Interspecific Comparative Lectin-Binding Analysis of Sea Urchin Adhesive Tube Feet

AbstractGlycans have been consistently reported as important constituents of nonpermanent adhesives produced by aquatic animals across multiple metazoan phyla. However, lectin-binding patterns associated with these glycans may vary among taxa, potentially reflecting phylogenetic relationships or adaptations to local environmental conditions. Despite growing interest in bioadhesion, the number of species investigated remains limited, constraining broader evolutionary interpretations. Here we present a large comparative analysis of 15 sea urchin species representing four orders, seven families, and 11 genera, living on diverse substrates (rock, sand, or algae) and subjected to different hydrodynamic regimes (intertidal or subtidal). Glycan diversity in their adhesive organs-tube feet-was assessed using a panel of 22 lectins employing two complementary approaches combining lectin histochemistry and lectin blotting. Our results show widespread binding of lectins recognizing N-acetylglucosamine- and N-acetylgalactosamine-containing glycans in the tube foot adhesive areas of examined species. However, lectin-binding patterns exhibited no consistent correlation with taxonomy or habitat. In contrast, we found no evidence of mannose-, sialic acid-, or fucose-containing glycans in these adhesive areas. Additionally, these glycans were shown to be conjugated to adhesive disc proteins whose apparent molecular weights varied among species yet displayed recurrent size classes suggestive of partial conservation. Our findings highlight the value of comparative, multispecies analysis of lectin-binding patterns to shed light on conserved features of glycosylation associated with temporary adhesion.