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141.
Martín González‐Andrade Paulina Del Valle Martha ;L. Macías‐Rubalcava Alejandro Sosa‐Peinado María Del Carmen González Rachel Mata 《化学与生物多样性》2013,10(3):328-337
An organic extract was prepared from the culture medium and mycelia of the marine fungus Aspergillus stromatoides Raper & Fennell . The extract was fractionated via column chromatography, and the resulting fractions were tested for their abilities to quench the fluorescence of the calmodulin (CaM) biosensor hCaM M124C‐mBBr. From the active fraction, emodin ( 1 ) and ω‐hydroxyemodin ( 2 ) were isolated as CaM inhibitors. Anthraquinones 1 and 2 quenched the fluorescence of the hCaM M124C‐mBBr biosensor in a concentration‐dependent manner with Kd values of 0.33 and 0.76 μM , respectively. The results were compared with those of chlorpromazine (CPZ), a classical inhibitor of CaM, with a Kd value of 1.25 μM . Docking analysis revealed that 1 and 2 bind to the same pocket of CPZ. The CaM inhibitor properties of 1 and 2 were correlated with some of their reported biological properties. Citrinin ( 3 ), methyl 8‐hydroxy‐6‐methyl‐9‐oxo‐9H‐xanthene‐1‐carboxylate ( 4 ), and coniochaetone A ( 5 ) were also isolated in the present study. The X‐ray structure of 5 is reported for the first time. 相似文献
142.
Zaizy Rocha-Pino María del Carmen Marín-Cervantes Marlet Martínez-Archundia Elizabeth Soriano-Blancas Sergio Revah Keiko Shirai 《Bioprocess and biosystems engineering》2013,36(5):531-539
Lecanicillium lecanii, Verticillium chlamydosporium, V. fungicola var flavidum and Beauveria bassiana were evaluated on their growth with pure n-hexane, toluene and n-hexane:toluene 17:83 (v:v) mixture. Another set of treatments were conducted with colloidal chitin as additional carbon source. All the strains of Lecanicillium were able to grow using hydrocarbons with or without the addition of chitin, although the presence of hydrocarbons showed significant inhibition evidenced by measured biomass, radial growth and microscopic analyses. Degradation of n-hexane ranged within 43 and 62 % and it was higher than that with toluene. The strains L460, L157 and L2149, which presented the highest growth, were further selected for determinations of hydrocarbon consumptions in microcosms. Strain L157 showed the highest consumption of n-hexane (55.6 %) and toluene (52.9 %) as sole carbon source and it also displayed activities of endochitinases, N-acetylhexosaminidase and production of hydrophobins class I and II. 相似文献
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144.
Michiel Stork Jan Grijpstra Martine P. Bos Carmen Ma?as Torres Nathalie Devos Jan T. Poolman Walter J. Chazin Jan Tommassen 《PLoS pathogens》2013,9(10)
The outer membrane of Gram-negative bacteria functions as a permeability barrier that protects these bacteria against harmful compounds in the environment. Most nutrients pass the outer membrane by passive diffusion via pore-forming proteins known as porins. However, diffusion can only satisfy the growth requirements if the extracellular concentration of the nutrients is high. In the vertebrate host, the sequestration of essential nutrient metals is an important defense mechanism that limits the growth of invading pathogens, a process known as “nutritional immunity.” The acquisition of scarce nutrients from the environment is mediated by receptors in the outer membrane in an energy-requiring process. Most characterized receptors are involved in the acquisition of iron. In this study, we characterized a hitherto unknown receptor from Neisseria meningitidis, a causative agent of sepsis and meningitis. Expression of this receptor, designated CbpA, is induced when the bacteria are grown under zinc limitation. We demonstrate that CbpA functions as a receptor for calprotectin, a protein that is massively produced by neutrophils and other cells and that has been shown to limit bacterial growth by chelating Zn2+ and Mn2+ ions. Expression of CbpA enables N. meningitidis to survive and propagate in the presence of calprotectin and to use calprotectin as a zinc source. Besides CbpA, also the TonB protein, which couples energy of the proton gradient across the inner membrane to receptor-mediated transport across the outer membrane, is required for the process. CbpA was found to be expressed in all N. meningitidis strains examined, consistent with a vital role for the protein when the bacteria reside in the host. Together, our results demonstrate that N. meningitidis is able to subvert an important defense mechanism of the human host and to utilize calprotectin to promote its growth. 相似文献
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147.
