This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Sargent, M. L. Articles by Briggs, W. R. Search for Related Content PubMed PubMed Citation Articles by Sargent, M. L. Articles by Briggs, W. R. Agricola Articles by Sargent, M. L. Articles by Briggs, W. R.

Articles

The Effects of Light on a Circadian Rhythm of Conidiation in Neurospora ¹

Department of Biological Sciences, Stanford University, Stanford, California 94305

The expression of a circadian rhythm of conidiation by timex, a strain of Neurospora crassa, is inhibited by growth in continuous white light. The action spectrum for this effect has a strong peak (with minor subpeaks) in the blue region of the visible spectrum, and a broad shoulder in the near ultraviolet. This action spectrum suggests that a carotenoid or flavin compound may be the photoreceptor, but does not allow one to determine conclusively whether the receptor is indeed a carotenoid, flavin, or some other unrelated pigment. Two lines of evidence suggest that a carotenoid is not the photoreceptor. First, the in vivo absorption spectrum of timex (representing the sum of the spectra of the individual pigments present, predominantly carotenoids) has peaks at wavelengths 10 to 20 mµ longer than those of the action spectrum peaks. Second, an albino-timex has normal photosensitivity, a situation requiring that the photoreceptor, if carotenoid, be a quantitatively minor constituent of the total carotenoid complement.

The magnitude and direction of phase-shift resulting from a standard dose of white light given at different times in the daily cycle of timex varies in the manner reported for other organisms. Additional phase-shift experiments have shown that there are no major transients in the attainment of a new equilibrium after a phase-shifting perturbation, and that 2 light reactions (rapidly and slowly saturating) may be involved in the phase-shift response.

³ Present address: Biological Laboratories, Harvard University, Cambridge, Massachusetts 02138.

¹ Supported by grants GB-2846 and GB-2751 to W. R. Briggs, from the National Science Foundation, a grant from Research Corporation to W. R. B., and by a National Science Foundation predoctoral fellowship to M. L. Sargent. Taken in part from a thesis submitted to Stanford University by M. L. S. in partial fulfillment of the requirements for the Ph.D. degree.

This article has been cited by other articles:

				J.C. Dunlap, J.J. Loros, H.V. Colot, A. Mehra, W.J. Belden, M. Shi, C.I. Hong, L.F. Larrondo, C.L. Baker, C.-H. Chen, et al. A Circadian Clock in Neurospora: How Genes and Proteins Cooperate to Produce a Sustained, Entrainable, and Compensated Biological Oscillator with a Period of about a Day Cold Spring Harb Symp Quant Biol, January 1, 2007; 72(0): 57 - 68. [Abstract] [PDF]

				M. W. Vitalini, R. M. de Paula, W. D. Park, and D. Bell-Pedersen The Rhythms of Life: Circadian Output Pathways in Neurospora. J Biol Rhythms, December 1, 2006; 21(6): 432 - 444. [Abstract] [PDF]

				B. Grimaldi, P. Coiro, P. Filetici, E. Berge, J. R. Dobosy, M. Freitag, E. U. Selker, and P. Ballario The Neurospora crassa White Collar-1 dependent Blue Light Response Requires Acetylation of Histone H3 Lysine 14 by NGF-1 Mol. Biol. Cell, October 1, 2006; 17(10): 4576 - 4583. [Abstract] [Full Text] [PDF]

				A. C. Froehlich, B. Noh, R. D. Vierstra, J. Loros, and J. C. Dunlap Genetic and Molecular Analysis of Phytochromes from the Filamentous Fungus Neurospora crassa Eukaryot. Cell, December 1, 2005; 4(12): 2140 - 2152. [Abstract] [Full Text] [PDF]

				V. D. Gooch, L. Freeman, and P. L. Lakin-Thomas Time-Lapse Analysis of the Circadian Rhythms of Conidiation and Growth Rate in Neurospora J Biol Rhythms, December 1, 2004; 19(6): 493 - 503. [Abstract] [PDF]

