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11.
Emeran A. Mayer Anatoly Kodner Xiao Ping Sun Jonathan Wilkes David Scott George Sachs 《The Journal of membrane biology》1992,125(2):107-118
Summary Intracellular calcium [Ca2+]
i
measurements in cell suspension of gastrointestinal myocytes have suggested a single [Ca2+]
i
transient followed by a steady-state increase as the characteristic [Ca2+]
i
response of these cells. In the present study, we used digital video imaging techniques in freshly dispersed myocytes from the rabbit colon, to characterize the spatiotemporal pattern of the [Ca2+]
i
signal in single cells. The distribution of [Ca2+]
i
in resting and stimulated cells was nonhomogeneous, with gradients of high [Ca2+]
i
present in the subplasmalemmal space and in one cell pole. [Ca2+]
i
gradients within these regions were not constant but showed temporal changes in the form of [Ca2+]
i
oscillations and spatial changes in the form of [Ca2+]
i
waves. [Ca2+]
i
oscillations in unstimulated cells (n = 60) were independent of extracellular [Ca2+] and had a mean frequency of 12.6 +1.1 oscillations per min. The baseline [Ca2+], was 171 ± 13 nm and the mean oscillation amplitude was 194 ± 12 nm. Generation of [Ca2+]
i
waves was also independent of influx of extracellular Ca2+. [Ca2+]
i
waves originated in one cell pole and were visualized as propagation mostly along the subplasmalemmal space or occasionally throughout the cytoplasm. The mean velocity was 23 +3 m per sec (n = 6). Increases of [Ca2+]
i
induced by different agonists were encoded into changes of baseline [Ca2+]
i
and the amplitude of oscillations, but not into their frequency. The observed spatiotemporal pattern of [Ca2+]
i
regulation may be the underlying mechanism for slow wave generation and propagation in this tissue. These findings are consistent with a [Ca2+]
i
regulation whereby cell regulators modulate the spatiotemporal pattern of intracellularly generated [Ca2+]
i
oscillations.The authors thank Debbie Anderson for excellent technical assistance with the electron microscopy and Dr. M. Regoli for providing the NK-1 agonist [Sar9,Met(O2)11]-SP. This work was supported by National Institutes of Health Grants DK 40919 and DK 40675 and Veterans Administration Grant SMI. 相似文献
12.
Identification of CpG islands in a physical map encompassing the Friedreich's ataxia locus 总被引:5,自引:0,他引:5
D Wilkes J Shaw R Anand J Riley P Winter J Wallis A G Driesel R Williamson S Chamberlain 《Genomics》1991,9(1):90-95
The Friedreich's ataxia locus has been previously assigned to chromosome 9q 13-21.1 by the demonstration of tight linkage to two anonymous DNA markers. MCT112 (Z greater than 80, theta = 0) and DR47 (Z greater than 50, theta = 0). The absence of recombination between these three loci has prevented the resolution of gene/probe order in this region, impeding strategies for gene isolation. We report physical mapping over a 4-Mb genomic interval, linking the markers MCT112 and DR47 on a common 460-kb NotI fragment and identifying 11 CpG islands in the 1.7-Mb interval most likely to contain the Friedreich's ataxia locus. Four of these islands were detected only by analysis of three YAC clones spanning a 700-kb interval including the MCT112/DR47 cluster. Without clear evidence of the precise location of the disease locus from recombination events, each of these regions must be considered as specifying a potential "candidate" sequence for the mutated gene. 相似文献
13.
