Critical analysis of phospholipid hydrolyzing activities in ripening tomato fruits. Study by spectrofluorimetry and high-performance liquid chromatography

Using the spectrofluorimetric method described by Wittenaueret al. [Wittenauer, L.A., Shirai, K., Jackson, R.L., and Johnson, J.D. (1984)Biochem. Biophys. Res. Commun. 118, 894–901] for phospholipase A₂ (PLA₂) measurement, we have detected a phospholipase activity in Ailsa Craig and in mutantrin tomatoes at their normal harvest time (mature green stage). This activity in Ailsa Craig tomatoes increased at the beginning of fruit ripening (green-orange stage) and then decreased slowly. The decrease in activity, however, was greater when ripening occurred after tomato picking at normal harvest time than when ripening occurred on tomato plants. This phospholipase activity was always higher inrin tomatoes than in normal ones. Thin-layer chromatography of compounds obtained after incubation of tomato extract demonstrated a decrease in the substrate 1-acyl-2-{6[(7-nitro-2,1,3, benzoxadiazol-4-yl)amino]-caproyl}-sn-glycero-3-phosphocholine (C₆-NBD-PC), and an increase in one product (NBD-aminohexanoic acid), but failed to detect the second product (1-acyl-sn-glycero-3-phosphocholine). We, therefore, developed a new one-step method for separation and quantification of a mixture of phospholipids and other lipids, using straight-phase-high-performance liquid chromatography with light-scattering detection. This method detected another fatty acid-releasing activity in enzyme extract from green-orange tomatoes. This lipolytic enzyme (or family of enzymes) slowly produced free fatty acids when 1-oleoyl-sn-glycero-3-phosphocholine was added as substrate. The production of fatty acids was stoichiometric and more rapid when 1-oleoyl-sn-glycero-3-phosphate and 1-oleoyl-sn-glycerol were used as substrates. On the other hand, the same tomato extract was unable to hydrolyze 1,2-dioleoyl-sn-glycero-3-phosphate and 1,2-dioleoyl-sn-glycerol. Crude tomato extract exhibited lipid acyl hydrolase activity according to the definition of Galliard [Galliard, T. (1979), inAdvances in the Biochemistry and Physiology of Plant Lipids (Appelqvist, L.A., and Liljenberg, C. eds.), pp. 121–132, Elsevier, Amsterdam]. But in order to demonstrate whether tomato extract contains PLA₂ activity and/or lysophospholipase activity, further work on purified tomato extract will be necessary.     

Effect of Gravity on Film Boiling Heat Transfer and Rewetting Temperature during Quenching

This paper describes the experimental strategy developed to improve the modeling of liquid-vapor flows during the chill down of rocket engines by cryogenic fluid in microgravity. A similarity analysis is performed to determine the relevant dimensionless numbers for the design of an experiment similar to engine flows. A literature review on reduced gravity quenching experiments, and on rewetting temperature and film boiling heat transfer shows the lack of validated models for microgravity. Experimental results obtained with the quenching of a glass tube by FC72 during parabolic flight are presented. Especially the impact of gravity and subcooling on rewetting temperature and film boiling heat transfer is investigated. Results show an increase in rewetting temperature, and a decrease in film boiling heat transfer under reduced gravity in agreement with the literature. The comparison of 0 g flow pattern with corresponding tests on ground points out a behavior at 0 g closest to 1 g upflow than 1 g downflow.     

Extracellular serotonin is enhanced in the striatum, but not in the dorsal hippocampus or prefrontal cortex, in rats subjected to an operant conflict procedure.

In rats trained in an operant fixed-interval-30-s schedule of food reward (FI-30s), acute exposure to contingent footshock resulted in a response suppression that was released by diazepam (DZP; 4 mg/kg ip) but not by buspirone (0.25 or 0.50 mg/kg ip). Compared with baseline, hippocampal and cortical extracellular levels of serotonin (5-HText) did not change, regardless of operant period (punished or nonpunished) and drug. In contrast, in the striatum, an increase of 5-HText levels (535%) occurred during the punished period, counteracted by DZP. This effect was observed only in rats that were low responders during both nonpunished and punished periods, that is, those that exerted an efficacious control over responding. Uncontrollable shocks or exposure to an unfamiliar open field did not modify striatal 5-HText. Together, these results suggest that an acute activation of 5-HT neurons afferent to the striatum allows the rats to efficiently block responses that are negatively reinforced. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

