arXiv 1402.35502014-02-14q-bio.CBcond-mat.soft

机械力在大肠杆菌小菌落生长中从平面到体相转变中的作用

The role of mechanical forces in the planar-to-bulk transition in growing Escherichia coli microcolonies

Matthew A. A. Grant, Bartłomiej Wacław, Rosalind J. Allen, Pietro Cicuta

摘要：

机械力在三维多细胞结构的组装中显然是重要的，但它们的详细作用往往不清楚。我们已经使用生长的细菌小菌落\emph{Escherichia coli}来研究机械力在从二维生长（在硬表面和软琼脂糖垫之间的界面上）到三维生长（琼脂糖的侵入）的转变中的作用。我们测量了菌落内发生侵袭转变的位置、菌落内的细胞密度以及转变时的菌落大小作为琼脂糖浓度的函数。我们使用现象学理论，结合基于个人的计算机模拟，以显示如何机械力作用于细菌细胞之间，以及细菌和周围的基质之间，导致我们的实验中观察到的复杂现象-特别是在琼脂糖浓度的过渡的菌落大小的非平凡的依赖。匹配这些方法导致预测细菌和琼脂糖之间的摩擦系数应如何随琼脂糖浓度变化。我们的实验条件模拟了细菌侵入软基质的许多临床和环境场景，以及在多细胞组件中二维和三维生长之间的过渡方面提供了更一般的光线。

英文摘要：

Mechanical forces are obviously important in the assembly of three-dimensional multicellular structures, but their detailed role is often unclear. We have used growing microcolonies of the bacterium \emph{Escherichia coli} to investigate the role of mechanical forces in the transition from two-dimensional growth (on the interface between a hard surface and a soft agarose pad) to three-dimensional growth (invasion of the agarose). We measure the position within the colony where the invasion transition happens, the cell density within the colony, and the colony size at the transition as functions of the concentration of the agarose. We use a phenomenological theory, combined with individual-based computer simulations, to show how mechanical forces acting between the bacterial cells, and between the bacteria and the surrounding matrix, lead to the complex phenomena observed in our experiments - in particular a non-trivial dependence of the colony size at the transition on the agarose concentration. Matching these approaches leads to a prediction for how the friction coefficient between the bacteria and the agarose should vary with agarose concentration. Our experimental conditions mimic numerous clinical and environmental scenarios in which bacteria invade soft matrices, as well as shedding more general light on the transition between two- and three-dimensional growth in multicellular assemblies.

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摘要：

英文摘要：

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