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201.
Sodium nitroprusside (SNP) elicits various physiological effects, in part through generation of the membrane permeable mediator nitric oxide (NO). In the heart, besides its role in regulating contractility, NO is involved in both protection from and induction of cellular damage. The present study investigated the role of SNP in the regulation of the mitogen-activated protein kinases (MAPKs) in isolated adult rat cardiomyocytes. SNP maximally activated Erk1, Erk2, p38 MAPK and MAPKAPK2 in 5-10 min. The activation of MAPKAPK2 by SNP was blocked by the soluble guanylyl cyclase inhibitor, 1H-[1, 2,4]oxadiazolol[4,3-a]quinoxalin-1-one (ODQ) and the p38 MAPK inhibitor, SB203580. The activation of Erk1 was insensitive to ODQ but completely blocked by the Mek1 inhibitor PD98059. The membrane-permeable homologue of cGMP, 8-Br-cGMP, also activated p38 MAPK (A(0.5) approximately 50 microM) but not Erk1 and Erk2. These results indicate that p38 MAPK and MAPKAPK2 are activated by SNP in cGMP-dependent pathways, while the Erk1 activation by SNP is independent of cGMP levels. 相似文献
202.
The extracellular proteases of Aspergillus nidulans are produced in response to limitation of carbon, nitrogen, or sulfur, even in the absence of exogenous protein. Mutations in the A. nidulans xprF and xprG genes have been shown to result in elevated levels of extracellular protease in response to carbon limitation. The xprF gene was isolated and sequence analysis indicates that it encodes a 615-amino-acid protein, which represents a new type of fungal hexokinase or hexokinase-like protein. In addition to their catalytic role, hexokinases are thought to be involved in triggering carbon catabolite repression. Sequence analysis of the xprF1 and xprF2 alleles showed that both alleles contain nonsense mutations. No loss of glucose or fructose phosphorylating activity was detected in xprF1 or xprF2 mutants. There are two possible explanations for this observation: (1) the xprF gene may encode a minor hexokinase or (2) the xprF gene may encode a protein with no hexose phosphorylating activity. Genetic evidence suggests that the xprF and xprG genes are involved in the same regulatory pathway. Support for this hypothesis was provided by the identification of a new class of xprG(-) mutation that suppresses the xprF1 mutation and results in a protease-deficient phenotype. 相似文献
203.
Determining the DNA bending angle induced by non-specific high mobility group-1 (HMG-1) proteins: a novel method 总被引:9,自引:0,他引:9
To study the DNA bending induced by non-sequence-specific HMG-1 domain proteins, we have engineered a fusion protein linking the yeast NHP6A with a sequence-specific DNA binding domain, the DNA binding domain of the Hin recombinase, Hin-DBD. A series of biochemical experiments were carried out to characterize the DNA binding property of this fusion protein. Our data showed that the fusion protein not only specifically recognizes a DNA fragment containing the Hin-DBD binding site, but also binds DNA with a higher affinity in comparison with either domain alone. Both domains of the fusion protein are bound to the DNA in juxtaposition. Permutation assays showed that the fusion protein induced a DNA bending at the site of NHP6A binding by an estimated value of 63 degrees. We believe that this experimental design provides an effective vehicle to determine the DNA bending induced by nonspecific HMG-1 proteins. 相似文献
204.
The effect of diethyl pyrocarbonate on chromatophores and isolated pigment--protein complexes of Chromatium minutissimum was studied. It is shown that modification of histidine residues results in the destruction of the core antenna LHI (B880) and in a spectral shift from 850 to 830 nm in the peripheral antenna LHII (B800-850). In the purple sulfur bacterium Chromatium minutissimum the pigment--protein complexes B800-B850 (peripheral antenna, LHII) and B880 (core antenna, LHI) collect and transmit the absorbed light energy to the reaction centers. The composition of pigments and proteins as well as primary structure of the majority of polypeptides in both types of complexes from various photosynthetic bacteria have been determined. 相似文献
205.
Photocontrol of chs gene expression in petunia flowers 总被引:4,自引:0,他引:4
206.
