NSFGEO-NERC: Collaborative Research: Novel imaging, physiology and numerical approaches for understanding biologically mediated, unsteady sinking in marine diatoms

NSFGEO-NERC：合作研究：用于了解海洋硅藻生物介导的不稳定下沉的新颖成像、生理学和数值方法

• 批准号: 2023434
• 负责人: Lee Karp-Boss
• 金额: $ 18.14万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023434&HistoricalAwards=false
• 关键词: NSFGEO; NERC; Collaborative; Research; Novel

This is a project that is jointly funded by the National Science Foundation's Directorate of Geosciences (NSF/GEO) and the National Environment Research Council (UKRI/NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own investigators and component of the work.This project takes a small-scale approach to look at individual cells to investigate the sinking of marine diatoms, which on larger scales has implications for how food for larger organisms, carbon, and organic particles move throughout the ocean. Diatoms are a type of phytoplankton, cells that use photosynthesis in surface waters to produce roughly half of the world’s oxygen and the food to support ocean food webs. They have a heavy, glass-like outer wall which causes them to sink and move up to 40% of particulate organic carbon from the ocean’s surface to the deep sea. The investigators are using novel methods to determine how diatoms regulate their sinking quickly in response to different environmental conditions. These include state-of-the-art video measurements of individual cells, a micoelectrode approach to understand changes at cell surfaces, and microscopy to see changes inside and at the surface of cells. The resulting information will be used to build a model to understand how and why diatoms use unsteady sinking behavior based on their environment. The project supports early career investigators, provides training for a postdoctoral scientist and undergraduate students, and develops a collaboration between US and UK scientists. The team is also developing lesson plans in conjunction with local high schools with high populations of underrepresented students in STEM fields. The problem of sinking and suspension of diatoms has received considerable attention because of its ecological, evolutionary and biogeochemical significance, yet understanding of the processes that regulate sinking rates remains rudimentary. The investigators have used new techniques to make preliminary observations showing that some species of diatom exhibit an unsteady sinking behavior that consists of rapid changes of buoyancy on time scales of seconds. However, it remains unclear how widely this behavior matters across species and ocean conditions. In this study, the team of investigators is using state-of-the-art video-based measurements of sinking rates of individual cells to assess the prevalence of unsteady sinking among centric and pennate diatoms of varying cell sizes and quantify how this behavior changes in response to sharp gradients in nutrients and light. The project leverages an interdisciplinary, international collaboration to combine innovative optical techniques, advanced tools to assess cell physiology, and numerical modeling approaches to characterize suspension properties for individual diatom cells. Results are likely to transform the way we think about the ecology of diatoms, their strategies for nutrient acquisition, and mechanisms to control their buoyancy, in particular the modulation of volume and membrane of the central vacuole. This project contributes to the development of novel tools for single cell physiological studies, most notably direct measurement of diffusive boundary layers around cells under varying flow conditions and numerical modeling of cell-level processes.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.

这是一个由国家科学基金会地球科学理事会（NSF/GEO）和联合王国国家环境研究理事会（UKRI/NERC）通过NSF/GEO-NERC牵头机构协议共同资助的项目。该协议允许美国/英国提交一份联合提案，并由研究者拥有最大预算比例的机构进行同行评审。一旦成功地共同确定了一项奖励，每个机构就为预算的一部分和与自己的调查人员和工作组成部分有关的调查人员提供资金，该项目采取小规模的方法，观察单个细胞，调查海洋硅藻的下沉，这在更大的规模上对大型生物的食物、碳和有机颗粒如何在整个海洋中移动产生影响。硅藻是一种浮游植物，这种细胞在表面沃茨中利用光合作用产生世界上大约一半的氧气和食物，以支持海洋食物网。它们有一个沉重的，玻璃状的外壁，这导致它们下沉，并将多达40%的颗粒有机碳从海洋表面转移到深海。研究人员正在使用新的方法来确定硅藻如何调节它们的下沉以应对不同的环境条件。这些包括单个细胞的最先进的视频测量，了解细胞表面变化的微电极方法，以及观察细胞内部和表面变化的显微镜。由此产生的信息将用于建立一个模型，以了解硅藻如何以及为什么根据其环境使用不稳定的下沉行为。该项目支持早期职业调查人员，为博士后科学家和本科生提供培训，并发展美国和英国科学家之间的合作。该团队还与当地高中合作制定课程计划，这些高中在STEM领域的学生人数偏少。硅藻的沉降和悬浮问题由于其生态、进化和地球化学意义而受到相当大的关注，但对调节沉降速率的过程的理解仍然是初步的。研究人员使用新技术进行了初步观察，结果表明，某些硅藻物种表现出不稳定的下沉行为，包括在几秒钟的时间尺度上浮力的快速变化。然而，目前还不清楚这种行为在物种和海洋条件中的影响有多大。在这项研究中，研究人员正在使用最先进的基于视频的单个细胞下沉率测量方法来评估不同细胞大小的中心和羽状硅藻之间不稳定下沉的普遍性，并量化这种行为如何响应于营养物质和光线的急剧梯度而变化。该项目利用跨学科的国际合作，结合联合收割机创新的光学技术，先进的工具来评估细胞生理学，和数值建模方法来表征单个硅藻细胞的悬浮特性。结果可能会改变我们对硅藻生态学的看法，它们获取营养的策略，以及控制浮力的机制，特别是中央液泡的体积和膜的调节。该项目为单细胞生理学研究的新工具的开发做出了贡献，最显著的是在不同的流动条件下直接测量细胞周围的扩散边界层和细胞水平过程的数值模拟。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Measurements of trajectories and spatial distributions of diatoms (Coscinodiscus spp.) at dissipation scales of turbulence

湍流耗散尺度下硅藻（Coscinodiscus spp.）的轨迹和空间分布测量

• DOI: 10.1007/s00348-021-03240-5
• 发表时间: 2021
• 期刊: Experiments in Fluids
• 影响因子: 2.4
• 作者: Pujara, Nimish;Du Clos, Kevin T.;Ayres, Stephanie;Variano, Evan A.;Karp-Boss, Lee
• 通讯作者: Karp-Boss, Lee