Splendipherin: The Aquatic Male Sex Pheromone of the Magnificent Tree Frog Litoria Splendida

Abstract

This chapter describes the isolation, structure determination and behavioural testing of splendipherin [GLVSSIGKALGGLLADVVKSKGQPA(OH)], the peptide male sex pheromone of the Magnificent Tree Frog Litoria splendida. Behavioural tests show that female L. splendida is attracted to the pheromone in water at nM concentrations, and indicate that the pheromone moves across the surface of water towards the frog. Surface pressure and X-ray reflectometry experiments confirm that splendipherin is surface active. The 2D NMR spectrum of splendipherin in trifluoroethanol/water (1:1. v/v) indicates a mainly amphipathic helical structure with a bend through G11 and G12. This structure is consistent with the hydrophilic side chains interacting with the water surface, and the hydrophobic side chains protruding into the air at the water/air interface. A mating between a male Litoria caerulea (the Green Tree Frog of Australia) and a female L. splendida produced five female interspecific hybrids. The females were not attracted to splendipherin. Six naturally occurring peptides related to splendipherin were tested for activity with female L. caerulea. No sex pheromone activity was noted. © 2010 by Nova Science Publishers, Inc. All rights reserved.