The distribution of sugar chains on the vomeronasal epithelium observed with an atomic force microscope

The distribution of sugar chains on tissue sections of the rat vomeronasal epithelium, and the adhesive force between the sugar and its specific lecti n were examined with an atomic force microscope (AFM). AFM tips were modifi ed with a lectin, Vicia villosa agglutinin, which recognizes terminal N-ace tyl-D-glactosamine (GalNAc). When a modified tip scanned the luminal surfac e of the sensory epithelium, adhesive interactions between the tip and the sample surface were observed. The final rupture force was calculated to be similar to 50 pN based on the spring constant of the AFM cantilever. Distri bution patterns of sugar chains obtained from the force mapping image were very similar to those observed using fluorescence-labeled lectin staining. AFM also revealed distribution patterns of sugar chains at a higher resolut ion than those obtained with fluorescence microscopy. Most of the adhesive interactions disappeared when the scanning solution contained 1 mM GalNAc. The adhesive interactions were restored by removing the sugar from the solu tion. Findings suggest that the adhesion force observed are related to the binding force between the lectin and the sugars distributed across the vome ronasal epithelium.