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arXiv 0906.2468q-bio.CBq-bio.SC
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单细胞直接梯度传感的准确性

Accuracy of direct gradient sensing by single cells

Robert G. Endres, Ned S. Wingreen

摘要:

许多类型的细胞能够准确地感知化学物质在其直径上的浅梯度,使细胞能够朝向或远离化学物质源。这种趋化能力依赖于细胞通过扩散随机到达细胞表面受体的颗粒推断梯度的显著能力。尽管已经探索了细胞浓度传感的物理极限,但还没有关于梯度传感的物理极限的理论。在这里,我们推导出这样一个理论,作为模型使用一个完美的吸收球和一个完美的监测球,这分别从被吸收的表面粒子密度或自由扩散的粒子在一个球形体积内的位置推断梯度。我们发现,完美的吸收球是优于完美的监测领域,无论是浓度和梯度传感,因为以前观察到的粒子从来没有重新测量。吸收球的优越性有助于解释信号降解酶在细胞表面的存在,例如Dictyosteobacterium discoideum(Dicty)中cAMP的PDE和酿酒酵母(Saccharomyces cerevisiae)(芽殖酵母)中交配因子α的BAR 1。从数量上看,我们的理论与最近对Dicty沿cAMP梯度向上移动的测量结果相比,这表明这些细胞在梯度检测的物理极限附近工作。

英文摘要:

Many types of cells are able to accurately sense shallow gradients of chemicals across their diameters, allowing the cells to move towards or away from chemical sources. This chemotactic ability relies on the remarkable capacity of cells to infer gradients from particles randomly arriving at cell-surface receptors by diffusion. Whereas the physical limits of concentration sensing by cells have been explored, there is no theory for the physical limits of gradient sensing. Here, we derive such a theory, using as models a perfectly absorbing sphere and a perfectly monitoring sphere, which, respectively, infer gradients from the absorbed surface particle density or the positions of freely diffusing particles inside a spherical volume. We find that the perfectly absorbing sphere is superior to the perfectly monitoring sphere, both for concentration and gradient sensing, since previously observed particles are never remeasured. The superiority of the absorbing sphere helps explain the presence at the surfaces of cells of signal degrading enzymes, such as PDE for cAMP in Dictyostelium discoideum (Dicty) and BAR1 for mating factor alpha in Saccharomyces cerevisiae (budding yeast). Quantitatively, our theory compares favorably to recent measurements of Dicty moving up a cAMP gradient, suggesting these cells operate near the physical limits of gradient detection.

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。

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