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排序方式: 共有310条查询结果,搜索用时 625 毫秒
261.
Ismael Soto Ross N. Cuthbert Danish A. Ahmed Antonín Kouba Sami Domisch Jaime R. G. Marquez Ayah Beidas Giuseppe Amatulli Jens Kiesel Longzhu Q. Shen Margarita Florencio Herlander Lima Elizabeta Briski Florian Altermatt Gaït Archambaud-Suard Peter Borza Zoltan Csabai Thibault Datry Mathieu Floury Maxence Forcellini Jean-François Fruget Patrick Leitner Marie-Hélène Lizée Anthony Maire Anthony Ricciardi Ralf B. Schäfer Rachel Stubbington Gea H. Van der Lee Gábor Várbíró Ralf C. M. Verdonschot Peter Haase Phillip J. Haubrock 《Diversity & distributions》2023,29(1):157-172
262.
Microbiologically influenced corrosion: looking to the future. 总被引:5,自引:0,他引:5
This review discusses the state-of-the-art of research into biocorrosion and the biofouling of metals and alloys of industrial usage. The key concepts needed to understand the main effects of microorganisms on metal decay, and current trends in monitoring and control strategies to mitigate the deleterious effects of biocorrosion and biofouling are also described. Several relevant cases of biocorrosion studied by our research group are provided as examples: (i) biocorrosion of aluminum and its alloys by fungal contaminants of jet fuels; (ii) sulfate-reducing bacteria (SRB)-induced corrosion of steel; (iii) biocorrosion and biofouling interactions in the marine environment; (iv) monitoring strategies for assessing biocorrosion in industrial water systems; (v) microbial inhibition of corrosion; (vi) use and limitations of electrochemical techniques for evaluating biocorrosion effects. Future prospects in the field are described with respect to the potential of innovative techniques in microscopy (environmental scanning electron microscopy, confocal scanning laser microscopy, atomic force microscopy), new spectroscopic techniques for the study of corrosion products and biofilms (energy dispersion X-ray analysis, X-ray photoelectron spectroscopy, electron microprobe analysis) and electrochemistry (electrochemical impedance spectroscopy, electrochemical noise analysis). 相似文献
263.
Paola C. Yannielli Martí n Cadeiras Liz Gregoretti Lucila Kargieman Daniel P. Cardinali Diego A. Golombek 《Biological Rhythm Research》2000,31(3):391-415
The aim of the present work is to discuss the available data on neonatal and adult antidepressant treatment in relation to animal models of depression and serotonergic modulation of the circadian system, with a particular emphasis on our own published and unpublished work on the effects of clomipramine (a serotonin reuptake inhibitor) on the Syrian hamster circadian behavior. Neonatal clomipramine treatment (15 mg/kg from postnatal days 8 to 21) significantly augmented the amplitude of the wheel running rhythm, as well as delayed its acrophase and increased the time to reentrain after a 6-h phase advance of the light-dark cycle. Neonatally clomipramine-treated hamsters had a shorter circadian period than saline-treated animals under constant light - but not under constant dark- conditions, exhibited decreased phase advances after light pulses applied at late subjective night and greater phase advances after i.p. administration of the 5-HT1A-receptor agonist 8-OH-DPA at midday. These animals also exhibited more locomotor activity than controls, but did not display the typical circadian variation in anxiety-related behavior, as measured in a plus-maze paradigm. They also showed an increased 5-HIAA/5-HT ratio in hypothalamus and midbrain raphe, while 5-HT content was decreased in frontal cortex and anterior hypothalamic areas. Since drugs linked to the serotonergic system are able to modify the circadian system, we decided to test whether acute and chronic clomipramine administration in adulthood was able to change: a) the phase of free running activity rhythms; (b) light-induced phase shifts, and (c) hypothalamic 5-HT turnover. Acute clomipramine injection had a phase-dependent effect on the free running activity rhythm, with phase advances at CT 0-8 being significantly higher than at CT 8-16. Pretreatment with clomipramine inhibited phase advances in response to light pulses when applied at CT 19 while phase delays at CT 14 remained unaffected. This acute treatment also decreased 5-HT turnover in the SCN at both CTs. In contrast, chronic clomipramine administration potentiated light-induced phase advances, without changes in period, amplitude or central 5-HT turnover. Taken together, these data support the view that clomipramine, as other antidepressant drugs, can affect the expression of the circadian rhythmicity in Syrian hamsters, possibly through serotonergic mechanisms in the case of acute treatments, and more complex behavioral interaction in the case of neonatal and chronic treatments. 相似文献
264.
