Meeting Abstract

25.11  Jan. 5  Gluing with an iron fist: crosslinking in molluscan adhesive gels SMITH, A.M.*; WERNEKE, S.W.; SWANN, C.; FARQUHARSON, L.A.; HAMILTON, K.S.; Ithaca College; Ithaca College; Ithaca College; Ithaca College; Ithaca College asmith@ithaca.edu

Many gastropod molluscs produce strong adhesion with soft, dilute gels. A major question is how such gels can become powerful adhesives. Previous research has identified specific glue proteins that appear to crosslink the gels and may be involved in interfacial adhesion, but the mechanism has not yet been identified. We studied the rapidly-setting defensive glue secreted by the slug Arion subfuscus. The proteins that constitute this gel are sensitive to the presence of iron. Atomic absorption spectroscopy on the dissolved glue and iron-specific stains on blots of the proteins show that the primary glue protein has iron bound at approximately a 1:1 molar ratio. This is the only protein in the glue that binds to iron strongly. Removal or binding of this iron with a high-affinity, iron-specific chelator shows that iron plays a major role in the function of the gel. Chelation of iron may inhibit the setting of the glue, as demonstrated by a marked increase in solubility when the chelator is added before the glue sets. Chelation also completely blocks the ability of the glue proteins to function in a gel-stiffening assay. This evidence suggests that iron associated with the glue proteins participates in crosslinking reactions that are essential for the mechanics and integrity of the gel. A mechanism involving iron could explain the ability to form strong, non-specific adhesion with dilute glues in an aqueous environment.