Environmental stress and signaling based on reactive oxygen species among planktonic protists

传统上，人们根据大小来研究海洋食物网，假设较大的生物体吃较小的生物体，并且它们吃给定大小范围内的所有东西。这种简化经受不住时间的考验，特别是对最小的微生物浮游生物来说。不仅较小的生物体有时会吃掉较大的生物体，越来越多的证据表明，化学信号和防御系统在这些小范围内发挥作用。这个项目解决了一个中心前提，即氧化应激反应是光养细胞系统的一种紧急性质，几乎涉及上层海洋浮游植物细胞生活的方方面面。氧化应激(OS)由多种环境应激源引起，可损伤细胞并导致化合物的释放，这些化合物被怀疑是调节原生生物行为的有力信号。通过化学信号，OS被假设为控制环境变异性、浮游植物状况和原生动物捕食之间的关系。对这些综合过程的研究有三个主要目标：1)在实验室中利用光胁迫产生氧化应激浮游植物，并使用一系列荧光探针、生化测量和生理分析来表征响应。此外，潜在信号分子的产生和释放将被量化。2)研究原生生物对氧化应激浮游植物的捕食和行为反应以及相关的化学信号。将通过操纵实验和由此产生的信号化学来研究响应。3)调查OS的流行率、与其环境相关的因素，以及当地海湾的微型浮游动物捕食反应。这些实验和观测活动将直接产生更广泛的影响。该项目将支持几名研究生，并通过香农角海洋中心的两个项目吸引本科生参与，其中一个项目针对的是未被充分代表的少数族裔。资金将支持大量异养原生生物分离物的收集。该荧光计将用于开发至少3门与西华盛顿大学海洋相关课程的新单元。此外，研究生将使用原生生物图像作为针对普通公众和K-12学生的扩展活动的基础。这项研究将有助于阐明OS响应可以影响浮游植物适应性的许多方式中的一些，表征关键沿海物种在OS响应光谱中的位置。这些发现还将为浮游生物群落中相对较新和令人兴奋的化学信号领域提供信息。最后，这项研究将有助于阐明浮游生态系统中环境压力、浮游植物反应和捕食之间的联系。这些联系涉及生物海洋学中的中心问题，包括影响水华死亡的捕食者-猎物相互作用，以及原生动物选择性觅食从而构建猎物群落的机制。这项研究是一项交叉努力，通过一个新的概念框架将通常孤立研究的受试者团结在一起。结果有可能对浮游食物网中这一关键营养环节的生态和进化调节产生广泛适用的见解。

Traditionally marine food webs have been studied on the basis of size, assuming that larger organisms eat smaller ones, and that they eat everything in a given size range. This simplification has not stood the test of time, especially for the smallest microbial plankton. Not only do smaller organisms sometimes eat larger ones, there is growing evidence that chemical signaling and defenses are acting at these small scales. This project addresses the central premise that the oxidative stress response is an emergent property of phototrophic cellular systems, with implications for nearly every aspect of a phytoplankton cell's life in the upper ocean. Oxidative stress (OS), arising from numerous environmental stressors, can damage cells and lead to release of compounds suspected to be potent signals regulating protist behavior. Through chemical signaling, OS is hypothesized to govern relationships among environmental variability, phytoplankton condition, and protist predation. The study of these integrated processes has three overarching objectives: 1) Use light stress to create oxidatively stressed phytoplankton in the laboratory, and characterize the response using an array of fluorescent probes, biochemical measurements, and physiological assays. In addition, production and release of potential signal molecules will be quantified. 2) Examine protist predation and behavioral responses to oxidatively stressed phytoplankton and associated chemical signals. Responses will be investigated by means of manipulation experiments and resulting signal chemistry. 3) Investigate the prevalence of OS, its environmental correlates, and the microzooplankton predation response in a local embayment. Broader impacts will build directly on these experimental and observational activities. The project will support several graduate students and involve undergraduates through two programs at Shannon Point Marine Center, including one targeting under-represented minorities. Funds will support a significant collection of heterotrophic protists isolates. The fluorometer will be used in developing new units for at least 3 different Western Washington University marine-related courses. In addition, graduate students will use protist images as the basis for outreach activities aimed at the general public and K-12 students.This research will help to elucidate some of the many ways in which the OS response can affect phytoplankton fitness, characterizing the position of key coastal species along an OS response spectrum. Findings will also inform the relatively new and exciting field of chemical signaling in planktonic communities. Finally, this study will help elucidate the links between environmental stress, phytoplankton response, and predation in planktonic ecosystems. These links relate to central issues in biological oceanography, including the predator-prey interactions that influence bloom demise, and the mechanisms by which protists feed selectively and thereby structure prey communities. The research is a cross-cutting endeavor that unites subjects usually studied in isolation through a novel conceptual framework. Outcomes have the potential to generate broadly applicable insights into the ecological and evolutionary regulation of this key trophic link in planktonic food webs.