Neutral N‐glycans of the gastropod Arion lusitanicus

The neutral N‐glycan structures of Arion lusitanicus (gastropod) skin, viscera and egg glycoproteins were examined after proteolytic digestion, release of the glycans from the peptides, fluorescent labelling with 2‐aminopyridine and fractionation by charge, size and hydrophobicity to obtain pure glycan structures. The positions and linkages of the sugars in the glycan were analysed by two dimensional HPLC (size and hydrophobicity) and MALDI‐TOF mass spectrometry before and after digestion with specific exoglycosidases. The most striking feature in the adult tissues was the high amount of oligomannosidic and small paucimannosidic glycans terminated with 3‐O‐methylated mannoses. The truncated structures often contained modifications of the inner core by β1,2‐linked xylose to the β‐mannose residue and/or an α‐fucosylation (mainly α1,6‐) of the innermost GlcNAc residue. Skin and viscera showed predominantly the same glycans, however, in different amounts. Traces of large structures carrying 3‐O‐methylated galactoses were also detected. The egg glycans contained mainly (≈ 75%) oligomannosidic structures and some paucimannosidic structures modified by xylose or α1,6‐fucose, but in this case no methylation of any monosaccharide was detected. Thus, gastropods seem to be capable of producing many types of structures ranging from those typical in human to structures similar to those found in nematodes, and therefore will be a valuable model to understand the regulation of glycosylation. Furthermore, this opens the way for using this organism as a host for the production of recombinant proteins. The detailed knowledge on glycosylation also may help to identify targets for pest control.