CHARACTERIZATION OF CEMENT PROTEIN DISTRIBUTION IN THE ACORN BARNACLE Amphibalanus amphitrite

Acorn barnacles are  major marine fouling organism s whose success is largely due to their ability to adhere to diverse substrates via a  sub-micron thick proteinaceous adhesive layer. Although the identities of s everal proteins  in the adhesive are known, one outstanding question concerns their spatial distribution throughout the organism. This information would be valuable in terms of understanding where these proteins are synthesized, how they are transported to the substrate interface , and their distribution and function throughout the organism.

To address these questions, we  utilized custom polyclonal  antibodies against two prominent proteins in the adhesive layer , AaCP19-1 and AaCP43-1, and characterized the immunostaining patterns in histological sections via confocal microscopy. P ositive immunostaining  was observed in separate and distinct acellular  tissue linings near the inner shell (Figure 1).

To confirm these proteins were located in areas other than the substrate interface, we performed proteomics on formaldehyde fixed paraffin embedded (FFPE) sections as well as tissue collected from freshly dissected barnacles (Table 1) .  Both proteins were identified  at an enriched level in samples where the adhesive layer was clearly present (FFPE Adhesive), but were also found in samples removed from the interface .

Our results indicate these two proteins, once thought to be unique to the adhesive layer, are located in other regions of the barnacle and likely have additional physiological functions.