title: Host defense peptides in skin secretions of the Oregon spotted frog Rana pretiosa: implications for species resistance to chytridiomycosis.
abstract: Population declines due to chytridiomycosis among frogs belonging to the Amerana (Rana boylii) species group from western North America have been particularly severe. Norepinephrine-stimulated skin secretions from the Oregon spotted frog Rana pretiosa Baird and Girard, 1853 were collected from individuals that had been previously infected with the causative agent Batrachochytrium dendrobatidis but had proved resistant to developing chytridiomycosis. These secretions contained a more diverse array of antimicrobial peptides than found in other species from the Amerana group and 14 peptides were isolated in pure form. Determination of their primary structures identified the peptides as esculentin-2PRa and -2PRb; ranatuerin-2PRa, -2PRb, -2PRc, -2PRd, and -2PRe; brevinin-1PRa, -1PRb, -1PRc, and -1PRd; and temporin-PRa, -PRb, and -PRc. The strongly cationic ranatuerin-2PRd and the esculentin-2 peptides, which have not been identified in the secretions of other Amerana species except for the closely related R. luteiventris, showed the highest growth inhibitory potency against microorganisms. The strongly hydrophobic brevinin-1PRd was the most cytotoxic to erythrocytes. Although no clear correlation exists between production of dermal antimicrobial peptides by a species and its resistance to fatal chytridiomycosis, the diversity of these peptides in R. pretiosa may be pivotal in defending the species against environmental pathogens such as B. dendrobatidis.
authors.affiliation: Department of Biochemistry, Faculty of Medicine and Health Sciences, United Arab Emirates University, 17666 Al-Ain, United Arab Emirates. jmconlon@uaeu.ac.ae
authors.forename: J Michael
authors.initials: JM
authors.lastname: Conlon
authors.forename: Milena
authors.initials: M
authors.lastname: Mechkarska
authors.forename: Eman
authors.initials: E
authors.lastname: Ahmed
authors.forename: Laurent
authors.initials: L
authors.lastname: Coquet
authors.forename: Thierry
authors.initials: T
authors.lastname: Jouenne
authors.forename: Jérôme
authors.initials: J
authors.lastname: Leprince
authors.forename: Hubert
authors.initials: H
authors.lastname: Vaudry
authors.forename: Marc P
authors.initials: MP
authors.lastname: Hayes
authors.forename: Gretchen
authors.initials: G
authors.lastname: Padgett-Flohr
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology*; D008411:Chytridiomycota / Q000502:physiology*; D006461:Hemolysis; D006801:Humans; D007113:Immunity, Innate; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009181:Mycoses / Q000276:immunology / Q000662:veterinary; D011898:Ranidae / Q000276:immunology* / Q000382:microbiology; D012867:Skin / Q000378:metabolism*
chemical_list: D023181:Antimicrobial Cationic Peptides