The Effects of Dissolved Sugars Upon the Temporary Adhesion of Barnacle Cyprids

Abstract

The effects of pentoses, hexoses and uronic acids upon the temporary adhesion of cypris larvae of five barnacle species from four families has been studied. A common, concentration dependent, inhibitory effect of D-glucose was observed for the five species, with maximum inhibition (to 60% of control levels) occurring at 10−8M glucose. UsingBalanus perforatuslarvae, glucose was shown to be acting at the antennular surface, most probably by interacting with polar groups associated with the temporary adhesive. The pentose, D-arabinose, was less active than glucose, reducing temporary adhesion to only ∞80% of control levels. D-glucuronic acid was more active, decreasing adhesion to 60% at 10−9M, whilst two other hexoses, D-mannose and D-galactose, showed similar activity to glucose. We suggest that hexoses interact with the same polar groups in the adhesive, glucuronic acid with the higher activity because of its more polar nature. The pentose possibly interacts with a different, less common, group. Our results suggest that the chemical identity of bacterial exopolymers, particularly in respect of their pentose: hexose and neutral suganuronic acid ratios, may be an important factor in determining the strength of temporary adhesion shown by barnacle cyprids towards bacterial films.