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Animal Bioresource in Japan

.: Home > Animal Bioresource in Japan > 2012 > Volume 59 Number 2 > Youichi Hayakawa, Shinpei Takita, Kazuya Kikuchi, Ayaka Yoshida, Makito Kobayashi

Involvement of olfaction in spawning success of medaka Oryzias latipes

Youichi Hayakawa, Shinpei Takita, Kazuya Kikuchi, Ayaka Yoshida, Makito Kobayashi
Department of Life Science, International Christian University, 3–10–2 Osawa, Mitaka, Tokyo 181–8585, Japan (e-mail:
Abstract :

The importance of olfaction in spawning of medaka Oryzias latipes was established for the first time by observation of spawning behavior by fish subjected to an olfactory blockage. Experimental fish were prepared by (1) covering the nostrils on both sides (bilateral treatment), thereby excluding all olfactory stimuli, and (2) covering nostrils on one side only (unilateral treatment), thereby giving partial exclusion. A control group comprised untreated (intact). Experiments conducted for both males (bilateral male-intact female, unilateral male-intact female and intact male-intact female) and females (bilateral female-intact male, unilateral female-intact male and intact female-intact male) resulted in no spawning by intact females paired with bilateral males, whereas spawning occurred in intact females paired with both unilateral and intact males. Spawning also occurred when intact males were paired with intact, unilateral or bilateral females, indicating that olfactory stimuli were necessary for males to complete spawning, but not so for females. Spawning acts exhibited from pairing started by bilateral males-intact female pairs included “following” (initial act of following female), “positioning” (lateral courtship display), and “quick circle” (turning in front of female), but they did not include “contact” (bodies in contact posteriorly prior to gamete release), “wrapping” (male embracing female using their dorsal and anal fins during gamete release). On the other hand, intact and unilateral males participated in all of the above spawning acts, indicating that olfactory stimuli are indispensable for behavior concerning emitting semen.

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Date Deposited : 25 Feb 2015 11:30

Last Modified : 25 Feb 2015 11:30

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Volume 59, Number 2, - 2012 , ISSN 111–124

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