Spécificité de l'action antiphage de substances synthétiques

Summary The effect of synthetic antiphages has been studied against different types of bacteriophage in the same bacterium, in this caseEscherichia coli. Most substances are active only against typesT ₁, 3, 5, 7 (and our type 207) but not against types 2, 4, 6. Others show activity only against type 1 (and our type 207). The antiphage activity of a substance therefore seems to depend upon a specific relationship between its chemical structure and that of the phage type against which it is active.     

Gonyauline: A novel endogenous substance shortening the period of the circadian clock of a unicellular alga

Summary The circadian clock in the unicellular algaGonyaulax polyedra is accelerated by a substance in extracts from the cells themselves. The extracts have been fractionated using the circadian rhythm of bioluminescence as bioassay. The active substance, termed gonyauline, has been isolated and characterized as a novel low molecular weight cyclopropanecarboxylic acid (S-methyl-cis-2-(methylthio) cyclopropanecarboxylic acid). Synthetic gonyauline has a similar shortening effect on the period of the circadian clock.     

Sur la présence de glycoprotéines dans les grains à microtubules des cellules sécrétrices paragoniales dedrosophila melanogaster meig

Summary Cytochemical observations of the paragonial microtubular granules during the first 2 weeks after emergence have shown the ultrastructural localization of glycoprotein in peripheral or central matrices by periodic acid-thiocarbohydrazide-silver proteinate method (PATAg). The microtubules do not appear to contain glycoprotein moiety. The functional significance of the components of paragonial secretion is discussed.     

A new alarm pheromone (2-decen-1-yl-acetate) isolated from the stings ofApis dorsata andApis florea (Hymenoptera: Apidae)

Summary From sting extracts ofApis dorsata andA. florea, a substance was isolated which is active in alarm behaviour of both of these species but not ofA. mellifera andA. cerana. The active substance was identified as 2-decen-1-yl-acetate.     

Species-specific protein patterns inDrosophila paragonial glands

Summary Electrophoretic analysis of the soluble proteins in the paragonial glands of 11Drosophila species demonstrated that the patterns are highly species-specific. The possible functional significance of these proteins is discussed.This work was supported by grants from the Schweizerischer Nationalfonds and the Georges und Antoine Claraz-Schenkung.     

Action de l'eau oxygénée sur un anaérobie strict

Summary A quantitative study on the action of H₂O₂ uponCl. saccharobutyricum shows that the primary action is produced upon a first substance X, very likely an enzyme, following a mechanism such as one equivalent of oxygen gives a reversible combination, and two equivalents an irreversible combination.     

Characterization of the host-specific toxins produced byHelminthosporium sacchari,the causal organism of eyespot disease of sugarcane

Summary Investigation of the host-specific toxin complex fromH. sacchari has led to the isolation of 3 isomeric glycosidic components C₃₉H₆₄O₂₂, each active at 2×10^–11 moles. The 3 isomers consist of 4 galactose units linked to an aglycone residue C₁₅H₂₄O₂.Acknowledgments. The Boyce Thompson-Cornell group thanks J.F. Rissler, University of Maryland, A.K. Bose, Stevens Institute of Technology, R. Barker and A. Serriani, Cornell University, and C. Grinnalds and J. Golay, Boyce Thompson Institute for help with various aspects of this work. Supported in part by a grant to V.M. from the US Department of Agriculture (8100720). The Zürich group thanks Dr G.A. Strobel, Department of Botany and Microbiology, Montana State University, Bozeman, for supplying a potent toxin-producing strain (M 36), a susceptible clone of sugarcane (51 NG 97), and a reference sample of helminthosporoside, Dr. K. Hostettmann and Mme M. Hostettmann-Kaldas, Pharmazeutisches Institut ETH Zürich, for assistance in developing the DCC separation and Sandoz A.G., Basel, for financial support.     

Juvenile hormone active principle inAttacus atlas L

Summary The ether extract ofAttacus atlas L., subjected to an isotope dilution method for the determination of known insect juvenile hormones, revealed the presence of an active substance which has a similar chromatographic behaviour with the known JH-3, methyl (2E, 6E)-10, 11-epoxy-3, 7, 11-trimethyl-2, 6-dodecadienoate.The work was supported as a research training by Dr.R. Maag Ltd., CH-8157 Dielsdorf, Switzerland.     

