Tunicate Larval Adhesives (TuniGlue)

Underwater glues of marine organisms elegantly integrate stiffness and elasticity, a major challenge in synthetic material sciences. Determining the mechanical and chemical basis of biological adhesion should provide important knowhow for biomimetic approaches. Marine biofoulers, including the Tunicates, are relevant to developing green anti-adhesives (for shipping or aquaculture) and biomimetic medicinal glues. Larval adhesives are of particular interest as they mediate the initial attachment and trigger sessile development but remain challenging due to their minute amounts. Several adult marine species were approached molecularly and revealed adhesive proteins that often, however, lack a functional proof. We are experts in analyzing the functions of proteins in tunicate larvae of the species Ciona intestinalis and can therefore fill the knowledge gap on adhesive protein functions. We have established a bioadhesion toolbox and published details on larval adhesive cells, adhesive preferences and markers shared between species. We propose that larval adhesives are composites of proteins and fibrillary material produced by separate granules in adhesive collocytes and surrounding cells, with adaptations and similarities between species. To identify the ascidian larval bioadhesives we will apply gene functional analyses in living Ciona guided by knowledge on adhesive strategies in two additional species (Phallusia and Botryllus) towards their advanced study under isolated conditions. Possible species similarities of larval adhesive granules or glue proteins will accompany deeper molecular and functional analyses of candidates identified from genetic repertoirs. Here, we will select adhesive candidates from groups of molecules found in the Ciona adhesive organ overlapping those in single cells, notably collocytes, or proteins detected in the adhesive deposits. Their involvement in bioadhesion is determined by a gene knockout (CRISPR) to cause loss of adhesive capacity in living Ciona larvae and by further cell biological characterization. Through expert collaboration, first synthetic proteins will be explored in isolation for adhesive properties on chemically defined substrates. This project is expected to result in an inventory of tunicate adhesive proteins and scaffolds from physiologic marine material that can serve as guide sequences towards non-toxic glues or anti-glues.