Regulatory gene networks and ecological distinctness in marine Synechococcus

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来确定如何调节特定的基因集定义这些谱系的生态“独特性”。我们建议把重点放在铁（Fe）的关键营养调节子，因为这些不仅被认为是重要的资源，控制初级生产的幅度在许多海洋环境中，而且还因为这些营养物质的浓度在空间和时间上都有变化，并具有明显的“差异”，在更稳定（或同质）寡营养开放的海洋系统相比，更不稳定（或异质）的沿海沃茨。因此，有很强的理由预期，在监管能力的差异之间存在的血统占领对比利基，这种监管的“约束”，或实际上缺乏约束，促进占领特定的利基（专家）或重叠的利基（opportunities）。事实上，我们已经观察到，在我的实验室最近注释的海洋聚球藻基因组序列中，缺乏Fe收购的关键调控成分，这可能会将这些分离株限制在更稳定的环境中。因此，该项目将着手全面了解营养调节子，促进我们认为是专业寡养生物，专业中养生物或机会生物中这些关键营养物质的获取，即具有不同的生活方式，我们假设这是他们成功殖民化的关键。

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 to identify how regulation of specific gene sets defines the ecological 'distinctness' of these lineages. We propose to focus on the key nutrient regulon of iron (Fe) since not only are these thought to be important resources controlling the magnitude of primary production in many oceanic environments, but also because the concentration of these nutrients varies both spatially and temporally and with obvious 'differences' in more stable (or homogeneous) oligotrophic open ocean systems compared to more unstable (or heterogeneous) coastal waters. Hence, there is strong reasoning to expect that differences in regulatory capacity exist between lineages occupying contrasting niches, and that such regulatory 'constraints', or indeed lack of constraints, facilitate occupation of specific niches (specialists) or overlapping niches (opportunists). Indeed, we have already observed an absence of a key regulatory component for Fe acquisition in sequenced marine Synechococcus genomes my lab has recently been annotating, which may constrain these isolates to more stable environments. Thus, this project will set out to obtain a comprehensive understanding of the nutrient regulons facilitating acquisition of these key nutrients in organisms we consider to be either specialist oligotrophs, specialist mesotrophs or opportunists i.e. with differing lifestyles, which we hypothesise is key to their successful colonization of vast tracts of the world oceans.