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941.
Evidence for a sodium electrogenic pump in airway smooth muscle 总被引:5,自引:0,他引:5
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We studied the course of early leaf area expansion and specificleaf area (SLA) in potato (Solanum tuberosum L.) and wheat (Triticumaestivum L.) genotypes and tested whether air temperature explainsdifferences in these courses within different environments.Such knowledge can be used to improve crop growth modelling.The relative rate of leaf area expansion (RL) of potato andwheat decreased with thermal time, but was nearly linear upto a leaf area index (L) of 1.0. TheRL (L < 1; mean: 17.9x 10-3°C-1 d-1) of potato showed an interaction betweengenotype and environment, and varied with year. TheRL (L <1; mean: 7.1 x 10-3°C-1 d-1) of winter wheat was lower thanthat of spring wheat (mean: 10.9 x 10-3°C-1 d-1), and bothvaried with year. SLAof potato increased nearly linearly withthermal time from 5 to 15 m2 kg-1at 50% emergence, to 20 to25 m2 kg-1at 155°Cd, and then decreased slightly. The SLAofboth winter and spring wheat began at 16 to 23 m2 kg-1and inmost cases increased slightly with thermal time. In potato,regression parameters of SLAwith thermal time were affectedby environment (management conditions and year) and genotype;in wheat they were affected by environment (year and site).Treatment effects on RLof potato were not correlated with thoseon SLA , and were only partly correlated for wheat. Thereforewe conclude that the early foliar expansion of potato is associatedwith a strong increase in SLA , and not so for wheat. For bothcrops the course of early leaf area expansion and ofSLA withair temperature is not robust over environments and genotypes.The consequences of these results for modelling are discussed.Copyright 2000 Annals of Botany Company Triticum aestivum, spring wheat, winter wheat, Solanum tuberosum, leaf area expansion, specific leaf area, early growth, genotype, environment, modelling 相似文献
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Johnathan L Meaders Erica F Geers Belen Fernandez‐Garcia Marvin E Tanenbaum 《The EMBO journal》2012,31(21):4179-4190
The microtubule motor protein kinesin‐5 (Eg5) provides an outward force on centrosomes, which drives bipolar spindle assembly. Acute inhibition of Eg5 blocks centrosome separation and causes mitotic arrest in human cells, making Eg5 an attractive target for anti‐cancer therapy. Using in vitro directed evolution, we show that human cells treated with Eg5 inhibitors can rapidly acquire the ability to divide in the complete absence of Eg5 activity. We have used these Eg5‐independent cells to study alternative mechanisms of centrosome separation. We uncovered a pathway involving nuclear envelope (NE)‐associated dynein that drives centrosome separation in prophase. This NE‐dynein pathway is essential for bipolar spindle assembly in the absence of Eg5, but also functions in the presence of full Eg5 activity, where it pulls individual centrosomes along the NE and acts in concert with Eg5‐dependent outward pushing forces to coordinate prophase centrosome separation. Together, these results reveal how the forces are produced to drive prophase centrosome separation and identify a novel mechanism of resistance to kinesin‐5 inhibitors. 相似文献
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Steven I. Higgins Robert B. O’Hara Olga Bykova Michael D. Cramer Isabelle Chuine Eva‐Maria Gerstner Thomas Hickler Xavier Morin Michael R. Kearney Guy F. Midgley Simon Scheiter 《Journal of Biogeography》2012,39(12):2132-2145
Aim To develop a physiologically based model of the plant niche for use in species distribution modelling. Location Europe. Methods We link the Thornley transport resistance (TTR) model with functions which describe how the TTR’s model parameters are influenced by abiotic environmental factors. The TTR model considers how carbon and nutrient uptake, and the allocation of these assimilates, influence growth. We use indirect statistical methods to estimate the model parameters from a high resolution data set on tree distribution for 22 European tree species. Results We infer, from distribution data and abiotic forcing data, the physiological niche dimensions of 22 European tree species. We found that the model fits were reasonable (AUC: 0.79–0.964). The projected distributions were characterized by a false positive rate of 0.19 and a false negative rate 0.12. The fitted models are used to generate projections of the environmental factors that limit the range boundaries of the study species. Main conclusions We show that physiological models can be used to derive physiological niche dimensions from species distribution data. Future work should focus on including prior information on physiological rates into the parameter estimation process. Application of the TTR model to species distribution modelling suggests new avenues for establishing explicit links between distribution and physiology, and for generating hypotheses about how ecophysiological processes influence the distribution of plants. 相似文献
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