Collaborative Research: Capturing the Elusive 37:4 Alkenone-predominating Lacustrine Haptophyte: Alkenone Biosynthesis, Genetics and Culture Manipulation

近年来，褐藻被认为是世界上最丰富、最多样化的初级生产者。这使得它们的代谢和碳固定途径成为最重要的问题。烯酮类脂是由异水藻目褐藻产生的，在世界上普遍存在。它是古温度重建的宝贵工具。然而，沉积物中培养的触觉植物与观测到的烯酮分布之间的不匹配阻碍了烯酮作为湖泊古温度的代用。为了将烯酮不饱和度用于湖泊古地温重建，有必要利用培养、脂质和分子表征等综合技术，全面了解湖泊产烯酮植物的生物学和生物化学特征。这一建议建立在我们成功地获得了第一种稳定的湖相共生藻类富集培养物的基础上，这种藻类主要产生C37:4烯酮，这种烯酮在淡水和半咸淡水环境中丰富。对乔治湖的湖水和浮游生物进行系统采样，并对环境参数进行现场测量，结合对我们的褐藻培养的广泛操作，将允许识别褐藻华的触发因素。我们的研究将促进多学科合作（有机地球化学、分子生物学、生理学、古气候学、湖沼学），研究重要的生物学、地球化学和古气候学问题，并允许研究生和本科生的跨学科培养。与布朗大学现有的NSF资助的GK-12项目密切互动，将使高中教师参与实地考察和实验室研究，并在当地学校进行讲座，将广泛传播我们的研究。从这项研究中产生的数据也将被纳入有机地球化学和分子生物学课程，针对高级本科/研究生水平，并帮助支持全日制研究生专注于湖泊触觉生物。

Haptophyte algae are recently credited as the most abundant and diverse primary producers in the world?s oceans, rendering their metabolic and carbon fixation pathways issues of utmost importance. Alkenone lipids produced by haptophyte algae of the order Isochrysidales occur ubiquitously in the world?s ocean and in numerous lakes and are an invaluable tool for paleotemperature reconstructions. However, the mismatch between cultured haptophytes and observed alkenone distributions in sediments has hindered the use of alkenones as a paleotemperature proxy in lakes. In order to confidently apply the alkenone unsaturation for paleotemperature reconstructions in lakes, it is necessary to fully understand the biology and biochemistry of the lacustrine alkenone-producing haptophytes using a consortium of techniques including culturing, lipid and molecular characterization. This proposal builds on our success in obtaining the first stable enrichment culture for a lacustrine haptophyte alga that produces predominantly C37:4 alkenones, the alkenone abundant in freshwater and brackish environments. Systematic sampling of lake water and plankton and in situ measurements of environmental parameters at Lake George, ND combined with extensive manipulation of our haptophyte culture will permit identification of the triggers for haptophyte algal blooms.Our study will promote multidisciplinary collaboration (organic geochemistry, molecular biology, phycology, paleoclimatology, limnology) to studying important biological, geochemical and paleoclimatological problems, and allow cross-discipline training of graduate and undergraduate students. Close interaction with Brown University's existing NSF funded GK-12 program will bring high school teachers to participate in field trips and laboratory research, and lectures given at local schools, will broadly disseminate our research. Data generated from this research will also be incorporated into organic geochemistry and molecular biology courses targeted at the advanced undergraduate/graduate level and help support a full-time graduate student focusing on lacustrine haptophytes.