximal part.     

Acid phosphatase in eggs of the zebrafish,Brachydanio rerio

Summary 2 isozymes of acid phosphatase have been identified by polyacrylamide disc gel electrophoresis in the ovary and mature, unfertilized eggs ofB. rerio. Histochemically, the enzyme appears to be localized in preyolk bodies of previtellogenic oocytes and in yolk platelets of vitellogenic and postvitellogenic oocytes. The contents of the cortical granules at all stages of oocyte differentiation were acid phosphatase negative.     

Effect of prenatal and neonatal pantothenic acid deficiency on rat intestinal phosphatases

Summary Alkaline phosphatase activity was increased in the distal part of the small intestine of pantothenic acid deficient neonatal rats, while acid phosphatase activity was slightly increased and protein concentration was decreased throughout the small intestine. The growth and maturation of the distal part of the small intestine were retarded more severely than in the proximal part.     

Mise en évidence d'une activitéα-amylasique dans les lysosomes d'Aspergillus oryzae

Summary The -amylase of mycelial cells ofAspergillus oryzae exists in a particular form in 8000 g pellet. The lysosomal localization of acid phosphatase is confirmed by electron microscopy. The purification of lysosomes by discontinuous gradient of sucrose in D₂O shows that -amylase activity is bound to these particles.     

A possible genetic component of obesity in childhood. Observations on acid phosphatase polymorphism

Phenotypes of acid phosphatase with low enzymatic activity (ACP1 A and BA) are correlated with the highest degree of body mass increase observed in a sample of obese children. Since acid phosphatase probably functions as a flavin-mononucleotide phosphatase, differential modulation of flavo-enzyme activity and energy metabolism due to acid phosphatase genetic variability may explain the observed association.     

A126 in the active site and TI167/168 in the TI loop are essential determinants of the substrate specificity of PTEN

PTEN prevents tumor genesis by antagonizing the PI3 kinase/Akt pathway through D3 site phosphatase activity toward PI(3,4)P₂ and PI(3,4,5)P₃. The structural determinants of this important specificity remain unknown. Interestingly, PTEN shares remarkable homology to voltage-sensitive phosphatases (VSPs) that dephosphorylate D5 and D3 sites of PI(4,5)P₂, PI(3,4)P₂, and PI(3,4,5)P₃. Since the catalytic center of PTEN and VSPs differ markedly only in TI/gating loop and active site motif, we wondered whether these differences explained the variation of their substrate specificity. Therefore, we introduced mutations into PTEN to mimic corresponding sequences of VSPs and studied phosphatase activity in living cells utilizing engineered, voltage switchable PTEN_CiV, a Ci-VSP/PTEN chimera that retains D3 site activity of the native enzyme. Substrate specificity of this enzyme was analyzed with whole-cell patch clamp in combination with total internal reflection fluorescence microscopy and genetically encoded phosphoinositide sensors. In PTEN_CiV, mutating TI167/168 in the TI loop into the corresponding ET pair of VSPs induced VSP-like D5 phosphatase activity toward PI(3,4,5)P₃, but not toward PI(4,5)P₂. Combining TI/ET mutations with an A126G exchange in the active site removed major sequence variations between PTEN and VSPs and resulted in D5 activity toward PI(4,5)P₂ and PI(3,4,5)P₃ of PTEN_CiV. This PTEN mutant thus fully reproduced the substrate specificity of native VSPs. Importantly, the same combination of mutations also induced D5 activity toward PI(3,4,5)P₃ in native PTEN demonstrating that the same residues determine the substrate specificity of the tumor suppressor in living cells. Reciprocal mutations in VSPs did not alter their substrate specificity, but reduced phosphatase activity. In summary, A126 in the active site and TI167/168 in the TI loop are essential determinants of PTEN’s substrate specificity, whereas additional features might contribute to the enzymatic activity of VSPs.