Laboratory of Aquatic Bioresources and Ecosystem, Field Science Center for Northern Biosphere and Division of Biosphere Science, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan.
PLoS One. 2010 Jan 8;5(1):e8633. doi: 10.1371/journal.pone.0008633.
Juvenile salmon have an olfactory ability to imprint their natal stream odors, but neither the odor properties of natal stream water nor the imprinting timing and duration have been clarified as yet. Here we show, using electrophysiological and behavioral experiments, that one-year-old lacustrine sockeye salmon (Oncorhynchus nerka) can be imprinted around the stage of parr-smolt transformation (PST) by a single amino acid, 1 microM L-proline (Pro), or L-glutamic acid (Glu). We also show by real-time PCR that changes occur in mRNA levels of the salmon olfactory imprinting-related gene (SOIG) around PST. The electro-olfactogram (EOG) responses of test fish exposed to Pro in March (before PST) and April-June (during PST) for 2 weeks were significantly (1.7-fold) greater than those of non-exposed control fish, but not those of test fish exposed in July (after PST). When Pro and control water were added to the water inlets of a two-choice test tank during the spawning season 2 years after the test water exposure, 80% of maturing and matured test fish exposed before and during PST showed a preference for Pro, whereas those exposed after PST did not. The EOG response of test fish exposed to Pro or Glu for 1 hour, 6 hours, 1 day, 7 days, or 14 days in May revealed that only the response after 14 days of exposure was significantly (1.8-fold) greater than the control. The expression levels of SOIG mRNA increased before and during PST, and decreased after PST. We conclude that one-year-old lacustrine sockeye salmon can be imprinted by a single amino acid before and during PST, and that imprinting requires exposure for at least 14 days.
幼鲑具有印记其出生地溪流气味的嗅觉能力，但出生地溪流水的气味特性以及印记的时间和持续时间尚未得到明确。在这里，我们通过电生理和行为实验表明，一年龄的湖泊红大麻哈鱼（Oncorhynchus nerka）可以在幼鱼-变态过渡（PST）阶段通过单一氨基酸 1 μM L-脯氨酸（Pro）或 L-谷氨酸（Glu）进行印记。我们还通过实时 PCR 表明，在 PST 周围，鲑鱼嗅觉印记相关基因（SOIG）的 mRNA 水平发生变化。暴露于 Pro 的测试鱼的电嗅觉图（EOG）反应在 3 月（PST 之前）和 4 月至 6 月（PST 期间）暴露于 Pro 2 周后显著（1.7 倍）高于未暴露于 Pro 的对照鱼，但在 7 月（PST 之后）暴露于 Pro 的测试鱼则不然。当在测试水暴露后的第二年繁殖季节将 Pro 和对照水添加到双选择测试罐的入水口中时，80%的 PST 之前和期间暴露的成熟和成熟测试鱼对 Pro 表现出偏好，而那些在 PST 之后暴露的鱼则没有。在 5 月，将 Pro 和 Glu 暴露于测试鱼 1 小时，6 小时，1 天，7 天或 14 天后，EOG 反应表明仅在暴露 14 天后的反应明显（1.8 倍）高于对照。SOIG mRNA 的表达水平在 PST 之前和期间增加，在 PST 之后减少。我们得出的结论是，一年龄的湖泊红大麻哈鱼可以在 PST 之前和期间通过单一氨基酸进行印记，并且印记需要至少 14 天的暴露。
