Photooxidative stress-inducible orange and pink water-soluble astaxanthin-binding proteins in eukaryotic microalga

摘要

a Light microscope view of Oki-4N. Cells were grown under non-stressed (left) or 0.5 M NaCl with high light (w/HL) for 4 days (middle) conditions and were continued for 2 weeks (right). Scale bar = 10 µm. b Scanning electron micrographs of Oki-4N. Scale bar = 10 µm. c Colour of aqueous cell extracts obtained after ultracentrifugation at 100,000 × g for 3 h. A 1 g aliquot of wet cells (the cell pellet after harvesting by centrifugation was lightly dried with filter paper to remove excess liquid medium) was suspended in 10 mL of cell suspension buffer (50 mM Tris-HCl at pH 7.5), disrupted by French press, and then ultra-centrifuged. Pigment concentrations were measured as optical density (OD) at 480 nm. The data are representative of at least three independent experiments. d Elution profiles of aqueous cell extracts from the cells under non-stressed or 0.5 M NaCl w/HL conditions for 2 or 4 days were evaluated by gel-filtration column chromatography. Elution profiles were monitored by using an HPLC photodiode array detector. The colour of the elution peak is shown above each elution peak. The data are representative of at least three independent experiments.