Collaborative Research and RUI: Assessing phosphorus-status in Prochlorococcus through kinetics and molecular approaches in chemostats and natural populations

合作研究和 RUI：通过恒化器和自然种群中的动力学和分子方法评估原绿球藻中的磷状态

• 批准号: 0453019
• 负责人: Lisa Moore
• 金额: --
• 依托单位: University of Southern Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0453019&HistoricalAwards=false
• 关键词: Collaborative; Research; RUI; Assessing; phosphorus

Global climate change, likely caused by human activities, is having an impact on the oceans. In the North Pacific Subtropical Gyre, a domain shift to an ecosystem dominated by prokaryotic organisms appears to be occurring due in part to climate-related increases in N2 fixation and subsequent phosphorus (P)-limitation. In this region, populations of the unicellular marine cyanobacterium Prochlorococcus have been increasing over the last several decades. It is not clear whether Prochlorococcus populations are P-limited or whether they have a competitive advantage under conditions of P limitation. Recently it has been reported that the HLII genotype of Prochlorococcus dominates in these P-limited waters, and HLI Prochlorococcus are present in very low concentrations. Studies on P utilization and P-stress response of axenic HLI and HLII Prochlorococcus isolates revealed significant differences in their ability to utilize organic P sources and in alkaline phosphatase activity, whereas a genomic comparison revealed few differences in their complement of P-related genes. This raises the question of what differentiates the P physiology of these two HL genotypes, and whether natural populations of Prochlorococcus experience P limitation and utilize organic P. The investigators will carry out a study employing physiological and genetic approaches on cultured isolates as well as natural populations. These will include P-limited uptake kinetic studies on axenic HL strains of Prochlorococcus to determine their relative competitive ability and examine expression of key P-related genes in P-limited chemostats. They will also carry out a field study to determine if, and which portions of, the Prochlorococcus populations are P-limited through examination of the genotype-specific gene expression and community response in natural populations and P-enrichment bottle experiments. The proposed work is designed to address one aspect of a larger scientific issue: what environmental factors regulate Prochlorococcus, the most abundant phytoplankton species in the world's oligotrophic oceans? The investigators will examine physiological and molecular responses of Prochlorococcus to P-limitation in cultured and natural populations. This combination of traditional physiological methods with state-of-the-art molecular techniques will allow a better understanding of the ecophysiology of Prochlorococcus and the genotype-specific physiological status of natural Prochlorococcus populations. Ultimately, the intent is to relate community structure to physiological function and possibly to changes in the marine P cycle. The project will support the work of two female investigators in the early stages of their academic careers as well as three graduate students, and multiple undergraduates at both institutions. The project will provide valuable research and field experience to undergraduates at USM, which is primarily an undergraduate institution serving mainly non-traditional students in the Southern Maine region. The cross-fertilization of ideas and techniques between USM and UW will have a direct influence on the content of course offerings at both institutions, through continued development of new, research-based laboratory assignments.

可能由人类活动引起的全球气候变化正在对海洋产生影响。 在北太平洋副热带环流中，似乎正在发生向以原核生物为主的生态系统的转变，部分原因是与气候相关的 N2 固定增加和随后的磷 (P) 限制。 在该地区，单细胞海洋蓝藻原绿球藻的数量在过去几十年中一直在增加。目前尚不清楚原绿球藻种群是否受到磷限制，或者它们在磷限制条件下是否具有竞争优势。 最近有报道称，HLII 基因型原绿球藻在这些 P 限制水域中占主导地位，而 HLI 原绿球藻的浓度非常低。 对纯 HLI 和 HLII 原绿球藻分离株的磷利用和磷胁迫反应的研究表明，它们利用有机磷源的能力和碱性磷酸酶活性存在显着差异，而基因组比较表明它们的磷相关基因的补体差异不大。 这就提出了一个问题：这两种 HL 基因型的 P 生理学有何不同，以及原绿球藻的自然群体是否经历 P 限制并利用有机 P。研究人员将采用生理和遗传学方法对培养分离株以及自然群体进行研究。 这些将包括对原绿球藻的无菌 HL 菌株进行 P 限制摄取动力学研究，以确定其相对竞争能力并检查 P 限制恒化器中关键 P 相关基因的表达。 他们还将开展实地研究，通过检查自然种群中的基因型特异性基因表达和群落反应以及磷富集瓶实验，确定原绿球藻种群是否以及哪些部分受到磷限制。 拟议的工作旨在解决一个更大的科学问题的一个方面：哪些环境因素调节原绿球藻（世界寡营养海洋中最丰富的浮游植物物种）？研究人员将检查培养和自然种群中原绿球藻对磷限制的生理和分子反应。 传统生理方法与最先进的分子技术的结合将有助于更好地了解原绿球藻的生态生理学和天然原绿球藻种群的基因型特异性生理状态。 最终，目的是将群落结构与生理功能以及可能的海洋磷循环的变化联系起来。 该项目将支持两个机构的两名处于学术生涯早期阶段的女性研究人员以及三名研究生和多名本科生的工作。 该项目将为 USM 的本科生提供宝贵的研究和现场经验，USM 是一所本科院校，主要为缅因州南部地区的非传统学生提供服务。 通过不断开发新的、基于研究的实验室任务，USM 和 UW 之间的思想和技术的交叉融合将直接影响两个机构的课程内容。