1Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, 2Research Center for Inland Seas, Kobe University, Awaji, Hyogo 656-2401, 3Advanced Technology Research Laboratories, Nippon Steel Corporation, Futtsu, Chiba 293-8511, 4Muroran Marine Station, Field Science for Northern Biosphere, Hokkaido University, Muroran, Hokkaido 051-0003, Japan
To understand the “chlorosis” in the thalli of Porphyra yezoensis, we examined the reduction of photosynthetic pigments and the changes in ultrastructures of cells and organelles. In two-week culture in the media without N, P or Fe, all thalli gradually discolored. Photosynthetic pigments (chlorophyll a, phycoerythrin and phycocyanin) extensively reduced, though the degree and the pattern of the reduction varied according to deprived nutrients. While the chloroplasts shrank due to the nutrient deprivation, the vacuoles swelled and the starch grains accumulated in cytoplasm.