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排序方式: 共有113条查询结果,搜索用时 31 毫秒
41.
Cyril J. Smyth Marie B. Marron Jane M.G.J. Twohig Stephen G.J. Smith 《FEMS immunology and medical microbiology》1996,16(2):127-139
Abstract Fimbriae are wiry (2 to 4 nm diam.) or rod-shaped (6 to 8 nm diam.), fibre-like structures on the surfaces of bacteria which mediate attachment to host cells. Much has been learned in recent years about the biogenesis, structure and regulation of expression of these adhesive organelles in Gram-negative bacteria. Analyses of the genetic determinants encoding the biogenesis of fimbriae has revealed that the adhesive interaction of fimbriae can be mediated by major subunits (CFA/I and CS1 fimbriae) or minor subunits (P, S, and type 1 fimbriae), with the adhesin being located either at the tip of the fimbria or along the length of the fimbrial shaft. Minor subunits can also act as adapters, anchors, initiators or elongators. Post-translational glycosylation of the type 4 pilins of Neisseria gonorrhoeae, Neisseria meningitidis and Pseudomonas aeruginosa has been demonstrated. The structures of the PapD chaperone of Escherichia coli and of N. gonorrhoeae type 4 fimbrin have been resolved at 2.0–2.6 Å. Rod-shaped fimbriae should not be thought of as being rigid inflexible structures but rather as dynamic structures which can undergo transition from a helicoidal to a fibrillar conformation to provide a degree of elasticity and plasticity to the fimbriae so that they can resist shear forces, rather like a bungee cord. At least four mechanisms have been identified in the assembly of fimbriae from fimbrin subunits, namely the chaperone-usher pathway (e.g., P-fimbriae of uropathogenic E. coli ), the general secretion assembly pathway (e.g., type 4 fimbriae or N -methylphenylalanine fimbriae of P. aeruginosa , the extracellular nucleation-precipitation pathway (e.g., curli of E. coli ) and the CFA/I, CS1 and CS2 fimbrial pathway. 相似文献
42.
We describe a new scaffold-free three-dimensional (3D) cell culture model using cholesteryl ester based lyotropic liquid crystal (LC) substrates. Keratinocytes were deposited randomly on the LC surface where they self-assembled into 3D microtissues or keratinospheroids. The cell density required to form spheroids was optimized. We investigated cell viability using dead/live cell assays. The adhesion characteristics of cells within the microtissues were determined using histological sectioning and immunofluorescence staining. Fourier transform infrared spectroscopy (FTIR) was used to characterize the biochemistry of the keratinospheroids. We found that both cells and microtissues could migrate on the LC surface. The viability study indicated approximately 80% viability of cells in the microtissues up to 20 days of culture. Strong intercellular adhesion was observed in the stratification of the multi-layered microspheroids using field emission-scanning electron microscopy (FE-SEM) and histochemical staining. The cytoskeleton and vinculins of the cells in the microtissues were expressed diffusely, but the microtissues were enriched with lipids and nucleic acids, which indicates close resemblance to the conditions in vivo. The basic 3D culture model based on LC may be used for cell and microtissue migration studies in response to cytochemical treatment. 相似文献
43.
Aristos J. Alexandrou Adam R. Brown Mark L. Chapman Mark Estacion Jamie Turner Malgorzata A. Mis Anna Wilbrey Elizabeth C. Payne Alex Gutteridge Peter J. Cox Rachel Doyle David Printzenhoff Zhixin Lin Brian E. Marron Christopher West Nigel A. Swain R. Ian Storer Paul A. Stupple Neil A. Castle James A. Hounshell Mirko Rivara Andrew Randall Sulayman D. Dib-Hajj Douglas Krafte Stephen G. Waxman Manoj K. Patel Richard P. Butt Edward B. Stevens 《PloS one》2016,11(4)
Human genetic studies show that the voltage gated sodium channel 1.7 (Nav1.7) is a key molecular determinant of pain sensation. However, defining the Nav1.7 contribution to nociceptive signalling has been hampered by a lack of selective inhibitors. Here we report two potent and selective arylsulfonamide Nav1.7 inhibitors; PF-05198007 and PF-05089771, which we have used to directly interrogate Nav1.7’s role in nociceptor physiology. We report that Nav1.7 is the predominant functional TTX-sensitive Nav in mouse and human nociceptors and contributes to the initiation and the upstroke phase of the nociceptor action potential. Moreover, we confirm a role for Nav1.7 in influencing synaptic transmission in the dorsal horn of the spinal cord as well as peripheral neuropeptide release in the skin. These findings demonstrate multiple contributions of Nav1.7 to nociceptor signalling and shed new light on the relative functional contribution of this channel to peripheral and central noxious signal transmission. 相似文献
44.
45.
