arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1709.04375cond-mat.softphysics.bio-phq-bio.CB
收藏

翻滚频率和持续性在最佳奔跑-翻滚趋化性中的作用

The role of tumbling frequency and persistence in optimal run-and-tumble chemotaxis

Julius B. Kirkegaard, Raymond E. Goldstein

摘要:

在自然界中发现的导航的最简单的例子之一是运行和翻滚趋化性。翻滚随机地重新定位细胞,细胞可以通过这些事件的频率偏移而朝向引诱剂或远离排斥剂漂移。翻滚后的游泳方向通常与先前的方向相关,如通过重定向角分布的方差所测量的。这种差异的范围可以从细菌的情况下很大,到很小,以至于翻滚事件是不可察觉的,如在领鞭毛虫中观察到的。这就提出了最优性的问题:为什么在自然界中观察到这样一系列的持久性?在这里,我们研究持久的运行和翻滚动力学,首先集中在优化的线性化的趋化反应内的翻滚频率和角度持久性的二维参数空间。虽然最佳持久性确实存在一个给定的翻滚频率,在整个参数空间有一个连续的最佳解决方案。引入依赖于持续性的有限翻滚时间可以改变这种情况,阐明了一种基于物种特异性重定向动力学选择翻滚持续性的可能方法。超越线性理论,我们发现存在最佳的趋化强度,并且当在错误的方向上游泳时,这些趋化强度使反应最大化,但是当沿着趋化剂梯度游泳时,即使是最轻微的投影也几乎没有反应。

英文摘要:

One of simplest examples of navigation found in nature is run-and-tumble chemotaxis. Tumbles reorient cells randomly, and cells can drift toward attractants or away from repellents by biasing the frequency of these events. The post-tumble swimming directions are typically correlated with those prior, as measured by the variance of the reorientation angle distribution. This variance can range from large, in the case of bacteria, to so small that tumble events are imperceptible, as observed in choanoflagellates. This raises the question of optimality: why is such a range of persistence observed in nature? Here we study persistent run-and-tumble dynamics, focusing first on the optimisation of the linearised chemotactic response within the two-dimensional parameter space of tumble frequency and angular persistence. Although an optimal persistence does exist for a given tumble frequency, in the full parameter space there is a continuum of optimal solutions. Introducing finite tumble times that depend on the persistence can change this picture, illuminating one possible method for selecting tumble persistence based on species-specific reorientation dynamics. Moving beyond linear theory we find that optimal chemotactic strengths exist, and that these maximise reaction when swimming in a wrong direction, but have little or no reaction when swimming with even the slightest projection along the chemoattractant gradient.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