An insect acetylcholinesterase inhibitor from compound eyes of Triatoma infestans (Hemiptera)

The presence of an acetylcholinesterase inhibitor in the compound eyes of adult Triatoma infestans was demonstrated. The inhibitory activity was localized in the ocular pigments separated by disc gel electrophoresis. The inhibitor was selective against insect acetylcholinesterase, reversible, noncompetitive and heart stable.     

Inhibition of the NADP-linked glutamate dehydrogenase fromTrypanosoma cruzi by silver nitrate

Summary The purified NADP-linked glutamate dehydrogenase fromTrypanosoma cruzi was strongly inhibited by silver nitrate. The inhibition was reversed by reduced glutathione, and was modified by the presence of the substrates during preincubation of the enzyme with the inhibitor.This work was supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the Secretaría de Estado de Ciencia y Technología de la República Argentina. JJC is a member of the Carrera del Investigador Científico, and SMJ a Research Fellow, of the former Institution.     

Regulatory properties of the citrate synthase fromRhodospirillum rubrum

Summary Citrate synthase, purified 600-fold fromRhodospirillum rubrum, is activated by KCl and inhibited by ATP and NADH; the effect of the latter inhibitor is completely counteracted by AMP and partially counteracted by KCl.This work was supported by grants from the Consejo Nacional de Investigaciones Cientificas y Técnicas de la República Argentina and the Consejo de Investigaciones de la Universidad Nacional de Rosario. JJC, and EM and AIH, are members of the Carrera del Investigador Cientifico of the former and the latter institutions, respectively.     

Narciclasine,an inhibitor of protein synthesis. Action onAllium cepa L. root meristems

Summary Shortening of nucleologenesis time in a synchronous cell population, labelled as binucleate, by a caffeine pulse and fall in frequency of prophases are related to narciclasine inhibition of protein synthesis inAllium cepa L. meristems.Acknowledgments. We gratefully acknowledge Dr D. Vázquez and Dr A. Jiménez, from the Instituto de Bioquímica de Macromoléculas, for calling our attention to this protein synthesis inhibitor and providing us samples both of narciclasine andNarcissus bulbs. We also greatly appreciate Dr B. Rodriguez and Dr F. M. Panizo of the Instituto de Química Orgánica (Departamento de Productos Naturales) for their valuable help in isolation and characterization of narciclasine, and for laboratory facilities. The work has been partially supported by the Comisión Asesora para la Investigación Científica (Spain). A.S. has a fellowship awarded by the Instituto de Cultura Hispánica, Spain.     

Tryptophan (Trp), serotonin (5-HT), monoamino oxidase (MAO) and 5-hydroxyindole acetic acid (5-HIAA) in brain and subesophagic ganglions of earthworms. Effects of Parathion

Summary Tryptophan, 5-HT, MAO and 5-HIAA were determined in the first 5 segments of earthworms (Oligochaetae) where the brain and subesophagic ganglions are located. Tranylcypromine (IMAO) decreased MAO activity increasing 5-HT and decreasing 5-HIAA. Motility and survival of worms were disturbed. InAllolobophora species (young worms), parathion fumigation decreased acetylcholinesterase (AChE) activity and increased Trp, 5-HT and 5-HIAA. Motility was diminished after 24 h: it worsened after 72, but returned to normal levels 40/50 days later.Publication of the National Institute of Agrarian Technology (INTA), Argentina.Acknowledgments. We are most grateful to Prof. Zlatko Tomsic (from the Lillo Institute, Tucumán) and to Leticia Alvarado (from INTA) and to Prof. Mirta P. de Matosian for earthworm classification.     

Eyestalks control of diurnal rhythm of acetylcholinesterase activity in the crabOziotelphusa senex senex

Summary The crab (Oziotelphusa) displays a diurnal rhythm of acetylcholinesterase activity, with maximal activity around midnight, alternating with minimal activity at noon. Bilateral eyestalk ablation eliminates the diurnal rhythm of acetylcholinesterase activity.Acknowledgments. We wish to express our gratitude to CSIR, New Delhi for providing financial support to PSR. Reprint requests should be addressed to Prof. R. Ramamurthi.     

Comparative study of the sensitivity of acetylcholinesterases and cholinesterases from animal and bacterial sources to inhibition by serotonin and its derivatives

Summary Serotonin was found to inhibit human erythrocyte and electric-eel acetylcholinesterase activities. The serotonin amino group, free of negative charges in its vicinity and its hydroxyl group, were important for the inhibition. Serotonin precursors and several related compounds had little or no effect. Human plasma cholinesterase was also inhibited by serotonin and tryptamine. In contrast to these animal enzymes, the cholinesterase ofPseudomonas aeruginosa was refractory to serotonin and its derivatives under the same experimental conditions.     

