Chromatic Adaptation in Porphyridium cruentum Expressed in the Distribution of Excitation Energy and in the Thylakoid High-Energy Fluorescence Quenching
In many red algae and cyanobacteria a phenomenon of chromatic adaptation occurs, in which there are no significant changes in the phycobiliprotein ratios but mostly in the chlorophyll pigments, their synthesis and organization (1,2). From low temperature fluorescence studies in P. cruentum grown in white or green lights it was indirectly estimated that PSI contained about 95% while PSII contained about 5% of the total chlorophyll and that the phycobilisomes transferred their excitation energy to PSII units (1). However, in P. cruentum grown in red or blue light PSII contained about 40% of the total chlorophyll. The yield of energy transfer from PSII to PSI was estimated for cells grown in white light in states 1 and 2 (1). The state 1 — state 2 transitions and energetics of the electron transport chain in P. cruentum undergoing chromatic and intensity adaptation are still unknown.
KeywordsTotal Chlorophyll Fluorescence Emission Spectrum Chromatic Adaptation PORPHYRIDIUM CRUENTUM PSII Unit
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