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 Sweeney, B. M. Search for Related Content PubMed PubMed Citation Articles by Sweeney, B. M. Agricola Articles by Sweeney, B. M.

Articles

The Loss of the Circadian Rhythm in Photosynthesis in an Old Strain of Gonyaulax polyedra¹

Department of Biological Sciences, University of California, Santa Barbara, California 93106

Cultures of Gonyaulax polyedra Stein maintained in the laboratory for 15 to 20 years, including an axenic strain isolated in 1960, have gradually lost the ability to survive in darkness. G. polyedra (70A), isolated in 1970 and maintained in a 12:12 light:dark cycle, now tolerates continuous darkness for a much shorter time than a strain isolated in 1981. I have compared the properties of strain 70A with those of this newer strain (81N), to investigate changes in Gonyaulax with length of time in culture, which may account for poor survival in darkness. When grown in continuous light (13, 12, or 4.5 watts per square meter), strains 70A and 81N have similar growth rates, yields, cell diameters, protein contents, C/N ratios, respiration rates, pigment complements, and photosynthetic rates. When entrained by a light:dark cycle (12L:12D), 70A showed no photosynthesis rhythm, although such a rhythm was formerly present. However, the circadian rhythms in bioluminescence and cell division were normal in both strains. Thus, the circadian clock is apparently still intact in 70A as in 81N. The rate of photosynthesis in strain 70A was constant at a low level, the consequent smaller accumulation of photosynthetic products probably accounting for the limited survival in darkness. The defect in strain 70A may be the loss of a component either directly affecting P_max or necessary for transduction from the circadian clock to photosynthesis.

This article has been cited by other articles:

				M. I. Latz, M. Bovard, V. VanDelinder, E. Segre, J. Rohr, and A. Groisman Bioluminescent response of individual dinoflagellate cells to hydrodynamic stress measured with millisecond resolution in a microfluidic device J. Exp. Biol., September 1, 2008; 211(17): 2865 - 2875. [Abstract] [Full Text] [PDF]

				C. H. Johnson and J. W. Hastings Circadian Phototransduction: Phase Resetting and Frequency of the Circadian Clock of Gonyaulax Cells in Red Light1 J Biol Rhythms, December 1, 1989; 4(4): 417 - 437. [Abstract] [PDF]