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801.
Cell attachment to the extracellular matrix (ECM) engages integrin signaling into the cell, but part of the signaling response
also stem from cell spreading (3). To analyze specific integrin signaling-mediated responses independent of cell spreading,
we developed a method engaging integrin signaling by use of an immobilized anti-integrin monoclonal antibody (mab) directed
against the fibronectin (FN) receptor integrin α5β1. ECV 304 cells were plated onto FN or immobilized mab JBS5 (anti-integrin
α5β1) or onto poly-L-lysin (P-L-L), which mediates integrin-independent attachment. Cells attached and spread on FN, while
cells on JBS5 or P-L-L attached but did not spread. Importantly, plating onto FN or mab JBS5 gave rise to identical integrin-induced
responses, including a down-regulation of the cyclin-dependent kinase (Cdk2) inhibitors p21CIP1 and p27KIP1, while attachment to P-L-L did not. We conclude that engagement of the FN-receptor integrin α5β1 induces integrin signaling
regulating the Cdk2-inhibitors independent of cell spreading and present a method for how integrin signaling can be analyzed
separate from the effects of cell spreading.
Published: November 11, 2002 相似文献
802.
Differential function of RNCAM isoforms in precise target selection of olfactory sensory neurons 总被引:2,自引:0,他引:2
Olfactory sensory neurons (OSNs) are individually specified to express one odorant receptor (OR) gene among approximately 1000 different and project with precision to topographically defined convergence sites, the glomeruli, in the olfactory bulb. Although ORs partially determine the location of convergence sites, the mechanism ensuring that axons with different OR identities do not co-converge is unknown. RNCAM (OCAM, NCAM2) is assumed to regulate a broad zonal segregation of projections by virtue of being a homophilic cell adhesion molecule that is selectively expressed on axons terminating in a defined olfactory bulb region. We have identified NADPH diaphorase activity as being an independent marker for RNCAM-negative axons. Analyses of transgenic mice that ectopically express RNCAM in NADPH diaphorase-positive OSNs show that the postulated function of RNCAM in mediating zone-specific segregation of axons is unlikely. Instead, analyses of one OR-specific OSN subpopulation (P2) reveal that elevated RNCAM levels result in an increased number of P2 axons that incorrectly co-converge with axons of other OR identities. Both Gpi-anchored and transmembrane-bound RNCAM isoforms are localized on axons in the nerve layer, while the transmembrane-bound RNCAM is the predominant isoform on axon terminals within glomeruli. Overexpressing transmembrane-bound RNCAM results in co-convergence events close to the correct target glomeruli. By contrast, overexpression of Gpi-anchored RNCAM results in axons that can bypass the correct target before co-converging on glomeruli located at a distance. The phenotype specific for Gpi-anchored RNCAM is suppressed in mice overexpressing both isoforms, which suggests that two distinct RNCAM isoform-dependent activities influence segregation of OR-defined axon subclasses. 相似文献
803.
804.
Attenuation of Pseudomonas aeruginosa virulence by quorum sensing inhibitors 总被引:28,自引:0,他引:28
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805.
Krawiec K Kierdaszuk B Kalinichenko EN Rubinova EB Mikhailopulo IA Eriksson S Munch-Petersen B Shugar D 《Nucleosides, nucleotides & nucleic acids》2003,22(5-8):1525-1529
Six non-conventional adenosine-2'- and 3'-triphosphate analogues of ATP were tested as potential phosphate donors for all four human, and D. melanogaster, deoxyribonucleoside kinases. With dCK (only dAdo as acceptor), TK1, TK2 and dNK only 3'-deoxyadenosine-2'-triphosphate was an effective donor (5-60% that for ATP). With dCK (dCyd as acceptor) and dGK (dGuo as acceptor), sharing 45% sequence identity, donor activities ranged from 13 to 119% that for ATP. Products were 5'-phosphates. In some instances, kinetics are dependent on the nature of the acceptor, and donor and acceptors properties are mutually interdependent. Results are highly relevant to studies on the modes of interaction with the enzymes, and to interpretations of reported crystal structures of dCK and dNK with bound ligands. 相似文献
806.
