Deng Pan, de Vargas Roditi Laura, van Ditmarsch Dave, Xavier Joao B
Program in Computational Biology, Memorial Sloan-Kettering Cancer Center, New York NY, USA.
New J Phys. 2014 Jan;16:015006-15006. doi: 10.1088/1367-2630/16/1/015006.
Understanding how large-scale shapes in tissues, organs and bacterial colonies emerge from local interactions among cells and how these shapes remain stable over time are two fundamental problems in biology. Here we investigate branching morphogenesis in an experimental model system, swarming colonies of the bacterium . We combine experiments and computer simulation to show that a simple ecological model of population dispersal can describe the emergence of branching patterns. In our system, morphogenesis depends on two counteracting processes that act on different length-scales: (1) colony expansion, which increases the likelihood of colonizing a patch at a close distance and (2) colony repulsion, which decreases the colonization likelihood over a longer distance. The two processes are included in a kernel based mathematical model using an integro-differential approach borrowed from ecological theory. Computer simulations show that the model can indeed reproduce branching, but only for a narrow range of parameter values, suggesting that has a fine-tuned physiology for branching. Simulations further show that hyperswarming, a process where highly dispersive mutants reproducibly arise within the colony and disrupt branching patterns, can be interpreted as a change in the spatial kernel.
理解组织、器官和细菌菌落中的大规模形状是如何从细胞间的局部相互作用中产生的，以及这些形状如何随时间保持稳定，是生物学中的两个基本问题。在这里，我们在一个实验模型系统中研究分支形态发生，即细菌的群体菌落。我们结合实验和计算机模拟，以表明一个简单的种群扩散生态模型可以描述分支模式的出现。在我们的系统中，形态发生取决于在不同长度尺度上起作用的两个相互抵消的过程：（1）菌落扩张，它增加了在近距离定殖一个斑块的可能性；（2）菌落排斥，它降低了在较长距离上的定殖可能性。这两个过程被纳入一个基于核的数学模型中，该模型使用了从生态理论借鉴的积分-微分方法。计算机模拟表明，该模型确实可以重现分支，但仅在狭窄的参数值范围内，这表明[细菌名称]具有微调的分支生理学特性。模拟进一步表明，超群体运动，即高度分散的突变体在菌落内可重复出现并破坏分支模式的过程，可以被解释为空间核的变化。
