We analyzed extracts from specialized male glands that are hypertrophied only during the courtship season in the terrestrial salamander Plethodon jordani (Plethodontidae). Protein analysis and gel electrophoresis revealed approximately 20 bands of protein components (as separated by molecular weight), many of which were glycoproteins. Analyses by high performance liquid chromatography and amino acid sequencing reveal that approximately 85% of the pheromone protein extract was accounted for by two components (and their isoforms). These components were termed Pj-22 and Pj-10 to reflect their respective molecular weights of approximately 22 kDa and 10 kDa. The chemical nature of Pj-22 fits the profile for odorants (known from other vertebrates) that stimulate the vomeronasal organ and can ultimately affect reproductive behavior. Our data are considered in the context of separate behavioral experiments with P. jordani that indicated: (a) delivery of pooled gland extracts resulted in increased female receptivity, and (b) an enriched solution of Pj-22 also was effective at increasing female receptivity.