Chronic stress promotes tumor growth and angiogenesis in a mouse model of ovarian carcinoma 总被引:11,自引:0,他引:11
Thaker PH Han LY Kamat AA Arevalo JM Takahashi R Lu C Jennings NB Armaiz-Pena G Bankson JA Ravoori M Merritt WM Lin YG Mangala LS Kim TJ Coleman RL Landen CN Li Y Felix E Sanguino AM Newman RA Lloyd M Gershenson DM Kundra V Lopez-Berestein G Lutgendorf SK Cole SW Sood AK 《Nature medicine》2006,12(8):939-944
Stress can alter immunological, neurochemical and endocrinological functions, but its role in cancer progression is not well understood. Here, we show that chronic behavioral stress results in higher levels of tissue catecholamines, greater tumor burden and more invasive growth of ovarian carcinoma cells in an orthotopic mouse model. These effects are mediated primarily through activation of the tumor cell cyclic AMP (cAMP)-protein kinase A (PKA) signaling pathway by the beta(2) adrenergic receptor (encoded by ADRB2). Tumors in stressed animals showed markedly increased vascularization and enhanced expression of VEGF, MMP2 and MMP9, and we found that angiogenic processes mediated the effects of stress on tumor growth in vivo. These data identify beta-adrenergic activation of the cAMP-PKA signaling pathway as a major mechanism by which behavioral stress can enhance tumor angiogenesis in vivo and thereby promote malignant cell growth. These data also suggest that blocking ADRB-mediated angiogenesis could have therapeutic implications for the management of ovarian cancer. 相似文献
265.
We address the global stability properties of the positive equilibrium in a general delayed discrete population model. Our results are used to investigate in detail a well-known model for baleen whale populations.E. Liz was supported in part by M.E.C. (Spain) and FEDER, under project MTM2004-06652-C03-02. 相似文献
266.
McNulty C Thompson J Barrett B Lord L Andersen C Roberts IS 《Molecular microbiology》2006,59(3):907-922
The export of large negatively charged capsular polysaccharides across the outer membrane represents a significant challenge to Gram negative bacteria. In the case of Escherichia coli group 2 capsular polysaccharides, the mechanism of export across the outer membrane was unknown, with no identified candidate outer membrane proteins. In this paper we demonstrate that the KpsD protein, previously believed to be a periplasmic protein, is an outer membrane protein involved in the export of group 2 capsular polysaccharides across the outer membrane. We demonstrate that KpsD and KpsE are located at the poles of the cell and that polysaccharide biosynthesis and export occurs at these polar sites. By in vivo chemical cross-linking and MALDI-TOF-MS analysis we demonstrate the presence of a multi-protein biosynthetic/export complex in which cytoplasmic proteins involved in polysaccharide biosynthesis could be cross-linked to proteins involved in export across the inner and outer membranes. In addition, we show that the RhsA protein, of previously unknown function, could be cross-linked to the complex and that a rhsA mutation reduces K5 biosynthesis suggesting a role for RhsA in coupling biosynthesis and export. 相似文献
267.
