剪切流中的跑滚趋化：时间效应 比较和其他并发症

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摘要翻译：
大肠杆菌是一种能动的细菌，它通过执行由交替运行和翻滚组成的有偏见的随机行走来向上移动。本文计算了在均匀、稳定的剪切流中进行趋化的大肠杆菌细胞的趋化漂移速度vd（趋化梯度上的平均速度），在剪切流中，弱的趋化梯度与流成直角。扩展了先前的模型，采用分析和数值相结合的方法来评估几种并发症的影响，即(i)细胞不能直接检测趋化剂梯度，而是对趋化剂浓度进行时间比较；(ii)翻滚具有方向持久性，即翻滚前后的游动方向是相关的；(iii)细胞由于旋转布朗运动而随机重定向；(iv)细胞的非球形影响其在剪切流中的旋转方式。这些并发症影响了vd对切变速率γ的依赖性。当它们都包括在内时，发现(a)剪切破坏趋化性，超过γ=2/秒的剪切速率导致细胞向下而不是向上游动；(b)就最大漂移速度而言，方向的持久性在静止流体中有利，但在剪切流中不利；(c)较长的体形在强剪切流中有利于进行趋化性。
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英文标题：
《Run and tumble chemotaxis in a shear flow: the effect of temporal
  comparisons and other complications》
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作者：
J. T. Locsei and T. J. Pedley
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最新提交年份：
2008
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分类信息：

一级分类：Quantitative Biology        数量生物学
二级分类：Quantitative Methods        定量方法
分类描述：All experimental, numerical, statistical and mathematical contributions of value to biology
对生物学价值的所有实验、数值、统计和数学贡献
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一级分类：Quantitative Biology        数量生物学
二级分类：Other Quantitative Biology        其他定量生物学
分类描述：Work in quantitative biology that does not fit into the other q-bio classifications
不适合其他q-bio分类的定量生物学工作
--

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英文摘要：
  Escherichia coli is a motile bacterium that moves up a chemoattractant gradient by performing a biased random walk composed of alternating runs and tumbles. This paper presents calculations of the chemotactic drift velocity vd (the mean velocity up the chemoattractant gradient) of an E. coli cell performing chemotaxis in a uniform, steady shear flow, with a weak chemoattractant gradient at right angles to the flow. Extending earlier models, a combined analytic and numerical approach is used to assess the effect of several complications, namely (i) a cell cannot detect a chemoattractant gradient directly but rather makes temporal comparisons of chemoattractant concentration, (ii) the tumbles exhibit persistence of direction, meaning that the swimming directions before and after a tumble are correlated, (iii) the cell suffers random re-orientations due to rotational Brownian motion, and (iv) the non-spherical shape of the cell affects the way that it is rotated by the shear flow. These complications influence the dependence of vd on the shear rate gamma. When they are all included, it is found that (a) shear disrupts chemotaxis and shear rates beyond gamma = 2/second cause the cell to swim down the chemoattractant gradient rather than up it, (b) in terms of maximising drift velocity, persistence of direction is advantageous in a quiescent fluid but disadvantageous in a shear flow, and (c) a more elongated body shape is advantageous in performing chemotaxis in a strong shear flow.
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PDF链接：
https://arxiv.org/pdf/0804.2352

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关键词：时间效应 并发症 Quantitative Experimental Contribution flow cell 细胞 complications