On the regulatory properties of a halophilic malic enzyme fromHalobacterium cutirubrum

Summary The NADP-linked malic enzyme fromHalobacterium cutirubrum is strongly inhibited by acetyl-CoA and NADH, and rather weakly inhibited by oxaloacetate and glyoxylate, in the presence of very high KCl concentrations (3,M), considered physiological for the extremely halophilic bacteria.This work was supported by grants from the consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, and the Consejo de Investigaciones de la Universidad Nacional de Rosario. JJC and MCV are members of the Carrera del Investigador Científico of the former and the latter institutions, respectively.     

A comparative study of the differentiation of dissociated nerve cells under different culture conditions

Summary In vitro differentiation of chick embryo brain cells was compared under several culture conditions. Morphological observations and acetylcholinesterase histochemical staining revealed that the development was similar in all conditions tested if cells have been derived from 7 days embryos. Considering the cultures from 11 days embryos, the cell dissociation by trypsin and the plastic surface proved to be the most favourable conditions in contrast to mechanical dissection and collagen surface.M. Sensenbrenner is Maitre de Recherche au CNRS.     

Chromosomal homology in southern Akodon

Summary Differential staining (G and C) of southern South AmericanAkodon are presented.A. olivaceus, A. longipilis andA. sanborni all have the same karyotype (2n=52, NF=58). A virtually identical band sequence is observed. This situation is interpreted using the canalization model of chromosomal evolution which stresses an optimum karyotype for each adaptive zone. Despite the high degree of conservation of the chromosome structures, the specific status of these species is supported by maintenance of distinctness when they occur in areas of sympatry.The research was partially supported by Proyecto de Investigación I-78-86, Dirección de Investigación, Universidad Austral de Chile and Programa Especial de Citogenética, U. de Chile sede Norte, Santiago, Chile.     

Stimulation of pyruvate carboxylation by gastric secretagogues

Summary Pyruvate carboxylation was stimulated by 2 gastric secretagogues, histamine and dibutyryl cyclic AMP, and by butyrate. Thiocyanate, an inhibitor of acid secretion, produced a slight decrease. Avidin significantly reduced acid secretion and this effect was overcome by biotin and oxalacetate. The results suggest that carboxylation of pyruvate is one of the reactions controlling oxidative metabolism and acid secretion in toad gastric mucosa.This investigation was supported by Consejo de Desarrollo Científico y Humanístico de la Universidad del Zulia, and by CONICIT Grant S1-0455.     

Actions d'un inhibiteur sélectif des acétylcholinestérases,le 3318 CT,sur la transmission neuromusculaire du chat

Summary 3318 CT [bis (piperidinomethylcoumaranyl-5) cetone dimethiodide], a specific inhibitor of acetylcholinesterase, antagonizes, in small dosages, the neuromuscular block induced by Flaxedil in the cat; in larger dosages, 3318 CT blocks the transmission: this paralysing action is not related to an accumulation of acetylcholine, as acetylcholine itself antagonizes it; decamethonium also restores, partially at least, the indirect contractions. Prostigmine and m-hydroxyphenyltrimethylammonium have no action. The neuromuscular block by 3318 CT thus appears as a competitive curarization in an animal with inhibited acetylcholinesterases. There was no indication that pseudo-cholinesterase can play a part in the neuromuscular transmission; whereas in the case of the vagal transmission such a possibility could not be ruled out.     

A kinetic model for nucleohistone-dependent DNA synthesis

Résumé A basse concentration de «template» et de déoxynucléoside triphosphate, la vitesse de synthèse de DNA par la DNA polymérase deE. coli suit la loi simple de Michaelis. Les valeurs deK _m et deV pour les réactions dépendant de la nucléohistone sont plus basses que les valeurs pour les réactions dépendant du DNA, mais les rapportsV/K _m sont semblables. Les additions supplémentaires de constituants du mélange réactionnel de la polymérase n'ont eu qu'un très faible effet sur le système dépendant de la nucléohistone.

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This work was conducted under a cooperative agreement between the Division of Biology, California Institute of Technology and the Western Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture. The work was supported in part by U.S. Public Health Service Grants Nos. GM-03977, GM-05143, AM-03102.Reference to a company or product name does not imply approval or recommendation of the product by the U.S. Department of Agriculture to the exclusion of others that may be suitable.     

Preparation of semithin serial sections of epon embedded material

Resumen Describese una tecnica para la obtención de cualquier número de cortes seriados de 0,5–1µm de espessura, de material incluso en Epon, usandose una cuchilla de diamante. Ademas de su uso para seriación de cortes, la tecnica muestrase útil para la montage de cortes para radioautografias.