Ya-ming Xu Marilyn T. Marron Emily Seddon Steven P. McLaughlin Dennis T. Ray Luke Whitesell A.A. Leslie Gunatilaka 《Bioorganic & medicinal chemistry》2009,17(6):2210-2214
Preparations of the roots of the medicinal plant Withania somnifera (L.) Dunal commonly called ashwagandha have been used for millennia in the Ayurvedic medical tradition of India as a general tonic to relieve stress and enhance health, especially in the elderly. In modern times, ashwagandha has been shown to possess intriguing antiangiogenic and anticancer activity, largely attributable to the presence of the steroidal lactone withaferin A as the major constituent. When cultured using the aeroponic technique, however, this plant was found to produce a new natural product, 2,3-dihydrowithaferin A-3β-O-sulfate (1), as the predominant constituent of methanolic extracts prepared from aerial tissues. The characteristic bioactivities exhibited by 1 including inhibition of cancer cell proliferation/survival, disruption of cytoskeletal organization and induction of the cellular heat-shock response paralleled those displayed by withaferin A (2). The delayed onset of action and reduced potency of 1 in cell culture along with previous observations demonstrating the requirement of the 2(3)-double bond in withanolides for bioactivity suggested that 1 might be converted to 2 in cell culture media and this was confirmed by HPLC analysis. The abundant yield of 1 from aeroponically cultivated plants, its good aqueous solubility and spontaneous conversion to 2 under cell culture conditions, suggest that 1 could prove useful as a readily formulated prodrug of withaferin A that merits further evaluation in animal models. 相似文献
46.
47.
Polyhydroxyalkanoates (PHAs) are biodegradable polymers produced by microbes to overcome environmental stress. Commercial
production of PHAs is limited by the high cost of production compared to conventional plastics. Another hindrance is the brittle
nature and low strength of polyhydroxybutyrate (PHB), the most widely studied PHA. The needs are to produce PHAs, which have
better elastomeric properties suitable for biomedical applications, preferably from inexpensive renewable sources to reduce
cost. Certain unique properties of Bacillus subtilis such as lack of the toxic lipo-polysaccharides, expression of self-lysing genes on completion of PHA biosynthetic process
– for easy and timely recovery, usage of biowastes as feed enable it to compete as potential candidate for commercial production
of PHA. 相似文献
48.
Sheran HW Law Rudolf SS Wu Patrick KS Ng Richard MK Yu Richard YC Kong 《BMC molecular biology》2006,7(1):15-13
Background
Hypoxia-inducible factors (HIFs) are involved in adaptive and survival responses to hypoxic stress in mammals. In fish, very little is known about the functions of HIFs. 相似文献49.
Nicolas Marron Véronique Storme Sophie Y. Dillen Catherine Bastien Luca Ricciotti Francesco Salani Maurizio Sabatti Anne M. Rae Reinhart Ceulemans Wout Boerjan 《Tree Genetics & Genomes》2009,6(4):533-554
Short-rotation coppice of hybrid poplar is a promising renewable feedstock for biofuel production. Breeding for high biomass
in short-rotation coppice has started only recently. Two hybrid poplar families were grown at two sites in Europe and phenotyped
for a variety of biomass-related traits (1) to examine the extent of phenotypic and genetic variation in biomass production,
ramification, resprouting, and phenology, (2) to search for genomic regions involved in productivity, and (3) to determine
the effect of the environment on the expression of these traits. The performance of both families differed within and among
sites. A pronounced heterosis was observed in most cases. Moderate to high heritability values were found. Seventeen quantitative
trait loci (QTL) for biomass production, 13 for ramification, ten for resprouting, 21 for bud burst, and ten for bud set were
identified. Genetic correlations and QTL colocation showed that high wood production was associated with high allocation of
wood into branches and with high production of resprouts after coppicing. Correlations and QTL colocation between biomass
production and phenology traits were weak. Our study provides valuable information on genomic regions involved in biomass
production, ramification, and phenology and on phenotypic and genetic relationships among these three trait categories. 相似文献
50.
Comt1 genotype and expression predicts anxiety and nociceptive sensitivity in inbred strains of mice
S. K. Segall A. G. Nackley L. Diatchenko W. R. Lariviere X. Lu J. S. Marron L. Grabowski‐Boase J. R. Walker G. Slade J. Gauthier J. S. Bailey B. M. Steffy T. M. Maynard L. M. Tarantino T. Wiltshire 《Genes, Brain & Behavior》2010,9(8):933-946
Catechol‐O‐methyltransferase (COMT) is a ubiquitously expressed enzyme that maintains basic biologic functions by inactivating catechol substrates. In humans, polymorphic variance at the COMT locus has been associated with modulation of pain sensitivity and risk for developing psychiatric disorders. A functional haplotype associated with increased pain sensitivity was shown to result in decreased COMT activity by altering mRNA secondary structure‐dependent protein translation. However, the exact mechanisms whereby COMT modulates pain sensitivity and behavior remain unclear and can be further studied in animal models. We have assessed Comt1 gene expression levels in multiple brain regions in inbred strains of mice and have discovered that Comt1 is differentially expressed among the strains, and this differential expression is cis‐regulated. A B2 short interspersed nuclear element (SINE) was inserted in the 3′‐untranslated region (3′‐UTR) of Comt1 in 14 strains generating a common haplotype that correlates with gene expression. Experiments using mammalian expression vectors of full‐length cDNA clones with and without the SINE element show that strains with the SINE haplotype (+SINE) have greater Comt1 enzymatic activity. +SINE mice also exhibit behavioral differences in anxiety assays and decreased pain sensitivity. These results suggest that a haplotype, defined by a 3′‐UTR B2 SINE element, regulates Comt1 expression and some mouse behaviors. 相似文献