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21.
The glucose transport system of the hyperthermophilic anaerobic bacterium Thermotoga neapolitana 总被引:1,自引:1,他引:0 下载免费PDF全文
The glucose transport system of the extremely thermophilic anaerobic bacterium Thermotoga neapolitana was studied with the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DOG). T. neapolitana accumulated 2-DOG against a concentration gradient in an intracellular free sugar pool that was exchangeable with external source of energy, such as pyruvate, and was inhibited by arsenate and gramicidin D. There was no phosphoenolpyruvate-dependent phosphorylation of glucose, 2-DOG, or fructose by cell extracts or toluene-treated cells, indicating the absence of a phosphoenolpyruvate:sugar phosphotransferase system. These data indicate that D-glucose is taken up by T. neapolitana via an active transport system that is energized by an ion gradient generated by ATP, derived from substrate-level phosphorylation. 相似文献
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Snetselaar, K. M., Bolker, M., and Kahmann, R. 1996. Ustilago maydis mating hyphae orient their growth toward pheromone sources. Fungal Genetics and Biology 20, 299-312. When small drops of Ustilago maydis sporidia were placed 100-200 μm apart on agar surfaces and covered with paraffin oil, sporidia from one drop formed thin hyphae that grew in a zig-zag fashion toward the other drop if it contained sporidia making the appropriate pheromone. For example, a2b2 mating hyphae grew toward a1b1 and a1b2 mating hyphae, and the filaments eventually fused tip to tip. Time-lapse photography indicated that the mating hyphae can rapidly change orientation in response to nearby compatible sporidia. When exposed to pheromone produced by cells in an adjacent drop, haploid sporidia with the a2 allele began elongating before sporidia with the a1 allele. Sporidia without functional pheromone genes responded to pheromone although they did not induce a response, and sporidia without pheromone receptors induced formation of mating hyphae although they did not form mating hyphae. Diploid sporidia heterozygous at b but not at a formed straight, rigid, aerial filaments when exposed to pheromone produced by the appropriate haploid sporidia. Again, the a2a2b1b2 strain formed filaments more quickly than the a1a1b1b2 strain. Taken together, these results suggest that the a2 pheromone diffuses less readily or is degraded more quickly than the a1 pheromone. 相似文献
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JZ Song KM Duan T Ware M Surette 《EURASIP Journal on Bioinformatics and Systems Biology》2007,2007(1):39382
A variety of high-throughput methods have made it possible to generate detailed temporal expression data for a single gene or large numbers of genes. Common methods for analysis of these large data sets can be problematic. One challenge is the comparison of temporal expression data obtained from different growth conditions where the patterns of expression may be shifted in time. We propose the use of wavelet analysis to transform the data obtained under different growth conditions to permit comparison of expression patterns from experiments that have time shifts or delays. We demonstrate this approach using detailed temporal data for a single bacterial gene obtained under 72 different growth conditions. This general strategy can be applied in the analysis of data sets of thousands of genes under different conditions.[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29] 相似文献
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Renée A. Scheepers Kiki M. J. M. H. Lombarts Marcel A. G. van Aken Maas Jan Heineman Onyebuchi A. Arah 《PloS one》2014,9(5)
Background
Worldwide, attending physicians train residents to become competent providers of patient care. To assess adequate training, attending physicians are increasingly evaluated on their teaching performance. Research suggests that personality traits affect teaching performance, consistent with studied effects of personality traits on job performance and academic performance in medicine. However, up till date, research in clinical teaching practice did not use quantitative methods and did not account for specialty differences. We empirically studied the relationship of attending physicians'' personality traits with their teaching performance across surgical and non-surgical specialties.Method
We conducted a survey across surgical and non-surgical specialties in eighteen medical centers in the Netherlands. Residents evaluated attending physicians'' overall teaching performance, as well as the specific domains learning climate, professional attitude, communication, evaluation, and feedback, using the validated 21-item System for Evaluation of Teaching Qualities (SETQ). Attending physicians self-evaluated their personality traits on a 5-point scale using the validated 10-item Big Five Inventory (BFI), yielding the Five Factor model: extraversion, conscientiousness, neuroticism, agreeableness and openness.Results
Overall, 622 (77%) attending physicians and 549 (68%) residents participated. Extraversion positively related to overall teaching performance (regression coefficient, B: 0.05, 95% CI: 0.01 to 0.10, P = 0.02). Openness was negatively associated with scores on feedback for surgical specialties only (B: −0.10, 95% CI: −0.15 to −0.05, P<0.001) and conscientiousness was positively related to evaluation of residents for non-surgical specialties only (B: 0.13, 95% CI: 0.03 to 0.22, p = 0.01).Conclusions
Extraverted attending physicians were consistently evaluated as better supervisors. Surgical attending physicians who display high levels of openness were evaluated as less adequate feedback-givers. Non-surgical attending physicians who were conscientious seem to be good at evaluating residents. These insights could contribute to future work on development paths of attending physicians in medical education. 相似文献26.
