Cynops

One well-analysed chemosignal system is that of the Red-bellied Newt (Cynops pyrrhogaster). Males of this species produce from the abdominal gland a semiochemical protein (sodefrin) with marked VNO activity as a female attractant (Kikuyama et al., 1997). Courtship displays of newts often contain tail-waving bouts, which direct cloacal or other secretions from the male toward female recipients (Fig. 3.1). A large stable molecule like sodefrin, alone or as part of a VNPr complex, is presumably suitable for such local transference. 

AOS responsiveness to hormonal influences is shown in the action of sodefrin on the lateral nasal sinus of newts (Cynops). The receptors in the accessory pocket are differentially affected by pituitary and ovarian hormones (Toyoda et al., 2000). The local EOG response to the pheromone (Fig. 5.1) was enhanced by the presence of prolactin or of estrogen alone. Receptor sensitivity increase is perhaps an alternate strategy to AOS receptor density increase several alternate routes of signal receptor adaptation (Fig. 7.1) have been hypothesised (Sorenson and Stacey, 1998). 

Jones F., Pfeiffer C. and Asashima M. (1994). Ultrastructure of the olfactory organ of the newt, Cynops pyrrhogaster. Ann Anat 176, 269-275. 

Toyoda F. and Kikuyama S. (2000). Hormonal influence on the olfactory response to a female-attracting pheromone, sodefrin, in the newt, Cynops pyrrhogaste. Comp Biochem Physiol [B] 126, 239-245. 

Yamamoto K., Kawai Y., Hayashi T., Ohe Y., et al. (2000). Silefrin, a sodefrin-like pheromone in the abdominal gland of the sword-tailed newt, Cynops ensicauda. FEBS Lett 472, 267-270. 

Red-bellied newt Cynops pyrrhogaster Male Abdominal gland (cloaca) Attracts female Sodefrin (decapeptide) Kikuyama etal, 1995... 

Sword-tailed newt Cynops ensicauda Male Abdominal gland Attracts female Silefrin (decapeptide) Yamamoto etal., 2000... 

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). 

Brodie, E. D., Hensel, J. L. and Johnson, D. A. 1974. Toxicity of the urodele amphibians Taricha, Notophthalmus, Cynops, and Paramesotriton. Copeia 506-511... 

There are seven species of fire belly newts (Cynops), all of which are found in semi-tropical regions of Japan and China and spend most of their lives in water. 

F. Toyoda Y. Hayakawa M. Ichikawa S. Kikuyama, Olfactory Responses to a Female Attracting Pheromone in the Newt, Cynops pyrrhogaster. In Advances in Chemical Signals in Vertebrates R. E. Johnston, D. Muller-Schwarze, P. W. Sorensen, Eds. Kluwer Press, Plenum New York, 1999 pp 607-615. 

Sodefrins, peptide pheromones from the red-bellied newt. The 10-peptide H-Ser-Ile-Pro-Ser-Lys-Asp-Ala-Leu-Leu-Lys -OH was first isolated from the abdominal gland of the male newt Cynops pyrrhogaster, while [Leu, Gln ]sodefrin occurs in C. ensicauda. The sodefrins are potent conspecific female-attracting pheromones, and act primarily on the lateral nasal sinus cells [S. Kikuyama et al.. Science 1995, 267,1643 T. Nakada et al.. Front. Neuroendicrinol. 2006, 27,149]. 

Tsuruda, K., Arakawa, O., and Noguchi, T. 2001. Toxicity and toxin properties of the newt Cynops pyrrhogaster collected from the western Japan. J. Nat. Toxins 10, 79-89. 

There are two main ways of gaining specificity in pheromone signals. One is by the evolution of a large unique molecule. Peptide pheromones, using the 20 coded amino acids available in eukaryotic systems, offer an extraordinary variety of unique sequences with a five amino-acid polypeptide there are 20 ( 3.2 million) (Browne et al., 1998). For example, two related species of the newt Cynops have species-specific decapeptide pheromones which differ by just two amino acids (Yamamoto et al., 2000). Among insects, a very few species use a unique complex molecule as a single component pheromone for example, periplanone-B is the sex pheromone of the American cockroach (Periplaneta americana) (Roelofe, 1995). 

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). 

Toyoda, F., Hayakawa, Y., Ichikawa, M., and Kikuyama, S., 1999, Olfactory responses to a female-attracting pheromone in the newt, Cynops pyrrhogaster, in R. E. Johnston, D. Mflller-Schwarze, and P. W. Sorensen, eds., Advances in Chemical Signals in Vertebrates, Kluwer Academic / Plenum, New York, pp. 607-615. 

Ducey, P. K., Anthony, C. D., and Brodie, E. D., Jr., 1991, Thresholds and escalation of antipredator responses in the Chinese saiamander Cynops cyanurus inter- and intra- individual variation, Behav. Process. 23 181-191. 

Kikuyama, S., Toyoda, F., Ohmiya, Y, Tanaka, S., Matsuda, K. Hayashi, H. 1995b. A sex-attractant in the cloacal gland of the newt, Cynops pyrrhogaster. Neth. J. Zool, 45, 169-162. 

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