Isabel Roncero Elvira Alvarez Carlos Acosta Carmen Sanz Pedro Barrio Veronica Hurtado-Carneiro Deborah Burks Enrique Blázquez 《PloS one》2013,8(4)
Insulin receptor substrate (IRS) proteins play important roles in hepatic nutrient homeostasis. Since glucokinase (GK) and glucokinase regulatory protein (GKRP) function as key glucose sensors, we have investigated the expression of GK and GKRP in liver of Irs-2 deficient mice and Irs2(−/−) mice where Irs2 was reintroduced specifically into pancreatic β-cells [RIP-Irs-2/IRS-2(−/−)]. We observed that liver GK activity was significantly lower (p<0.0001) in IRS-2(−/−) mice. However, in RIP-Irs-2/IRS-2(−/−) mice, GK activity was similar to the values observed in wild-type animals. GK activity in hypothalamus was not altered in IRS-2(−/−) mice. GK and GKRP mRNA levels in liver of IRS-2(−/−) were significantly lower, whereas in RIP-Irs-2/IRS-2(−/−) mice, both GK and GKRP mRNAs levels were comparable to wild-type animals. At the protein level, the liver content of GK was reduced in IRS-2(−/−) mice as compared with controls, although GKRP levels were similar between these experimental models. Both GK and GKRP levels were lower in RIP-Irs-2/IRS-2(−/−) mice. These results suggest that IRS-2 signalling is important for maintaining the activity of liver GK. Moreover, the differences between liver and brain GK may be explained by the fact that expression of hepatic, but not brain, GK is controlled by insulin. GK activity was restored by the β-cell compensation in the RIP-Irs-2/IRS-2 mice. Interestingly, GK and GKRP protein expression remained low in RIP-Irs-2/IRS-2(−/−) mice, perhaps reflecting different mRNA half-lives or alterations in the process of translation and post-translational regulation. 相似文献
148.
Luis E. López-Cortés Juan Gálvez-Acebal María D. del Toro Carmen Velasco Marina de Cueto Francisco J. Caballero Miguel A. Muniain álvaro Pascual Jesús Rodríguez-Ba?o 《PloS one》2013,8(12)
Introduction
Statins have pleiotropic effects that could influence the prevention and outcome of some infectious diseases. There is no information about their specific effect on Staphylococcus aureus bacteremia (SAB).Methods
A prospective cohort study including all SAB diagnosed in patients aged ≥18 years admitted to a 950-bed tertiary hospital from March 2008 to January 2011 was performed. The main outcome variable was 14-day mortality, and the secondary outcome variables were 30-day mortality, persistent bacteremia (PB) and presence of severe sepsis or septic shock at diagnosis of SAB. The effect of statin therapy at the onset of SAB was studied by multivariate logistic regression and Cox regression analysis, including a propensity score for statin therapy.Results
We included 160 episodes. Thirty-three patients (21.3%) were receiving statins at the onset of SAB. 14-day mortality was 21.3%. After adjustment for age, Charlson index, Pitt score, adequate management, and high risk source, statin therapy had a protective effect on 14-day mortality (adjusted OR = 0.08; 95% CI: 0.01–0.66; p = 0.02), and PB (OR = 0.89; 95% CI: 0.27–1.00; p = 0.05) although the effect was not significant on 30-day mortality (OR = 0.35; 95% CI: 0.10–1.23; p = 0.10) or presentation with severe sepsis or septic shock (adjusted OR = 0.89; CI 95%: 0.27–2.94; p = 0.8). An effect on 30-day mortality could neither be demonstrated on Cox analysis (adjusted HR = 0.5; 95% CI: 0.19–1.29; p = 0.15).Conclusions
Statin treatment in patients with SAB was associated with lower early mortality and PB. Randomized studies are necessary to identify the role of statins in the treatment of patients with SAB. 相似文献149.
Elahe Radmaneshfar Despoina Kaloriti Michael C. Gustin Neil A. R. Gow Alistair J. P. Brown Celso Grebogi M. Carmen Romano Marco Thiel 《PloS one》2013,8(7)
The cell cycle is a sequence of biochemical events that are controlled by complex but robust molecular machinery. This enables cells to achieve accurate self-reproduction under a broad range of different conditions. Environmental changes are transmitted by molecular signalling networks, which coordinate their action with the cell cycle. The cell cycle process and its responses to environmental stresses arise from intertwined nonlinear interactions among large numbers of simpler components. Yet, understanding of how these pieces fit together into a coherent whole requires a systems biology approach. Here, we present a novel mathematical model that describes the influence of osmotic stress on the entire cell cycle of S. cerevisiae for the first time. Our model incorporates all recently known and several proposed interactions between the osmotic stress response pathway and the cell cycle. This model unveils the mechanisms that emerge as a consequence of the interaction between the cell cycle and stress response networks. Furthermore, it characterises the role of individual components. Moreover, it predicts different phenotypical responses for cells depending on the phase of cells at the onset of the stress. The key predictions of the model are: (i) exposure of cells to osmotic stress during the late S and the early G2/M phase can induce DNA re-replication before cell division occurs, (ii) cells stressed at the late G2/M phase display accelerated exit from mitosis and arrest in the next cell cycle, (iii) osmotic stress delays the G1-to-S and G2-to-M transitions in a dose dependent manner, whereas it accelerates the M-to-G1 transition independently of the stress dose and (iv) the Hog MAPK network compensates the role of the MEN network during cell division of MEN mutant cells. These model predictions are supported by independent experiments in S. cerevisiae and, moreover, have recently been observed in other eukaryotes. 相似文献
150.
Alberto Crespo Guardo Carmen álvarez-Fernández Hodei Arberas Javier García-Pérez Felipe García Manuel Enric Bargalló María José Maleno José María Gatell Beatriz Mothe José Alcami Sonsoles Sánchez-Palomino Montserrat Plana 《PloS one》2013,8(3)