Ahamed Saokat, Hassan Mohammad Maksudul, Mustary Umme Habiba, Amin Mohammad Tohidul, Tokumoto Toshinobu
Department of Bioscience, Graduate School of Science and Technology, National University Corporation Shizuoka University, Shizuoka, Japan.
PLoS One. 2024 Aug 1;19(8):e0300759. doi: 10.1371/journal.pone.0300759. eCollection 2024.
Successful fertilization in fish mating occurs when egg maturation in the ovary of the female, ovulation, sperm maturation in the testis of the male, and reproductive behaviors in both sexes are triggered in synchrony. The male sexual behavior of fish is induced by hormones and pheromones. In a previous study, we demonstrated that externally applied hormones added to the water can induce oocyte maturation and ovulation in female zebrafish. Here, we attempted to establish a similar method to induce the sexual behavior of male zebrafish. The male sex steroid testosterone (Tes) triggered sexual behavior within several hours in vivo when administered directly into the surrounding water. A selective agonist for membrane progesterone receptor (mPR), Org OD-02 (Org), also induced sexual behavior. Through trials of various combinations of compounds, we found that the most effective conditions were achieved by treatment with a mixture of testosterone (Tes) and Org. The effect of treatment was evaluated by the number of fertilized eggs obtained by pairing with females with induced ovulation in vivo. The period necessary for the induction of male sexual behavior was evaluated by time course experiments. The success rate of mating and the number of fertilized eggs reached the maximum level at 3-4 hours of treatment. The duration of hormonal treatment was confirmed by counting the number of hooking occurrences, which is the final cue to induce spawning by females. In summary, we have established a method to induce male sexual behavior in zebrafish in vivo. The method can be used to obtain fertilized eggs in zebrafish by simply adding agents into the water.
当雌性卵巢中的卵子成熟、排卵，雄性睾丸中的精子成熟，以及两性的生殖行为同步触发时，鱼类交配才能成功受精。鱼类的雄性性行为由激素和信息素诱导。在之前的一项研究中，我们证明了添加到水中的外源激素可诱导雌性斑马鱼的卵母细胞成熟和排卵。在此，我们试图建立一种类似的方法来诱导雄性斑马鱼的性行为。当直接施用于周围水体时，雄性甾体激素睾酮（Tes）在数小时内就能在体内引发性行为。膜孕酮受体（mPR）的选择性激动剂Org OD-02（Org）也能诱导性行为。通过对各种化合物组合的试验，我们发现用睾酮（Tes）和Org的混合物处理可达到最有效的条件。通过与体内诱导排卵的雌性交配获得的受精卵数量来评估处理效果。通过时间进程实验评估诱导雄性性行为所需的时间。在处理3-4小时时，交配成功率和受精卵数量达到最高水平。通过计算钩住次数来确定激素处理的持续时间，钩住是诱导雌鱼产卵的最终信号。总之，我们建立了一种在体内诱导斑马鱼雄性性行为的方法。该方法可通过简单地向水中添加试剂来获得斑马鱼的受精卵。
