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1.
Augmentation of c-fos mRNA expression by activators of protein kinase C in fresh, terminally differentiated resting macrophages. 总被引:6,自引:6,他引:0 下载免费PDF全文
Expression of c-fos mRNA was investigated in fresh, normal peritoneal macrophages (M phi), which are terminally differentiated, nonproliferating cells. The levels of c-fos mRNA were dramatically increased by stimulation with phorbol myristate acetate (PMA), calcium ionophore, or 1-oleoyl-2-acetoyl glycerol (OAG). Induction of c-fos mRNA by all the above agents followed similar kinetics, with a peak of mRNA 30 min after stimulation. These results demonstrate that c-fos mRNA can be augmented in fresh, terminally differentiated cells. Since the stimuli increasing c-fos mRNA are direct or indirect activators of protein kinase C, our data suggest that in M phi c-fos mRNA is controlled by protein kinase C activation. PMA, calcium ionophore, and OAG were biologically active in M phi. PMA and calcium ionophore induced respiratory burst and tumoricidal activity, respectively, whereas OAG and PMA were chemotactic for M phi. Interferons beta and gamma, potent M phi activators eliciting tumoricidal activity, did not alter the levels of c-fos mRNA. These results indicate that c-fos mRNA augmentation is a stimulus-specific rather than a function-specific response connected to activation of protein kinase C. 相似文献
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Summary Genetic determinants of the Muc+ character were investigated in two ropy strains,Lactobacillus delbrueckii ssp.bulgaricus 201 andL. casei ssp.casei NCIB 4114, which secrete a large amount of slime in culture media. Plasmid DNA analysis revealed the presence of two plasmids (4.5 and 2.3 Mdal) inL. casei ssp.casei, whileL. delbrueckii ssp.bulgaricus was plasmid free, suggesting a chromosomal location of Muc+ character in this strain. Curing experiments carried out onL. casei ssp.casei NCIB 4114 indicated a correlation between the Muc+ phenotype and the 4.5 Mdal plasmid. 相似文献
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B Bottazzi N Nobili A Mantovani 《Journal of immunology (Baltimore, Md. : 1950)》1990,144(12):4878-4882
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The signal transduction pathway involved in the migration induced by a monocyte chemotactic cytokine 总被引:16,自引:0,他引:16
S Sozzani W Luini M Molino P Jílek B Bottazzi C Cerletti K Matsushima A Mantovani 《Journal of immunology (Baltimore, Md. : 1950)》1991,147(7):2215-2221
Recombinant monocyte-chemotactic and activating factor (rMCAF; alternative acronyms MCP-1, TDCF, human JE) induced migration of human monocytes across polycarbonate or nitrocellulose filters. Maximal induction of migration was observed at a concentration of 10 ng/ml (10(-9) M). Checkerboard analysis revealed that rMCAF elicited true gradient-dependent chemotactic migration, although a gradient independent chemokinetic effect was observed at low concentrations (1-5 ng/ml). rMCAF caused a rapid (less than 5 s) and transient (approximately 1.5 min) increase of free cytosolic Ca2+ ions, as assessed by the fura-2 probe. No Ca2+ increase was detected in neutrophils or lymphocytes stimulated by rMCAF. Studies conducted in the absence of extracellular Ca2+ or in the presence of Ni2+ (an inhibitor of Ca2+ influx) suggested that the increase of intracellular Ca2+ induced by rMCAF is dependent on the influx of extracellular Ca2+ through plasma membrane channels. Bordetella pertussis toxin inhibited the intracellular Ca2+ elevation and chemotaxis caused by rMCAF. The possible involvement of Ca(2+)-dependent protein kinases in rMCAF signaling pathway(s) was explored using inhibitors. Inhibitors of GMP-dependent kinase and myosin L chain kinase had no effect on rMCAF-induced monocyte migration. In contrast, protein kinase C/cAMP-dependent kinase inhibitors (such as, C-I, H-7, HA-1004, KT5720, and Staurosporine) markedly decreased rMCAF induced chemotaxis suggesting the involvement of a serine/threonine protein kinase, possibly protein kinase C, in rMCAF signaling pathway. 相似文献
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FLUXNET and modelling the global carbon cycle 总被引:3,自引:0,他引:3
ANDREW D. FRIEND ALMUT ARNETH† NANCY Y. KIANG‡ MARK LOMAS§ JÉRÔME OGÉE¶ CHRISTIAN RÖDENBECK STEVEN W. RUNNING JEAN-DIEGO SANTAREN STEPHEN SITCH†† NICOLAS VIOVY F. IAN WOODWARD§ SÖNKE ZAEHLE†† 《Global Change Biology》2007,13(3):610-633
Measurements of the net CO2 flux between terrestrial ecosystems and the atmosphere using the eddy covariance technique have the potential to underpin our interpretation of regional CO2 source–sink patterns, CO2 flux responses to forcings, and predictions of the future terrestrial C balance. Information contained in FLUXNET eddy covariance data has multiple uses for the development and application of global carbon models, including evaluation/validation, calibration, process parameterization, and data assimilation. This paper reviews examples of these uses, compares global estimates of the dynamics of the global carbon cycle, and suggests ways of improving the utility of such data for global carbon modelling. Net ecosystem exchange of CO2 (NEE) predicted by different terrestrial biosphere models compares favourably with FLUXNET observations at diurnal and seasonal