| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1995: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
It has been well accepted that during courtship, male newts attract sexually developed females using chemical cues. In the red-bellied newt, Cynops pyrrhogaster, sexually mature females are attracted to water in which sexually active male newts have been kept, but not to water in which abdominal gland-ablated male newts have been kept, indicating that the female-attracting pheromone is secreted by the abdominal gland. An attempt has been made to isolate and characterize this pheromone from the abdominal glands of sexually mature male newts. Recently, female-attracting pheromone was revealed to be a decapeptide with the amino acid sequence Ser-Ile-Pro-Ser-Lys-Asp-Ala-Leu-Leu-Lys. The peptide showed no sequence homology with any known peptide. Thus the novel peptide was designated sodefrin. In this study, to reveal the localization of sodefrin in the abdominal gland of the red-bellied newt and to develop a specific radioimmunoassay system for the measurement of sodefrin, we generated an
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antiserum against sodefrin in a rabbit by injecting sodefrin that was extended on its COOH-terminus with Cys coupled to keyhole limpet hemocyanin. Frozen sections of abdominal glands stained with the antiserum to sodefrin by immunofluorescenece showed that the apical region of the epithelial cells was positive for sodefrin. Staining of sections with the antiserum preadsorbed with an excess amount of sodefrin reduced the immunofluorescenece, indicating that the antiserum specifically recognizes sodefrin in the tissue. An immunoelectron microscopic study of the abdominal gland was performed using sodefrin antiserum and goat anti-rabbit IgG labeled with gold particles as a second antibody. The gold particles were distributed mainly on the secretory granules, indicating clearly that sodefrin is secreted by the epithelial cells of the abdominal gland. Furthermore, it was confirmed that female-attracting activity was markedly reduced by subjecting the water to an anti-sodefrin column. The unadsorbed fraction obtained by subjecting the male water to a normal rabbit IgG column exhibited its activity that was close to the activity of the untreated water. This indicates that sodefrin is the major female-attracting substance in the male water. Less
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