title: Evidence from peptidomic analysis of skin secretions that allopatric populations of Xenopus gilli (Anura:Pipidae) constitute distinct lineages.
abstract: The International Union for Conservation of Nature (IUCN) Endangered Cape Platanna Xenopus gilli inhabits disjunct ranges at the tip of Cape Peninsula and near the town of Kleinmond on opposite sides of False Bay in the extreme southwest of Africa. Peptidomic analysis of host-defense peptides in norepinephrine-stimulated skin secretions from frogs from the Cape Peninsula range resulted in the identification of two magainins, two peptide glycine-leucine-amide (PGLa) peptides, two xenopsin-precursor fragment (XPF) peptides, nine caerulein-precursor fragment (CPF) peptides, and a peptide related to peptide glycine-glutamine (PGQ) previously found in an extract of Xenopus laevis stomach. The primary structures of the peptides indicate a close phylogenetic relationship between X. gilli and X. laevis but only magainin-1, PGLa and one CPF peptide are identical in both species. Consistent with previous data, the CPF peptides show the greatest antimicrobial potency but are hemolytic. There are appreciable differences in the expression of host-defense peptide genes in frogs from the population of animals sampled near Kleinmond as peptides corresponding to magainin-G2, XPF-G1, XPF-G2, and four CPF peptides, present in secretions from the Cape Peninsula frogs, were not identified in the skin secretions from Kleinmond frogs. Conversely, PGLa-G3, XPF-G3, and three CPF peptides were identified in the Kleinmond frogs but not in the Cape Peninsula animals. The data support the conclusion from morphometric analyses and comparisons of the nucleotide sequences of mitochondrial genes that the disjunct populations of X. gilli have undergone appreciable genetic, morphological, and phenotypic divergence.
authors.affiliation: Department of Biochemistry, College of Medicine and Health Sciences, United Arab Emirates University, 17666 Al Ain, United Arab Emirates; SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, UK. Electronic address: m.conlon@ulster.ac.uk.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Conlon
authors.affiliation: Department of Biochemistry, College of Medicine and Health Sciences, United Arab Emirates University, 17666 Al Ain, United Arab Emirates.
authors.forename: Milena
authors.initials: M
authors.lastname: Mechkarska
authors.affiliation: PISSARO, Institute for Research and Innovation in Biomedicine (IRIB), University of Rouen, 76821 Mont-Saint-Aignan, France; CNRS UMR 6270, University of Rouen, 76821 Mont-Saint-Aignan, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Coquet
authors.affiliation: INSERM U-982, PRIMACEN, CNRS, IRIB, University of Rouen, 76821 Mont-Saint-Aignan, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Leprince
authors.affiliation: PISSARO, Institute for Research and Innovation in Biomedicine (IRIB), University of Rouen, 76821 Mont-Saint-Aignan, France; CNRS UMR 6270, University of Rouen, 76821 Mont-Saint-Aignan, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Jouenne
authors.affiliation: INSERM U-982, PRIMACEN, CNRS, IRIB, University of Rouen, 76821 Mont-Saint-Aignan, France.
authors.forename: Hubert
authors.initials: H
authors.lastname: Vaudry
authors.affiliation: Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: G John
authors.initials: GJ
authors.lastname: Measey
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis; D006801:Humans; D007928:Lethal Dose 50; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D012867:Skin / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; C570329:PGLa-H peptide, Xenopus; D029867:Xenopus Proteins; C053300:magainin 1 peptide, Xenopus
keywords: Allopatric; Antimicrobial peptide; Frog skin; Magainin; Pipidae, Xenopus