Fig. 2

Multistage tandem mass spectrometry analysis of the permethylated LLO-released oligosaccharide isolated from C. reinhardtii XTA mutant (a–c) and from wild-type (d–f). ESI-MSⁿ spectra with n = 2 (a and d), n = 3 (b and e and n = 4 (c and f) of the [M + 2Na]²⁺ m/z 1107.6 precursor ion of the permethylated Hex₈HexNAc₂ derivative isolated from either the C. reinhardtii XTA mutant or the wild-type cells. The precursor ion selected for the fragmentation analysis is shown with a diamond and its fragmentation pattern is proposed according to Prien et al. [40]. Black square: N-acetylglucosamine; grey circle: mannose, black circle: glucose. The fragment ions are labelled according to the nomenclature of Domon and Costello [41]