Echevarria Michael L, Wolfe Gordon V, Taylor Alison R
Department of Biology and Marine Biology, University of North Carolina, Wilmington, 601 South College Road, Wilmington, NC 28403, USA
Department of Biological Sciences, California State University, 1205 W. 7th Street, Chico, CA 95929-0515, USA.
J Exp Biol. 2016 Feb;219(Pt 3):445-56. doi: 10.1242/jeb.121871. Epub 2015 Nov 13.
Alveolate (ciliates and dinoflagellates) grazers are integral components of the marine food web and must therefore be able to sense a range of mechanical and chemical signals produced by prey and predators, integrating them via signal transduction mechanisms to respond with effective prey capture and predator evasion behaviors. However, the sensory biology of alveolate grazers is poorly understood. Using novel techniques that combine electrophysiological measurements and high-speed videomicroscopy, we investigated the sensory biology of Favella sp., a model alveolate grazer, in the context of its trophic ecology. Favella sp. produced frequent rhythmic depolarizations (∼500 ms long) that caused backward swimming and are responsible for endogenous swimming patterns relevant to foraging. Contact of both prey cells and non-prey polystyrene microspheres at the cilia produced immediate mechanostimulated depolarizations (∼500 ms long) that caused backward swimming, and likely underlie aggregative swimming patterns of Favella sp. in response to patches of prey. Contact of particles at the peristomal cavity that were not suitable for ingestion resulted in depolarizations after a lag of ∼600 ms, allowing time for particles to be processed before rejection. Ingestion of preferred prey particles was accompanied by transient hyperpolarizations (∼1 s) that likely regulate this step of the feeding process. Predation attempts by the copepod Acartia tonsa elicited fast (∼20 ms) animal-like action potentials accompanied by rapid contraction of the cell to avoid predation. We have shown that the sensory mechanisms of Favella sp. are finely tuned to the type, location, and intensity of stimuli from prey and predators.
肺泡状（纤毛虫和甲藻）食草动物是海洋食物网的重要组成部分，因此必须能够感知猎物和捕食者产生的一系列机械和化学信号，并通过信号转导机制将它们整合起来，以做出有效的猎物捕获和捕食者逃避行为。然而，人们对肺泡状食草动物的感觉生物学了解甚少。我们使用结合了电生理测量和高速视频显微镜的新技术，在其营养生态学的背景下研究了一种典型的肺泡状食草动物 Favella sp. 的感觉生物学。Favella sp. 会产生频繁的有节奏的去极化（约500毫秒长），导致向后游动，并与觅食相关的内源性游动模式有关。猎物细胞和非猎物聚苯乙烯微球与纤毛接触时，会立即产生机械刺激去极化（约500毫秒长），导致向后游动，这可能是 Favella sp. 对猎物斑块做出反应的聚集游动模式的基础。不适合摄取的颗粒与口周腔接触后，会在约600毫秒的延迟后产生去极化，从而在排斥之前有时间对颗粒进行处理。摄取偏好的猎物颗粒会伴随着短暂的超极化（约1秒），这可能会调节进食过程的这一步骤。桡足类动物中华哲水蚤的捕食尝试会引发快速（约20毫秒）的类似动物的动作电位，并伴随着细胞的快速收缩以避免被捕食。我们已经表明，Favella sp. 的感觉机制能够精细地调节对来自猎物和捕食者的刺激的类型、位置和强度的反应。
