Li Yaxi, Yan Zhi, Lin Ainuo, Yang Xiao, Li Xiaodong, Yin Xiuli, Li Weiming, Li Ke
Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
iScience. 2024 Apr 3;27(5):109660. doi: 10.1016/j.isci.2024.109660. eCollection 2024 May 17.
Alarm substances signal imminent predation thread and enable anti-predation strategies. In shoaling fish, alarm cues diffuse from injured skins that induce intense fear and anti-predation behaviors in other members. While these "fear substances" are shown to be present in numerous fishes and thought to exist in roughly 8,000 Ostariophysan species, their chemical nature remains largely unknown. We posited that fish alarm cues comprise small compounds and induce specific behaviors characteristic of fish exposed to skin extracts. Using the behaviors as bioassays, we tracked the alarm function of zebrafish skin extract to two compounds, 24-methyl-5-cholestane-3,7,12,24,28-pentahydroxy 28-sulfate, an oxysterol sulfate, and 5-cyprinol sulfate. At concentrations of less than one nanomolar, each compound induced anti-predator behaviors and increased cortisol levels in zebrafish. Their mixture, at the natural ratio, replicated the skin extract in eliciting the full suite of anti-predator behavior patterns. Our findings reveal a molecular mechanism whereby fish escape predation danger.
警报物质发出即将面临捕食威胁的信号，并启动反捕食策略。在群居鱼类中，警报信号从受伤的皮肤中扩散出来，会引起其他成员强烈的恐惧和反捕食行为。虽然这些“恐惧物质”已被证明存在于许多鱼类中，并且据认为大约8000种骨鳔鱼类中都有，但它们的化学性质在很大程度上仍然未知。我们推测鱼类警报信号由小分子化合物组成，并能引发暴露于皮肤提取物中的鱼类所特有的特定行为。我们以这些行为作为生物测定方法，追踪到斑马鱼皮肤提取物的警报功能源自两种化合物，一种氧甾醇硫酸盐，即24-甲基-5-胆甾烷-3,7,12,24,28-五羟基28-硫酸盐，以及硫酸鲤醇。在浓度低于一纳摩尔时，每种化合物都会引发斑马鱼的反捕食行为，并提高其皮质醇水平。它们以天然比例混合时，能像皮肤提取物一样引发全套反捕食行为模式。我们的研究结果揭示了鱼类逃避捕食危险的分子机制。
