ROLE OF PERIDININ-CHLOROPHYLL A-PROTEINS IN PHOTOSYNTHETIC LIGHT ADAPTION OF MARINE DINOFLAGELLATE, GLENODINIUM-SP

The marine dinoflagellate, Glenodinium sp., was cultured at a series of light levels, and growth, pigmentation and photosynthetic rates were compared. Under decreasing light conditions growth rates decreased, cellular chlorophyll a and peridinin content per cell increased, and maximum cellular photosynthetic rates remained unchanged. Pigemntation changes were related to alterations in cellular concentrations of a peridinin-chlorophyll a-protein and an unidentified chlorophyll a component of the chloroplast membrane. Maintenance of photosynthetic rates with decreased irradiance is interpreted as an increase in the number of pigment molecules in the light-harvesting antenna associated with the reaction centers of the photosynthetic apparatus, thus increasing the potential for photon capture for photosynthesis.