Spiral waves in chemistry and biology.
Spiral waves in chemistry and biology.
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化学和生物学中的螺旋波。
DOI：
10.1126/science.252.5002.67
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发表时间：
1991
期刊：
影响因子：
56.9
通讯作者：
I. Epstein
中科院分区：
文献类型：
--
作者：
I. Epstein
半主义者投入了大量的精力来设计和构建分子系统，这些系统可以模仿生物结构和功能的许多方面，并可能提供对生物结构和功能的许多方面的见解。例如，已经合成并研究了选择性结合和运输离子或充当“人工酶”的分子。在更高层次的组织中，化学反应被认为是理解生命系统中时间和空间组织的工具。在本期《科学》杂志中，Lechleiter 等人 (1) 为实现这一承诺迈出了重要一步，他们描述了非洲爪蟾卵母细胞中钙螺旋波传播的观察结果。化学系统中时空模式形成的一个引人注目的例子发生在 Belousov-Zhabotinskii (BZ) 反应中，即在亚铁菲绕啉（ferroin）催化剂存在下，丙二酸被溴酸根离子溴化 (2)。反应混合物的最初均匀红色溶液可以自发地形成同心蓝色环图案，称为目标图案，从一组中心向外传播。如果环被机械剪切或浓度梯度剪切，它们就会演变成螺旋传播 (3)（图 1A）。当波接触时，它们就会湮灭；蓝色曲线消失，邻近介质返回到红色状态。化学家和数学家已经根据可兴奋介质的行为对这一过程有了理解。（可兴奋介质的其他例子包括心脏和神经组织。）在这种介质中，均匀静止状态的小扰动会迅速减弱，但大于临界尺寸的扰动会导致介质在返回其初始状态之前经历活性物质浓度的大幅偏移。如果这样的介质包含起搏器核，即一个能够产生周期性超临界扰动的小区域，那么，由于扩散，将会形成化学反应的靶状模式（4）。如果这些圆圈被打破，松散的末端就会卷入
HEMISTS HAVE DEVOTED CONSIDERABLE EFFORT TO DE-signing and building molecular systems that mimic and, possibly, provide insights into many aspects of biological structure and function. For example, molecules that selectively bind and transport ions or serve as" artificial enzymes" have been synthesized and studied. At a higher level of organization, chemical reactions have been heralded as vehicles for understanding temporal and spatial organization in living systems. In this issue of Science a major step is taken toward realization of this promise by Lechleiter et al.(1), who describe observations of propagating spiral waves of calcium in Xenopus laevis oocytes. A striking example of spatiotemporal pattern formation in chemical systems occurs in the Belousov-Zhabotinskii (BZ) reaction, the bromination of malonic acid by bromate ion in the presence of a ferrous phenanthroline (ferroin) catalyst (2). An initially homoge-neous red solution of reaction mixture can spontaneously develop a pattern of concentric blue rings, known as target patterns, that propagate outward from a set of centers. If the rings are sheared, mechanically or as a result ofconcentration gradients, they evolve to propagating spirals (3)(Fig. 1A). When waves come in contact, they annihilate; the blue curves disappear and the neighboring medium returns to the red state.Chemists and mathematicians have developed an understanding of this process in terms of the behavior of an excitable medium.(Other examples of excitable media include cardiac and neural tissues.) In such a medium, small perturbations ofthe homogeneous stationary state are rapidly damped out, but disturbances larger than a critical size cause the medium to undergo a large excursion in the concentrations of reactive species before returning to its initial state. If such a medium contains a pacemaker nucleus, a small region capable of generating periodic supercritical perturbations, then, as a result of diffusion, targetlike patterns of chemical reactivity will develop (4). If these circles are broken, the loose ends wrap into