White noise analysis of Phycomyces light growth response system. I. Normal intensity range

Biophysical Journal
E D Lipson

Abstract

The Wiener-Lee-Schetzen method for the identification of a nonlinear system through white gaussian noise stimulation was applied to the transient light growth response of the sporangiophore of Phycomyces. In order to cover a moderate dynamic range of light intensity I, the imput variable was defined to be log I. The experiments were performed in the normal range of light intensity, centered about I0 = 10(-6) W/cm2. The kernels of the Wierner functionals were computed up to second order. Within the range of a few decades the system is reasonably linear with log I. The main nonlinear feature of the second-order kernel corresponds to the property of rectification. Power spectral analysis reveals that the slow dynamics of the system are of at least fifth order. The system can be represented approximately by a linear transfer function, including a first-order high-pass (adaptation) filter with a 4 min time constant and an underdamped fourth-order low-pass filter. Accordingly a linear electronic circuit was constructed to simulate the small scale response characteristics. In terms of the adaptation model of Delbrück and Reichardt (1956, in Cellular Mechanisms in Differentiation and Growth, Princeton University Press), kernels were de...Continue Reading

Citations

Oct 20, 1977·Journal of Mathematical Biology·G Palm, T Poggio
Jun 1, 1983·The Journal of General Physiology·E D Lipson, S M Block
Dec 21, 1977·Journal of Theoretical Biology·J R Medina, E Cerdá-Olmedo
May 16, 2019·Journal of the Royal Society, Interface·Yasmine MerozL Mahadevan
Nov 22, 2020·The New Phytologist·Yasmine Meroz
Feb 14, 1979·Biochemical and Biophysical Research Communications·R J CohenM M Atkinson
Jan 1, 1986·Biological cybernetics·R C PoeE D Lipson
Jan 1, 1986·Biological cybernetics·R C PoeE D Lipson

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