Collaborative Research: Alternative Nutritional Strategies in Antarctic Protists

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。大多数生物通过光合作用（光养）或摄入/同化有机物质（异养）来满足它们的碳和能量需求。然而，结合光养和异养的营养策略-混合营养-在地理和分类上广泛存在于水生系统中。虽然混合营养体在南大洋的存在是最近才知道的，但初步证据表明它在南大洋食物网中起着重要作用。最近对南大洋鞭毛藻（Kleptodinium）的研究表明，它可以隔离开花形成的褐藻（Phaeocystis antarctica）的功能叶绿体。这种鞭毛藻在罗斯海非常丰富，在南大洋的其他地方也有报道，并且可能具有环极分布。通过结合营养模式。混合营养可能比纯自养和异养生物具有竞争优势。该项目的目标是了解在同一生物体中结合光养和吞噬过程的南极物种的替代营养策略的重要性。这项研究将结合对南大洋浮游生物和冰群落的实地调查，以及对Kleptodinium的实验室实验，以及最近从我们的南极文化收藏中发现的混合营养体。研究内容包括：1)光养和吞噬在南极混合营养体中的相对贡献；2)贼狼啉及其贼狼体关系的性质；3)南大洋春季/夏季混合营养体和Kleptodinium的分布及丰度；4)混合营养体和Kleptodinium对猎物种群的影响、影响这些行为的因素以及这些群体在自然环境中的生理状况。该项目将有助于维持异养、光养和混合营养南极原生生物的培养收藏，以供科学界使用，并将培训天普大学的研究生和本科生。研究成果和活动将通过pi的网站和其他公共论坛向非科学受众进行总结，并将通过与COSEE-New England合作，让中学教师参与其中。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Most organisms meet their carbon and energy needs using photosynthesis (phototrophy) or ingestion/assimilation of organic substances (heterotrophy). However, a nutritional strategy that combines phototrophy and heterotrophy - mixotrophy - is geographically and taxonomically widespread in aquatic systems. While the presence of mixotrophs in the Southern Ocean is known only recently, preliminary evidence indicates a significant role in Southern Ocean food webs. Recent work on Southern Ocean dinoflagellate, Kleptodinium, suggests that it sequesters functional chloroplasts of the bloom-forming haptophyte, Phaeocystis antarctica. This dinoflagellate is abundant in the Ross Sea, has been reported elsewhere in the Southern Ocean, and may have a circumpolar distribution. By combining nutritional modes. mixotrophy may offer competitive advantages over pure autotrophs and heterotrophs. The goals of this project are to understand the importance of alternative nutritional strategies for Antarctic species that combine phototrophic and phagotrophic processes in the same organism. The research will combine field investigations of plankton and ice communities in the Southern Ocean with laboratory experiments on Kleptodinium and recently identified mixotrophs from our Antarctic culture collections. The research will address: 1) the relative contributions of phototrophy and phagotrophy in Antarctic mixotrophs; 2) the nature of the relationship between Kleptodinium and its kleptoplastids; 3) the distributions and abundances of mixotrophs and Kleptodinium in the Southern Ocean during austral spring/summer; and 4) the impacts of mixotrophs and Kleptodinium on prey populations, the factors influencing these behaviors and the physiological conditions of these groups in their natural environment. The project will contribute to the maintenance of a culture collection of heterotrophic, phototrophic and mixotrophic Antarctic protists that are available to the scientific community, and it will train graduate and undergraduate students at Temple University. Research findings and activities will be summarized for non-scientific audiences through the PIs' websites and through other public forums, and will involve middle school teachers via collaboration with COSEE-New England.