Production and Fate of Oxylipins in Waters of the Western Antarctic Penninsula: Linkages Between UV Radiation, Lipid Peroxidation, and Carbon Cycling

南极上空平流层臭氧的消耗导致到达海洋表面的太阳紫外线辐射异常高。尽管对破坏臭氧层的污染物颁布了禁令，但预计这种现象将在下半个世纪继续下去。 近表层海洋中的浮游植物受到不同量的UVR的影响，并含有大量的脂质（脂肪）。 由于浮游植物处于食物链的底部，它们的脂质进入南极海洋生态系统的食物网。 紫外线辐射很容易改变浮游植物脂类的分子结构。 当这种情况发生时，它们的脂质可以从健康分子转化为已知对生殖和发育过程具有破坏性的潜在有害分子（氧化脂质）。该项目将使用最先进的分子方法来回答有关紫外线辐射对浮游植物中脂质分子的破坏程度，以及这些分子如何影响南极洲附近海洋中的食物链的问题。 脂质过氧化通常被援引为浮游植物暴露于紫外线产生的活性氧（ROS）的增加的结果，但文献几乎是沉默的过氧化脂质及其副产品（即氧脂）在海洋中。 在西南极半岛（WAP）的沃茨，春季硅藻的大量繁殖对整个海洋初级生产力有重要贡献。 来自硅藻的氧脂蛋白具有高度的生物活性;它们对浮游动物、食草动物、细菌和其他浮游植物的影响一直是深入研究的主题。 然而，几乎所有的这些工作都集中在通过酶促途径产生氧脂，而不是通过涉及UVR和/或ROS的途径。 此外，严格的实验工作的影响，氧脂已被限制几乎完全纯文化和人工社区。 因此，这些分子破坏碳循环的真正潜力是非常不受约束的，并且在WAP的沃茨中完全未知。 凭借基于高质量分辨率质谱法的新的高灵敏度，最先进的分析技术，首席研究员和他的研究小组已经开始发现天然WAP植物群落中氧化脂质的精致多样性。 这些技术将被应用于了解紫外线，活性氧，氧脂和碳循环之间的联系。该项目将回答的问题，紫外线辐射，通过活性氧，影响氧化油脂生产硅藻在WAP表面沃茨在控制实验中进行的现场站。 有了这个问题的答案，该项目还将在一次研究航行中设法回答这一现象如何影响碳的流动，特别是系统中有机碳的出口。在WAP中，富含氧脂素的水生生物群落所经历的紫外线辐射引起的压力水平是独一无二的，这使得南极洲成为回答这些基本问题的唯一地点。主要活动将包括人工膜和硅藻培养物的实验室实验，以及WAP沃茨中浮游植物、浮游动物和细菌的实地实验。

The depletion of stratospheric ozone over Antarctica leads to abnormally high levels of ultraviolet radiation (UVR) from the sun reaching the surface of the ocean. This phenomenon is predicted to continue for the next half century, despite bans on ozone-destroying pollutants. Phytoplankton in the near surface ocean are subjected to variable amounts of UVR and contain a lot of lipids (fats). Because phytoplankton are at the base of the food chain their lipids makes their way into the Antarctic marine ecosystem's food web. The molecular structures of phytoplankton lipids are easily altered by UVR. When this happens, their lipids can be transformed from healthy molecules into potentially harmful molecules(oxylipins) known to be disruptive to reproductive and developmental processes. This project will use state-of-the-art molecular methods to answer questions about extent to which UVR damages lipid molecules in phytoplankton, and how these resultant molecules might effect the food chain in the ocean near Antarctica. Lipid peroxidation is often invoked as consequence of increased exposure of phytoplankton to UVR-produced reactive oxygen species (ROS), but the literature is practically silent on peroxidized lipids and their byproducts (i.e. oxylipins) in the ocean. In waters of the West Antarctic Peninsula (WAP), spring-time blooms of diatoms contribute significantly to overall marine primary production. Oxylipins from diatoms can be highly bioactive; their impact on zooplankton grazers, bacteria, and other phytoplankton has been the subject of intense study. However, almost all of this work has focused on the production of oxylipins via enzymatic pathways, not by pathways involving UVR and/or ROS. Furthermore, rigorous experimental work on the effects of oxylipins has been confined almost exclusively to pure cultures and artificial communities. Thus, the true potential of these molecules to disrupt carbon cycling is very poorly-constrained, and is entirely unknown in the waters of the WAP. Armed with new highly-sensitive, state-of-the-art analytical techniques based on high-mass-resolution mass spectrometry, the principal investigator and his research group have begun to uncover an exquisite diversity of oxylipins in natural WAP planktonic communities. These techniques will be applied to understand the connections between UVR, ROS, oxylipins, and carbon cycling. The project will answer the question of how UVR, via ROS, affects oxylipin production by diatoms in WAP surface waters in controlled experiments conducted at a field station. With the answer to this question in hand, the project will also seek to answer how this phenomenon impacts the flow of carbon, particularly the export of organic carbon from the system, during a research cruise. The level of UVR-induced stresses experienced by oxylipin-rich planktonic communities in the WAP is unique, making Antarctica the only location for answering these fundamental questions. Major activities will include laboratory experiments with artificial membranes and diatom cultures, as well field experiments with phytoplankton, zooplankton, and bacteria in WAP waters.