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121.
122.
Reilly K Gómez-Vásquez R Buschmann H Tohme J Beeching JR 《Plant molecular biology》2004,56(4):625-641
A major constraint to the development of cassava (Manihot esculenta Crantz) as a crop to both farmers and processors is its starchy storage roots’ rapid post-harvest deterioration, which can render it unpalatable and unmarketable within 24–72 h. An oxidative burst occurs within 15 min of the root being injured, that is followed by the altered regulation of genes, notably for catalase and peroxidase, related to the modulation of reactive oxygen species, and the accumulation of secondary metabolites, some of which show antioxidant properties. The interactions between these enzymes and compounds, in particular peroxidase and the coumarin, scopoletin, are largely confined to the vascular tissues where the visible symptoms of deterioration are observed. These, together with other data, are used to develop a tentative model of some of the principal events involved in the deterioration process. 相似文献
123.
Lopez C Jorge V Piégu B Mba C Cortes D Restrepo S Soto M Laudié M Berger C Cooke R Delseny M Tohme J Verdier V 《Plant molecular biology》2004,56(4):541-554
Two economically important characters, starch content and cassava bacterial blight resistance, were targeted to generate a large collection of cassava ESTs. Two libraries were constructed from cassava root tissues of varieties with high and low starch contents. Other libraries were constructed from plant tissues challenged by the pathogen Xanthomonas axonopodis pv.manihotis. We report here the single pass sequencing of 11 954 cDNA clones from the 5’ ends, including 111 from the 3’ ends. Cluster analysis permitted the identification of a unigene set of 5700 sequences. Sequence analyses permitted the assignment of a putative functional category for 37% of sequences whereas ~ 16% sequences did not show any significant similarity with other proteins present in the database and therefore can be considered as cassava specific genes. A group of genes belonging to a large multigene family was identified. We characterize a set of genes detected only in infected libraries putatively involved in the defense response to pathogen infection. By comparing two libraries obtained from cultivars contrasting in their starch content a group of genes associated to starch biosynthesis and differentially expressed was identified. This is the first large cassava EST resource developed today and publicly available thus making a significant contribution to genomic knowledge of cassava. 相似文献
124.
A mixture model for estimating the local false discovery rate in DNA microarray analysis 总被引:3,自引:0,他引:3
MOTIVATION: Statistical methods based on controlling the false discovery rate (FDR) or positive false discovery rate (pFDR) are now well established in identifying differentially expressed genes in DNA microarray. Several authors have recently raised the important issue that FDR or pFDR may give misleading inference when specific genes are of interest because they average the genes under consideration with genes that show stronger evidence for differential expression. The paper proposes a flexible and robust mixture model for estimating the local FDR which quantifies how plausible each specific gene expresses differentially. RESULTS: We develop a special mixture model tailored to multiple testing by requiring the P-value distribution for the differentially expressed genes to be stochastically smaller than the P-value distribution for the non-differentially expressed genes. A smoothing mechanism is built in. The proposed model gives robust estimation of local FDR for any reasonable underlying P-value distributions. It also provides a single framework for estimating the proportion of differentially expressed genes, pFDR, negative predictive values, sensitivity and specificity. A cervical cancer study shows that the local FDR gives more specific and relevant quantification of the evidence for differential expression that can be substantially different from pFDR. AVAILABILITY: An R function implementing the proposed model is available at http://www.geocities.com/jg_liao/software 相似文献
125.
