SAITO Toru Nippon Veterinary and Animal Science University, Department of Veterinary Science, Professor, 獣医学部, 教授 (70211258)
TANIGUCHI Kazuyuki Iwate University, Faculty of Agreculture, Professor, 農学部, 教授 (70148089)
|Budget Amount *help
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2006: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
In this study, we investigated the olfactory epithelium (OE) and vomeronasal epithelium (VNE) of the aquatic larvae, and postmetamorphic immature and adult Japanese newt, Cynops pyrrhogaster. Immunohistochemistry for GTP-binding proteins and acetylated tubulin, a specific marker of cilia, showed that adult newts have both Go-microvillous and Golf-ciliated olfactory neurons (ORNs) in the same OE, similar to fish. At the aquatic larval stage, the tadpoles also have the OE consisting of both Go- and Golf-ORNs. In the postmetamorphic immature newt, Go-ORNs decreased gradually and disappeared, while Golf-ORNs remained in the OE after transition to the terrestrial life. Interestingly, the VNE of the terrestrial immature newt consisted of both Go- and Golf-vomeronasal neurons (VRNs). In addition, we isolated partial fragment of the Japanese newt type II vomeronasal receptor (V2Rs) and demonstrated the expression of V2Rs mRNA in the OE and VNE using RT-PCR. In Xenopus, Go- and Golf-ORNs are segregated into distinct chambers and involved in detection of nonvolatile and volatile odorants, respectively. Therefore, the Japanese newt may have ORNs for both nonvolatile and volatile odorants in single olfactory chamber, unlike other tetrapod vertebrates. The OE and VNE of the Japanese newt may change their functions during the transition from aquatic to terrestrial life in the development and maturation process.