Gerrit Wienhausen Stefan Bruns Sabiha Sultana Leon Dlugosch Luna-Agrippina Groon Heinz Wilkes Meinhard Simon 《The ISME journal》2022,16(11):2599
Biotin (vitamin B7) is involved in a wide range of essential biochemical reactions and a crucial micronutrient that is vital for many pro- and eukaryotic organisms. The few biotin measurements in the world’s oceans show that availability is subject to strong fluctuations. Numerous marine microorganisms exhibit biotin auxotrophy and therefore rely on supply by other organisms. Desthiobiotin is the primary precursor of biotin and has recently been detected at concentrations similar to biotin in seawater. The last enzymatic reaction in the biotin biosynthetic pathway converts desthiobiotin to biotin via the biotin synthase (BioB). The role of desthiobiotin as a precursor of biotin synthesis in microbial systems, however, is largely unknown. Here we demonstrate experimentally that bacteria can overcome biotin auxotrophy if they retain the bioB gene and desthiobiotin is available. A genomic search of 1068 bacteria predicts that the biotin biosynthetic potential varies greatly among different phylogenetic groups and that 20% encode solely bioB and thus can potentially overcome biotin auxotrophy. Many Actino- and Alphaproteobacteria cannot synthesize biotin de novo, but some possess solely bioB, whereas the vast majority of Gammaproteobacteria and Flavobacteriia exhibit the last four crucial biotin synthesis genes. We detected high intra- and extracellular concentrations of the precursor relative to biotin in the prototrophic bacterium, Vibrio campbellii, with extracellular desthiobiotin reaching up to 1.09 ± 0.15*106 molecules per cell during exponential growth. Our results provide evidence for the ecological role of desthiobiotin as an escape route to overcome biotin auxotrophy for bacteria in the ocean and presumably in other ecosystems.Subject terms: Water microbiology, Ecosystem ecology, Marine microbiology 相似文献
14.
Eric Wilkes 《BMJ (Clinical research ed.)》1980,281(6253):1471
15.
Vaccinia virus infection induces dendritic cell maturation but inhibits antigen presentation by MHC class II 总被引:2,自引:0,他引:2
Yao Y Li P Singh P Thiele AT Wilkes DS Renukaradhya GJ Brutkiewicz RR Travers JB Luker GD Hong SC Blum JS Chang CH 《Cellular immunology》2007,246(2):92-102
Vaccinia virus (VV) infection is known to inhibit dendritic cells (DC) functions in vitro. Paradoxically, VV is also highly immunogenic and thus has been used as a vaccine. In the present study, we investigated the effects of an in vivo VV infection on DC function by focusing on early innate immunity. Our data indicated that DC are activated upon in vivo VV infection of mice. Splenic DC from VV-infected mice expressed elevated levels of MHC class I and co-stimulatory molecules on their cell surface and exhibited the enhanced potential to produce cytokines upon LPS stimulation. DC from VV-infected mice also expressed a high level of interferon-beta. However, a VV infection resulted in the down-regulation of MHC class II expression and the impairment of antigen presentation to CD4 T cells by DC. Thus, during the early stage of a VV infection, although DC are impaired in some of the critical antigen presentation functions, they can promote innate immune defenses against viral infection. 相似文献
16.
During development of the central nervous system, oligodendrocyte progenitor cells differentiate into mature myelinating cells. The molecular signals that promote this process, however, are not well defined. One molecule that has been implicated in oligodendrocyte differentiation is the Src family kinase Fyn. In order to probe the function of Fyn in this system, a yeast two hybrid screen was performed. Using Fyn as bait, p190 RhoGAP was isolated in the screen of an oligodendrocyte cDNA library. Coimmunoprecipitation and in vitro binding assays verified that p190 RhoGAP bound to the Fyn SH2 domain. Phosphorylation of p190 required active Fyn tyrosine kinase and was increased threefold upon differentiation of primary oligodendrocytes. Moreover, complex formation between p190 and p120 RasGAP occurred in differentiated oligodendrocytes. p190 RhoGAP activity is known to regulate the RhoGDP:RhoGTP ratio. Indeed, expression of dominant negative Rho in primary oligodendrocytes caused a hyperextension of processes. Conversely, constitutively activated Rho caused reduced process formation. These findings define a pathway in which Fyn activity regulates the phosphorylation of p190, leading to an increase in RhoGAP activity with a subsequent increase in RhoGDP, which in turn, regulates the morphological changes that accompany oligodendrocyte differentiation. 相似文献
17.
