Presence of galactosylated core fucose on N-glycans in the planaria Dugesia japonica

Planarial species are of especial interest to biologists due to the phenomenon of pluripotency and, in comparison to other developmental processes, it can be hypothesised that glycan-lectin interactions may play a role. In order to examine the N-glycans of one of these organisms, Dugesia japonica, peptide:N-glycosidase A was employed and the released glycans were subject to pyridylamination, HPLC and mass spectrometric analysis. A range of oligomannosidic glycans was observed with a trimethylated Man(5) GlcNAc(2) structure being the dominant species. Three glycans were also observed to contain deoxyhexose; in particular, a glycan with the composition Hex(4) HexNAc(2) Fuc(1) Me(2) was revealed by exoglycosidase digestion, in combination with MS/MS, to contain a galactosylated core α1,6-fucose residue, whereas this core modification was found to be capped with a methylhexose residue in the case of a Hex(5) HexNAc(2) Fuc(1) Me(3) structure. This is the first report of these types of structures in a platyhelminth and indicates that the 'GalFuc' modification of N-glycans is not just restricted to molluscs and nematodes.