The Oceanography of B-Vitamins: evaluating how nutrients and trace metals influence their synthesis, cycling, and biogeochemical impact

B 族维生素的海洋学：评估营养物质和微量金属如何影响其合成、循环和生物地球化学影响

• 批准号: 0962209
• 负责人: Sergio Sanudo-Wilhelmy
• 金额: $ 81.94万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0962209&HistoricalAwards=false
• 关键词: Oceanography; Vitamins; evaluating; how; nutrients

It is well known that the B-vitamins are important growth factors involved in a large number of metabolic pathways. However, to date, very little work has been done regarding the importance of those growth factors in regulating biological activity in marine systems. Genomic data indicates that the supply of B-vitamins in marine systems depends mainly on biosynthesis by prokaryotes. In contrast, half of the currently tested eukaryotic phytoplankton have been determined to be auxotrophic for at least one vitamin. Therefore, the lack of an exogenous source of these growth factors from prokaryotic cells may strongly impact the efficiency of the so-called biological pump, which is dominated by large eukaryotic cells. In this project, researchers at the University of Southern California will carry out the first in-depth evaluation of the sources and cycling of arguably one of the most important growth factors in the ocean, the B-vitamins (B1, B7, and B12). This will be accomplished by combining field studies in three different oceanographic regimes (San Pedro Ocean Time Series site (SPOTS) off Southern California, The Hawaii Ocean Time-Series (HOT) station ALOHA, and a cruise of opportunity to the East Tropical South Pacific (ETSP) with lab manipulation experiments of cultures of different marine prokaryotic species. The field study sites are selected to give the maximum amount of information about the cycling of vitamins in a broad range of marine environments. Based on preliminary results, the research team hypothesizes: (1) that there are several potential producers of B-vitamins in the ocean: non-diazotrophic cyanobacteria and heterotrophic bacteria in the upper euphotic zone of the world ocean, and that the availability of B-vitamins is further augmented by diazotrophic cyanobacteria in subtropical-tropical LNLC regions of the world ocean; (2) that the synthesis of some B-vitamins is controlled by the availability of specific dissolved trace metals such as Co (for B12) and Fe (for B2 and B7) and organic and inorganic nutrients; and (3) that the balance between B vitamin production (found in the particulate phase) and release (found in the dissolved phase) dictates vitamin availability and environmental cycling, and that this balance is set by three factors: the activity of a subset of the pico and microplankton, physical transport, and uptake by auxotrophic plankton. In order to test these hypotheses, they developed a new method, using a triple quadrupole mass spectrometer coupled to a liquid chromatographer, which allows them to measure directly all B-vitamins simultaneously in less than a liter of seawater as well as in the intracellular and particulate pools. Broader impacts: The scientific and societal impacts of this project include elucidating the cycling of B-vitamins, without which we will never have a complete understanding of all of the essential substances needed to sustain major biological processes such as primary production and nitrogen fixation in the ocean. Both graduate and undergraduate students will participate in this project. The principal investigators are active participants in the COSEE-West program, which involves a network of marine scientists, K-12 educators, and the general public.

众所周知，B族维生素是重要的生长因子，参与多种代谢途径。然而，迄今为止，关于这些生长因子在调节海洋系统生物活动方面的重要性所做的工作很少。基因组数据表明，海洋系统中B族维生素的供应主要依赖原核生物的生物合成。相比之下，目前测试的真核浮游植物中，有一半被确定为至少一种维生素的营养缺乏症。因此，缺乏来自原核细胞的这些生长因子的外源可能会强烈影响由大的真核细胞主导的所谓生物泵的效率。在这个项目中，南加州大学的研究人员将对海洋中最重要的生长因子之一--维生素B(B1、B7和B12)的来源和循环进行首次深入评估。这将通过在三个不同的海洋学制度(南加州附近的圣佩德罗海洋时间序列站点(SPOTS)、夏威夷海洋时间序列(HOT)站ALOHA和东热带南太平洋机遇号邮轮)的实地研究与不同海洋原核生物物种培养的实验室操纵实验相结合来实现。选择实地研究地点是为了提供关于在广泛的海洋环境中维生素循环的最大信息量。根据初步结果，研究小组假设：(1)海洋中存在几种潜在的B-维生素生产者：世界海洋上层真光带的非重氮蓝细菌和异养细菌，世界亚热带-热带LNLC区域的重氮蓝细菌进一步增加了B-维生素的可获得性；(2)一些B-维生素的合成受特定溶解的痕量金属如Co(对B12)和Fe(对B2和B7)以及有机和无机营养物的可获得性控制；(3)维生素B的产生(在颗粒相)和释放(在溶解相)之间的平衡决定了维生素的可获得性和环境循环，这种平衡由三个因素决定：微微浮游生物和微型浮游生物的活动，物理运输和营养缺陷型浮游生物的摄取。为了验证这些假设，他们开发了一种新方法，将三重四极杆质谱仪与液体色谱仪连接在一起，使他们能够在不到一升的海水以及细胞内和颗粒池中同时直接测量所有B族维生素。更广泛的影响：该项目的科学和社会影响包括阐明B族维生素的循环，否则我们永远不会完全了解维持主要生物过程所需的所有基本物质，如海洋中的初级生产和固氮。研究生和本科生都将参与这个项目。主要调查人员是COSEE-WEST计划的积极参与者，该计划涉及一个由海洋科学家、K-12教育工作者和普通公众组成的网络。