Chromosome-breaking activity of extracts of the mushroomPaxillus involutus Fries ex Batsch

Summary Dry and presoaked seeds ofNigella damascena were treated with aqueous extracts of the mushroomPaxillus involutus. At the first mitosis after the onset of germination, metaphase chromosomes showed damage independent of the origin of the mushrooms. The damaging substance(s) is (are) thermostable. Except a few achromatic gaps, all the lesions observed are of the chromosome type, i.e. are induced at the pre-synthetic G1 stage.     

Oxidative stress triggers neuronal caspase-independent death: Endonuclease G involvement in programmed cell death-type III

To characterize neuronal death, primary cortical neurons (C57/Black 6 J mice) were exposed to hydrogen peroxide (H₂O₂) and staurosporine. Both caused cell shrinkage, nuclear condensation, DNA fragmentation and loss of plasma membrane integrity. Neither treatment induced caspase-7 activity, but caspase-3 was activated by staurosporine but not H₂O₂. Each treatment caused redistribution from mitochondria of both endonuclease G (Endo G) and cytochrome c. Neurons knocked down for Endo G expression using siRNA showed reduction in both nuclear condensation and DNA fragmentation after treatment with H₂O₂, but not staurosporine. Endo G suppression protected cells against H₂O₂-induced cell death, while staurosporine-induced death was merely delayed. We conclude that staurosporine induces apoptosis in these neurons, but severe oxidative stress leads to Endo G-dependent death, in the absence of caspase activation (programmed cell death-type III). Therefore, oxidative stress triggers in neurons a form of necrosis that is a systematic cellular response subject to molecular regulation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Insulin activates Gαil,2 protein in rat hepatoma (HTC) cell membranes

Insulin action is initiated by binding to its cognate receptor, which then triggers multiple cellular responses by activating different signaling pathways. There is evidence that insulin receptor signaling may involve G protein activation in different target cells. We have studied the activation of G proteins in rat hepatoma (HTC) cells. We found that insulin stimulated binding of guanosine 5′-O-(3-thiotriphosphate) (GTP-γ-³⁵S) to plasma membrane proteins of HTC cells, in a dose-dependent manner. This effect was completely blocked by pertussis toxin treatment of the membranes, suggesting the involvement of G proteins of the Gα _i/Gα _o family. The expression of these Gα proteins was checked by Western blotting. Next, we used blocking antibodies to sort out the specific Gα protein activated by insulin stimulation. Anti-Gα _il,2 antibodies completely prevented insulin-stimulated GTP binding, whereas anti-Gα _o,i3 did not modify this effect of insulin on GTP binding. Moreover, we found physical association of the insulin receptor with Gα _i1,2 by copurification studies. These results further support the involvement of a pertussis toxin-sensitive G protein in insulin receptor signaling and provides some evidence of specific association and activation of Gα _i1,2 protein by insulin. These findings suggest that Gα _i1,2 proteins might be involved in insulin action. Received 23 September 1998; received after revision 23 November 1998; accepted 25 November 1998     

Innervation and control of the heart of a gastropod,Rapana

Summary The innervation and control of the heart of a prosobranch mollusc,Rapana thomasiana, were studied. Acetylcholine was found to be an inhibitory neurotransmitter. Both serotonin and FMRFamide (Phe-Met-Arg-Phe-NH₂) showed excitatory effects on the heart; FMRFamide had greater inotropic and more regulatory chronotropic effects than serotonin. The effects of serotonin were blocked by methysergide, while the effects of FMRFamide and of stimulating the excitatory cardiac nerves were not blocked. Stimulation of circumesophageal ganglia elicited a slow enhancement of heart beat together with body movement. This enhancement was blocked by methysergide. Serotonin was considered to act at the heart as a local neurohormone. Although the mechanism of action of FMRFamide is still not yet clarified, it is possible that FMRFamide plays a physiological role as a cardioregulatory substance, as indicated by the physiological and histological findings.     

The occurrence of arachidonic acid in the venom duct of the marine snailConus textile

Summary A crude extract of the venom of the marine snailConus textile Linné caused a powerful contraction in the guinea-pig isolated ileum. The extract of the venom has been fractionated, and the fractions monitored by the contractile effect. Arachidonic acid was shown to be present as an active substance.Acknowledgment. We are grateful to Mr Z. Nagahama of Okinawa island for suppling specimens ofC. textile and to Dr T. Higashijima and Prof. T. Miyazawa (Department of Biophysics and Biochemistry, Tokyo University) for 270 MHz¹H-NMR-measurements.     

