MCA: Developing transcriptomics as a tool to investigate toxic diatom responses to ocean heatwave and upwelling events

硅藻伪菱形藻形成大的，有毒的有害藻华沿着美国西海岸，杀死野生动物和损害宝贵的海洋渔业。了解这些水华的原因并预测其发生，无论是现在还是未来不断变化的气候条件下，对沿海环境和经济健康至关重要。令人困惑的是，这些水华似乎发生在沿海海水涌升导致寒冷、营养丰富、pH值低的海面条件的时期，也发生在热浪事件导致温暖、营养贫乏、pH值高的时期。据预测，随着气候变化，这两种极端情况将变得更加严重。 该项目是实验测试如何伪菱形藻响应涌升和热浪事件使用测量细胞生长，毒素生产和基因表达。 该项目的更广泛影响包括培训新基因表达方法的主要研究者，研究生和本科生研究培训，高中研究指导经验，以及针对商业捕鱼业的推广和交流活动。 社会效益包括更好地了解有毒藻华的破坏性原因，以及它们在未来沿海海洋中可能如何变化。有毒的硅藻伪菱形藻每年都会在美国西海岸沿着造成有害的水华，在这个地区，风驱动的上升流将丰富的营养供应带入真光层。然而，该区域也正在经历与全球变暖有关的前所未有的间歇性海洋热浪事件。因此，该地区未来的气候趋势表明，目前的物理化学极端之间的夸大更冷，更丰富的营养，低pH值的上升流，和温暖，更营养耗尽，更高的pH值热浪。令人惊讶的是，有毒的假菱形藻属（Pseudo-nitzschia spp.）在上升流和热浪条件下都可以开花，尽管在营养物，温度和碳酸盐化学等关键环境控制方面存在相反的趋势。该项目通过首先获得两种假菱形藻分离物的每个单独因素，温度，pCO 2，磷，氮和硅的完整响应曲线来测试这是如何发生的。然后，这些变量相结合的整体上升流和热浪情景孵化实验，比较生长和毒性的影响，在两个文化和自然水华的伪菱形藻。PI正在利用她在藻类生理学方面的现有专业知识评估这些实验中的有毒硅藻反应，并通过扩大她的专业视野，与罗得岛大学的Bethany Jenkins博士合作开发转录组生物信息学的新技能。 实验进行了测试的生理反应，在模拟上升流或热浪发生的营养浓度，温度和pCO 2的变化，并测量关键的代谢途径基因的表达，如毒素合成途径。该项目有助于理解和解释有毒的假菱形藻在不断变化的海洋中令人惊讶的生态位灵活性，同时为PI未来的职业发展提供了新的途径。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The diatom Pseudo-nitzschia forms large, toxic harmful algal blooms along the U.S. West Coast, killing wildlife and harming valuable ocean fisheries. Understanding the causes of these blooms and predicting their occurrence, both now and under future changing climate conditions, is critical to coastal environmental and economic health. Puzzlingly, these blooms seem to happen during periods when coastal seawater upwelling results in cold, nutrient-rich, low pH sea surface conditions, and also during times when heat wave events cause warm, nutrient-poor, high pH conditions. These two extremes are forecast to get even more intense with climate change. This project is experimentally testing how Pseudo-nitzschia responds to upwelling and heat wave events using measurements of cell growth, toxin production, and gene expression. Broader impacts of this project include training the principal investigator in new gene expression methods, graduate and undergraduate research training, high school research mentoring experiences, and outreach and communications activities aimed at the commercial fishing industry. Societal benefits include obtaining a better understanding of the causes of damaging toxic algal blooms, and how they may change in the future coastal ocean. The toxic diatom Pseudo-nitzschia causes annual harmful blooms along the US West Coast, a region where wind-driven upwelling brings rich nutrient supplies into the euphotic zone. However, this region is also experiencing unprecedented episodic ocean heatwave events linked to global warming. Thus, future climate trends in this region suggest an exaggeration of current physio-chemical extremes between colder, more nutrient-rich, low pH upwelling, and warmer, more nutrient-depleted, higher pH heatwaves. Surprisingly, toxic Pseudo-nitzschia spp. can bloom under both upwelling and heatwave conditions, despite opposite trends in key environmental controls like nutrients, temperature, and carbonate chemistry. This project is testing how this happens by first obtaining full response curves for each of the individual factors, temperature, pCO2, phosphorus, nitrogen, and silicon for two Pseudo-nitzschia isolates. Then, these variables are combined in holistic upwelling and heatwave scenario incubation experiments, to compare how growth and toxicity is affected in both cultures and natural blooms of Pseudo-nitzschia. The PI is assessing toxic diatom responses in these experiments using her existing expertise in algal physiology, as well as by expanding her professional horizons to develop new skills in transcriptome bioinformatics in partnership with Dr. Bethany Jenkins from the University of Rhode Island. Experiments are conducted to test the physiological responses of Pseudo-nitzschia to changes in nutrient concentrations, temperature and pCO2 during simulated upwelling or heatwave occurrences, and measure expression of key metabolic pathway genes such as toxin synthesis pathways. This project is helping to understand and interpret the surprising niche flexibility of toxic Pseudo-nitzschia in a changing ocean, and at the same time offers the PI a new avenue forward for her future career development.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.