, Volume 74, Issue 2, pp 141-150

Nutrient-dependent low-light adaptation in the dinoflagellate Gonyaulax polyedra

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Abstract

Gonyaulax polyedra Stein was grown under bright light (330 μE m2 s-1) and then transferred to low light (80 μE m2 s-1), where the rates of photoadaptation were measured as a function of increasing cell density in increasingly nutrient-limited batch cultures. Photoadaptation required the synthesis of new pigment molecules for the photosynthetic units of the thylakoid membrane. However, as older bright-light cultures were shifted to low-light conditions, the onset of pigment synthesis was delayed, the rates of new chlorophyll synthesis slowed, and final yields of cell chlorophyll were sharply reduced. Moreover, photoadaptive capabilities of photosynthesis observed in log-phase cultures were lost in nutrient-limited stationary cultures. Addition of inorganic nutrients to stationary cultures at the time of transfer to low-light levels induced pigments synthesis at a rate and magnitude comparable to log-phase cultures and led to short-term increases in the rates of cell-and carbon-based photosynthesis. The nutrient status of the population also increased, as witnessed by increased carbon and nitrogen content and a large, but transient, increase in nitrate reductase activity. Improved photosynthetic status did not increase cell division rates over control populations. The study was made from December 1980 through March 1981.

Communicated by N. D. Holland, La Jolla