				Y. Yoshida and K. Hasunuma Reactive Oxygen Species Affect Photomorphogenesis in Neurospora crassa J. Biol. Chem., February 20, 2004; 279(8): 6986 - 6993. [Abstract] [Full Text] [PDF]

				T. Granshaw, M. Tsukamoto, and S. Brody Circadian Rhythms in Neurospora Crassa: Farnesol or Geraniol Allow Expression of Rhythmicity in the Otherwise Arrhythmic Strains frq 10, wc-1, and wc-2 J Biol Rhythms, August 1, 2003; 18(4): 287 - 296. [Abstract] [PDF]

				Y. Liu Molecular Mechanisms of Entrainment in the Neurospora Circadian Clock J Biol Rhythms, June 1, 2003; 18(3): 195 - 205. [Abstract] [PDF]

				A. C. Froehlich, Y. Liu, J. J. Loros, and J. C. Dunlap White Collar-1, a Circadian Blue Light Photoreceptor, Binding to the frequency Promoter Science, August 2, 2002; 297(5582): 815 - 819. [Abstract] [Full Text] [PDF]

				M. A. Collett, N. Garceau, J. C. Dunlap, and J. J. Loros Light and Clock Expression of the Neurospora Clock Gene frequency Is Differentially Driven by but Dependent on WHITE COLLAR-2 Genetics, January 1, 2002; 160(1): 149 - 158. [Abstract] [Full Text] [PDF]

				Y. Sadakane and H. Nakashima Light-Induced Phase Shifting of the Circadian Conidiation Rhythm Is Inhibited by Calmodulin Antagonists in Neurospora crassa J Biol Rhythms, September 1, 1996; 11(3): 234 - 240. [Abstract] [PDF]

				V. D. Gooch, R. A. Wehseler, and C. G. Gross Temperature Effects on the Resetting of the Phase of the Neurospora Circadian Rhythm J Biol Rhythms, March 1, 1994; 9(1): 83 - 94. [Abstract] [PDF]

				C. H. Johnson and H. Nakashima Cycloheximide Inhibits Light-Induced Phase Shifting of the Circadian Clock in Neurospora J Biol Rhythms, June 1, 1990; 5(2): 159 - 167. [Abstract] [PDF]

				H. Nakashima and J.W. Hastings Phase Determination of the Circadian Rhythm of Conidiation in Heterocaryons between two out-of-Phase Mycelia in Neurospora crassa J Biol Rhythms, September 1, 1989; 4(3): 377 - 387. [Abstract] [PDF]

				J. J. Loros and J. F. Feldman Loss of Temperature Compensation of Circadian Period Length in the frq-9 Mutant of Neurospora crassa J Biol Rhythms, September 1, 1986; 1(3): 187 - 198. [Abstract] [PDF]

				A. T. Winfree Suppressing Drosophila Circadian Rhythm with Dim Light Science, March 8, 1974; 183(4128): 970 - 972. [Abstract] [PDF]

				W. F. Zimmerman and T. H. Goldsmith Photosensitivity of the Circadian Rhythm and of Visual Receptors in Carotenoid-Depleted Drosophila Science, March 19, 1971; 171(3976): 1167 - 1169. [Abstract] [PDF]

				K. D. Frank and W. F. Zimmerman Action Spectra for Phase Shifts of a Circadiain Rhythm in Drosophila Science, February 14, 1969; 163(3868): 688 - 689. [Abstract] [PDF]

				V. G. Bruce and D. H. Minis Circadian Clock Action Spectrum in a Photoperiodic Moth Science, February 7, 1969; 163(3867): 583 - 585. [Abstract] [PDF]

				Y. Ogura, Y. Yoshida, N. Yabe, and K. Hasunuma A Point Mutation in Nucleoside Diphosphate Kinase Results in a Deficient Light Response for Perithecial Polarity in Neurospora crassa J. Biol. Chem., June 8, 2001; 276(24): 21228 - 21234. [Abstract] [Full Text] [PDF]