Pheromones amphibian

Male red-bellied newts, Cynops pyrrhogaster (Salamandridae), attract females with a pheromone that is released into the water from epithelial cells of the abdominal gland of the cloaca. A decapeptide called sodefrin (Ser-Ile-Pro-Ser-Lys-Asp-Ala-Leu-Leu-Lys) is the first amphibian pheromone with female-attracting properties ever chemically identified (Kikuyama etal., 1995). Silefrin in the related sword-tailed newt, Cynops ensicauda, is a similar decapeptide and differs from sodefrin in only two amino acid residues (Yamamoto et al, 2000) (Table 7.3). 

The period between the first and tenth symposium saw the discovery of the first reptile pheromones (garter snakes Mason et al., 1989) first fish pheromones (goldfish Sorensen, 1992), and the first amphibian pheromones (salamanders Kikuyama et al., 1995 frogs Wabnitz etal., 1999). 

Amphibian pheromones have been previously isolated fh>m newt and salamander species, however, this peptide, which we have named splendipherin, is the first pheromone isolated fiom any anuran species. The delivery method of those previously isolated amphibian species are very clear. Sodefiin, the ten-residue peptide pheromone of Cynops pyrrhogaster and silefiin, the ten residue peptide pheromone of Cynops ensicauda are both sent through the water by the male newts by a vigorous shaking movement of the tail (Kikuyama et al., 1995 Yamamoto et al., 2000). The 20 kDa proteinaceous male courtship pheromone of Plethodon jordani is applied to the female s sldn by direct contact (Rollman et al., 1999). 

The two components of the VN system examined in the present study are the vomeronasal organ and the accessory olfactory bulb. The VNO is a paired, chemoreceptive structure present at the base of the nasal septum in most terrestrial mammals, amphibians and reptiles. The VNO s bipolar receptor neurons detect pheromonal signals (Halpem, 1987 Farbman, 1992). 

Amphibian species have also been fotmd to use peptide and protein pheromones. For example, the structure of the decapeptide sodefrin, the first peptide... 

Kikuyama S, Yamamoto K, Iwata T, and Toyoda E (2002) Peptide and protein pheromones in amphibians. Comparative Biochemistry and Physiology Part B 132 69-74. 

The study of chemical communication, semiochemicals, and pheromones in amphibians and reptiles has benefited from a great deal of attention in recent years. Amphibians and reptiles present a number of problems with regard to studying both the behaviors elicited by chemical cues, and the elucidation of the chemical signals themselves. For example, many taxa of amphibians have both life history and environmental constraints that expose a given animal to an aqueous environment as a larva, then in just a few weeks, metamorphosis imposes a terrestrial existence. 

Although chemical cues are obviously used in kin discrimination in larval amphibians, the nature of the kin recognition chemical signal(s) (pheromone)... 

The use of chemical cues in predator/prey interaction appears widespread among amphibians (Kats Dill 1998). Chemical alarm pheromones have been examined most extensively in larval frogs and toads (Chivers Smith 1998). However, recent experiments also suggest that caudate amphibians use chemical alarm pheromones. Numerous studies have investigated the use of chemical substances that make amphibians noxious or toxic to predators. Chemical cues from predators often induce antipredator responses in amphibian prey. In some cases, chemical cues may be the primary sensory stimuli used for predator recognition. Chemosen-sory-induced antipredator responses may include behavioral defenses as well as alterations in life-history characteristics. 

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