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991.
992.
Gang Fan Mario Kaßmann Yingqiu Cui Claudia Matthaeus Sverine Kunz Cheng Zhong Shuai Zhu Yu Xie Dmitry Tsvetkov Oliver Daumke Yu Huang Maik Gollasch 《Aging cell》2020,19(4)
Caveolae position CaV3.2 (T‐type Ca2+ channel encoded by the α‐3.2 subunit) sufficiently close to RyR (ryanodine receptors) for extracellular Ca2+ influx to trigger Ca2+ sparks and large‐conductance Ca2+‐activated K+ channel feedback in vascular smooth muscle. We hypothesize that this mechanism of Ca2+ spark generation is affected by age. Using smooth muscle cells (VSMCs) from mouse mesenteric arteries, we found that both Cav3.2 channel inhibition by Ni2+ (50 µM) and caveolae disruption by methyl‐ß‐cyclodextrin or genetic abolition of Eps15 homology domain‐containing protein (EHD2) inhibited Ca2+ sparks in cells from young (4 months) but not old (12 months) mice. In accordance, expression of Cav3.2 channel was higher in mesenteric arteries from young than old mice. Similar effects were observed for caveolae density. Using SMAKO Cav1.2?/? mice, caffeine (RyR activator) and thapsigargin (Ca2+ transport ATPase inhibitor), we found that sufficient SR Ca2+ load is a prerequisite for the CaV3.2‐RyR axis to generate Ca2+ sparks. We identified a fraction of Ca2+ sparks in aged VSMCs, which is sensitive to the TRP channel blocker Gd3+ (100 µM), but insensitive to CaV1.2 and CaV3.2 channel blockade. Our data demonstrate that the VSMC CaV3.2‐RyR axis is down‐regulated by aging. This defective CaV3.2‐RyR coupling is counterbalanced by a Gd3+ sensitive Ca2+ pathway providing compensatory Ca2+ influx for triggering Ca2+ sparks in aged VSMCs. 相似文献
993.
Lukas S. Stelzl Philip W. Fowler Mark S.P. Sansom Oliver Beckstein 《Journal of molecular biology》2014
The major facilitator superfamily (MFS) transporter lactose permease (LacY) alternates between cytoplasmic and periplasmic open conformations to co-transport a sugar molecule together with a proton across the plasma membrane. Indirect experimental evidence suggested the existence of an occluded transition intermediate of LacY, which would prevent leaking of the proton gradient. As no experimental structure is known, the conformational transition is not fully understood in atomic detail. We simulated transition events from a cytoplasmic open conformation to a periplasmic open conformation with the dynamic importance sampling molecular dynamics method and observed occluded intermediates. Analysis of water permeation pathways and the electrostatic free-energy landscape of a solvated proton indicated that the occluded state contains a solvated central cavity inaccessible from either side of the membrane. We propose a pair of geometric order parameters that capture the state of the pathway through the MFS transporters as shown by a survey of available crystal structures and models. We present a model for the occluded state of apo-LacY, which is similar to the occluded crystal structures of the MFS transporters EmrD, PepTSo, NarU, PiPT and XylE. Our simulations are consistent with experimental double electron spin–spin distance measurements that have been interpreted to show occluded conformations. During the simulations, a salt bridge that has been postulated to be involved in driving the conformational transition formed. Our results argue against a simple rigid-body domain motion as implied by a strict “rocker-switch mechanism” and instead hint at an intricate coupling between two flexible gates. 相似文献
994.
Robertson DC Schmidt O Ninkina N Jones PA Sharkey J Buchman VL 《Journal of neurochemistry》2004,89(5):1126-1136
The growing body of evidence suggests that intermediate products of alpha-synuclein aggregation cause death of sensitive populations of neurones, particularly dopaminergic neurones, which is a critical event in the development of Parkinson's disease and other synucleinopathies. The role of two other members of the family, beta-synuclein and gamma-synuclein, in neurodegeneration is less understood. We studied the effect of inactivation of gamma-synuclein gene on mouse midbrain dopaminergic neurones. Reduced number of dopaminergic neurones was found in substantia nigra pars compacta (SNpc) but not in ventral tegmental area (VTA) of early post-natal and adult gamma-synuclein null mutant mice. Similar reductions were revealed in alpha-synuclein and double alpha-synuclein/gamma-synuclein null mutant animals. However, in none of these mutants did this lead to significant changes of striatal dopamine or dopamine metabolite levels and motor dysfunction. In all three studied types of null mutants, dopaminergic neurones of SNpc were resistant to methyl-phenyl-tetrahydropyridine (MPTP) toxicity. We propose that both synucleins are important for effective survival of SNpc neurones during critical period of development but, in the absence of these proteins, permanent activation of compensatory mechanisms allow many neurones to survive and become resistant to certain toxic insults. 相似文献
995.
Bone morphogenetic protein‐2 is a stronger inducer of osteogenesis within muscle tissue than heterodimeric bone morphogenetic protein‐2/6 and ‐2/7: Implications for expedited gene‐enhanced bone repair 下载免费PDF全文
996.
