Meeting Abstract
Bacterial biofilms are required for the induction of settlement and metamorphosis of many benthic marine invertebrates. The identity of the cues that mediate these interactions, however, remain largely unknown. The marine polychaete worm, Hydroides elegans, is one organism whose larvae settle and metamorphose in response to specific bacteria and bacterial products. Recently, we determined that one of the bacterial cues capable of inducing settlement in this species is outer membrane vesicles produced by the bacterium Cellulophaga lytica. Outer membrane vesicles are proteoliposomes produced ubiquitously by Gram-negative bacteria, and seem to be particularly prevalent in strains that associate with Eukaryotes. OMVs are composed of proteins, phospholipids, lipopolysaccharide, and occasionally genetic material and/or virulence factors. Among biological processes associated with OMVs are: cell-cell signalling; antibiotic resistance; virulence; and horizontal gene transfer. The mechanisms underlying these functions, however, are poorly understood. As a first step in determining how OMVs induce metamorphosis, OMVs were subjected to a range of enzymatic tests including DNase, RNase, protease and lipase treatments. Enzyme-treated OMVs were bio-assayed for metamorphic activity to determine which component of these complex delivery systems is involved in inducing metamorphosis of H. elegans. These experiments are ongoing; ultimately, the information they provide will be essential to understanding chemical cueing by bacteria in the larval metamorphic process.
