Léonetti M, Dubois-Violette E, Homblé F
Institut de Recherche sur les Phénomènes Hors Equilibre, Unité Mixte de Recherche, Centre National de la Recherche Scientifique 6594 and Universités Aix-Marseille I and II, Technopôle de Château-Gombert, Marseille, France.
Proc Natl Acad Sci U S A. 2004 Jul 13;101(28):10243-8. doi: 10.1073/pnas.0402335101. Epub 2004 Jul 1.
Stationary and nonstationary spatiotemporal pattern formations emerging from the cellular electric activity are a common feature of biological cells and tissues. The nonstationary ones are well explained in the framework of the cable model. Inversely, the formation of the widespread self-organized stationary patterns of transcellular ionic currents remains elusive, despite their importance in cell polarization, apical growth, and morphogenesis. For example, the nature of the breaking symmetry in the Fucus zygote, a model organism for the experimental investigation of embryonic pattern formation, is still an open question. Using an electrodiffusive model, we report here an unexpected property of the cellular electric activity: a phase-space domain that gives rise to stationary patterns of transcellular ionic currents at finite wavelength. The cable model cannot predict this instability. In agreement with experiments, the characteristic time is an ionic diffusive one (<2 min). The critical radius is of the same order of magnitude as the cell radius (30 microm). The generic salient features are a global positive differential conductance, a negative differential conductance for one ion, and a difference between the diffusive coefficients. Although different, this mechanism is reminiscent of Turing instability.
细胞电活动产生的静止和非静止时空模式形成是生物细胞和组织的一个共同特征。非静止模式在电缆模型的框架内得到了很好的解释。相反，尽管跨细胞离子电流广泛的自组织静止模式在细胞极化、顶端生长和形态发生中很重要，但其形成机制仍然难以捉摸。例如，在用于胚胎模式形成实验研究的模式生物——墨角藻合子中，对称性破缺的本质仍然是一个悬而未决的问题。在这里，我们使用一个电扩散模型报告了细胞电活动的一个意外特性：一个在有限波长下产生跨细胞离子电流静止模式的相空间域。电缆模型无法预测这种不稳定性。与实验一致，特征时间是离子扩散时间（<2分钟）。临界半径与细胞半径（30微米）处于同一数量级。一般的显著特征是全局正微分电导、一种离子的负微分电导以及扩散系数之间的差异。尽管有所不同，但这种机制让人联想到图灵不稳定性。
