Growth-Phase Dependent Variation in Photosynthetic Activity and Cellular Protein Expression Profile in the Harmful Raphidophyte Chattonella antiqua

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This study investigated temporal variations in the potential maximum quantum yield of photosystem II (F_v/F_m ratio) and growth-phase dependent cellular protein expressions of Chattonella antiqua under laboratory conditions. Despite the culture conditions, significant positive correlations between the F_v/F_m ratio and daily growth rate were observed. Threshold F_v/F_m ratios associated with positive cell growth were calculated to be >0.44, >0.44, and >0.37, and those associated with active cell growth (growth rate >0.5 div. d⁻¹) were >0.58, >0.60, and >0.49 under control culture, low nutrient and intense light conditions, respectively. Proteome profiles obtained by two-dimensional gel electrophoresis (2-DE) indicated that 42 protein spots were differentially expressed at various growth phases of C. antiqua, which indicates changes in cellular physiological status throughout the growth cycle, and suggests that oxygen evolving enhancer 1 and 2-cysteine peroxiredoxin play roles in maintaining the positive growth of C. antiqua.