Leah Cuthbertson Geraint B Rogers Alan W Walker Anna Oliver Laura E Green Thomas W V Daniels Mary P Carroll Julian Parkhill Kenneth D Bruce Christopher J van der Gast 《The ISME journal》2016,10(5):1081-1091
Pulmonary symptoms in cystic fibrosis (CF) begin in early life with chronic lung infections and concomitant airway inflammation leading to progressive loss of lung function. Gradual pulmonary function decline is interspersed with periods of acute worsening of respiratory symptoms known as CF pulmonary exacerbations (CFPEs). Cumulatively, CFPEs are associated with more rapid disease progression. In this study multiple sputum samples were collected from adult CF patients over the course of CFPEs to better understand how changes in microbiota are associated with CFPE onset and management. Data were divided into five clinical periods: pre-CFPE baseline, CFPE, antibiotic treatment, recovery, and post-CFPE baseline. Samples were treated with propidium monoazide prior to DNA extraction, to remove the impact of bacterial cell death artefacts following antibiotic treatment, and then characterised by 16S rRNA gene-targeted high-throughput sequencing. Partitioning CF microbiota into core and rare groups revealed compositional resistance to CFPE and resilience to antibiotics interventions. Mixed effects modelling of core microbiota members revealed no significant negative impact on the relative abundance of Pseudomonas aeruginosa across the exacerbation cycle. Our findings have implications for current CFPE management strategies, supporting reassessment of existing antimicrobial treatment regimens, as antimicrobial resistance by pathogens and other members of the microbiota may be significant contributing factors. 相似文献
997.
F.-Nora Vögtle Björn Brändl Austin Larson Manuela Pendziwiat Marisa W. Friederich Susan M. White Alice Basinger Cansu Kücükköse Hiltrud Muhle Johanna A. Jähn Oliver Keminer Katherine L. Helbig Carolyn F. Delto Lisa Myketin Dirk Mossmann Nils Burger Noriko Miyake Audrey Burnett Ingo Helbig 《American journal of human genetics》2018,102(4):557-573
998.
Jack A. Gilbert Dawn Field Paul Swift Lindsay Newbold Anna Oliver Tim Smyth Paul J. Somerfield Sue Huse Ian Joint 《Environmental microbiology》2009,11(12):3132-3139
Very few marine microbial communities are well characterized even with the weight of research effort presently devoted to it. Only a small proportion of this effort has been aimed at investigating temporal community structure. Here we present the first report of the application of high‐throughput pyrosequencing to investigate intra‐annual bacterial community structure. Microbial diversity was determined for 12 time points at the surface of the L4 sampling site in the Western English Channel. This was performed over 11 months during 2007. A total of 182 560 sequences from the V6 hyper‐variable region of the small‐subunit ribosomal RNA gene (16S rRNA) were obtained; there were between 11 327 and 17 339 reads per sample. Approximately 7000 genera were identified, with one in every 25 reads being attributed to a new genus; yet this level of sampling far from exhausted the total diversity present at any one time point. The total data set contained 17 673 unique sequences. Only 93 (0.5%) were found at all time points, yet these few lineages comprised 50% of the total reads sequenced. The most abundant phylum was Proteobacteria (50% of all sequenced reads), while the SAR11 clade comprised 21% of the ubiquitous reads and ~12% of the total sequenced reads. In contrast, 78% of all operational taxonomic units were only found at one time point and 67% were only found once, evidence of a large and transient rare assemblage. This time series shows evidence of seasonally structured community diversity. There is also evidence for seasonal succession, primarily reflecting changes among dominant taxa. These changes in structure were significantly correlated to a combination of temperature, phosphate and silicate concentrations. 相似文献
999.
When fed in restricted amounts, rodents show robust activity in the hours preceding expected meal delivery. This process, termed food anticipatory activity (FAA), is independent of the light-entrained clock, the suprachiasmatic nucleus, yet beyond this basic observation there is little agreement on the neuronal underpinnings of FAA. One complication in studying FAA using a calorie restriction model is that much of the brain is activated in response to this strong hunger signal. Thus, daily timed access to palatable meals in the presence of continuous access to standard chow has been employed as a model to study FAA in rats. In order to exploit the extensive genetic resources available in the murine system we extended this model to mice, which will anticipate rodent high fat diet but not chocolate or other sweet daily meals (Hsu, Patton, Mistlberger, and Steele; 2010, PLoS ONE e12903). In this study we test additional fatty meals, including peanut butter and cheese, both of which induced modest FAA. Measurement of core body temperature revealed a moderate preprandial increase in temperature in mice fed high fat diet but entrainment due to handling complicated interpretation of these results. Finally, we examined activation patterns of neurons by immunostaining for the immediate early gene c-Fos and observed a modest amount of entrainment of gene expression in the hypothalamus of mice fed a daily fatty palatable meal. 相似文献
1000.
Kooistra O Bedoux G Brecker L Lindner B Sánchez Carballo P Haras D Zähringer U 《Carbohydrate research》2003,338(23):2667-2677
Lipopolysaccharides (LPS) were isolated from rough-type mutant strains of Pseudomonas aeruginosa (Delta algC) derived from wild-type strains PAO1 (serogroup O5) and PAC1R (serogroup O3). Structural studies of the LPS core region with a special focus on the phosphorylation pattern were performed by 2D NMR spectroscopy, including a 1H,(31)P HMQC-TOCSY experiment, MALDI-TOF MS, and Fourier-transform ion cyclotron resonance ESIMS using the capillary skimmer dissociation technique. Both LPS were found to contain two residues each of 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) and L-glycero-D-manno-heptose (Hep), one residue of N-(L-alanyl)-D-galactosamine and one O-carbamoyl group (Cm) on the distal Hep residue. The following structures of a tetrasaccharide trisphosphate from strain PAC1R Delta algC and that carrying an additional ethanolamine phosphate group (PEtN) from strain PAO1 Delta algC were elucidated: [carbohydrate structre: see text] where R=P in PAC1R Delta algC and PPEtN in PAO1 Delta algC. To our knowledge, in this work the presence of ethanolamine diphosphate is unambiguously confirmed and its position established for the first time in the LPS core of a rough-type strain of P. aeruginosa. In addition, the structure of the complete LPS core of wild-type strain P. aeruginosa PAO1 was reinvestigated and the position of the phosphorylation sites was revised. 相似文献