García-González V Govantes F Shaw LJ Burns RG Santero E 《Applied and environmental microbiology》2003,69(12):6987-6993
Pseudomonas sp. strain ADP uses the herbicide atrazine as the sole nitrogen source. We have devised a simple atrazine degradation assay to determine the effect of other nitrogen sources on the atrazine degradation pathway. The atrazine degradation rate was greatly decreased in cells grown on nitrogen sources that support rapid growth of Pseudomonas sp. strain ADP compared to cells cultivated on growth-limiting nitrogen sources. The presence of atrazine in addition to the nitrogen sources did not stimulate degradation. High degradation rates obtained in the presence of ammonium plus the glutamine synthetase inhibitor MSX and also with an Nas(-) mutant derivative grown on nitrate suggest that nitrogen regulation operates by sensing intracellular levels of some key nitrogen-containing metabolite. Nitrate amendment in soil microcosms resulted in decreased atrazine mineralization by the wild-type strain but not by the Nas(-) mutant. This suggests that, although nitrogen repression of the atrazine catabolic pathway may have a strong impact on atrazine biodegradation in nitrogen-fertilized soils, the use of selected mutant variants may contribute to overcoming this limitation. 相似文献
268.
269.
Enhanced biodegradation in the rhizosphere has been reported for many organic xenobiotic compounds, although the mechanisms are not fully understood. The purpose of this study was to discover whether rhizosphere-enhanced biodegradation is due to selective enrichment of degraders through growth on compounds produced by rhizodeposition. We monitored the mineralization of [U-(14)C]2,4-dichlorophenoxyacetic acid (2,4-D) in rhizosphere soil with no history of herbicide application collected over a period of 0 to 116 days after sowing of Lolium perenne and Trifolium pratense. The relationships between the mineralization kinetics, the number of 2,4-D degraders, and the diversity of genes encoding 2,4-D/alpha-ketoglutarate dioxygenase (tfdA) were investigated. The rhizosphere effect on [(14)C]2,4-D mineralization (50 microg g(-1)) was shown to be plant species and plant age specific. In comparison with nonplanted soil, there were significant (P < 0.05) reductions in the lag phase and enhancements of the maximum mineralization rate for 25- and 60-day T. pratense soil but not for 116-day T. pratense rhizosphere soil or for L. perenne rhizosphere soil of any age. Numbers of 2,4-D degraders in planted and nonplanted soil were low (most probable number, <100 g(-1)) and were not related to plant species or age. Single-strand conformational polymorphism analysis showed that plant species had no impact on the diversity of alpha-Proteobacteria tfdA-like genes, although an impact of 2,4-D application was recorded. Our results indicate that enhanced mineralization in T. pratense rhizosphere soil is not due to enrichment of 2,4-D-degrading microorganisms by rhizodeposits. We suggest an alternative mechanism in which one or more components of the rhizodeposits induce the 2,4-D pathway. 相似文献
270.
Tissue inhibitor of metalloproteinases-2 growth-stimulatory activity is mediated by nuclear factor-kappa B in A549 lung epithelial cells 总被引:1,自引:0,他引:1
Lizárraga F Maldonado V Meléndez-Zajgla J 《The international journal of biochemistry & cell biology》2004,36(8):1655-1663
Tissue inhibitors of metalloproteinases (TIMPs) are pleiotropic factors that function as key regulators of extracellular matrix remodeling. They exhibit multifunctional roles including cell growth-stimulating activities and protection from apoptosis. In the present study, we showed that human recombinant TIMP-2 (hrTIMP-2) promotes growth of A549 lung cells. This effect was accompanied by increase in nuclear factor-kappa B (NF-kappaB) activity 24h after exposure as determined by electrophoretic mobility shift assay (EMSA) analysis. This effect was correlated with downregulation of IkappaBalpha and beta proteins and later increases in Bcl-3, IkappaB, and cyclin D1 proteins. Blocking induction of NF-kappaB activity using a dominant-negative mutated version of IkappaBalpha abrogated NF-kappaB activation and cell proliferation. 相似文献