Meeting Abstract
126.3 Monday, Jan. 7 Antibacterial peptides from the caribbean octocoral Swiftia exserta. MENZEL, L.P.*; BIGGER, C.H.; Florida International University; Florida International University lorenzo.menzel@fiu.edu
Endogenous small antimicrobial proteins (and peptides) are important components of the innate immune response of animals. Microbicidal peptides are widespread and have been found in all living organisms studied. Since our understanding of the evolution of innate immunity is not well developed, particularly those immune responses in cnidaria, our lab endeavors to study such immune responses in the octocoral Swiftia exserta (an azooxanthellate, ahermatypic anthozoan). Understanding aspects of coral immune responses may lead to ameliorating the precipitous decline of these important marine animals. The survival of sessile marine animals depends heavily on an efficient mechanism to protect themselves against infection/colonization by the multitude of microbes in the surrounding water column.
In order to study the proteinaceous effectors of Swiftia’s antimicrobial defense we extracted branches in acidified water. Nuclei and large debris were removed, the clarified extract size fractionated with a 10 kDa cutoff membrane, and the filtrate then partially purified via continuous electrophoresis. Timed fractions were collected, concentrated by centrifugal evaporation, and tested for antibacterial activity with a two-stage radial diffusion assay. Several fractions exhibited potent antibacterial activity against gram-negative (E. coli, P. aeruginosa), and gram-positive (S. aureus, L monocytogenes) bacteria.
These preliminary results from an anthozoan supplement the 2006 report on Aurelin (from the scyphozoan Aurelia aurita) to establish a repertoire of antibacterial peptides in cnidaria. Characterization of the antibacterial proteins (amino acid sequence and structure) found in Swiftia (and other cnidaria, animals that diverged before the protostome-deuterostome split) will further our understanding of the evolution of this crucial aspect of innate immunity.
