抄録
Microbial biofilms were allowed to develop on glass slides immersed 1.5 m below the sea surface in Tachibana Bay, Nagasaki, Japan, for different periods of time from May, 1999, to March, 2001. Effects of age or bacterial and diatom densities of the biofilms on the settlement of cyprids of the barnacle Amphibalanus amphitrite were investigated in the laboratory. Furthermore, biofilms were subjected to various treatments in order to investigate the nature of the chemical cue for settlement. Cyprids of A. amphitrite responded differently to various biofilms. Of the 58 biofilms tested, 3 induced settlement of A. amphitrite larvae, while 4 significantly inhibited it. The other 51 films had no effect on larval settlement. No positive correlation was observed between age or bacterial and diatom densities of biofilms and their respective capacities to induce larval settlement. Inactivation of biofilms by ethanol and heat treatments resulted in the induction of larval settlement, suggesting that the treatments made a potential settlement cue in the films available to A. amphitrite larvae. Moreover, LCA (lentil agglutinin), WGA (wheat germ agglutinin), and H5IO6 treatment of active biofilms resulted in the reduction their settlement-inducing activity. This finding suggested that the settlement-inducing compound in certain marine biofilms contains specific sugar chains that have similarities to the SIPC (Settlement-Inducing Protein Complex) from adult barnacle shells.
