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81.
In this study we measured the exogenous production and the intracellular content of elemental sulfur (S0) in the thermophilic sulfur-oxidizing bacteriaHydrogenobacter spp. andBacillus schlegelii during mixolithoautotrophic growth on hydrogen and thiosulfate. Under these conditions, all strains produced and released white-yellow hydrophilic S0 particles into the growth medium. Hydrophilic S0 was separated from cells by a differential low-speed centrifugation procedure. The S0 pellets were dried, and the S0 was purified by column chromatography and by thin-layer chromatography (TLC). The S0 TLC-band could be stained with triphenyltetrazolium chloride and piperidine procedure. Determination of intracellular S0 content was performed from fresh cells absolutely free of exogenous S0 particles. quantitation of S0 was performed by high-performance liquid chromatography, colorimetric thiocyanate procedure, and by UV-spectra analyses. All the strains studied, in particularB. schlegelii strains, released significant quantities of S0 into the growth media. In contrast, the intracellular S0 content was very low. Significant rhodanese activity in the presence of thiosulfate was measured with toluenepermeabilized cells and cell-free extracts ofB. schlegelii (type strain) andHydrogenobacter spp. (strain T3). 相似文献
82.
Valérie Michel Gérard Fonty Liliane Millet Frédérique Bonnemoy Philippe Gouet 《FEMS microbiology letters》1993,110(1):5-9
Abstract To better define the antigenic structure of the outer cell membranes of Legionellae, a panel of 6 monoclonal antibodies was raised against partially purified outer membranes of Legionella pneumophila serogroup 1, Corby strain. This study describes the purification and characterization of one of these monoclonal antibodies reacting with a 135-kDa protein, which was shown to be common to all 14 serogroups of Legionella pneumophila . It shows no cross-reactivity with 20 other Legionella species, or 9 other Gram-negative species tested by SDS-PAGE and Western blotting procedures. The epitope would appear to be predominantly surface exposed and, from preliminary detergent extraction studies, not peptidoglycan-associated. 相似文献
83.
Rizky Pasthika Kirana Kumar Gaurav Sanu Arora Gerlinde Wiesenberger Maria Doppler Sebastian Michel Simone Zimmerl Magdalena Matic Chinedu E. Eze Mukesh Kumar Ajla Topuz Marc Lemmens Rainer Schuhmacher Gerhard Adam Brande B. H. Wulff Hermann Buerstmayr Barbara Steiner 《Plant biotechnology journal》2023,21(1):109-121
Aegilops tauschii is the diploid progenitor of the wheat D subgenome and a valuable resource for wheat breeding, yet, genetic analysis of resistance against Fusarium head blight (FHB) and the major Fusarium mycotoxin deoxynivalenol (DON) is lacking. We treated a panel of 147 Ae. tauschii accessions with either Fusarium graminearum spores or DON solution and recorded the associated disease spread or toxin-induced bleaching. A k-mer-based association mapping pipeline dissected the genetic basis of resistance and identified candidate genes. After DON infiltration nine accessions revealed severe bleaching symptoms concomitant with lower conversion rates of DON into the non-toxic DON-3-O-glucoside. We identified the gene AET5Gv20385300 on chromosome 5D encoding a uridine diphosphate (UDP)-glucosyltransferase (UGT) as the causal variant and the mutant allele resulting in a truncated protein was only found in the nine susceptible accessions. This UGT is also polymorphic in hexaploid wheat and when expressed in Saccharomyces cerevisiae only the full-length gene conferred resistance against DON. Analysing the D subgenome helped to elucidate the genetic control of FHB resistance and identified a UGT involved in DON detoxification in Ae. tauschii and hexaploid wheat. This resistance mechanism is highly conserved since the UGT is orthologous to the barley UGT HvUGT13248 indicating descent from a common ancestor of wheat and barley. 相似文献
84.
Induction of phagocytic behaviour in human epithelial cells by Escherichia coli cytotoxic necrotizing factor type1 总被引:7,自引:0,他引:7
Loredana Falzano Carla Fiorentini Gianfranco Donelli Eric Michel Christine Kocks Pascale Cossart Lucien Cabanié Eric Oswald Patrice Boquet 《Molecular microbiology》1993,9(6):1247-1254
Cytotoxic necrotizing factor type 1 (CNF1) from strains of pathogenic Escherichia coli induces in human epithelial HEp-2 cells, a profound reorganization of the actin cytoskeleton into prominent stress fibres and membrane ruffles. We report here that this process is associated with induction of phagocytic-like activity. CNF1-treated cells acquired the ability to ingest latex beads as well as non-invasive bacteria such as Listeria innocua, which were taken as a model system. Uptake of bacteria was similar to pathogen-induced phagocytosis, since L. innocua transformed with DNA coding for the pore-forming toxin listeriolysln O behaved, with respect to intracellular growth, like the invasive, pathogenic species L. monocytogenes. Our results raise the possibility that, in vivo, pathogenic CNF1 -producing E. coli may invade epithelia by this novel induced phagocytic-like mechanism. 相似文献
85.
