Fig. 6: Shed cell walls and red bodies contain ketocarotenoids and a long-chain alkyl diol.

A Light microscopy of the red sediment (RS) mixture and a preparation enriched in the shed red bodies (RBE). Differential interference contrast (DIC) and green autofluorescence (GAF). The scale bar in each pair of images equals 5 µm. Red sediment collection and enrichment were performed numerous times (at least 10) and examined in this way for quality control. Example images from one of those experiments is shown. B Extracted ion chromatograms (EIC) from UHPLC-HRMS in APCI mode of organic solvent extracts from red sediment (RS) and red body enrichment (RBE) samples. Shown is the EIC of m/z 597.3944, m/z 565.4046, and m/z 483.5136 ± m/z 0.01 for identification of astaxanthin, canthaxanthin, and C₃₂ long-chain diols, respectively. Identity of astaxanthin and canthaxanthin was confirmed by authentic standards. Identification of the C₃₂ long-chain diols was based on its accurate mass (<5 ppm) and the observed in-source fragmentation of this compound in APCI (Supplementary Fig. 10).