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The author was supported by a fellowship from CAPES, Brazil.     

DNA and RNA content in diploid and tetraploid amphibians

Resumen En el anuro tetraploide naturalOdontophrynus americanus, el contenido de DNA es el doble que el determinado, bioquimicamente, en los especimens de la población diploide deO. americanus. Sin embargo el contenido de RNA de ejemplares de las dos poblaciones es aproximadamente igual. Aparentemente, mecanismos de regulación bloquean el esceso de material genético en el tetraploide.

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This work was supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo, the Conselho Nacional de Pesquisas, the Fundo de Pesquisas do Instituto Butantan and the Rockefeller Foundation.     

Characterization of the estrogen receptors in the uterine and blood eosinophil leukocytes

Summary Estrogen receptors are found in the rat uterine and in the eosinophil-rich human blood leukocyte 24,000g fractions, but not in the low-eosinophil count human blood leukocyte 24,000g fraction. The total number of binding sites per blood eosinophil leukocyte is 7,400 sites per cell, and theK _d =5.6×10^–10 M.Acknowledgments. This work was supported in part by funds from the Unité de Recherches sur le Métabolisme Moléculaire et la Physio-Pathologie des Stéroïdes de l'INSERM, Hôpital de Bicetre, France, and by grant No. 2015 from the Oficina Técnica de Desarrollo Científico y Creación Artística of the University of Chile.     

Electrical membrane constants of sartorius muscle fibers from the South American froǵ,Leptodactylus ocellatus

Résumé Les constantes électriques de la membrane du m. sartorius, de la grenouille sudaméricaine,Leptodactylus ocellatus, ont été mesurées. Les résultats pour les cellules, dans du Ringer normal (2.5 mM potassium), s'accordent avec ceux deHubbard pourRana temporaria. En 2.5 mM cesium Ringer, une diminution de diamètre de 12% et une augmentation de 16% de la capacité de la membrane ont été observées.

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This work was supported in part by the US Navy department (offfice of Navy research), the US Automic Energy Commission, and the Direction General de Investtgations y Desarrollo, Ministerio de Defensa National Argentina.     

Glutathione andγ -glutamyl cycle enzymes in rat mammary gland

Summary The main enzymes of theγ-glutamyl cycle during the lactogenic cycle in rat mammary gland were studied. A significant increase was found in all of them with the onset of lactogenesis. The effect of methionine sulfoximine on reduced glutathione concentration was studied in tissue slices of lactating mammary gland. The findings suggest that this compound affects glutathione synthesis by inhibitingγ-glutamylcysteine synthetase. This work was supported by grant B1138-8223 from the Servicio de Desarrollo Cientifico, Universidad de Chile.     

Characterization of DNAs fromCoprinus lagopus andMucor azygospora

Resumé Les rapports G+C des ADN deCoprinus lagopus etMucor azygospora ont été étudiés. Le profil de fusion indique que l'ADN duC. lagopus est composé de deux fractions, une principale (90%) de rapport G+C 52 moles pourcent, une mineure (10%) de G+C 32 moles pourcent. Par contre l'ADN deM. azygospora contient une fraction unique de G+C 38 moles pourcent. L'étude de la cinétique de réassociation DNA:DNA montre que la dimension génomique («genome size») deC. lagopus est de 2×10¹² et qu'il y a moin de 10% de DNA à séquences répétées de nucléotides.

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This research was supported in part by the U.S. Atomic Energy Commission Contract No. AT (40-1) 4182 and the Research Corporation, New York, to S.K.D. We are grateful to ProfessorG. Turian, University of Geneva, for making possibleM. Ojha's participation in this research.     

Sex determining mechanismXY 1Y2 inArtibeus lituratus lituratus (Chiroptera-phyllostomidae)

Resumen En el murciélagoArtibeus lituratus lituratus el nÚmero de cromosomas es de 2n=30 en la hembra y de 2n=31 en el macho. El mecanismo de determination del sexo esXX/XY ₁Y₂. La translocación de un autosoma alX resultó en la diferenciación del neo-Y. Son descritos los aspectos del comportamiento del trivalente sexual durante la meiosis. Estos son comparados a los que presenta la especieNoctilio leporinus (2n=34) cuyo mecanismo esXX/X Y.

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This work was supported by Public Health Service Research Grant No. GM-14577-03 from the National Institute of General Medical Sciences and by the Fundo de Pesquisas do Instituto Butantan. R. F. B. holds a FAPESP training fellowship.