Elucidating niche adaptation mechanisms in a ubiquitous marine phototroph: a targeted 'omics approach

海洋在决定世界气候方面发挥着重要作用。这部分是由于非常小的单细胞生物产生氧气和消耗二氧化碳，这些生物被称为光合微型浮游生物。海洋蓝细菌的密切相关的属原绿球藻和聚球藻是光合微型浮游生物的原核组成部分。我实验室目前和以前的工作表明，这些生物的原位群落结构相当复杂，特定的生态类型或谱系占据不同的生态位，以填充世界海洋，使它们能够在广泛的环境条件下生长和光合作用。虽然这样的分子生态学研究可以有效地绘制特定基因型的空间分布图，但决定这种全球群落结构的因素仍然很难定义。这是很重要的，因为占主导地位的picocyanobacteria谱系的变化表明主要领域的变化，在亚热带生态系统和观察和解释他们的分布和生理状态，我们基本上是评估的变化率的地球化学循环。为了更全面地了解这种生态位适应的分子基础，我们建议在这里进行一个分子的方法，专注于海洋聚球藻，以确定特定的基因集在定义这些谱系的生态“独特性”中发挥的作用。因此，拟议的项目将寻求提供一个更基本的了解环境（即进化压力）如何塑造一个重要的海洋光养生物的种群基因组，从而促进其在其首选的生态位的成功。此外，通过分析在特定环境中表达的基因的类型（和丰度），该项目将有可能提供有关决定这些生物生长速度和产量的关键环境参数的重要新信息，这些信息对于确定控制海洋光合作用至关重要。

The oceans play a major role in determining the world's climate. In part this is due to the production of oxygen and the consumption of carbon dioxide by very small, single celled organisms, which are referred to as the photosynthetic picoplankton. Marine cyanobacteria of the closely-related genera Prochlorococcus and Synechococcus are the prokaryotic components of the photosynthetic picoplankton. Current and previous work in my lab has demonstrated that the in situ community structure of these organisms is fairly complex, with specific ecotypes or lineages occupying different niches to populate the world's oceans, allowing them to grow and photosynthesise under a broad range of environmental conditions. Whilst such molecular ecological studies can effectively map the spatial distributions of specific genotypes, the factors that dictate this global community structure are still poorly defined. This is important because changes in dominant picocyanobacterial lineages indicate major domain shifts in planktonic ecosystems and by observing and interpreting their distributions and physiological states we are essentially assessing changes in the rates of biogeochemical cycles. To more completely understand the molecular basis of this niche adaptation we propose here to undertake a molecular approach focusing on marine Synechococcus so as to identify the role that specific gene sets play in defining the ecological 'distinctness' of these lineages. The proposed project will thus seek to provide a more fundamental understanding of how the environment (i.e. evolutionary pressure) shapes the population genome of an important marine phototroph, so facilitiating its success within its preferred ecological niche. Moreover, via analysis of the types (& abundance) of genes expressed in specific environments the project will potentially provide important new information on the key environmental parameters that dictate the growth rate and yield of these organisms, information which is critical for defining controls on marine photosynthesis.