Glycans 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.
Placentotrophy, the most complex mode of nutrient transfer from a parental organism to developing embryos, has evolved multiple times among Metazoa, being a well-known example of convergent evolution. However, the molecular mechanisms underlying the development and physiology of placenta-like systems in invertebrates remain unknown. Phylum Bryozoa is an excellent model for studying the evolution of placentotrophy, since this reproductive strategy evolved repeatedly within this group. Cyclostome bryozoans are characterized by a unique syncytial/coenocytic placental analogue that nourishes polyembryonic progeny inside polymorphic zooids (gonozooids). Here, we provide transcriptomic analysis of the gonozooids in the cyclostome Crisiella producta. We generated a high-quality transcriptome assembly from reproducing colonies of C. producta and compared gene expression between feeding zooids and gonozooid developmental stages. Our analyses identified a core set of candidate transport proteins likely involved in nutrient delivery to progeny, as well as pronounced activation of extracellular matrix development and remodeling, consistent with ultrastructural data. Additionally, we tested the hypothesis of endocrine regulation in gonozooid development and revealed differential expression of insulin-like neuropeptides and the conserved nuclear receptor FTZ-F1. Together, these findings support the hypothesis that bryozoan placentotrophy is regulated by endocrine signaling, provide evidence for the transport function of the cyclostome placental analogue, and highlight the importance of the extracellular matrix in these processes.
