Pratap P, Palit A, Lipson E D
Biophys J. 1986 Oct;50(4):653-60. doi: 10.1016/S0006-3495(86)83505-6.
The light-growth response of the Phycomyces sporangiophore was studied further with the sum-of-sinusoids method of nonlinear system identification. The first- and second-order frequency kernels, which represent the input-output relation of the system, were determined at 12 wavelengths (383-529 nm) and 4 temperatures (17 degrees, 20 degrees, 23 degrees, and 26 degrees C). The parametric model of the light-growth response system, introduced in the preceding paper, consists of nonlinear and linear dynamic subsystems in cascade. The model parameters were analyzed as functions of wavelength and temperature. At longer wavelengths, the system becomes more nonlinear. The latency and the bandwidth (cutoff frequency) of the system also vary significantly with wavelength. In addition, the latency decreases progressively with temperature (Q10 = 1.6). At low temperature (17 degrees C), the bandwidth is reduced. The results indicate that about half of the latency is due to physical processes such as diffusion, and the other half to enzymatic reactions. The dynamics of the nonlinear subsystem also vary with wavelength. The dependence of various model components on wavelength supports the hypothesis that the light-growth response, as well as phototropism, are mediated by multiple interacting photoreceptors.
利用非线性系统辨识的正弦波总和法，对毛霉孢子囊柄的光生长反应进行了进一步研究。在12个波长（383 - 529纳米）和4个温度（17摄氏度、20摄氏度、23摄氏度和26摄氏度）下，确定了代表系统输入输出关系的一阶和二阶频率核。在前一篇论文中引入的光生长反应系统的参数模型，由级联的非线性和线性动态子系统组成。对模型参数作为波长和温度的函数进行了分析。在较长波长下，系统变得更加非线性。系统的潜伏期和带宽（截止频率）也随波长显著变化。此外，潜伏期随温度逐渐降低（Q10 = 1.6）。在低温（17摄氏度）下，带宽减小。结果表明，约一半的潜伏期是由于扩散等物理过程，另一半是由于酶促反应。非线性子系统的动力学也随波长变化。各种模型组件对波长的依赖性支持了这样的假设，即光生长反应以及向光性是由多个相互作用的光感受器介导的。