Fedeniuk RW Boison JO MacNeil JD 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2004,802(2):307-315
A method for the quantitation of pg/ml levels of 17beta-estradiol and 17beta-trenbolone in bovine serum by gas chromatography/electron-capture mass spectrometry has been developed and validated. Using the area ratios of the integrated molecular-ion peaks of the analytes to their corresponding deuterated internal standards, [2,4,16,16-2H4] 17beta-estradiol (17beta-estradiol-d(4)) and [16,16-2H2] 17beta-trenbolone (17beta-trenbolone-d(2)), and non-weighted linear regression, two calibration curves per analyte; 5-50 and 50-500 pg/ml for 17beta-estradiol in sera, and 25-250 and 250-2500 pg/ml for 17beta-trenbolone in sera, respectively, were constructed. Splitless injection of 200 fg 17beta-estradiol and 1000 fg 17beta-trenbolone could be detected and quantified. Tested batches of control bovine sera did not exhibit interference for 17beta-trenbolone, and showed expected background presence of endogenous 17beta-estradiol. Intra-day residual errors did not exceed 20%, and regression correlations were greater than 0.99. Intra-day precision data was similar to inter-day precision data. Using this method, 16 samples can be processed within one working day. 相似文献
126.
Modeling Sustainability of Arctic Communities: An Interdisciplinary Collaboration of Researchers and Local Knowledge Holders 总被引:1,自引:0,他引:1
Jack A. Kruse Robert G. White Howard E. Epstein Billy Archie Matt Berman Stephen R. Braund F. Stuart Chapin III Johnny Charlie Sr. Colin J. Daniel Joan Eamer Nick Flanders Brad Griffith Sharman Haley Lee Huskey Bernice Joseph David R. Klein Gary P. Kofinas Stephanie M. Martin Stephen M. Murphy William Nebesky Craig Nicolson Don E. Russell Joe Tetlichi Arlon Tussing Marilyn D. Walker Oran R. Young 《Ecosystems》2004,7(8):815-828
How will climate change affect the sustainability of Arctic villages over the next 40 years? This question motivated a collaboration of 23 researchers and four Arctic communities (Old Crow, Yukon Territory, Canada; Aklavik, Northwest Territories, Canada; Fort McPherson, Northwest Territories, Canada; and Arctic Village, Alaska, USA) in or near the range of the Porcupine Caribou Herd. We drew on existing research and local knowledge to examine potential effects of climate change, petroleum development, tourism, and government spending cutbacks on the sustainability of four Arctic villages. We used data across eight disciplines to develop an Arctic Community Synthesis Model and a Web-based, interactive Possible Futures Model. Results suggested that climate warming will increase vegetation biomass within the herd’s summer range. However, despite forage increasing, the herd was projected as likely to decline with a warming climate because of increased insect harassment in the summer and potentially greater winter snow depths. There was a strong negative correlation between hypothetical, development-induced displacement of cows and calves from utilized calving grounds and calf survival during June. The results suggested that climate warming coupled with petroleum development would cause a decline in caribou harvest by local communities. Because the Synthesis Model inherits uncertainties associated with each component model, sensitivity analysis is required. Scientists and stakeholders agreed that (1) although simulation models are incomplete abstractions of the real world, they helped bring scientific and community knowledge together, and (2) relationships established across disciplines and between scientists and communities were a valuable outcome of the study. Additional project materials, including the Web-based Possible Futures Model, are available at http://www.taiga.net/sustain. 相似文献
127.
Orthologous gene-expression profiling in multi-species models: search for candidate genes 总被引:2,自引:0,他引:2
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Microarray-driven gene-expression profiles are generally produced and analyzed for a single specific experimental model. We have assessed an analytical approach that simultaneously evaluates multi-species experimental models within a particular biological condition using orthologous genes as linkers for the various Affymetrix microarray platforms on multi-species models of ventilator-associated lung injury. The results suggest that this approach may be a useful tool in the evaluation of biological processes of interest and selection of process-related candidate genes. 相似文献
128.