timescales. However, complete model validation, particularly over the full annual cycle, requires information on the balance between assimilation and decomposition processes, information not readily available for most FLUXNET sites. Site history, when known, can greatly help constrain the model‐data comparison. Flux measurements made over four vegetation types were used to calibrate the land‐surface scheme of the Goddard Institute for Space Studies global climate model, significantly improving simulated climate and demonstrating the utility of diurnal FLUXNET data for climate modelling. Land‐surface temperatures in many regions cool due to higher canopy conductances and latent heat fluxes, and the spatial distribution of CO2 uptake provides a significant additional constraint on the realism of simulated surface fluxes. FLUXNET data are used to calibrate a global production efficiency model (PEM). This model is forced by satellite‐measured absorbed radiation and suggests that global net primary production (NPP) increased 6.2% over 1982–1999. Good agreement is found between global trends in NPP estimated by the PEM and a dynamic global vegetation model (DGVM), and between the DGVM and estimates of global NEE derived from a global inversion of atmospheric CO2 measurements. Combining the PEM, DGVM, and inversion results suggests that CO2 fertilization is playing a major role in current increases in NPP, with lesser impacts from increasing N deposition and growing season length. Both the PEM and the inversion identify the Amazon basin as a key region for the current net terrestrial CO2 uptake (i.e. 33% of global NEE), as well as its interannual variability. The inversion's global NEE estimate of −1.2 Pg [C] yr−1 for 1982–1995 is compatible with the PEM‐ and DGVM‐predicted trends in NPP. There is, thus, a convergence in understanding derived from process‐based models, remote‐sensing‐based observations, and inversion of atmospheric data. Future advances in field measurement techniques, including eddy covariance (particularly concerning the problem of night‐time fluxes in dense canopies and of advection or flow distortion over complex terrain), will result in improved constraints on land‐atmosphere CO2 fluxes and the rigorous attribution of mechanisms to the current terrestrial net CO2 uptake and its spatial and temporal heterogeneity. Global ecosystem models play a fundamental role in linking information derived from FLUXNET measurements to atmospheric CO2 variability. A number of recommendations concerning FLUXNET data are made, including a request for more comprehensive site data (particularly historical information), more measurements in undisturbed ecosystems, and the systematic provision of error estimates. The greatest value of current FLUXNET data for global carbon cycle modelling is in evaluating process representations, rather than in providing an unbiased estimate of net CO2 exchange. 相似文献
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Pier Sandro Cocconcelli Elena Ferrari Filippo Rossi Vittorio Bottazzi 《FEMS microbiology letters》1992,94(3):203-207
To apply recombinant DNA techniques to the genetic manipulation of cellulolytic ruminal bacteria, a plasmid vector transformation system must be available. The objective of this work was to develop a system for plasmid transformation of Ruminococcus albus. Using high voltage electrotransformation, pSC22 and pCK17 plasmid vectors, derived from lactic acid bacteria plasmids and replicating via single-stranded DNA intermediate, were successfully introduced into three freshly isolated R. albus strains and into R. albus type strain ATCC 27210. The optimization of the electrotransformation condition raised the electroporation efficiency up to 3 x 10(5) transformants per microgram of pSC22 plasmid. 相似文献
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VIVIANE LANQUAR ASTRID AGORIO JÉRÔME GIRAUDAT THOMAS ROACH ANJA KRIEGER‐LISZKAY SÉBASTIEN THOMINE 《Plant, cell & environment》2013,36(4):804-817
Cadmium (Cd) is highly toxic to plants causing growth reduction and chlorosis. It binds thiols and competes with essential transition metals. It affects major biochemical processes such as photosynthesis and the redox balance, but the connection between cadmium effects at the biochemical level and its deleterious effect on growth has seldom been established. In this study, two Cd hypersensitive mutants, cad1‐3 impaired in phytochelatin synthase (PCS1), and nramp3nramp4 impaired in release of vacuolar metal stores, have been compared. The analysis combines genetics with measurements of photosynthetic and antioxidant functions. Loss of AtNRAMP3 and AtNRAMP4 function or of PCS1 function leads to comparable Cd sensitivity. Root Cd hypersensitivities conferred by cad1‐3 and nramp3nramp4 are cumulative. The two mutants contrast in their tolerance to oxidative stress. In nramp3nramp4, the photosynthetic apparatus is severely affected by Cd, whereas it is much less affected in cad1‐3. In agreement with chloroplast being a prime target for Cd toxicity in nramp3nramp4, the Cd hypersensitivity of this mutant is alleviated in the dark. The Cd hypersensitivity of nramp3nramp4 mutant highlights the critical role of vacuolar metal stores to supply essential metals to plastids and maintain photosynthetic function under Cd and oxidative stresses. 相似文献