Collaborative Research: Osmoregulation in marine dinoflagellates

海洋浮游植物生活在动态多变的环境中。盐度、温度和营养物质的变化是控制浮游植物种群生长和分布的主要因素。沿海水域的盐度差异很大，因此许多沿海浮游植物物种都进化出了快速调节体内水浓度的机制，这一过程被称为渗透调节。作为对盐度下降的反应，在墨西哥湾产生有毒赤潮的甲藻Karenia brevis产生的梯形框架聚醚(LFP)迅速增加10倍，其中包括一种名为Brivetoxin的强大神经毒素。LFP在K.brevis中的功能作用尚不清楚；然而，如此大量的生产表明，肯定存在关键的细胞作用。结合生理学实验、细胞成像、下一代测序和代谢组谱的跨学科方法将被用来探索基因转录和生理/代谢反应之间的关系。为了确定LFP的产生是否是甲藻渗透调节的常见机制，将对其他种类的甲藻进行类似的实验，也已知的是产生LFP。LFP产量对低盐度的响应变化可能解释了K.brevis和其他产生毒素的甲藻如何在沿海生态系统中蓬勃发展。该项目的结果将为“赤潮”甲藻的毒素产生提供解释，并揭示目前生长速度缓慢的有毒甲藻如何在未来条件下在沿海环境中成功竞争。该项目的更广泛影响包括培训和教育一名博士后研究员、三名研究生和本科生，使用最先进的技术来解决进化论和生态学的问题。研究结果还将用于TAMU教授的一门分子生态学研究生课程，为学生提供实际实验数据的实践经验，以便在这个迅速崛起的领域进行培训。

Marine phytoplankton live in a dynamic and variable environment. Changes in salinity, temperature and nutrients are major factors that control the growth and distribution of phytoplankton populations. Salinity can vary significantly in coastal waters, so many coastal phytoplankton species have evolved mechanisms to quickly regulate their internal water concentration, a process known as osmoregulation. In response to decreases in salinity, the dinoflagellate, Karenia brevis, responsible for producing toxic red tides in the Gulf of Mexico, produces a rapid 10-fold increase in ladder frame polyethers (LFPs), which include the potent neurotoxins called brevetoxin. The functional role of LFPs in K. brevis is unknown; however, the production of such large quantities suggests that there must be a critical cellular role. An interdisciplinary approach combining physiological experiments, cell imaging, next generation sequencing, and metabolomic profiling will be used to explore the relationship between gene transcription and physiological/metabolic responses. To determine if LFP production is a common mechanism for osmoregulation in dinoflagellates, similar experiments will be conducted with additional species of dinoflagellates also known to produce LFPs. Changes in LFP production in response to low salinity may explain how K. brevis and other toxin-producing dinoflagellates can thrive in coastal ecosystems. The project's outcome will provide an explanation for toxin production in 'red tide' dinoflagellates and reveal how toxic dinoflagellates, with slow growth rates now, may compete successfully in coastal environments under future conditions. The project's broader impacts include training and education of a post-doctoral researcher, three graduate students, and undergraduate students using state-of-the-art techniques to address questions in evolution and ecology. Results will also be utilized in a graduate Molecular Ecology course taught at TAMU providing students with hands-on experience with actual experimental data for training in this rapidly emerging field.