Meeting Abstract

77.3  Sunday, Jan. 6  Barnacle Cement Polymerization DICKINSON, G.H.*; RITTSCHOF, D.; ORIHUELA, B.; WAHL, K.J.; Duke University Marine Laboratory; Duke University Marine Laboratory; Duke University Marine Laboratory; US Naval Research Laboratory, Code 6176 ghd2@duke.edu

Barnacles adhere with a proteinaceous cement. The morphology of barnacle cement varies among individuals when grown on silicone foul release surfaces. On silicone, a portion of individuals generate a thick, gummy cement, whereas the majority of barnacles generate a thin, hard cement. The propensity to develop thick, gummy cement is a heritable trait (Holm et al. 2005). The soft nature of the thick, gummy cement suggests that the cement in these individuals does not cure (or calcify) completely. We have compared barnacles with thin, hard cement to those with thick, gummy cement using various techniques including atomic force microscopy (AFM), SDS-PAGE (gel electrophoresis), Fourier transformed infrared spectroscopy (FTIR), protein assays and immunostaining. Development of techniques for collecting and utilizing unpolymerized cement has facilitated our investigations. AFM of barnacle cement reveals a fibrous ultrastructure, consistent with protein cross-linking. SDS-PAGE of unpolymerized cement shows 12 proteins between 10 � 200 kDa. Cement proteins vary both in number and concentration between barnacles with thin, hard cement versus those with thick, gummy cement. Cement from thick, gummy barnacles contains more protein than does cement from hard, thin barnacles. Infrared Spectroscopy and SDS-PAGE show that cement polymerization is rapid (<15 min) and occurs more quickly in thick, gummy barnacles. Using immunostaining we have identified enzymes involved in cement polymerization and have shown that enzyme concentration is greater in barnacles with thick, gummy cement than those with hard, thin cement. We suggest that the generation of thick, gummy cement in some barnacles is due to a heritable defect in the cement polymerization process, namely overproduction of cement proteins and enzymes. This research was funded by the Office of Naval Research (N000140510469).