La réglementation de la cryptologie en france de 1990 à 2005

The cryptology has been for a long time the fact of the army. The cryptography was considered not as a mean of communication but as a weapon. Nowadays, in France the cryptography can be used with a free access. The supply, the importation and the exportation of means and services of cryptology have been liberalized. The purpose of this article is to study the relations between liberty and security in the frame of the cryptology, for France. The process of liberalization can be explain by the deregulation in the telecommunication field for a small part, and by the emergence of the electronic trade for the biggest part. The security has not been forgotten. The cryptology is not a tool as the others. Some few restrictions of authorizations and declarations have been maintained. The non respect of these restrictions can generate sanctions not always used. The relation liberty/security appeared also in the electronic signature, adopted by the European Union in 1999 and in the European countries, especially in France. The electronic signature, by the way of the certification services need to use the cryptology, to be recognized and protected. The industrials have succeed, with the liberalization of the cryptology and their software, to build a famous system, not already finished: the security of the society information.     

Silicon analogues of the retinoid agonists TTNPB and 3-methyl-TTNPB, disila-TTNPB and disila-3-methyl-TTNPB: chemistry and biology

Twofold sila-substitution (C/Si exchange) in the saturated ring of the tetrahydronaphthalene skeleton of the retinoid agonists TTNPB (1 a) and 3-methyl-TTNPB (2 a) leads to disila-TTNPB (1 b) and disila-3-methyl-TTNPB (2 b), respectively. The silicon compounds 1 b and 2 b were synthesized in multiple steps, and their identities were established by elemental analyses, multinuclear NMR experiments, and single-crystal X-ray diffraction studies. Like TTNPB (1 a) and 3-methyl-TTNPB (2 a), the analogous silicon-based arotinoids 1 b and 2 b are strong pan-RAR agonists and display the same strong differentiation and apoptosis-inducing activity in NB4 promyelocytic leukemia cells as the parent carbon compounds. These results are in keeping with the nearly isomorphous structures of 1 a and 1 b bound to the complex of the RARbeta ligand-binding domain with the nuclear receptor (NR) box 2 peptide of the SRC-1 coactivator. The contacts within the ligand-binding pocket are identical except for helix H11, for which two turns are shifted in the disila-TTNPB (1 b) complex. This study represents the first comprehensive structure-function analysis of a carbon/silicon switch in a signaling molecule and demonstrates that silicon analogues can have the same biological functionalities and conserved structures as their parent carbon compounds, and it illustrates at the same time that silicon analogues of biologically active compounds have the potential to induce alternative allosteric effects, as in the case of helix H11, which might allow for novel options in drug design.     

Variation of clearance considering viscosity of the solution used in the reservoir and following scleral lens wear over time

Purpose

This study aims to evaluate the settling of a scleral lens and if this process is influenced by the nature of the fluid layer.

Effect of Nitrogen on Properties of Na2O–CaO–SrO–ZnO–SiO2 Glasses

Glasses in the Na₂O–CaO–SrO–ZnO–SiO₂ system have previously been investigated for suitability as a reagent in Al‐free glass polyalkenoate cements (GPCs). These materials have many properties that offer potential in orthopedics. However, their applicability has been limited, to date, because of their poor strength. This study was undertaken with the aim of increasing the mechanical properties of a series of these Zn‐based GPC glasses by doping with nitrogen to give overall compositions of: 10Na₂O–10CaO–20SrO–20ZnO–(40?3x)SiO₂–xSi₃N₄ (x is the no. of moles of Si₃N₄). The density, glass‐transition temperature, hardness, and elastic modulus of each glass were found to increase fairly linearly with nitrogen content. Indentation fracture resistance also increases with nitrogen content according to a power law relationship. These increases are consistent with the incorporation of N into the glass structure in threefold coordination with silicon resulting in extra cross‐linking of the glass network. This was confirmed using ²⁹Si MAS‐NMR which showed that an increasing number of Q² units and some Q³ units with extra bridging anions are formed as nitrogen content increases at the expense of Q¹ units. A small proportion of Zn ions are found to be in tetrahedral coordination in the base oxide glass and the proportion of these increases with the presence of nitrogen.