title: Development of antimicrobial peptide defenses of southern leopard frogs, Rana sphenocephala, against the pathogenic chytrid fungus, Batrachochytrium dendrobatidis.
abstract: Amphibian species face the growing threat of extinction due to the emerging fungal pathogen Batrachochytrium dendrobatidis, which causes the disease chytridiomycosis. Antimicrobial peptides (AMPs) produced in granular glands of the skin are an important defense against this pathogen. Little is known about the ontogeny of AMP production or the impact of AMPs on potentially beneficial symbiotic skin bacteria. We show here that Rana (Lithobates) sphenocephala produces a mixture of four AMPs with activity against B. dendrobatidis, and we report the minimum inhibitory concentration (MIC) of synthesized replicates of these four AMPs tested against B. dendrobatidis. Using mass spectrometry and protein quantification assays, we observed that R. sphenocephala does not secrete a mature suite of AMPs until approximately 12 weeks post-metamorphosis, and geographically disparate populations produce a different suite of peptides. Use of norepinephrine to induce maximal secretion significantly reduced levels of culturable skin bacteria.
authors.affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Whitney M
authors.initials: WM
authors.lastname: Holden
authors.affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Laura K
authors.initials: LK
authors.lastname: Reinert
authors.affiliation: Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA.
authors.forename: Shane M
authors.initials: SM
authors.lastname: Hanlon
authors.affiliation: Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Parris
authors.affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA; Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA. Electronic address: louise.rollins-smith@vanderbilt.edu.
authors.forename: Louise A
authors.initials: LA
authors.lastname: Rollins-Smith
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000276:immunology*; D023181:Antimicrobial Cationic Peptides / Q000276:immunology*; D008411:Chytridiomycota / Q000276:immunology*; D008826:Microbial Sensitivity Tests; D009638:Norepinephrine / Q000494:pharmacology; D011898:Ranidae / Q000276:immunology*; D012867:Skin / Q000276:immunology / Q000382:microbiology
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D009638:Norepinephrine
keywords: Amphibian; Antimicrobial peptide; Batrachochytrium dendrobatidis; Chytridiomycosis; Rana sphenocephala; Symbiotic skin bacteria