Meeting Abstract

126.1  Monday, Jan. 7  Antimicrobial peptide defenses of southern leopard frogs (Rana sphenocephala) against the pathogenic chytrid fungus, Batrachochytrium dendrobatidis GAMMILL, WM; ROLLINS-SMITH, LA*; Vanderbilt University School of Medicine; Vanderbilt University School of Medicine louise.rollins-smith@vanderbilt.edu

Southern leopard frogs (Rana sphenocephala) coexist in habitats in which the pathogenic chytrid fungus, Batrachochytrium dendrobatidis (Bd) is prevalent. Because this species is not in serious decline, it is likely that it possesses adequate skin defenses against this pathogen. One important innate defense is the production and release of antimicrobial peptides (AMPs) into the mucus of the skin. Four antimicrobial peptides have previously been described for this species, but their activity against Bd in growth inhibition assays has not previously been tested. We confirmed the presence of these four AMPs in R. sphenocephala adults collected in Tennessee by MALDI-TOF and tandem mass spectrometry. We showed that the natural mixture of hydrophobic peptides found in the skin mucus effectively inhibits Bd growth, and the individual pure synthetic peptides inhibited at micromolar concentrations. Injection of norepinephrine results in long-term depletion of skin peptides, and ongoing studies will determine whether peptide depletion results in greater susceptibility to Bd infection. These studies are designed to demonstrate whether AMP defenses are essential for protection of this species from Bd infections. Support: NSF grants 0843207 and 1121758 to LR-S.