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41.
Christophe F. Deroanne Alain C. Colige Betty V. Nusgens Charles M. Lapiere 《Experimental cell research》1996,224(2):215
A model of collagen-inducedin vitroangiogenesis was used to investigate the modulation of expression and assembly of focal adhesion plaque-associated proteins during the process of differentiation. Human umbilical vein endothelial cells (HUVEC), first attached on an adhesive substratum (gelatin-, fibronectin-, or laminin-coated dish) or adherent collagen gel and then covered by an overlaying collagen gel, organized within 3–4 days in tube-like structures (TLS). Removing the overlaying collagen gel from fully differentiated HUVEC induced a reversion of the process and HUVEC returned to a monolayer pattern. Modulations of focal adhesion-associated proteins occurring in HUVEC during thein vitrodifferentiation process and its reversal were investigated by Western blot analysis. A significant decrease of expression of vinculin, the integrin α2subunit, talin, α-actinin, and actin was observed in TLS whereas the amount of FVIII-related antigen did not vary as compared to control monolayer cultures. During reversal, all the reduced proteins were markedly reexpressed. Human skin fibroblasts (HSF), submitted to the same experimental conditions, did not form TLS. Most of the focal adhesion proteins in HSF were similarly modulated by an overlaying collagen gel with the exception of vinculin, which was not modified. This particular protein was therefore more thoroughly investigated. In a nondifferentiated monolayer of HUVEC, a significant proportion of vinculin was organized into a detergent-resistant juxtamembranous structure (focal adhesion plaque) which disassembled early in TLS formation and reassembled during the reversal of the process. The reduction of vinculin during TLS formation was preceded by a downregulation of its mRNA while this mRNA was upregulated during reversal of the morphotype. These results suggest that the modulations of the cytoskeletal and focal adhesion proteins and more specifically of vinculin coupled to its subcellular redistribution are critical and early events in the cascade of mechanochemical signaling duringin vitroangiogenesis induced by fibrillar collagen. 相似文献
42.
Christophe Bailly Abdelilah Benamar Françoise Corbineau Daniel Come 《Physiologia plantarum》1996,97(1):104-110
Sunflower ( Helianthus annuus L.) seeds progressively lost their ability to germinate at 25°C, the optimal temperature for germination, after accelerated aging was carried out at 45°C (a temperature too high to permit germination) in water or at 76 or 100% relative humidity (RH). The deleterious effects of the high-temperature treatment increased with increasing seed moisture content. Incubation of seeds at 45°C in water resulted in electrolyte leakage, which indicated a loss of membrane integrity. A relationship between leakage and loss of seed viability could not be assumed, since no increase in electrolyte efflux occurred after aging al 100% RH. Accelerated aging induced accumulation of malondialdehyde, suggesting that seed deterioration was associated with lipid peroxidation. However, there was no direct relationship between lipid peroxidation and deterioration in membrane integrity. Loss of seed viability was also associated with a decrease in superoxide dismutase, catalase and glutathione reductase activities. Finally, the results obtained suggest that sunflower seed deterioration during accelerated aging is closely related to a decrease in the activities of detoxifying enzymes and to lipid peroxidation. 相似文献
43.
Detection and analysis of QTLs based on RAPD markers for polygenic resistance to Plasmodiophora brassicae Woron in Brassica oleracea L. 总被引:1,自引:0,他引:1
C. Grandclément G. Thomas 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,93(1-2):86-90
Resistance to Plasmodiophora brassicae Woron, the causal fungus of clubroot, was examined in an F2 population of a cross between a clubroot-resistant kale (Brassica oleracea L. var. acephala) and a susceptible cauliflower (Brassica oleracea L. var. botrytis). QTL detection was performed with RAPD markers. Two resistance notations, carried out at different times after inoculation, were used. Three markers were associated with these two notations and three were specifically linked to only one notation. QTL analysis suggests the existence of at least two genetic mechanisms implicated in the resistance phenomenon. 相似文献
44.
