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991.
Wenyaw Chan Asha S. Kapadia Alice Z. Chuang 《Biometrical journal. Biometrische Zeitschrift》2001,43(1):53-62
A stochastic model describing the movements, resulting from a smoking cessation program, of a cohort of individuals from the smoking to the non‐smoking compartment is proposed. The distribution and first two moments of the number of smokers are derived. 相似文献
992.
993.
994.
A sequence-specific heparin pentasaccharide activates the serpin, antithrombin, to inhibit factor Xa through an allosteric mechanism, whereas full-length heparin chains containing this sequence further activate the serpin to inhibit thrombin by an alternative bridging mechanism. To test whether the factor Xa specificity of allosterically activated antithrombin is encoded in the serpin reactive center loop, we mutated the factor Xa-preferred P2 Gly to the thrombin-preferred P2 Pro. Kinetic studies revealed that the mutation maximally enhanced the reactivity of antithrombin with thrombin 15-fold and decreased its reactivity toward factor Xa 2-fold when the serpin was activated by heparin pentasaccharide, thereby transforming antithrombin into an allosterically activated inhibitor of both factor Xa and thrombin. Surprisingly, the enhanced thrombin specificity of the mutant antithrombin was attenuated when a full-length bridging heparin was the activator, due both to a reduced rate of covalent reaction of the mutant serpin and thrombin and preferred reaction of the mutant serpin as a substrate. These results demonstrate that the reactive center loop sequence determines the specificity of allosterically activated antithrombin for factor Xa and that the conformational flexibility of the P2 Gly may be critical for optimal bridging of antithrombin and thrombin by physiologic heparin and for preventing antithrombin from reacting as a substrate in the bridging complex. 相似文献
995.
Mei-Chin Lai Chi-Ming Shu Ming-Shing Chiou Tong-Yung Hong Ming-Jen Chuang Jack Jay Hua 《Current microbiology》1999,39(2):79-84
A new methanogenic isolate, designated as strain N2M9705 (=OCM 668), was isolated from an aquaculture fishpond near Wang-gong,
Taiwan. This strain grew on trimethylamine and methanol, but it did not catabolize H2-CO2, acetate, or formate. The cells were stained Gram-negative, nonmotile, irregular coccus 0.6–0.8 μm in diameter. Gas vacuoles
were observed and cell aggregated to form various sizes of granules. Cells grew optimally at 32°–37°C with 1% NaCl. The pH
range of growth was 6.2–7.4, and higher pH inhibited the cell growth. The cells grew well in minimal medium, but growth was
greatly stimulated by yeast extract and peptone. A comparison of 16S rDNA sequences of this organism phylogenetically related
to Methanosarcina mazei. This is the first report of methyltrophic methanogenic isolated from an aquaculture fishpond.
Received: 16 March 1999 / Accepted: 16 April 1999 相似文献
996.
Rhodopsin's carboxy-terminal cytoplasmic tail acts as a membrane receptor for cytoplasmic dynein by binding to the dynein light chain Tctex-1. 总被引:17,自引:0,他引:17
The interaction of cytoplasmic dynein with its cargoes is thought to be indirectly mediated by dynactin, a complex that binds to the dynein intermediate chain. However, the roles of other dynein subunits in cargo binding have been unknown. Here we demonstrate that dynein translocates rhodopsin-bearing vesicles along microtubules. This interaction occurs directly between the C-terminal cytoplasmic tail of rhodopsin and Tctex-1, a dynein light chain. C-terminal rhodopsin mutations responsible for retinitis pigmentosa inhibit this interaction. Our results point to an alternative docking mechanism for cytoplasmic dynein, provide novel insights into the role of motor proteins in the polarized transport of post-Golgi vesicles, and shed light on the molecular basis of retinitis pigmentosa. 相似文献
997.
