Increasing complexity of the N-glycome during Caenorhabditis development.

Caenorhabditis elegans is a frequently-employed genetic model organism and has been the object of a wide range of developmental, genetic, proteomic and glycomic studies. Here, using an off-line MALDI-TOF-MS approach, we have analysed the N-glycans of mixed embryos and liquid- or plate-grown L4 larvae. Of the over 200 different annotatable N-glycan structures, variations between the stages as well as the mode of cultivation were observed. While the embryonal N-glycome appears less complicated overall, the liquid- and plate-grown larvae differ especially in terms of methylation of bisecting fucose, α-galactosylation of mannose and di-β-galactosylation of core α1,6-fucose. Furthermore, we analysed the O-glycans by LC-ESI-MS following β-elimination; especially the embryonal O-glycomes included a set of phosphorylcholine-modified structures, previously not shown to exist in nematodes. However, the set of glycan structures cannot be clearly correlated with levels of glycosyltransferase transcripts in developmental RNA-seq datasets, but there is an indication for co-ordinated expression of clusters of potential glycosylation-relevant genes. Thus, there are still questions to be answered in terms of how and why a simple nematode synthesizes such a diverse glycome.