Wüster W Allum CS Bjargardóttir IB Bailey KL Dawson KJ Guenioui J Lewis J McGurk J Moore AG Niskanen M Pollard CP 《Proceedings. Biological sciences / The Royal Society》2004,271(1556):2495-2499
Predator avoidance of noxious prey, aposematism and defensive mimicry are normally associated with bright, contrasting patterns and colours. However, noxious prey may be unable to evolve conspicuous coloration because of other selective constraints, such as the need to be inconspicuous to their own prey or to specialist predators. Many venomous snakes, particularly most vipers, display patterns that are apparently cryptic, but nevertheless highly characteristic, and appear to be mimicked by other, non-venomous snakes. However, predator avoidance of viper patterns has never been demonstrated experimentally. Here, the analysis of 813 avian attacks on 12,636 Plasticine snake models in the field shows that models bearing the characteristic zigzag band of the adder (Vipera berus) are attacked significantly less frequently than plain models. This suggests that predator avoidance of inconspicuously but characteristically patterned noxious prey is possible. Our findings emphasize the importance of mimicry in the ecological and morphological diversification of advanced snakes. 相似文献
129.
Borbiev T Birukova A Liu F Nurmukhambetova S Gerthoffer WT Garcia JG Verin AD 《American journal of physiology. Lung cellular and molecular physiology》2004,287(5):L911-L918
We have previously shown that thrombin induces endothelial cell barrier dysfunction via cytoskeleton activation and contraction and have determined the important role of endothelial cell myosin light chain kinase (MLCK) in this process. In the present study we explored p38 MAP kinase as a potentially important enzyme in thrombin-mediated endothelial cell contractile response and permeability. Thrombin induces significant p38 MAP kinase activation in a time-dependent manner with maximal effect at 30 min, which correlates with increased phosphorylation of actin- and myosin-binding protein, caldesmon. Both SB-203580 and dominant negative p38 adenoviral vector significantly attenuated thrombin-induced declines in transendothelial electrical resistance. Consistent with these data SB-203580 decreased actin stress fiber formation produced by thrombin in endothelium. In addition, dominant negative p38 had no effect on thrombin-induced myosin light chain diphosphorylation. Thrombin-induced total and site-specific caldesmon phosphorylation (Ser789) as well as dissociation of caldesmon-myosin complex were attenuated by SB-203580 pretreatment. These results suggest the involvement of p38 MAP kinase activities and caldesmon phosphorylation in the MLCK-independent regulation of thrombin-induced endothelial cell permeability. 相似文献
130.
Girgis RE Li D Zhan X Garcia JG Tuder RM Hassoun PM Johns RA 《American journal of physiology. Heart and circulatory physiology》2003,285(3):H938-H945
The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have been shown to improve multiple normal endothelial cell functions and inhibit vascular wall cell proliferation. We hypothesized that one such agent, simvastatin, would attenuate chronic hypoxic pulmonary hypertension. Male adult Sprague-Dawley rats were exposed (14 days) to normoxia (N), normoxia plus once-a-day administered simvastatin (20 mg/kg ip) (NS), hypoxia (10% inspired O2 fraction) (H), or hypoxia plus simvastatin (HS). Mean pulmonary artery pressure, measured in anesthetized, ventilated rats with an open-chest method, was reduced from 25 +/- 2 mmHg in H to 18 +/- 1 in HS (P < 0.001) but did not reach normoxic values (12 +/- 1 mmHg). Similarly, right ventricular/left ventricular plus interventricular septal weight was reduced from 0.53 +/- 0.02 in the H group to 0.36 +/- 0.02 in the HS group (P < 0.001). The increased hematocrit in H (0.65 +/- 0.02) was prevented by simvastatin treatment (0.51 +/- 0.01, P < 0.001). Hematocrit was similar in N versus NS. Alveolar vessel muscularization and medial thickening of vessels 50-200 microM in diameter induced by hypoxia were also significantly attenuated in the HS animals. Lung endothelial nitric oxide synthase (eNOS) protein expression in the HS group was less than H (P < 0.01) but was similar in N versus NS. We conclude that simvastatin treatment potently attenuates chronic hypoxic pulmonary hypertension and polycythemia in rats and inhibits vascular remodeling. Enhancement of lung eNOS expression does not appear to be involved in mediating this effect. 相似文献