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991.
992.
Dufourmantel N Dubald M Matringe M Canard H Garcon F Job C Kay E Wisniewski JP Ferullo JM Pelissier B Sailland A Tissot G 《Plant biotechnology journal》2007,5(1):118-133
Plant 4-hydroxyphenylpyruvate dioxygenase (HPPD) is part of the biosynthetic pathway leading to plastoquinone and vitamin E. This enzyme is also the molecular target of various new bleaching herbicides for which genetically engineered tolerant crops are being developed. We have expressed a sensitive bacterial hppd gene from Pseudomonas fluorescens in plastid transformants of tobacco and soybean and characterized in detail the recombinant lines. HPPD accumulates to approximately 5% of total soluble protein in transgenic chloroplasts of both species. As a result, the soybean and tobacco plastid transformants acquire a strong herbicide tolerance, performing better than nuclear transformants. In contrast, the over-expression of HPPD has no significant impact on the vitamin E content of leaves or seeds, quantitatively or qualitatively. A new strategy is presented and exemplified in tobacco which allows the rapid generation of antibiotic marker-free plastid transformants containing the herbicide tolerance gene only. This work reports, for the first time, the plastome engineering for herbicide tolerance in a major agronomic crop, and a technology leading to marker-free lines for this trait. 相似文献
993.
Kotaro Matsumoto Philippe Parola Jean-Marc Rolain Kathryn Jeffery Didier Raoult 《BMC microbiology》2007,7(1):74
Background
To date, 6 tick-borne rickettsiae pathogenic for humans are known to occur in Africa and 4 of them were first identified in ticks before being recognized as human pathogens. 相似文献994.
Alina Tirsoaga Alexey Novikov Minou Adib-Conquy Catherine Werts Catherine Fitting Jean-Marc Cavaillon Martine Caroff 《Applied microbiology》2007,73(6):1803-1808
A method for obtaining highly purified endotoxin (lipopolysaccharide [LPS]) in a few hours by repurification of commercial or laboratory preparations was devised. It avoids the use of phenol, which is not suitable for phenol-soluble lipopolysaccharides nor for some industrial purposes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and matrix-assisted laser desorption ionization mass spectrometry analysis confirmed the integrity of the purified LPSs. The purified products did not activate Toll-like receptor 2 (TLR2), nuclear oligomerization domain 1 (NOD1), or NOD2 but did activate TLR4. Applied to different lipopolysaccharides, the method also improved their mass spectra, thus facilitating their structural analysis. 相似文献
995.
Lafontaine C Valleton JM Orange N Norris V Mileykovskaya E Alexandre S 《Biochimica et biophysica acta》2007,1768(11):2812-2821
Assembly of the tubulin-like protein FtsZ at or near the cytoplasmic membrane is one of the earliest steps in division of bacteria such as Escherichia coli. Exactly what constitutes the site at which FtsZ acts is less clear. To investigate the influence of the membrane phospholipids on FtsZ localization and assembly, we have elaborated with the Langmuir technique a two-lipid monolayer made of dilauryl-phosphatidylethanolamine (DLPE) and dipalmitoyl-phosphatidylglycerol (DPPG). This monolayer comprised stable condensed domains in an expanded continuous phase. In the presence of GTP, FtsZ assembly disrupts the condensed domains within 5 min. After several hours, with or without GTP, FtsZ assembled into large aggregates at the domain interface. We suggest that the GTP-induced polymerization of FtsZ is coupled to the association of FtsZ protofilaments with domain interfaces. 相似文献
996.
Jean-Marc Azaïs Jean-Luc Dortet-Bernadet 《Biometrical journal. Biometrische Zeitschrift》1999,41(7):873-890
This paper studies the modelling of linkage between chromosomes in tetraploids. A general model based on the assumptions of Kimber and Alonso (1981) is presented. It depends on the “elementary probabilities” associated with the different configurations of pairing of the four chromosome arms depending on the same quadruplet. Because of the incomplete information about these pairings given by the microscopic observation of the cells, some problems about the identifiability of the parameters arise. We will present a set of the most general parameters that are identifiable and we will describe the set of the elementary probabilities that correspond to these parameters. Finally, we shall discuss some various possible sub-models. 相似文献
997.
