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111.
Bullatantriol has been isolated from Annona bullata. Its constitution and relative configuration have been established by X-ray analysis. Its absolute configuration has been assigned by chiroptical investigation of the corresponding 7-ketone. 相似文献
112.
Koseki M Hirano K Masuda D Ikegami C Tanaka M Ota A Sandoval JC Nakagawa-Toyama Y Sato SB Kobayashi T Shimada Y Ohno-Iwashita Y Matsuura F Shimomura I Yamashita S 《Journal of lipid research》2007,48(2):299-306
Lipid rafts on the cell surface are believed to be very important as platforms for various cellular functions. The aim of this study was to know whether defective lipid efflux may influence lipid rafts on the cell surface and their related cellular functions. We investigated macrophages with defective lipid efflux from ATP binding cassette transporter A1-deficient (Abca1-KO) mice. Lipid rafts were evaluated by the following two novel probes: a biotinylated and protease (subtilisin Carlsberg)-nicked derivative of theta-toxin and a fluorescein ester of polyethylene glycol-derived cholesterol. Lipid rafts in Abca1-KO macrophages were increased, as demonstrated by both probes. Moreover, activities of nuclear factor kappaB, mRNA and intracellular distribution, and secretion of tumor necrosis factor-alpha (TNF-alpha) were examined after stimulation by lipopolysaccharides (LPSs). LPS-induced responses of the activation of nuclear factor kappaB and TNF-alpha were more prompt and accelerated in the Abca1-KO macrophages compared with wild-type macrophages. Modification of lipid rafts by cyclodextrin and nystatin corrected the abnormal response, suggesting an association between the increased lipid rafts and abnormal TNF-alpha secretion. We report here that Abca1-KO macrophages with defective lipid efflux exhibited increased lipid rafts on the cell surface and accelerated TNF-alpha secretion. 相似文献
113.
Alcides AP Brazier JS Pinto LJ Balassiano IT Boente RF de Paula GR Ferreira EO Avelar KE Miranda KR Ferreira MC Domingues RM 《Antonie van Leeuwenhoek》2007,92(1):53-59
A total of 35 Brazilian isolates of Clostridium difficile from faecal stools and four isolates from hospital environments were analyzed by PCR ribotyping. A whole cell protein profile
(as an alternative for serogrouping), in vitro toxin production and susceptibility to vancomycin, metronidazole and clindamycin
were also investigated. All strains were typeable by both phenotypic and genotypic methods, and a total of 13 different PCR
ribotypes were identified, of which seven (132, 133, 134, 135, 136, 142 and 143) were considered new types and accounted for
78.5% of all samples evaluated (including hospital environments). A non-toxigenic C. difficile PCR ribotype 133 was detected in all children groups examined (inpatients, outpatients and healthy children), whilst toxigenic
PCR ribotypes 015, 131, 134 and 135 were associated mostly with symptomatic children. Serogroups G and D were disseminated
both in patients from the community and from the pediatric hospital, with group G prevalent among outpatient children. All
strains were susceptible to vancomycin and metronidazole but high levels of resistance to clindamycin were found, especially
among serogroups G and D. Co-existence of different ribotypes and serogroups in the same individual was observed. The new
seven ribotypes found in this investigation may represent strains characteristic of this region of Brazil. 相似文献
114.
Sandoval A Arikkath J Monjaraz E Campbell KP Felix R 《Cellular and molecular neurobiology》2007,27(7):901-908
(1) Voltage-gated Ca2+ (CaV) channels are multi-subunit membrane complexes that allow depolarization-induced Ca2+ influx into cells. The skeletal muscle L-type CaV channels consist of an ion-conducting CaV1.1 subunit and auxiliary α2δ−1, β1 and γ1 subunits. This complex serves both as a CaV channel and as a voltage sensor for excitation–contraction coupling. (2) Though much is known about the mechanisms by which
the α2δ−1 and β1 subunits regulate CaV channel function, there is far less information on the γ1 subunit. Previously, we characterized the interaction of γ1 with the other components of the skeletal CaV channel complex, and showed that heterologous expression of this auxiliary subunit decreases Ca2+ current density in myotubes from γ1 null mice. (3) In the current report, using Western blotting we show that the expression of the CaV1.1 protein is significantly lower when it is heterologously co-expressed with γ1. Consistent with this, patch-clamp recordings showed that transient transfection of γ1 drastically inhibited macroscopic currents through recombinant N-type (CaV2.2/α2δ−1/β3) channels expressed in HEK-293 cells. (4) These findings provide evidence that co-expression of the auxiliary γ1 subunit results in a decreased expression of the ion-conducting subunit, which may help to explain the reduction in Ca2+ current density following γ1 transfection. 相似文献
115.