Background
Tools for the evaluation, improvement and promotion of the teaching excellence of faculty remain elusive in residency settings. This study investigates (i) the reliability and validity of the data yielded by using two new instruments for evaluating the teaching qualities of medical faculty, (ii) the instruments'' potential for differentiating between faculty, and (iii) the number of residents'' evaluations needed per faculty to reliably use the instruments.Methods and Materials
Multicenter cross-sectional survey among 546 residents and 629 medical faculty representing 29 medical (non-surgical) specialty training programs in the Netherlands. Two instruments—one completed by residents and one by faculty—for measuring teaching qualities of faculty were developed. Statistical analyses included factor analysis, reliability and validity exploration using standard psychometric methods, calculation of the numbers of residents'' evaluations needed per faculty to achieve reliable assessments and variance components and threshold analyses.Results
A total of 403 (73.8%) residents completed 3575 evaluations of 570 medical faculty while 494 (78.5%) faculty self-evaluated. In both instruments five composite-scales of faculty teaching qualities were detected with high internal consistency and reliability: learning climate (Cronbach''s alpha of 0.85 for residents'' instrument, 0.71 for self-evaluation instrument, professional attitude and behavior (0.84/0.75), communication of goals (0.90/0.84), evaluation of residents (0.91/0.81), and feedback (0.91/0.85). Faculty tended to evaluate themselves higher than did the residents. Up to a third of the total variance in various teaching qualities can be attributed to between-faculty differences. Some seven residents'' evaluations per faculty are needed for assessments to attain a reliability level of 0.90.Conclusions
The instruments for evaluating teaching qualities of medical faculty appear to yield reliable and valid data. They are feasible for use in medical residencies, can detect between-faculty differences and supply potentially useful information for improving graduate medical education. 相似文献27.
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Mohammod Jobayer Chisti Mohammed Abdus Salam Rubhana Raqib Sayera Banu Abu ASMSB Shahid KM Shahunja Lazina Sharmin Hasan Ashraf Abu Syed Golam Faruque Pradip Kumar Bardhan Tahmeed Ahmed 《PloS one》2015,10(5)
BackgroundThe diagnosis of tuberculosis (TB) in young children can be challenging, especially in severely malnourished children. There is a critical need for improved diagnostics for children. Thus, we sought to evaluate the performance of a technique that measures antibodies in lymphocyte supernatant (ALS) for the diagnosis of TB in severely malnourished children presenting with suspected pneumonia.MethodsChildren less than 5 years with severe acute malnutrition and radiological features of pneumonia admitted to the Dhaka Hospital of International Centre for Diarrhoeal Disease Research, Bangladesh, were enrolled consecutively following informed written consent. In addition to clinical and radiological assessment, samples taken for TB diagnosis included gastric lavage fluid and induced sputum for microbiological confirmation. ALS was measured from venous blood, and results were evaluated in children classified as “confirmed”, “non-confirmed TB” or “not TB”.ResultsAmong 224 children who had ALS analysis, 12 (5.4%) children had microbiologically “confirmed TB”, a further 41 (18%) had clinically diagnosed “non-confirmed TB” and the remaining 168 (75%) were considered not to have TB. ALS was positive in 89 (40%) and negative in 85 (39%) of children, with a large number (47 or 21%) reported as “borderline”. These proportions were similar between the three diagnostic groups. The sensitivity and specificity of ALS when comparing “Confirmed TB” to “Not TB” was only 67% (95% CI: 31–91%) and 51% (95% CI: 42–60%), respectively.
Conclusions and Significance
Our data suggest that ALS is not sufficiently accurate to improve the diagnosis of TB in children with severe malnutrition. 相似文献29.
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To facilitate identification and characterization of genomic functional elements, we have developed a chromatin architecture alignment algorithm (ArchAlign). ArchAlign identifies shared chromatin structural patterns from high-resolution chromatin structural datasets derived from next-generation sequencing or tiled microarray approaches for user defined regions of interest. We validated ArchAlign using well characterized functional elements, and used it to explore the chromatin structural architecture at CTCF binding sites in the human genome. ArchAlign is freely available at http://www.acsu.buffalo.edu/~mjbuck/ArchAlign.html. 相似文献