An in situ study of the nanomechanical properties of barnacle (Balanus amphitrite) cyprid cement using atomic force microscopy (AFM)

Abstract

Cyprids are the final planktonic stage in the larval dispersal of barnacles and are responsible for surface exploration and attachment to appropriate substrata. The nanomechanical properties of barnacle (Balanus amphitrite) cyprid permanent cement were studied in situ using atomic force microscopy (AFM). Force curves were recorded from the cement disc continually over the course of its curing and these were subsequently analysed using custom software. Results showed a narrowing of the pull-off force distribution with time, as well as a reduction in molecular stretch length over time. In addition, there was a strong correlation between maximum pull-off force and molecular stretch length for the cement, suggesting ‘curing’ of the adhesive; some force curves also contained a ‘fingerprint’ of modular protein unfolding. This study provides the first direct experimental evidence in support of a putative ‘tanning’ mechanism in barnacle cyprid cement.     

Microdetermination of phosphorylated intermediates of sodium-potassium adenosine triphosphatase

We have described a simple, rapid, reliable, and sensitive method for measuring the covalent phosphoenzyme intermediates that form in the reaction of ATP and sodium-potassium sensitive adenosine triphosphatase. Results are reproducible even when microgram amounts of microsomal protein are used. The method involves recovery of ³²P-labeled phosphoenzyme intermediates on a Millipore filter.