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Interplay between the Reactions to Light and to Gravity in Phycomyces

Varjú, D. and Edgar, Lois and Delbrück, M. (1961) Interplay between the Reactions to Light and to Gravity in Phycomyces. Journal of General Physiology, 45 (1). pp. 47-58. ISSN 0022-1295. http://resolver.caltech.edu/CaltechAUTHORS:VARjgp61

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Abstract

Sporangiophores of Phycomyces do not grow directly towards a horizontal beam of light, but equilibrate at an angle of about 30° above the horizontal. After describing several related observations, this paper suggests that the dioptric properties of an obliquely illuminated cylindrical lens, illustrated by a dummy cell, as well as a negative geotropic response, play major roles in determining the direction of growth. The shift of the equilibrium direction of growth towards the vertical, or a purely geotropic response, over a tenfold range of very low intensities (around 10^6 quanta/cm^2 sec., or 10^-13 watt/cm^2) has been studied, and an action spectrum made, measuring the quantum fluxes producing a standard intermediate equilibrium direction of growth at different wavelengths. This may differ from the action spectra at higher intensities in lacking conspicuous maxima from 370 to 490 mµ. However, in the ultraviolet it parallels the other spectra, although without showing the much higher quantum efficiency of ultraviolet relative to visible light previously noted. Possible interpretations are discussed.


Item Type:Article
Additional Information:Copyright © 1961 by The Rockefeller University Press. RUP grants the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode. Received for publication, February 17, 1961. This investigation was supported by a grant from the National Science Foundation.
Record Number:CaltechAUTHORS:VARjgp61
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:VARjgp61
Alternative URL:http://www.jgp.org/cgi/content/abstract/45/1/47
Usage Policy:RUP grants the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode.
ID Code:10845
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:13 Jun 2008
Last Modified:26 Dec 2012 10:05

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