En-Gen: A functional genomic analysis of how a major calcifying phytoplankter responds to ocean acidification predicted for the end of the century

球石浮游动物Emily huxleyi是世界海洋中最丰富的钙化浮游植物。由于其丰富和广泛的赋存范围，深海出口的CaC03球石对海洋碱度平衡，进而对大气-海洋二氧化碳交换起着重要作用。自工业时代开始以来，由于化石燃料的燃烧和土地利用的变化，二氧化碳的大气分压(PCO2)一直在稳步增加，预计到本世纪末将达到750ppm。因此，与工业化前相比，海水的pH值和碳酸盐离子浓度预计都将大幅下降。钙化生物对碳酸盐离子浓度的变化很敏感，然而，这种敏感性的程度及其生理基础都不是很清楚。本项目的目的是研究湖北龙须草在生理上适应环境变化的机制(S)，以了解海水碳酸盐化学变化对这种重要的浮游钙化生物的影响。来自两个基因不同生态型的细胞将在目前和预计2100年在氮或磷限制下的PCO2水平的恒化器中培养。短期(2周)和长期(2年)实验将分别考察对碳酸盐化学变化的驯化和适应反应。在每个实验中，将使用由E.huxleyi基因组测序项目开发的微阵列来研究基因表达模式。基因表达将作为生理表现(光合作用与辐射)、钙化率和细胞营养含量的函数进行分析。该项目的结果将产生一组新的候选生物标志物基因，用于分析球藻的环境生理学，并有助于更好地预测E.huxleyi在下个世纪大气-海洋二氧化碳交换中的作用。由于E.huxleyi是一种全球分布的生物，经常形成大规模水华，因此有许多研究人员对其进行研究，因此这项研究将引起科学界的广泛兴趣。研究生、博士后研究员和高中生将在该项目期间接受培训，未被充分代表的少数民族将参与该研究项目。这项研究的公众宣传将通过Romberg Tiburon中心和NSF资助的湾区发现博物馆进行。

The coccolithophore Emiliania huxleyi is the most abundant calcifying phytoplankton species in the world's oceans. Due to its abundance and broad range of occurrence, deep-sea export of its CaC03 coccoliths plays a significant role in the oceans alkalinity balance, and in turn, air-sea CO2 exchange. Since the start of the industrial age, atmospheric partial pressure of CO2 (pCO2) has steadily increased due to fossil fuel combustion and land use change, and is projected to reach 750 ppm by the end of this century. As a consequence, both seawater pH and carbonate ion concentration are expected to drop significantly relative to pre-industrial times. Calcifying organisms are sensitive to changes in carbonate ion concentration, however, neither the extent of this sensitivity, nor its physiological basis, are well understood. The purpose of this project is to examine the mechanism (s) by which E. huxleyi physiologically acclimates and adapts to changes in its environment in order to understand the impact of changes in seawater carbonate chemistry on this important planktonic calcifying organism. Cells from two genetically distinct ecotypes will be cultured in chemostats at present day and projected year 2100 levels of pCO2 under nitrogen or phosphorus limitation. Both short- (2 week) and long-term (2 year) experiments will be conducted to investigate acclimation and adaptation responses to changes in carbonate chemistry, respectively. In each experiment, patterns of gene expression will be investigated using a microarray that has been developed by the E. huxleyi genome sequencing projects. Gene expression will be analyzed as a function of physiological performance (photosynthesis vs. irradiance), calcification rates and cellular nutrient content. The results of this project will generate a novel set of candidate biomarker genes for analysis of the environmental physiology of coccolithophorids and contribute to a better prediction of the role of E. huxleyi in air-sea CO2 exchange in the next century. Since E. huxleyi is a globally distributed organism that frequently forms massive blooms, there are numerous investigators studying it and this research will therefore be of broad interest to the scientific community. Graduate students, a postdoctoral investigator, and high school students will be trained during this project and underrepresented minorities will participate in this research project. Public outreach on this research will be conducted through the Romberg Tiburon Center and the NSF-funded Bay Area Discovery Museum.