Ontario''s Medical Expert Panel on Duty to Inform was formed to consider the duty of Ontario physicians in circumstances where a patient threatens to kill or cause serious bodily harm to a third party. The panel was concerned about the implications of any duty to inform on the integrity of the physician-patient relationship, particularly with respect to confidentiality. The panel agreed that regulations safeguarding the confidentiality of patient information ought to be changed only if there is a critical reason for doing so, but, after deliberation, the panel members concluded that the need to protect the public from serious risk of harm is a paramount concern that should supersede the duty of confidentiality. The recommendations reported here were endorsed in principle by the panelists and the groups they represented (the Royal College of Physicians and Surgeons of Canada, the Canadian Medical Protective Association, the College of Physicians and Surgeons of Ontario, the Ontario College of Family Physicians and the Ontario Medical Association) and are being implemented by the College of Physicians and Surgeons of Ontario. 相似文献
207.
Katz LA 《Trends in ecology & evolution》1998,13(12):471-497
From the initial application of molecular techniques to the study of microbial organisms, three domains of life emerged, with eukaryotes and archaea as sister taxa. However, recent analyses of an expanding molecular data set reveal that the eukaryotic genome is chimeric with respect to archaea and bacteria. Moreover, there is now evidence that the primitive eukaryotic group ‘Archezoa' once harbored mitochondia. These discoveries have challenged the traditional stepwise model of the evolution of eukaryotes, in which the nucleus and microtubules evolve before the acquisition of mitochondria, and consequently compel a revision of existing models of the origin of eukaryotic cells. 相似文献
208.
Michael J. Blum K. Jun Bando M. Katz Donald R. Strong 《Journal of Biogeography》2007,34(12):2055-2069
Aim To examine the distribution and structure of genetic variation among native Spartina alterniflora and to characterize the evolutionary mechanisms underlying the success of non‐native S. alterniflora. Location Intertidal marshes along the Atlantic, Gulf and Pacific coasts of North America. Methods amova , parsimony analysis, haplotype networks of chloroplast DNA (cpDNA) sequences, neighbour‐joining analysis, Bayesian analysis of population structure, and individual assignment testing were used. Results Low levels of gene flow and geographic patterns of genetic variation were found among native S. alterniflora from the Atlantic and Gulf coasts of North America. The distribution of cpDNA haplotypes indicates that Atlantic coast S. alterniflora are subdivided into ‘northern’ and ‘southern’ groups. Variation observed at microsatellite loci further suggests that mid‐Atlantic S. alterniflora are differentiated from S. alterniflora found in southern Atlantic and New England coastal marshes. Comparisons between native populations on the Atlantic and Gulf coasts and non‐native Pacific coast populations substantiate prior studies demonstrating reciprocal interspecific hybridization in San Francisco Bay. Our results corroborate historical evidence that S. alterniflora was introduced into Willapa Bay from multiple source populations. However, we found that some Willapa Bay S. alterniflora are genetically divergent from putative sources, probably as a result of admixture following secondary contact among previously allopatric native populations. We further recovered evidence in support of models suggesting that S. alterniflora has secondarily spread within Washington State, from Willapa Bay to Grays Harbor. Main conclusions Underlying genetic structure has often been cited as a factor contributing to ecological variation of native S. alterniflora. Patterns of genetic structure within native S. alterniflora may be the result of environmental differences among biogeographical provinces, of migration barriers, or of responses to historical conditions. Interactions among these factors, rather than one single factor, may best explain the distribution of genetic variation among native S. alterniflora. Comprehensive genetic comparisons of native and introduced populations can illustrate how biological invasions may result from dramatically different underlying factors – some of which might otherwise go unrecognized. Demonstrating that invasions can result from several independent or interacting mechanisms is important for improving risk assessment and future forecasting. Further research on S. alterniflora not only may clarify what forces structure native populations, but also may improve the management of non‐native populations by enabling post‐introduction genetic changes and the rapid evolution of life‐history traits to be more successfully exploited. 相似文献
209.
210.
Dharanesh Gangaiah Kristen M. Webb Tricia L. Humphreys Kate R. Fortney Evelyn Toh Albert Tai Samantha S. Katz Allan Pillay Cheng-Yen Chen Sally A. Roberts Robert S. Munson Jr. Stanley M. Spinola 《PLoS neglected tropical diseases》2015,9(7)