Newts, sodefrin

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). 

Kikuyama S., Toyoda F., Ohmiya Y., Matsuda K., et al. (1995). Sodefrin a female-attracting peptide hormone in newt cloacal glands. Science 267, 1643-1645. 

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. 

Multiple lines of evidence suggest that SPF, a single protein within the 20-25 kDa pheromone fraction, is responsible for female behavioural response. First, this major protein component within the D. ocoee fraction was genetically very similar to the precursor of sodefrin (Palmer, Watts, Houck, Picard and Arnold 2007), and sodefrin is a known reproductive pheromone in newts (Kikuyama, Toyoda, Ohmiya, Matsuda, Tanaka and Hayashi 1995 Kikuyama and Toyoda 1999). Second, a separate study showed that the cDNA library of proteins expressed in male D. ocoee mental glands contained a high proportion (25%) of... 

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

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). 

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]. 

Kikuyama, S., Toyoda, F., Ohmiya, Y., Matsuda, K., Tanaka, S. Hayashi, H. 1995a. Sodefrin A female-attracting peptide pheromone in newt cloacal glands. Science, 267, 1643—1645. 

A preference test revealed that 10 ng of native sodefrin absorbed by a sponge block was enough to attract female newts placed in a container filled with 3000 ml of water (Kikuyama et aL, 1995). It was also confirmed that male newts are never attracted by sodefrin (Toyoda, Hayashi, Ohmiya, Tanaka, Mochida, Matsuda Kikuyama, 1995). Synthetic sodefrin was prepared by solid-phase chemistry. It exhibited female-attracting activ-... 

We describe here a female-attracting pheromone, sodefrin, that is secreted by the abdominal gland of the male newt, C. pyrrhogaster. Secretion of this novel peptide phero-... 

Toyoda, F., Hayakawa, Y, Ichikawa, M. Kikuyama, S. 1997. Olfactory response to a female-attracting peptide pheromone, sodefrin in the newt, Cynops pyrrhogaster. Abstract, Chemical Signals in Vertebrates 8. 

A newt pheromone, sodefrin, has been isolated from the abdominal gland of the male Cynops pyrrhogaster. It is a decapeptide that has a potent activity in attracting con-specific females (Kikuyama et al, 1995). Sexually undeveloped female newts do not respond to the pheromone. Treatment of these newts with prolactin (PRL) and gonadotropin makes them responsive to the pheromone. The attraction to sodefrin of hormone-treated newts was completely abolished by bilateral nostril plugging and was restored by the removal of the plugs (Toyoda, Hayashi, Ohmiya, Tanaka, Mochida, Matsuda, Kikuyama,... 

In the sexually undeveloped newts of both sexes, the EOG response of vomeronasal epithelium to sodefrin was very low. Intraperitoneal injections to such females with PRL (1 lU) and human cholionic gonadotropin (25 lU) every day for 7 days significantly enhanced the response to sodefrin, but similar treatment of adult male newts had no effect (Figure 6). On the other hand, EOG responses to various concentrations of L-serine were not different among the groups (hormone-treated males and females, and saline-injected males and females). 

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