Functional and crystal structure analysis of active site adaptations of a potent anti-angiogenic human tRNA synthetase 总被引:1,自引:0,他引:1
Yang XL Guo M Kapoor M Ewalt KL Otero FJ Skene RJ McRee DE Schimmel P 《Structure (London, England : 1993)》2007,15(7):793-805
Higher eukaryote tRNA synthetases have expanded functions that come from enlarged, more differentiated structures that were adapted to fit aminoacylation function. How those adaptations affect catalytic mechanisms is not known. Presented here is the structure of a catalytically active natural splice variant of human tryptophanyl-tRNA synthetase (TrpRS) that is a potent angiostatic factor. This and related structures suggest that a eukaryote-specific N-terminal extension of the core enzyme changed substrate recognition by forming an active site cap. At the junction of the extension and core catalytic unit, an arginine is recruited to replace a missing landmark lysine almost 200 residues away. Mutagenesis, rapid kinetic, and substrate binding studies support the functional significance of the cap and arginine recruitment. Thus, the enzyme function of human TrpRS has switched more to the N terminus of the sequence. This switch has the effect of creating selective pressure to retain the N-terminal extension for functional expansion. 相似文献
116.
Peña-Rico Miguel A. Bravo-D Humberto R. Roldan-Sabino Crisanto Castro-Cerritos Karla V. Huerta-Heredia Ariana Navarro-Mtz A. Karin 《Antonie van Leeuwenhoek》2022,115(1):89-102
Antonie van Leeuwenhoek - Bacillus thuringiensis is the major bioinsecticide worldwide produced due to the Cry protein activity. Several studies have been done to improve the... 相似文献
117.
Hydrobiologia - Theory predicts that species can only coexist if they are sufficiently different in their resource and/or microhabitat utilization; if their needs are too similar, the stronger... 相似文献
118.
119.
Marc Solà-Ginés Juan José González-López Karla Cameron-Veas Nuria Piedra-Carrasco Marta Cerdà-Cuéllar Lourdes Migura-Garcia 《Applied and environmental microbiology》2015,81(11):3604-3611
Flies may act as potential vectors for the spread of resistant bacteria to different environments. This study was intended to evaluate the presence of Escherichia coli strains resistant to cephalosporins in flies captured in the areas surrounding five broiler farms. Phenotypic and molecular characterization of the resistant population was performed by different methods: MIC determination, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and phylotyping. The presence of extended-spectrum beta-lactamase (ESBL) genes, their plasmid location, and the mobile genetic elements involved in their mobilization were studied. Additionally, the presence of 35 genes associated with virulence was evaluated. Out of 682 flies captured, 42 yielded ESBL-producing E. coli. Of these isolates, 23 contained blaCTX-M-1, 18 contained blaCTX-M-14, and 1 contained blaCTX-M-9. ESBL genes were associated mainly with the presence of the IncI1 and IncFIB replicons. Additionally, all the strains were multiresistant, and five of them also harbored qnrS. Identical PFGE profiles were found for E. coli isolates obtained from flies at different sampling times, indicating a persistence of the same clones in the farm environment over months. According to their virulence genes, 81% of the isolates were considered avian-pathogenic E. coli (APEC) and 29% were considered extraintestinal pathogenic E. coli (ExPEC). The entrance of flies into broiler houses constitutes a considerable risk for colonization of broilers with multidrug-resistant E. coli. ESBLs in flies reflect the contamination status of the farm environment. Additionally, this study demonstrates the potential contribution of flies to the dissemination of virulence and resistance genes into different ecological niches. 相似文献
120.
Karla?V.?Figueiredo Marciel?T.?Oliveira Emília?C.?P.?Arruda Bárbara?C.?F.?Silva Mauro?G.?SantosEmail author 《Acta Physiologiae Plantarum》2015,37(6):108
Jatropha curcas and Jatropha mollissima plants were evaluated under conditions of high (HSM) and low (LSM) soil moisture in a semi-arid environment, as changes in the content and concentration of epicuticular wax and the leaf metabolism which could have a relationship with drought tolerance. Besides epicuticular wax, gas exchange, antioxidant system and biochemical parameters of the photosynthetic metabolism were measured. The epicuticular wax content increased only in J. mollissima leaves 95 % under LSM, when compared with HSM conditions. Therefore, J. curcas invested less in the production of long-chain n-alkanes than did J. mollissima under LSM conditions. J. mollissima plants showed the highest CO2 assimilation rate during the HSM period compared to J. curcas. Both species showed high stability in some leaf biochemistry products, highlighting the highest sugar content, free amino acids, total soluble protein, and photosynthetic pigments in the leaves of J. mollissima plants under both of the soil moisture conditions. Moreover, the stability and performance of the different parameters, such as morphologic variables, seem to allow J. mollissima plants to tolerate semi-arid conditions. 相似文献