BIOCHEMISTRY OF RHYTHMIC SYSTEMS *
BIOCHEMISTRY OF RHYTHMIC SYSTEMS *
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节律系统的生物化学*
DOI：
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发表时间：
1962
影响因子：
5.2
通讯作者：
V. C. Bode
中科院分区：
文献类型：
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作者：
J. W. Hastings;V. C. Bode
人们并不总是意识到，对生物振荡的研究可能指向生物系统中变量之间的相互关系，这些变量要么是以前未被怀疑的，要么是几乎没有实验证据的。在这篇论文中，我将讨论我们一直在观察的一种特殊的生物节律，以及我们用来阐明它产生的相互作用的方法。振荡周期约为5分钟，这使它在分析这类生物节律时比大多数其他已被研究过的生物节律更有优势，这些生物节律要么快得令人不快，要么慢得令人不快。如果植物的根（如蚕豆）生长在弱导电的盐溶液中，根会建立电场，使电流流过根和周围的溶液（图1）。外部电流可以通过测量相对于溶液中远点的根部附近的各个点的电势来映射。电位通常为几毫伏，电流约为1安培。每厘米2根的总电耗散功率约为10- 9 W。（Scott等人，1955年;斯科特和马丁，1962年。）在靠近根部的特定位置，只要根部不受干扰，电位几乎保持恒定。然而，如果它被短暂地刺激（通过各种机械、电或化学手段），电位会发生变化，并且通常在再次达到稳定值之前以逐渐减小的幅度振荡（图2）。这些阻尼振荡的周期通常接近5分钟。一些根的行为更加引人注目的方式。在没有任何明显刺激的情况下，电场突然开始振荡，振荡通常持续几个小时（图3）。虽然振幅可能波动，但值得注意的是，振荡是显著的正弦曲线，具有也接近5分钟的恒定周期（Scott，1957）。我们已经仔细地寻找了环境中的任何振荡变化，根的领域可能会对此做出反应。我们最后得出结论，这是一个自发的和真正的内源性的节奏设置的根。问题是，“它是如何产生的？”我以前的学生和同事I博士。S.詹金森和我试图找到答案。振荡如此接近正弦曲线的事实，在我们看来并不表明是弛豫过程。我们印象最深的是，生物电场的行为与许多反馈控制系统的行为相似。我们知道，在反馈回路中不可避免地存在一些延迟，如果系统受到干扰，这很可能导致瞬态振荡。此外，如果反馈回路中的放大率逐渐增加，在许多情况下会达到系统突然开始振荡或“振荡”的阶段。振荡在许多情况下是正弦的，并且它们的周期可以
I t is not always realized that a study of biological oscillations may point to interrelationships between variables in biological systems that were either unsuspected previously or for which little experimental evidence was available. In this paper, I shall discuss a particular biological rhythm that we have been observing and the methods that we have used to throw some light on the interactions through which it is generated. The period of the oscillation is about 5 min., and this gives it an advantage for an analysis of this kind over most of the other biological rhythms that have been studied, which were either inconveniently fast or inconveniently slow. If the root of a plant such as a broad bean is growing in a weakly conducting salt solution, the root sets up an electric field which causes currents to flow through the root and the surrounding solution (FIGURE 1). The external current flow can be mapped by measuring the potentials a t various points near the root relative to a distant point in the solution. The potentials are usually oiily a few millivolts, and the current, about lpamp. per cm.2 The total power dissipated electrically by the root is about 10-9w. (Scott et al., 1955; Scott and Martin, 1962.) At a particular position near the root, the potential remains practically constant provided that the root is undisturbed. If, however, i t is stimulated briefly (by various mechanical, electrical, or chemical means) the potential changes and usually oscillates with diminishing amplitude before it reaches once more a steady value (FIGURE 2). The periods of these damped oscillations are usually close to 5 min. A few roots behave in a much more striking manner. Without any apparent stimulation, the electric field suddenly starts to oscillate, the oscillations often continuing for several hours (FIGURE 3). Although the amplitude may fluctuate, it is noticeable that the oscillations are remarkably sinusoidal, with a constant period that is also close to 5 min. (Scott, 1957). We have made a careful search for any oscillatory changes in the environment to which the root’s field might be responding. We finally concluded that this was a spontaneous and truly endogenous rhythm set up by the root. The question was, “how was it generated?” My former student and colleague Dr. I. S. Jenkinson, and I have attempted to find an answer. The fact that the oscillations were so nearly sinusoidal did not seem to us to indicate relaxation processes. We were most impressed by the similarity in the behavior of the bioelectric field to that of many feedback-controlled systems. We knew that there is inevitably some delay in a feedback loop and that this is likely to cause a transient oscillation if the system is disturbed. Furthermore, if the amplification in the feedback loop is gradually increased, a stage is reached in many cases at which the system will suddenly start to oscillate or “hunt.” The oscillations are in many cases sinusoidal, and their periods may