Spatial and temporal regulation of glycosylation during Drosophila eye development

Glycosylation plays an essential role during development, in processes such as morphogen distribution, cell-to-cell communication, and extracellular matrix formation. Glycosylation is regulated during development in both a spatial and temporal manner. This study presents a detailed description of glycan distribution from late pupal to adult stages in Drosophila ommatidia by using nine different lectins. The lectins ConA, LCA, and DSA, which recognize high-mannose or complex types of N-linked glycans stain both apical and basolateral membranes of photoreceptor cells, whereas SBA, DBA, and ABA lectins, which bind to mucin-type O-glycans, label the inter-rhabdomeral space. The O-linked GlcNAc moiety is strongly labeled by WGA on the nuclear membrane. The localization of these glycans does not change throughout late pupal development. In contrast, the abundance of O-linked glycans, bisected oligosaccharides, and GlcNAc-containing glycans detected by PNA, PHA-E4, and WGA, respectively, is reduced in rhabdomeres and other subcellular domains during late pupal development. Some of these glycans have also been detected in the Golgi and/or putative secretory vesicles, suggesting their dynamic transport during development. These glycans, whose expression is dynamically regulated in a spatial and temporal manner, may therefore play critical roles in ommatidial development.