ANT LIA: Collaborative Research: Adaptations of Southern Ocean Diatoms to Manganese Scarcity: Can Physiological Ingenuity Overcome Unfavorable Chemistry?

目前对控制南大洋生产力的因素的理解主要是基于藻类生长所需的金属化合物--海水中的溶解铁--的稀缺性。越来越多的证据表明，锰在维持藻类生长方面也发挥着关键作用，如果在低浓度下被发现，可能会在限制初级生产力方面发挥作用。由于藻类生长是从大气中吸收二氧化碳的主要参与者，了解是什么控制了生产力，有助于我们理解南大洋在全球碳循环中扮演的角色。这项研究建议研究南极硅藻吸收锰的藻类过程，南极硅藻是该地区主要的初级生产者之一。另一个方面将是了解锌，一种与锰具有相似动态的微量营养素，如何抑制其吸收。私人投资机构建议对从南大洋分离的培养硅藻进行实验室实验，以获得他们关于微量营养素动态的问题的答案，并将与从温带水域分离的硅藻物种的结果进行比较。这项拟议的研究将有助于NSF了解寒冷环境中的生命以及它们与海洋其他部分的不同之处。该项目将支持地球科学领域的两名初出茅庐的科学家和一名女性研究人员。两名研究生也将得到支持，这项研究中使用的科学技术将在学术机构赞助的开放参观活动中分享，并与当地暑期学校分享。这项提议代表了两位职业生涯早期的研究人员在探索南极硅藻中锰(Mn)限制的合作研究。硅藻是南大洋碳循环的核心角色，那里的微量营养素化学与其他海洋有根本的不同。南大洋的特点是普遍存在低锰和高锌。高水平的锌对硅藻具有潜在的毒性，因为锌可以竞争性地抑制锰的吸收和代谢，损害构建关键细胞成分的能力，从而影响生物泵。利用一系列微量营养素处理(锰、锌、铁)和辐射的培养实验，并使用生理和转录方法，以及生化原理，首席研究人员将解决中心假设(来自南大洋的硅藻对低锰/高锌具有生理机制)，以量化吸收速率和转运体结合常数。转录组方法将有助于寻找可能为南极硅藻在低锰/高锌环境中提供生理机制的候选基因。该项目不需要实地调查，而是利用4种硅藻(3种南极和1种温带)进行培养实验。建议的方法还将实现开发用于评估锰胁迫或锌毒性的生物标记物(S)的目标，生理实验的结果将有助于将南大洋微量营养素限制的模型参数化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The current understanding of what controls productivity in the Southern Ocean is based mostly on the scarcity of a metal compound needed for algal growth, Dissolved Iron in seawater. There is growing evidence that Manganese also plays a critical role in maintaining algal growth and if found in low concentrations can play a role in limiting primary productivity. As algal growth is a major player in absorbing carbon dioxide from the atmosphere, understanding what controls productivity increases our understanding of what role the Southern Ocean plays in the global carbon cycle. This study proposes to study the algal processes that take up Manganese in Antarctic diatoms, one of the main primary producers in the region. Another aspect will be to understand how Zinc, a micronutrient with similar dynamics than Manganese, can inhibit its uptake. The PIs propose lab experiments with cultured diatoms isolated from the Southern Ocean to obtain answers to their questions on micronutrient dynamics and will compare results from those obtained with a diatom species isolated from temperate waters. The proposed research will benefit NSF’s goals of understanding life in cold environments and how they differ from other parts of the ocean. This project will support two first-time early career scientists and a female researcher in Earth Sciences. Two graduate students will also be supported, and scientific techniques used in this research will be shared at open houses sponsored by the academic institutions and with local summer schools. This proposal represents collaborative research to explore manganese (Mn) limitation in Antarctic diatoms by two early career investigators. Diatoms are central players in the Southern Ocean carbon cycle, where the micronutrient chemistry is fundamentally different from other oceans. The Southern Ocean is characterized by widespread low Mn, coupled with high zinc (Zn). High Zn levels are potentially toxic to diatoms as Zn can competitively inhibit Mn uptake and metabolism, compromising the ability of building critical cellular components, thus impacting the biological pump. Using culture experiments with a matrix of micronutrient treatments (Mn, Zn, Fe) and irradiances, and using physiological and transcriptomic approaches, along with biochemical principles, the Principal Investigators will address the central hypothesis (diatoms from the Southern Ocean possess physiological mechanisms to low Mn/high Zn) to quantify rates of uptake and transporter binding constants. The transcriptomics approach will help to identify candidate genes that may provide Antarctic diatoms physiological mechanisms in low Mn/high Zn environment. The project does not require fieldwork but instead would make use of culture experiments with 4 diatom species (3 Antarctic, and 1 temperate). The proposed approach will also enable the goal of developing biomarker(s) for assessing Mn stress or Zn toxicity and results from the physiological experiments will help parameterize models of micronutrient limitation in the Southern Ocean.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.