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Masaki Uchida Ayaka Kishimoto Hiroyuki Muraoka Takayuki Nakatsubo Hiroshi Kanda Hiroshi Koizumi 《Journal of plant research》2010,123(1):79-85
We examined factors controlling temporal changes in net ecosystem production (NEP) in a high Arctic polar semi-desert ecosystem
in the snow-free season. We examined the relationships between NEP and biotic and abiotic factors in a dominant plant community
(Salix polaris–moss) in the Norwegian high Arctic. Just after snowmelt in early July, the ecosystem released CO2 into the atmosphere. A few days after snowmelt, however, the ecosystem became a CO2 sink as the leaves of S. polaris developed. Diurnal changes in NEP mirrored changes in light incidence (photosynthetic photon flux density, PPFD) in summer.
NEP was significantly correlated with PPFD when S. polaris had fully developed leaves, i.e., high photosynthetic activity. In autumn, NEP values decreased as S. polaris underwent senescence. During this time, CO2 was sometimes released into the atmosphere. In wet conditions, moss made a larger contribution to NEP. In fact, the water
content of the moss regulated NEP during autumn. Our results indicate that the main factors controlling NEP in summer are
coverage and growth of S. polaris, PPFD, and precipitation. In autumn, the main factor controlling NEP is moss water content. 相似文献
55.
Deletion mapping and heterogenote analysis of a mutation responsible for osmosis-sensitive growth, spectinomycin resistance, and alteration of cytoplasmic membrane in Escherichia coli 总被引:2,自引:4,他引:2 下载免费PDF全文
Lambda transducing phages carrying Escherichia coli deoxyribonucleic acid of various lengths from the aroE-rpsL region were lysogenized into the F'3 plasmid and were used for heterogenote analysis of YM101, a sucrose-dependent, spectinomycin-resistant mutant of E. coli. Three characteristics of the mutant strain, resistance to spectinomycin, sucrose dependence of growth, and lack of I-19 protein in the cytoplasmic membrane, were shown to be the result of a mutation in a region designated delta 53-spcl. This region extends over 3.6-kilobase pairs and is located within a cluster of ribosomal genes. The mutation is recessive to the wild-type allele. 相似文献
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Fujii R Shimonaka S Uchida N Gardiner AT Cogdell RJ Sugisaki M Hashimoto H 《Photosynthesis research》2008,95(2-3):327-337
Typical purple bacterial photosynthetic units consist of supra-molecular arrays of peripheral (LH2) and core (LH1-RC) antenna
complexes. Recent atomic force microscopy pictures of photosynthetic units in intact membranes have revealed that the architecture
of these units is variable (Scheuring et al. (2005) Biochim Bhiophys Acta 1712:109–127). In this study, we describe methods for the construction of heterologous photosynthetic
units in lipid-bilayers from mixtures of purified LH2 (from Rhodopseudomonas acidophila) and LH1-RC (from Rhodopseudomonas viridis) core complexes. The architecture of these reconstituted photosynthetic units can be varied by controlling ratio of added
LH2 to core complexes. The arrangement of the complexes was visualized by electron-microscopy in combination with Fourier
analysis. The regular trigonal array of the core complexes seen in the native photosynthetic membrane could be regenerated
in the reconstituted membranes by temperature cycling. In the presence of added LH2 complexes, this trigonal symmetry was
replaced with orthorhombic symmetry. The small lattice lengths for the latter suggest that the constituent unit of the orthorhombic
lattice is the LH2. Fluorescence and fluorescence-excitation spectroscopy was applied to the set of the reconstituted membranes
prepared with various proportions of LH2 to core complexes. Remarkably, even though the LH2 complexes contain bacteriochlorophyll
a, and the core complexes contain bacteriochlorophyll b, it was possible to demonstrate energy transfer from LH2 to the core complexes. These experiments provide a first step along
the path toward investigating how changing the architecture of purple bacterial photosynthetic units affects the overall efficiency
of light-harvesting. 相似文献
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Acquired Thermotolerance and Temperature-Induced Protein Accumulation in the Extremely Thermophilic Bacterium Rhodothermus obamensis 总被引:1,自引:0,他引:1 下载免费PDF全文
Ken Takai Takuro Nunoura Yoshihiko Sako Aritsune Uchida 《Journal of bacteriology》1998,180(10):2770-2774
Temperature-induced changes in thermotolerance and protein composition were examined in heat-shocked cells and high-temperature-grown cells of the extremely thermophilic bacterium Rhodothermus obamensis. The survival at temperatures superoptimal for growth (90 and 95°C) was enhanced in both heat-shocked cells and high-temperature-grown cells relative to that of cells grown at optimal temperatures. In a comparison of protein composition using two-dimensional gel electrophoresis, putative heat shock proteins (HSPs) and high-temperature growth-specific proteins (HGPs) were detected. N-terminal amino acid sequence analysis revealed that the putative HSPs were quite similar to the ATP-binding subunits of ABC transporters and the HGPs were proteins corresponding to domains II and III of elongation factor Tu. These results suggested that this extreme thermophile has developed temperature-induced responses that include increased survival under hyperthermal conditions, changes in protein composition, and also the production of novel HSPs. 相似文献
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Fenofibrate, a drug in the fibrate class of amphiphathic carboxylic acids, has multiple blood lipid modifying actions, which are beneficial to the prevention of atherosclerosis. One of its benefits is in lowering fasting and postprandial blood triglyceride (TG) concentrations. The goal of this study was to determine whether the hypotriglyceridemic actions of fenofibrate in the postprandial state include alterations in TG and fatty acid metabolism in the small intestine. We found that the hypotriglyceridemic actions of fenofibrate in the postprandial state of high-fat (HF) fed mice include a decrease in supply of TG for secretion by the small intestine. A decreased supply of TG for secretion was due in part to the decreased dietary fat absorption and increased intestinal fatty acid oxidation in fenofibrate compared to vehicle treated HF fed mice. These results suggest that the effects of fenofibrate on the small intestine play a critical role in the hypotriglyceridemic effects of fenofibrate. 相似文献
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Mori T Hidaka M Lin YC Yoshizawa I Okabe T Egashira S Kojima H Nagano T Koketsu M Takamiya M Uchida T 《Biochemical and biophysical research communications》2011,406(3):5355-443
Pin1, a peptidyl prolyl cis/trans isomerase (PPIase), is a potential target molecule for cancer, infectious disease, and Alzheimer’s disease. We established a high-throughput screening method for Pin1 inhibitors, which employs a real-time fluorescence detector. This screening method identified 66 compounds that inhibit Pin1 out of 9756 compounds from structurally diverse chemical libraries. Further evaluations of surface plasmon resonance methods and a cell proliferation assay were performed. We discovered a cell-active inhibitor, TME-001 (2-(3-chloro-4-fluoro-phenyl)-isothiazol-3-one). Surprisingly, kinetic analyses revealed that TME-001 is the first compound that exhibits dual inhibition of Pin1 (IC50 = 6.1 μM) and cyclophilin, another type of PPIase, (IC50 = 13.7 μM). This compound does not inhibit FKBP. This finding suggests the existence of similarities of structure and reaction mechanism between Pin1 and cyclophilin, and may lead to a more complete understanding of the active sites of PPIases. 相似文献
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