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101.
Stephanie Waters Sanjana Luther Torsten Joerger Gary P. Richards E. Fidelma Boyd Michelle A. Parent 《Microbiology and immunology》2013,57(4):323-328
Vibrio parahaemolyticus is the most common cause of bacterial, seafood‐related illness in the USA. Currently, there is a dearth of published reports regarding immunity to infection with this pathogen. Here, production of both pro‐ and anti‐inflammatory cytokines by V. parahaemolyticus‐infected RAW 264.7 murine macrophages was studied. It was determined that this infection results in increased concentrations of IL‐1α, IL‐6, TNF‐α and IL‐10. Additionally, decreases in cell surface TLR2 and TLR4 and increases in T‐cell co‐stimulatory molecules CD40 and CD86 were discovered. The data presented here begin to identify the immune variables required to eliminate V. parahaemolyticus from infected host tissues. 相似文献
102.
Previous studies have shown that elevated nitric oxide (NO) reduces adhesion in diatom, bacterial and animal cells. This article reports experiments designed to investigate whether elevated NO reduces the adhesion of zoospores of the green alga Ulva, an important fouling species. Surface-normalised values of NO were measured using the fluorescent indicator DAF-FM DA and parallel hydrodynamic measurements of adhesion strength were made. Elevated levels of NO caused by the addition of the exogenous NO donor SNAP reduced spore settlement by 20% and resulted in lower adhesion strength. Addition of the NO scavenger cPTIO abolished the effects of SNAP on adhesion. The strength of attachment and NO production by spores in response to four coatings (Silastic® T2; Intersleek® 700; Intersleek® 900 and polyurethane) shows that reduced adhesion is correlated with an increase in NO production. It is proposed that in spores of Ulva, NO is used as an intracellular signalling molecule to detect how conducive a surface is for settlement and adhesion. The effect of NO on the adhesion of a range of organisms suggests that NO-releasing coatings could have the potential to control fouling. 相似文献
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Stephanie Iserbyt 《法国昆虫学会纪事》2013,49(2):217-244
Les bourdons constituent l’un des groupes de pollinisateurs les plus importants dans les écosystèmes montagnards. Cependant, la faune des bourdons du Parc National des Pyrénées occidentales (PNPO) est encore peu connue. Pendant trois ans, la faune des bourdons du Parc National des Pyrénées occidentales a fait l’objet d’une surveillance. Les inventaires effectués en juillet- août 2002, 2003 et 2005 ont permis l’observation de 5889 spécimens de bourdons de 29 espèces. Si l’on tient compte des observations des cinquante dernières années, la diversité spécifique du parc s’élève à 30 espèces de bourdons. Une telle diversité spécifique est remarquable et comparable à celle observée dans d’autres secteurs du massif pyrénéen. La faible différence entre les faunes du Parc et des réserves naturelles d’Eyne et de Nohèdes (Pyrénées-Orientales) rend compte du caractère exceptionnellement diversifié de la faune des bourdons du massif pyrénéen en général. 相似文献
106.
Hiroyuki Hosokawa Phat Vinh Dip Maria Merkulova Anastasia Bakulina Zhenjie Zhuang Ashok Khatri Xiaoying Jian Shawn M. Keating Stephanie A. Bueler John L. Rubinstein Paul A. Randazzo Dennis A. Ausiello Gerhard Grüber Vladimir Marshansky 《The Journal of biological chemistry》2013,288(8):5896-5913
Previously, we reported an acidification-dependent interaction of the endosomal vacuolar H+-ATPase (V-ATPase) with cytohesin-2, a GDP/GTP exchange factor (GEF), suggesting that it functions as a pH-sensing receptor. Here, we have studied the molecular mechanism of signaling between the V-ATPase, cytohesin-2, and Arf GTP-binding proteins. We found that part of the N-terminal cytosolic tail of the V-ATPase a2-subunit (a2N), corresponding to its first 17 amino acids (a2N(1–17)), potently modulates the enzymatic GDP/GTP exchange activity of cytohesin-2. Moreover, this peptide strongly inhibits GEF activity via direct interaction with the Sec7 domain of cytohesin-2. The structure of a2N(1–17) and its amino acids Phe5, Met10, and Gln14 involved in interaction with Sec7 domain were determined by NMR spectroscopy analysis. In silico docking experiments revealed that part of the V-ATPase formed by its a2N(1–17) epitope competes with the switch 2 region of Arf1 and Arf6 for binding to the Sec7 domain of cytohesin-2. The amino acid sequence alignment and GEF activity studies also uncovered the conserved character of signaling between all four (a1–a4) a-subunit isoforms of mammalian V-ATPase and cytohesin-2. Moreover, the conserved character of this phenomenon was also confirmed in experiments showing binding of mammalian cytohesin-2 to the intact yeast V-ATPase holo-complex. Thus, here we have uncovered an evolutionarily conserved function of the V-ATPase as a novel cytohesin-signaling receptor. 相似文献
107.
