Collaborative Research: Alternative Nutritional Strategies in Antarctic Protists

该奖项由2009年《美国复苏和再投资法案》(公法111-5)资助。大多数生物通过光合作用(光合作用)或有机物质的摄取/同化(异质营养)来满足其碳和能量需求。然而，一种结合了光养和异养的营养策略--混合营养--在地理和分类学上在水生系统中很普遍。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，它们在南大洋食物网中发挥着重要作用。最近对南大洋甲藻的研究表明，它隔离了南极洲棕囊藻的功能叶绿体。这种甲藻在罗斯海很丰富，在南大洋的其他地方也有报道，可能有绕极分布。通过结合营养模式。与纯自养和异养相比，混合营养可能提供竞争优势。该项目的目标是了解南极物种在同一生物体中结合光营养和吞噬过程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，以及对克雷普氏菌和最近从我们的南极培养标本中发现的混合营养生物的实验室实验。这项研究将涉及：1)南极混合营养体中光营养和吞噬的相对贡献；2)克雷普兰与其kletop质体关系的性质；3)南大洋春季/夏季混养和克雷普兰的分布和丰度；4)混合营养和克来普兰对猎物种群的影响、影响这些行为的因素以及这些群体在其自然环境中的生理条件。该项目将有助于维护科学界可获得的异养、光养和混合营养南极原生生物的培养收藏，并将培训坦普尔大学的研究生和本科生。研究结果和活动将通过私人投资机构的网站和其他公共论坛向非科学受众总结，并将通过与新英格兰COSEE的合作让中学教师参与。

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.