Catherine Boucabeille Dominique Mengin-Lecreulx Gilles Henckes Jean-Marc Simonet Jean van Heijenoort 《FEMS microbiology letters》1997,153(2):295-301
Linenscin OC2 is an antibacterial substance produced by the orange cheese coryneform bacterium Brevibacterium linens OC2. It inhibits the growth of Gram-positive bacteria but it is inactive against Gram-negative bacteria. The intact outer membrane of Gram-negative bacteria was shown to be an effective permeability barrier against linenscin OC2. At high dosage the effect of linenscin OC2 was bacteriolytic on Listeria innocua. Bacteriostasis was observed at low dosage and peptidoglycan biosynthesis was affected at an early step upstream of the UDP-N-acetylglucosamine. Hemolytic activity of this substance on sheep erythrocytes suggested a common mode of action on prokaryotic and eukaryotic cells. It also suggested that the cytoplasmic membrane might be the primary target of linenscin OC2. 相似文献
998.
Franoise Bono Jean-Pascal Herault Corinne Avril Paul Schaeffer Jean-Claude Lormeau Jean-Marc Herbert 《Journal of cellular physiology》1997,172(1):36-43
The binding of [125I]-factor Xa to human umbilical vein endothelial cell (HUVEC) monolayers was studied. At 7°C, [125I]-factor Xa bound to a single class of binding sites with a dissociation constant value of 6.6 ± 0.8 nM and a binding site density of 57,460 ± 5,200 sites/cell (n = 3). Association and dissociation kinetics were of a pseudo-first order and gave association and dissociation rate constant values of 0.15 × 106 M-1 s-1 and 4.0 × 10-4 s-1, respectively. [125I]-factor Xa binding was inhibited by factor Xa but was not affected by factor X, thrombin or monoclonal antibodies against factor V, antithrombin-III or tissue factor pathway inhibitor (TFPI) but was inhibited by an antibody specific for the effector cell protease receptor-1 (EPR-1), a well-known receptor of factor Xa on various cell types. [125I]-factor Xa binding to HUVEC was not affected by various inhibitors of factor Xa such as DX 9065, pentasaccharide-antithrombin-III or TFPI. Factor Xa increased intracellular free calcium levels and phosphoinositide turnover in endothelial cells and, when added to HUVEC in culture, factor Xa was a potent mitogen, stimulating an increase in cell number at a 0.3 to 100 nM concentration. HUVEC-bound factor Xa promoted prothrombin activation in the presence of factor Va only. This effect was inhibited by both indirect and direct inhibitors of factor Xa. These findings indicate that HUVEC express functional high affinity receptors for factor Xa, related to EPR-1, which may be of importance in the regulation of coagulation and homeostasis of the vascular wall. J. Cell. Physiol. 172:36–43, 1997. © 1997 Wiley-Liss, Inc. 相似文献
999.
1000.
Relationship between rate of crop growth at date of fertiliser N application and fate of fertiliser N applied to winter wheat 总被引:1,自引:0,他引:1
To investigate the relationship between the timing of fertiliser N applications and the N use efficiency of wheat, three field
experiments with 15N were set up on winter wheat, on three different soils in France. Different crop N demands on the day of fertiliser application
were obtained by varying either crop densities or date of fertiliser application. Labelled 15NH4
15NO3 was applied at tillering and during stem elongation. The 15N recovered from plant and soil at different dates after 15N addition and at maturity of wheat was measured. The fate of fertiliser N was rapidly determined, most of the fertiliser
N accumulated in the wheat at maturity having been taken up within a few days of application. 15N recovery by the crop at final harvest (%) varied greatly (19–55% N applied) according to crop density, soil type and date
of application. It was linearly related to the instantaneous crop growth rate calculated at the day of 15N application. The amount of fertiliser N immobilised in the soil was constant at 20 kg N ha−1, for all soil types and crop densities. Because residual mineral 15N in the soil at harvest was negligible and immobilisation was constant, the level of total 15N measured in the different N pools (soil+plant) reflected the% 15N uptake by the plant. There was consequently a negative linear relationship between the percentage of 15N not recovered for measurement, and crop growth rate (i.e. crop N demand) at date of fertiliser application. These results
suggest that crop N demand at the time of N application determines the ability of the crop to compete for N with other processes,
and may be a major factor determining the division of N between soil and crop.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献