Bouchra Ta?b Khalil Bouyakdan Cécile Hryhorczuk Demetra Rodaros Stephanie Fulton Thierry Alquier 《The Journal of biological chemistry》2013,288(52):37216-37229
Hypothalamic controls of energy balance rely on the detection of circulating nutrients such as glucose and long-chain fatty acids (LCFA) by the mediobasal hypothalamus (MBH). LCFA metabolism in the MBH plays a key role in the control of food intake and glucose homeostasis, yet it is not known if glucose regulates LCFA oxidation and esterification in the MBH and, if so, which hypothalamic cell type(s) and intracellular signaling mechanisms are involved. The aim of this study was to determine the impact of glucose on LCFA metabolism, assess the role of AMP-activated Kinase (AMPK), and to establish if changes in LCFA metabolism and its regulation by glucose vary as a function of the kind of LCFA, cell type, and brain region. We show that glucose inhibits palmitate oxidation via AMPK in hypothalamic neuronal cell lines, primary hypothalamic astrocyte cultures, and MBH slices ex vivo but not in cortical astrocytes and slice preparations. In contrast, oleate oxidation was not affected by glucose or AMPK inhibition in MBH slices. In addition, our results show that glucose increases palmitate, but not oleate, esterification into neutral lipids in neurons and MBH slices but not in hypothalamic astrocytes. These findings reveal for the first time the metabolic fate of different LCFA in the MBH, demonstrate AMPK-dependent glucose regulation of LCFA oxidation in both astrocytes and neurons, and establish metabolic coupling of glucose and LCFA as a distinguishing feature of hypothalamic nuclei critical for the control of energy balance. 相似文献
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Stephanie A. Schaefer Ming Dong Renee P. Rubenstein Wayne A. Wilkie Brian J. Bahnson Colin Thorpe Sharon Rozovsky 《Journal of molecular biology》2013,425(2):222-231
Sulfur, a key contributor to biological reactivity, is not amendable to investigations by biological NMR spectroscopy. To utilize selenium as a surrogate, we have developed a generally applicable 77Se isotopic enrichment method for heterologous proteins expressed in Escherichia coli. We demonstrate 77Se NMR spectroscopy of multiple selenocysteine and selenomethionine residues in the sulfhydryl oxidase augmenter of liver regeneration (ALR). The resonances of the active-site residues were assigned by comparing the NMR spectra of ALR bound to oxidized and reduced flavin adenine dinucleotide. An additional resonance appears only in the presence of the reducing agent and disappears readily upon exposure to air and subsequent reoxidation of the flavin. Hence, 77Se NMR spectroscopy can be used to report the local electronic environment of reactive and structural sulfur sites, as well as changes taking place in those locations during catalysis. 相似文献
110.
Stephanie Pfaffen Raz Abdulqadir Nick E. Le Brun Michael E. P. Murphy 《The Journal of biological chemistry》2013,288(21):14917-14925
A novel ferritin was recently found in Pseudo-nitzschia multiseries (PmFTN), a marine pennate diatom that plays a major role in global primary production and carbon sequestration into the deep ocean. Crystals of recombinant PmFTN were soaked in iron and zinc solutions, and the structures were solved to 1.65–2.2-Å resolution. Three distinct iron binding sites were identified as determined from anomalous dispersion data from aerobically grown ferrous soaked crystals. Sites A and B comprise the conserved ferroxidase active site, and site C forms a pathway leading toward the central cavity where iron storage occurs. In contrast, crystal structures derived from anaerobically grown and ferrous soaked crystals revealed only one ferrous iron in the active site occupying site A. In the presence of dioxygen, zinc is observed bound to all three sites. Iron oxidation experiments using stopped-flow absorbance spectroscopy revealed an extremely rapid phase corresponding to Fe(II) oxidation at the ferroxidase site, which is saturated after adding 48 ferrous iron to apo-PmFTN (two ferrous iron per subunit), and a much slower phase due to iron core formation. These results suggest an ordered stepwise binding of ferrous iron and dioxygen to the ferroxidase site in preparation for catalysis and a partial mobilization of iron from the site following oxidation. 相似文献