Rabus R Wilkes H Schramm A Harms G Behrends A Amann R Widdel F 《Environmental microbiology》1999,1(2):145-157
Denitrifying bacteria were enriched from freshwater sediment with added nitrate as electron acceptor and crude oil as the only source of organic substrates. The enrichment cultures were used as laboratory model systems for studying the degradative potential of denitrifying bacteria with respect to crude oil constituents, and the phylogenetic affiliation of denitrifiers that are selectively enriched with crude oil. The enrichment culture exhibited two distinct growth phases. During the first phase, bacteria grew homogeneously in the aqueous phase, while various C1 –C3 alkylbenzenes, but no alkanes, were utilized from the crude oil. During the second phase, bacteria also grew that formed aggregates, adhered to the crude oil layer and emulsified the oil, while utilization of n -alkanes (C5 to C12 ) from the crude oil was observed. During growth, several alkylbenzoates accumulated in the aqueous phase, which were presumably formed from alkylbenzenes. Application of a newly designed, fluorescently labelled 16S rRNA-targeted oligonucleotide probe specific for the Azoarcus / Thauera group within the β-subclass of Proteobacteria revealed that the majority of the enriched denitrifiers affiliated with this phylogenetic group. 相似文献
18.
Zhou HM Weskamp G Chesneau V Sahin U Vortkamp A Horiuchi K Chiusaroli R Hahn R Wilkes D Fisher P Baron R Manova K Basson CT Hempstead B Blobel CP 《Molecular and cellular biology》2004,24(1):96-104
Congenital heart disease is the most common form of human birth defects, yet much remains to be learned about its underlying causes. Here we report that mice lacking functional ADAM19 (mnemonic for a disintegrin and metalloprotease 19) exhibit severe defects in cardiac morphogenesis, including a ventricular septal defect (VSD), abnormal formation of the aortic and pulmonic valves, leading to valvular stenosis, and abnormalities of the cardiac vasculature. During mouse development, ADAM19 is highly expressed in the conotruncus and the endocardial cushion, structures that give rise to the affected heart valves and the membranous ventricular septum. ADAM19 is also highly expressed in osteoblast-like cells in the bone, yet it does not appear to be essential for bone growth and skeletal development. Most adam19(-/-) animals die perinatally, likely as a result of their cardiac defects. These findings raise the possibility that mutations in ADAM19 may contribute to human congenital heart valve and septal defects. 相似文献
19.
Differential trafficking of transforming growth factor-beta receptors and ligand in polarized epithelial cells
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Murphy SJ Doré JJ Edens M Coffey RJ Barnard JA Mitchell H Wilkes M Leof EB 《Molecular biology of the cell》2004,15(6):2853-2862
Epithelial cells in vivo form tight cell-cell associations that spatially separate distinct apical and basolateral domains. These domains provide discrete cellular processes essential for proper tissue and organ development. Using confocal imaging and selective plasma membrane domain activation, the type I and type II transforming growth factor-beta (TGFbeta) receptors were found to be localized specifically at the basolateral surfaces of polarized Madin-Darby canine kidney (MDCK) cells. Receptors concentrated predominantly at the lateral sites of cell-cell contact, adjacent to the gap junctional complex. Cytoplasmic domain truncations for each receptor resulted in the loss of specific lateral domain targeting and dispersion to both the apical and basal domains. Whereas receptors concentrate basolaterally in regions of direct cell-cell contact in nonpolarized MDCK cell monolayers, receptor staining was absent from areas of noncell contact. In contrast to the defined basolateral polarity observed for the TGFbeta receptor complex, TGFbeta ligand secretion was found to be from the apical surfaces. Confocal imaging of MDCK cells with an antibody to TGFbeta1 confirmed a predominant apical localization, with a stark absence at the basal membrane. These findings indicate that cell adhesion regulates the localization of TGFbeta receptors in polarized epithelial cultures and that the response to TGFbeta is dependent upon the spatial distribution and secretion of TGFbeta receptors and ligand, respectively. 相似文献
20.