807.
Identification by RNA profiling and mutational analysis of the novel copper resistance determinants CrdA (HP1326), CrdB (HP1327), and CzcB (HP1328) in Helicobacter pylori 总被引:1,自引:0,他引:1
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Waidner B Melchers K Ivanov I Loferer H Bensch KW Kist M Bereswill S 《Journal of bacteriology》2002,184(23):6700-6708
808.
809.
Bikshandarkoil R. Srinivasan Sunder N. Dhuri Wolfgang Bensch 《Inorganica chimica acta》2005,358(2):279-287
The title compounds 1,3-propanediammonium tetrathiomolybdate, (1,3-pnH2)[MoS4], 1 and, N,N,N′,N′-tetramethylethylenediammonium tetrathiomolybdate, (tmenH2)[MoS4], 2, were prepared by reacting the ammonium salt of [MoS4]2− with the corresponding organic diamine. In 1 and 2 the organic diamines 1,3-propanediamine (1,3-pn) and N,N,N′,N′-tetramethylethylenediamine (tmen) are present in their diprotonated form. The reaction of 1 or 2 with [Ni(en)3]Cl2 · 2H2O (en is ethylenediamine) results in the formation of the highly insoluble complex tris(ethylenediamine)Ni(II) tetrathiomolybdate, [Ni(en)3][MoS4], in quantitative yields. 1 and 2 have been characterized by chemical analysis, vibrational, UV-Vis and NMR spectroscopy, TG-DTA-MS and single crystal X-ray crystallography. Compound 1 is thermally more stable compared to 2. Both complexes decompose in a single step forming amorphous molybdenum sulfide. The structure of the title complexes can be described as consisting of tetrahedral [MoS4]2− dianions which accept a complex series of H-bonds from the organic dications. The strength and number of these hydrogen bonds affect the Mo-S bond lengths. 相似文献
810.
Hansson B Bensch S Hasselquist D 《Evolution; international journal of organic evolution》2004,58(11):2546-2557
Dispersal is of prime importance for many evolutionary processes and has been studied for decades. The reproductive consequences of dispersal have proven difficult to study, simply because it is difficult to keep track of dispersing individuals. In most previous studies evaluating the fitness effects of dispersal, immigrants at a study locality have been lumped into one category and compared to philopatric individuals. This is unfortunate, because there are reasons to believe that immigrants with long and short dispersal distances may differ substantially in reproductive success. In the present study, we used a combination of capture-recapturing and multilocus microsatellite genotyping to categorize great reed warblers at our Swedish study site as philopatric individuals or short- or long-distance dispersing immigrants. We then performed novel comparisons of lifetime reproductive success (LRS) and survival rates of these three dispersal categories. The birds belonged to cohorts 1987-1996, and data for their LRS were gathered between 1988 and 2003. The analyses showed that philopatric males attracted more females, produced more fledglings and recruits throughout their lives, and survived better than immigrants. Among the immigrant males, those categorized as long-distance dispersers had lowest LRS and survival probability. Models that included covariates of potential importance showed that the difference in LRS between dispersal categories was partly caused by corresponding variation in number of breeding years at our study site. These results indicate that short- and, in particular, long-distance dispersers were of poor phenotypic quality, but it may also be proposed that immigrants attracted few females because they were poorly adapted to the local social environment. In females, the number of local recruits corrected for the number of breeding years (as well as for number of fledglings) differed between dispersal categories in a pattern that suggests an intermediate optimal dispersal distance. Short-distance dispersers recruited more offspring per year (and per fledgling) than both philopatric individuals and long-distance dispersers. Data suggest that the low LRS of philopatric females was related to costs of inbreeding. The low LRS of long-distance dispersing females may have resulted from their offspring being especially prone to disperse outside the study area, but also other potential explanations exist, such as local maladaptation. Our study highlights the importance of separating immigrant birds on the basis of their genetic similarity to the local study population when analyzing variation in LRS and inferring realized gene flow. 相似文献