Clare Gough Pascale Hemon Maurice Tronchet Christophe Lacomme Yves Marco Dominique Roby 《Molecular genetics and genomics : MGG》1995,247(3):323-337
A family of genes, the so-called msr genes (multiple stimulus response), has recently been identified on the basis of sequence homology in various plant species. Members of this gene family are thought to be regulated by a number of environmental or developmental stimuli, although it is not known whether any one member responds more specifically to one stimulus, or whether each gene member responds to various environmental stimuli. In this report, we address this question by studying the tobacco msr gene str246C. Using transgenic tobacco plants containing 2.1 kb of 5′ flanking DNA sequence from the str246C gene fused to the β-glucuronidase (GUS) coding region, the complex expression pattern of the str246C promoter has been characterized. Expression of the str246C promoter is strongly and rapidly induced by bacterial, fungal and viral infection and this induction is systemic. Elicitor preparations from phytopathogenic bacteria and fungi activate the str246C promoter to high levels, as do wounding, the application of auxin, auxin and cytokinin, salicylic acid or copper sulfate, indicating the absence of gene specialization within the msr gene family, at least for str246C. In addition, GUS activity was visualized. histochemically in root meristematic tissues of tobacco seedlings and is restricted to roots and sepals of mature plants. Finally, analysis of a series of 5′ deletions of the str246C promoter-GUS gene fusion in transgenic tobacco plants confirms the involvement of multiple regulatory elements. A region of 83 by was found to be necessary for induction of promoter activity in response to Pseudomonas solanacearum, while auxin inducibility and root expression are apparently not controlled by this element, since its removal does not abolish either response. An element of the promoter with a negative effect on promoter activation by P. solanacearum was also identified. 相似文献
45.
The effects of deregulation of NR gene expression on growth and nitrogen metabolism of Nicotiana plumbaginifolia plants 总被引:1,自引:0,他引:1
46.
V. Patinec J. J. Yaouanc H. Handel J. C. Clment H. des Abbayes 《Inorganica chimica acta》1994,220(1-2):347-348
After reaction with alkyl iodides and subsequent oxidative removal of the M(CO)3 triprotection, molybdenum and chromium fac-LM(CO)3 complexes of cyclen (L) unexpectedly lead to N1,N7-dialkylated cyclen derivatives. 相似文献
47.
To investigate morphogenesis and in particular circularization mechanisms in young mycelia, we observe cultures of the zygomyceteMucor spinosus and develop discrete models of two-dimensional filamental branching growth. The models are based on the hypothesis that the
fungus secretes a regulatory substance that diffuses into the surrounding medium and is detected by the growing hyphae. We
also present a simple Markovian growth model without such a feedback, but yielding to analytical computations. 相似文献
48.
Effects of sub-minimal inhibitory concentrations of EDTA on growth of Escherichia coli and the release of lipopolysaccharide 总被引:1,自引:0,他引:1
Christophe Pelletier Pierre Bourlioux Jean van Heijenoort 《FEMS microbiology letters》1994,117(2):203-206
Abstract Release of lipopolysaccharide from E. coli was studied in the presence of sub-minimal inhibitory concentrations of ethylenediaminetetraacetic acid (EDTA). In untreated cells no release was detected with 50 mM Mg2+ in the medium, but a steady release of over 50% of the synthesized lipopolysaccharide was observed with 0.1 mM Mg2+ . EDTA at MIC/8 led to a 2- to 3-fold higher release, presumably by an adjustment of the concentration of unchelated Mg2+ to a value still sustaining normal growth but giving rise to a highly unstable outer membrane. No structural difference was observed between cell-bound and released lipopolysaccharide. 相似文献
49.
Michel J. Gauthier Gilles N. Flatau René L. Clément Patrick M. Munro 《Microbial ecology》1993,26(1):29-35
Using strains with or without the PhoE porin or different components of the phosphate regulon, we determined that maintenance of the culturability of Escherichia coli in seawater depended significantly on the presence of structures allowing access of phosphate ions to the periplasm, then to the cytoplasm of cells. Cells totally deprived of the two main phosphate transport systems (Pit, Pst) exhibited the highest loss of culturability. Most of this effect resulted from the loss of the high-affinity Pst system, and more specifically that of the periplasmic phosphate-binding protein PhoS. Survival was enhanced in seawater supplemented with phosphate (0.5 mm), whether or not these structures were present. From an ecological point of view, it is assumed that the presence of phosphate ions, even at low concentrations, can influence the behavior of E. coli cells in seawater.
Offprint requests to: M.J. Gauthier 相似文献
50.
Christine Delporte Anne Van Praet Andre Herchuelz Jacques Winand Jean Christophe 《Peptides》1993,14(6):1111-1118
The effects of PACAPs on [Ca2+]i were compared to those of carbachol in human neuroblastoma NB-OK-1 cells. PACAP(1–27) and PACAP(1–38) increased [Ca2+]i in a biphasic manner: a transient rise and a secondary plateau. The transient phase reflected the mobilization of [Ca2+]i pool(s) via the inositol phosphate pathway. The modest sustained plateau required extracellular Ca2+. Carbachol also increased [Ca2+]i in a biphasic manner, but it mobilized intracellular Ca2+ pool(s) with a higher efficacy than PACAPs, then greatly increased Ca2+ entry, this being accompanied by a more marked and prolonged elevation of IP3 and IP4 than with PACAPs. It is likely that cAMP-mediated phosphorylations due to PACAPs facilitated desensitization at the PACAP receptor-phospholipase C level, so that there was less Ca2+ handling through PACAP receptors than with muscarinic M1 receptors. 相似文献