Specific reaction of aloe extract with serum proteins of various animals

Summary We found that aloe extract contains a lectin-like substance which reacts with serum proteins of various animals. Furthermore, in human serum 2 proteins,a ₂-macroglobulin anda ₁-antitrypsin, were shown to be reactive with aloe extract.     

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.     

Versuche zur chromatographischen Trennung der im Augenstiel vonAstacus astacus enthaltenen myotropen Wirkstoffe

Summary The detection of two myotropic substances in the eyestalk and the brain of the crayfishAstacus astacus and the shrimpCrangon crangon was described². Both substances have an action on the isolated ileum of the guinea pig. The substance extracted from the eyestalk has a positive myotropic one, the substance extracted from the brain an inhibiting one.Further a method is given for the separation and purification of the positive myotropic substance of the eyestalk by paper-chromatography.     

Partial purification of an endogenous elicitor from suspension-cultured cells of red bean,Vigna angularis

Brief irradiation with a germicidal UV lamp of cells of red bean,Vigna angularis, cultured in suspension in a quartz flask caused the release into the culture medium of an endogenous substance with elicitor activity, as well as the accumulation of isoflavone glucoside stress metabolites in the cells. The active compound was fractionated using phenylalanine ammonia lyase (PAL)-inducing activity in fresh cells as a marker. The elicitor active principle appears to be a low molecular weight (<2000 MW) water-soluble acidic oligosaccharide.     

Einfluß von Penicillin auf die Wurzelkultur(Zea mays) Nachweis von β-Indolylessigsäure (Heteroauxin) im Handelspenicillin

Summary (1) Pure Penicillin Sodium G (150 U/cm³) gives no inhibition in the growth-rate ofmays-roots in sterile organe culture.(2) Commercial penicillin (Penicillin Sodium Squibb, 5 U/cm³) inhibits the growth-rate ofmays-roots in a fairly high degree, due to its content of indole acetic acid. We have been able to separate the substance from the yellow dyes of commercial penicillin by chromatographic adsorption and to identify it colorimetrically as indole acetic acid.     

Effects of isoxazolyl-naphthoquinoneimines on growth and oxygen radical production inTrypanosoma cruzi andCrithidia fasciculata

Several 4-(aminomethylisoxazolyl)-1,2-naphthoquinones inhibited growth and DNA synthesis inTrypanosoma cruzi and stimulated O₂ uptake and generation by the parasite epimastigotes and their mitochondrial and microsomal membranes; these results support the idea that oxygen radicals play a role in quinone toxicity. Maximal effects on respiration and generation were observed with antimycin-inhibited cells. Similar results as well as stimulation of H₂O₂ production were obtained withCrithidia fasciculata despite the presence of catalase in this organism.Acknowledgments. This work was aided by grants from the University of Buenos Aires, the Scientific Office of the American States Organization and CEDIQUIFA (Buenos Aires). S.G.G. and M.P.M.P. are Research Fellows and A.O.M.S. is Career Investigator of CONICET (Argentina). L. T. Viñas and M. G. Gutierrez lent able technical assistance.     

Substance P-induced fibrinolysis in the forearm of healthy humans

Physiological saline with or without substance P (50 ng/ml) was infused into the humeral artery in 6 healthy males. Indices of fibrinolytic activity (whole blood diluted lysis time, euglobulin lysis time, lysis areas in non-heated fibrin plates produced by plasma or euglobulin precipitate, plasminogen plasma levels, ₂-macroglobulin, Cl-inhibitor, and ₂-antiplasmin) were evaluated in the homolateral antecubital vein before and after 5 min of substance P or saline infusion. After substance P the fibrinolytic activity increased, as can be seen from the shortening of lysis times (p<0.01) and enlargement of the lysis areas (p<0.01). A reduction of plasminogen plasma levels (p<0.01), associated with a decrease in ₂-anitplasmin (p<0.01), was also found. Alpha₂-macroglobulin and Cl-inhibitor were instead unaltered by the peptide. The saline infusion, on the other hand, was unable to modify any of the examined indices. We concluded that exogenous substance P given intra-arterially increases fibrinolytic activity in locally-sampled venous blood through a mechanism which remains to be elucidated.