An in vitro test method for general metal toxicity screening was designed, based on the cellular response to stress. The expression of a transfected human growth hormone gene sequence driven by the human heat-shock protein 70 promoter in NIH/3T3 cells was used as marker of noxious contact with metal compounds. Out of a series of31 metals, 17 were competentfor inducing this stress response system. According to the effective concentration and to the intensity of the response, three different clusters of positive compounds emerged and were ranked as strong, intermediate strength and weak inducers. These results correlated well with data from other in vivo and in vitro metal toxicity studies, including LD50 in mice. Apparently the positivelnegative compounds also fitted well with data from genotoxicity and carcinogenesis studies on metal salts.Abbreviations hGH
human growth hormone
- hsp70
70 kDa heat-shock protein 相似文献
86.
A system for somatic embryogenesis and plant regeneration of spinach from hypocotyl segments has been established. Callus
was induced on solid media supplemented with 8.5–15.0 mg.l−1 of indole-3-acetic acid and 3.46–34.64 mg.l−1 gibberellic acid. Callus was then subcultured on different media (solid or liquid) with or without IAA, or continuously maintained
on the initiating media. Somatic embryos were obtained in subcultures on IAA-containing media as well as in long-term cultures
on initiating media. The best results were achieved in liquid subcultures. About 60% of plantlets survived after transplanting
in pots. 相似文献
87.
88.
Holly L. Neibergs Daniel S. Gallagher Michel Georges Leslie S. Sargeant Allan B. Dietz James E. Womack 《Mammalian genome》1993,4(6):328-332
The gene for the -A subunit of inhibin (INHBA) was assigned to bovine syntenic group U13 by bovine x rodent hybrid somatic cells and the polymerase chain reaction (PCR). A 482-bp PCR fragment was used to clone a 37-kb cosmid. This cosmid was assigned to bovine Chromosome (Chr) 4 (BTA 4) by fluorescence in situ hybridization (FISH). This is the first assignment of a U13 marker to a bovine chromosome. A restriction fragment length polymorphism (RFLP) was detected with PstI within the INHBA cosmid. 相似文献
89.
Brice Maxime Nkouayeb Nangmou Hermine Laure Maza Djomkam Georges Bellier Tabekoueng Willifred Dongmo Tékapi Tsopgni Gabin Thierry Mbahbou Bitchagno Michel Arnaud Mbock Raceline Gounoue Kamkumo Marcel Frese Bruno Ndjakou Lenta Silvère Augustin Ngouela Nobert Sewald Anatole Guy Blaise Azebaze 《化学与生物多样性》2023,20(4):e202200271
The root extract of Nauclea xanthoxylon (A.Chev.) Aubrév. displayed significant 50 % inhibition concentration (IC50s) of 0.57 and 1.26 μg/mL against chloroquine resistant and sensitive Plasmodium falciparum (Pf) Dd2 and 3D7 strains, respectively. Bio-guided fractionation led to an ethyl acetate fraction with IC50s of 2.68 and 1.85 μg/mL and subsequently, to the new quinovic acid saponin named xanthoxyloside ( 1 ) with IC50s of 0.33 and 1.30 μM, respectively against the tested strains. Further compounds obtained from ethyl acetate and hexane fractions were the known clethric acid ( 2 ), ursolic acid ( 3 ), quafrinoic acid ( 4 ), quinovic acid ( 5 ), quinovic acid 3-O-β-D-fucopyranoside ( 6 ), oleanolic acid ( 7 ), oleanolic acid 3-acetate ( 8 ), friedelin ( 9 ), β-sitosterol ( 10a ), stigmasterol ( 10b ) and stigmasterol 3-O-β-D-glucopyranoside ( 11 ). Their structures were characterised with the aid of comprehensive spectroscopic methods (1 and 2D NMR, Mass). Bio-assays were performed using nucleic acid gel stain (SYBR green I)-based fluorescence assay with chloroquine as reference. Extracts and compounds exhibited good selectivity indices (SIs) of >10. Significant antiplasmodial activities measured for the crude extract, the ethyl acetate fraction and xanthoxyloside ( 1 ) from that fraction can justify the use of the root of N. xanthoxylon in ethnomedicine to treat malaria. 相似文献
90.