The Light Growth Response of Phycomyces

With the help of an automated tracking system we have studied the characteristics of the transient light growth response of Phycomyces. The response shows a sharply defined latency. The Q10 of the reciprocal latency is 2.4. Response patterns at different peaks of the action spectrum are the same. The gradual variation of response magnitude over a wide range of adapted intensifies parallels that of phototropism. The responses to saturating stimuli exhibit a strong oscillation with a constant period of 1.6 min and variable damping. The growth responses to sinusoidally varying light intensities show a system bandwidth of 2.5 x 10-3 Hz. The linear dependence of phase shift on frequency is largely attributable to the latency observed with pulse stimuli. In the high intensity range a previously suspected increase of the steady-state growth rate with intensity has been confirmed. The light growth responses of mutants selected for diminished phototropism have been investigated. Many of these mutants have sizable but grossly distorted growth responses.

[1]  H. Gruen,et al.  ACTION SPECTRA FOR THE POSITIVE AND NEGATIVE PHOTOTROPISM OF PHYCOMYCES SPORANGIOPHORES. , 1959, Proceedings of the National Academy of Sciences of the United States of America.

[2]  M. Delbrück,et al.  Action and Transmission Spectra of Phycomyces. , 1960, Plant physiology.

[3]  K. Naka,et al.  White-Noise Analysis of a Neuron Chain: An Application of the Wiener Theory , 1972, Science.

[4]  W A RUSHTON,et al.  Dark‐adaptation and the regeneration of rhodopsin , 1961, The Journal of physiology.

[5]  W. Reichardt.  Eine Inversionsphase der phototropischen Reaktion (Experimente an dem Pilz Phycomyces blakesleanus) , 1958 .

[6]  R. Glantz,et al.  Visual adaptation: a case of nonlinear summation. , 1972, Vision research.

[7]  W. A. Hagins,et al.  Kinetics of the photocurrent of retinal rods. , 1972, Biophysical journal.

[8]  W J Crozier,et al.  The Journal of General Physiology , 1919, Botanical Gazette.

[9]  A. H. Blaauw.  Die Perzeption des Lichtes , 1909 .

[10]  A. H. Blaauw.  Licht und Wachstum , 1918 .

[11]  K. Naka,et al.  Effects of temperature change on the catfish S-potentials. , 1970, Vision research.

[12]  M. Delbrück,et al.  Phycomyces , 1969, Bacteriological reviews.

[13]  M. Delbrück,et al.  System analysis for the light growth reactions of Phycomyces , 1956 .

[14]  N R BARTLETT,et al.  Effect of flash and field luminance upon human reaction time. , 1954, Journal of the Optical Society of America.

[15]  B. Hess,et al.  Oscillatory phenomena in biochemistry. , 1971, Annual review of biochemistry.

[16]  E. S. Castle.  PHOTOTROPISM AND THE LIGHT-SENSITIVE SYSTEM OF PHYCOMYCES , 1930, The Journal of general physiology.

[17]  E. S. Castle.  Light Responses of Phycomyces , 1966, Science.

[18]  E. S. Castle.  DARK ADAPTATION AND THE LIGHT-GROWTH RESPONSE OF PHYCOMYCES , 1929, The Journal of general physiology.

[19]  Leo E. Lipetz,et al.  The Relation of Physiological and Psychological Aspects of Sensory Intensity , 1971 .

[20]  K. Foster.  The photoresponses of phycomyces : analysis using manual techniques and an automated machine which precisely tracks and measures growth during programmed stimuli , 1972 .