Quach Kathleen T, Hughes Gillian A, Chalasani Sreekanth H
Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.
Elife. 2025 Mar 31;13:RP98262. doi: 10.7554/eLife.98262.
Prey must balance predator avoidance with feeding, a central dilemma in prey refuge theory. Additionally, prey must assess predatory imminence-how close threats are in space and time. Predatory imminence theory classifies defensive behaviors into three defense modes: pre-encounter, post-encounter, and circa-strike, corresponding to increasing levels of threat--suspecting, detecting, and contacting a predator. Although predatory risk often varies in spatial distribution and imminence, how these factors intersect to influence defensive behaviors is poorly understood. Integrating these factors into a naturalistic environment enables comprehensive analysis of multiple defense modes in consistent conditions. Here, we combine prey refuge and predatory imminence theories to develop a model system of nematode defensive behaviors, with as prey and as predator. In a foraging environment comprised of a food-rich, high-risk patch and a food-poor, low-risk refuge, innately exhibits circa-strike behaviors. With experience, it learns post- and pre-encounter behaviors that proactively anticipate threats. These defense modes intensify with predator lethality, with only life-threatening predators capable of eliciting all three modes. SEB-3 receptors and NLP-49 peptides, key stress regulators, vary in their impact and interdependence across defense modes. Overall, our model system reveals fine-grained insights into how stress-related signaling regulates defensive behaviors.
猎物必须在躲避捕食者与进食之间取得平衡，这是猎物避难所理论中的一个核心难题。此外，猎物还必须评估捕食的紧迫性——威胁在空间和时间上有多接近。捕食紧迫性理论将防御行为分为三种防御模式：遭遇前、遭遇后和接近攻击，分别对应于不断增加的威胁程度——怀疑、察觉和接触捕食者。尽管捕食风险在空间分布和紧迫性上往往各不相同，但人们对这些因素如何相互作用以影响防御行为却知之甚少。将这些因素整合到自然环境中，能够在一致的条件下对多种防御模式进行全面分析。在这里，我们结合猎物避难所和捕食紧迫性理论，开发了一个线虫防御行为的模型系统，以线虫为猎物，[未提及的捕食者]为捕食者。在一个由食物丰富、高风险斑块和食物匮乏、低风险避难所组成的觅食环境中，线虫天生表现出接近攻击行为。随着经验的积累，它学会了能主动预测威胁的遭遇后和遭遇前行为。这些防御模式会随着捕食者的致命性而增强，只有危及生命的捕食者才能引发所有三种模式。关键应激调节因子SEB-3受体和NLP-49肽在不同防御模式下的影响和相互依赖性各不相同。总体而言，我们的模型系统揭示了与应激相关的信号传导如何调节防御行为的详细见解。
