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Stable isotope analyses and derived population-level metrics were used to quantitatively analyse spatial and seasonal heterogeneity in the fish trophic dynamics in relation to environmental variables in Mwanza Gulf, Lake Victoria (Tanzania). The fish community in Lake Victoria, including the top predator Nile perch, is generally omnivorous with a heavy reliance on invertebrates. This is in contrast to findings based on stomach content analyses of Nile perch, which showed a stronger reliance on fish. We tested two hypotheses: (1) during the rainy seasons multiple carbon sources influence the food-web structure inside the Gulf, leading to increased carbon ranges and trophic diversity. (2) During dry periods, the food-web structure mainly relies on pelagic primary production, reducing carbon ranges and trophic diversity. Carbon sources indeed varied seasonally and spatially, affecting the fish community at the highest trophic levels. With the onset of rains, carbon sources became spatially highly differentiated with enriched δ13C values of fish in shallow water inside the Gulf and depleted δ13C values in open waters. Metrics associated with niche size correlated significantly with seasonally varying environmental variables, while δ13C ranges correlated with spatially varying environmental variables.  相似文献   
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R F Genovese  L A Dykstra 《Life sciences》1986,39(19):1713-1719
The analgesic efficacy of the kappa-opioid benzodiazepine, tifluadom, was examined in squirrel monkeys using electric shock titration and tail-immersion procedures. Tifluadom produced dose-dependent increases in the shock intensity that maintained responding under the shock titration schedule without substantially decreasing response rates. Tifluadom also increased the latency of tail-withdrawal from 55 degrees C water. Naloxone attenuated tifluadom's effects under both procedures. These results extend previous reports of tifluadom's analgesic characteristics and suggest that the tail-immersion procedure is a useful analgesic assay in squirrel monkeys.  相似文献   
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Daoxyribonucleic acid (DNA) polymerase Isolated from visne virus has been separated into three enzymatically active polypeptides by column chromatography on DEAE-cellulose. They are designated polymerase I, II and III according to the order of elutlon from the column. The three enzymes are different in their pH optimum, sensitivity to N-ethylmaleimide, rate of catalytic reaction, and preference of template. The molecular weights were estimated to be 125, 000 for polymerase I and 18, 000 for II.  相似文献   
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OBJECTIVES: Fibrosis and cancer are characterized by extracellular matrix (ECM) remodeling. The basement membrane is mainly composed by collagen type IV and laminin. Tumstatin is a matrix metalloproteinase-9 (MMP-9) generated matrikine of collagen type IV α3 chain. We evaluated the potential of tumstatin as a diagnostic biomarker of lung disorders. METHODS: A monoclonal antibody was raised against the neo-epitope tumstatin. A novel competitive enzyme-linked immunosorbent assay for detection of tumstatin (TUM), was developed and technically characterized. Levels of TUM were measured in serum of patients with idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD), and non–small cell lung cancer (NSCLC) belonging to two cohorts. RESULTS: The developed TUM enzyme-linked immunosorbent assay (ELISA) was technically robust. In cohort 1, levels of TUM were significantly higher in NSCLC compared to healthy controls, IPF, and COPD (P = 0.007, P = 0.03 and P = 0.001, respectively). The area under the receiver operating characteristics (AUROC) for separation of patients with NSCLC from healthy controls was 0.97, for separation of NSCLC and IPF patients was 0.98, and for separation of NSCLC and COPD patients was 1.0. In cohort 2, levels of TUM were also significantly higher in patients with NSCLC compared to healthy controls (P = 0.002), and the AUROC for separation of NSCLC and healthy controls was 0.73. CONCLUSIONS: We developed a technically robust competitive ELISA targeting the fragment tumstatin. The level of TUM in circulation was significantly higher in patients with NSCLC compared to patients with IPF, COPD and healthy controls. The assay provided high diagnostic accuracy in separating NSCLC patients from other lung disorders and from healthy controls.  相似文献   
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