P.I. : KANA, Todd M. Proposal No: 96-33633 Title: On a Dynamic Balance Theory of Photosynthetic Pigment Regulation in Unicellular Algae: Tests of a Novel Hypothesis ABSTRACT Environmental control of photosynthetic pigmentation in microalgae is hypothesized to depend on a simple control mechanism operating around photosystem II dynamics. The mechanisms responsible for photoacclimation of photosynthetic pigments have eluded researchers for more than 5 decades. A "dynamic balance" theory of photoacclimation is described based on general behavior of the photosynthetic apparatus in constant and fluctuating environments. This novel theory is the first to explain how pigment concentrations are optimized over a broad range of light, nutrient, and temperature environments. The proposed research will directly test the dynamic balance theory. Four taxonomically diverse microalgal species are targeted for investigations. Controlled growth experiments under differing photoacclimative conditions will provide a basis for relating photosynthetic response, pigmentation, and photosystem II dynamics. It is anticipated that experimental support for the theory will lead to the development of models combining other known photosynthetic regulatory mechanisms, resulting in a more general appreciation of constraints on photosynthesis and mechanisms of energy balance in photosynthetic organisms.
