Collaborative Research: Osmoregulation in marine dinoflagellates

海洋浮游植物生活在一个动态多变的环境中。盐度、温度和养分的变化是控制浮游植物种群生长和分布的主要因素。沿海水域的盐度变化很大，因此许多沿海浮游植物物种已经进化出快速调节其内部水浓度的机制，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鞭毛藻短卡雷氏菌（Karenia brevis）产生的梯架聚醚（lfp）迅速增加10倍，其中包括一种强效的神经毒素，称为短藻毒素。lfp在短链乳杆菌中的功能作用尚不清楚；然而，如此大量的生产表明，必须有一个关键的细胞作用。结合生理实验、细胞成像、下一代测序和代谢组学分析的跨学科方法将用于探索基因转录与生理/代谢反应之间的关系。为了确定LFP的产生是否是鞭毛藻渗透调节的共同机制，将对已知产生LFP的其他种类的鞭毛藻进行类似的实验。低盐度下LFP产量的变化可能解释了短链乳杆菌和其他产生毒素的鞭毛藻如何在沿海生态系统中茁壮成长。该项目的结果将为“赤潮”鞭毛藻的毒素产生提供解释，并揭示现在生长速度缓慢的有毒鞭毛藻如何在未来条件下在沿海环境中成功竞争。该项目更广泛的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，他们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的研究生分子生态学课程，为学生提供实际实验数据的实践经验，为这一快速发展的领域提供培训。

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.