M L Chuang H Ting T Otsuka X G Sun F Y Chiu W L Beaver J E Hansen D A Lewis K Wasserman 《Journal of applied physiology》1999,87(3):1048-1058
Previous studies have shown that a metabolic alkalosis develops in the muscle during early exercise. This has been linked to phosphocreatine hydrolysis. Over a similar time frame, the femoral vein blood pH and plasma K(+) and HCO(-)(3) concentrations increase without an increase in PCO(2). Thus CO(2) from aerobic metabolism is converted to HCO(-)(3) rather than being eliminated by the lungs. The purpose of this study was to quantify the increase in early CO(2) stores and the component due to the exercise-induced metabolic alkalosis (E-I Alk). To avoid masking the increase in CO(2) stores by CO(2) released as HCO(-)(3) buffers lactic acid, the transient increase in CO(2) stores was measured only for work rates (WRs) below the lactic acidosis threshold (LAT). The increase in CO(2) stores was evident at the airway starting at approximately 15 s; the increase reached a peak at approximately 60 s and was complete by approximately 3 min of exercise. The increase in CO(2) stores was greater, but the kinetics were unaffected at the higher WR. Three components of the change in aerobically generated CO(2) stores were considered relevant: the carbamate component of the Haldane effect, the increase in CO(2) stores due to increase in tissue PCO(2), and the E-I Alk. The Haldane effect was calculated to be approximately 5%. Physically dissolved CO(2) in the tissues was approximately 30% of the store increase. The remaining E-I Alk CO(2) stores averaged 61 and 68% for 60 and 80% LAT WRs, respectively. The kinetics of O(2) uptake correlated with the time course of the increase in CO(2) stores; the size of the O(2) deficit correlated with the size of the E-I Alk component of the CO(2) stores. We conclude that a major component of the aerobically generated increase in CO(2) stores is the new HCO(-)(3) generated as phosphocreatine is converted to creatine. 相似文献
998.
The subsystems approach to genome annotation and its use in the project to annotate 1000 genomes 总被引:12,自引:1,他引:12
Overbeek R Begley T Butler RM Choudhuri JV Chuang HY Cohoon M de Crécy-Lagard V Diaz N Disz T Edwards R Fonstein M Frank ED Gerdes S Glass EM Goesmann A Hanson A Iwata-Reuyl D Jensen R Jamshidi N Krause L Kubal M Larsen N Linke B McHardy AC Meyer F Neuweger H Olsen G Olson R Osterman A Portnoy V Pusch GD Rodionov DA Rückert C Steiner J Stevens R Thiele I Vassieva O Ye Y Zagnitko O Vonstein V 《Nucleic acids research》2005,33(17):5691-5702
The release of the 1000th complete microbial genome will occur in the next two to three years. In anticipation of this milestone, the Fellowship for Interpretation of Genomes (FIG) launched the Project to Annotate 1000 Genomes. The project is built around the principle that the key to improved accuracy in high-throughput annotation technology is to have experts annotate single subsystems over the complete collection of genomes, rather than having an annotation expert attempt to annotate all of the genes in a single genome. Using the subsystems approach, all of the genes implementing the subsystem are analyzed by an expert in that subsystem. An annotation environment was created where populated subsystems are curated and projected to new genomes. A portable notion of a populated subsystem was defined, and tools developed for exchanging and curating these objects. Tools were also developed to resolve conflicts between populated subsystems. The SEED is the first annotation environment that supports this model of annotation. Here, we describe the subsystem approach, and offer the first release of our growing library of populated subsystems. The initial release of data includes 180177 distinct proteins with 2133 distinct functional roles. This data comes from 173 subsystems and 383 different organisms. 相似文献
999.
1000.
白洋淀蝗区东亚飞蝗的分布与土壤的关系研究 总被引:9,自引:2,他引:7
从土壤的质地、含水量、pH值和含盐量等方面 ,研究了白洋淀东亚飞蝗Locustamigratoriamanilensis(Meyen)蝗区的土壤状况 ;并结合实地考察的样点处蝗虫密度情况 ,研究了蝗虫不同密度区土壤之间的差异。结果表明 ,研究区蝗虫密度在 3 0头 m2 以上的地区 ,土壤质地为粉砂壤土 ,土壤pH值为7 2 6~ 8 1 2 ,土壤含盐量为 0 0 67%~ 0 2 0 7%。粉砂壤土中 ,砂粒含量较多、粗粉粒含量较少的地方 ,是东亚飞蝗比较理想的生存与活动场所 ;土壤含水量偏高、呈弱碱性的地方 ,适于东亚飞蝗的生存和活动。在研究区 ,土壤含盐量差异对东亚飞蝗的密度分布没有明显的影响。 相似文献