From the North Sea to the Arctic Ocean: The impact of temperature on eukaryotic phytoplankton

直接建立在我们的初步未发表的数据和资助的测序赠款（联合基因组研究所，美国），将大力支持这一项目，我们将联合收割机环境宏基因组学（来自生物群落的基因组）和元转录组学（来自生物群落的表达基因）通过有针对性的功能分子遗传学和生物地球化学研究，首次证明海洋表面的温度对海洋生物有重要影响。对真核海洋浮游植物（微藻）群落结构和代谢影响。海洋浮游植物（微藻和蓝藻）贡献了全球约50%的碳生产，因此对元素的地球化学循环和气候产生重大影响。尽管温度对海洋中的进化、新陈代谢和生物地球化学循环具有重要意义，但对天然真核浮游植物群落的确切影响仍然存在很多争议，但对于预测地球上一些最重要的初级生产者的全球变暖结果具有重要意义。然而，我们的初步未发表的数据的基础上获得的真核海洋浮游植物元转录组从1）北太平洋，2）中赤道太平洋，3）南大洋，4）北大西洋，和5）北冰洋第一个证据表明，温度至少是一样重要的营养物质和光的群落结构和海洋微藻在全球表层海洋的代谢。特别是硅藻和甲藻代谢的基础上表达的基因在5个调查的海洋栖息地显示出高度的相关性与温度和少得多，所以与任何测量的营养物质。mRNA翻译成蛋白质似乎是海洋微藻中最依赖于温度的过程，表明温度和核糖体转录本丰度之间的负相关性。蛋白质合成是一个显著的原因。75%的细胞总能量预算和核糖体含量可以高达细胞中总蛋白质的25%。因此，温度可能对核糖体蛋白质的丰度有显着的影响，也可能对海洋微藻中的总蛋白质含量的海洋食物网和海洋地球化学循环的碳和氮在不同纬度的温度区的表面海洋。在这个研究项目中，我们的目标是海洋中对温度最敏感的区域之一：北大西洋和北冰洋。预计许多北极浮游植物物种将无法适应变暖，因为预测的环境变化将在一个时间尺度上发生太快，进化过程无法做出反应。因此，更有可能的是，适应北极低温环境的物种将被来自北极圈外低纬度地理区域的入侵者所取代，这一过程已经在进行中。因此，我们要采样自然浮游植物群落的宏基因组学和metatranscriptomics从北海南部到高北冰洋的横断面调查的差异，从北大西洋的潜在入侵者社区的社区组成和代谢相比，北冰洋的极地社区。我们还将通过使用抗体和蛋白质印迹来研究在较低温度下增加核糖体转录物是否会导致北大西洋和北极硅藻和甲藻物种中核糖体蛋白浓度更高。将通过测量选定的微藻物种和自然群落在不同温度下的细胞蛋白质浓度和颗粒有机碳和氮来调查生物地球化学循环的潜在后果。该项目将首次深入了解温度变化将如何影响北大西洋和北极海洋微藻群落的组成和代谢。

Building directly on our preliminary unpublished data and a funded sequencing grant (Joint Genome Institute, US) that will substantially support this project, we will combine environmental metagenomics (genomes from a community of organisms) and metatranscriptomics (expressed genes from a community of organisms) with targeted functional molecular genetics and biogeochemical studies to provide first evidence that temperature in the surface ocean has a significant impact on eukaryotic marine phytoplankton (microalgae) community structure and metabolism. Marine phytoplankton (microalgae and cyanobacteria) contribute about 50% of global carbon production and so have significant impact on biogeochemical cycling of elements and therefore climate. Despite the significance of temperature for evolution, metabolism and biogeochemical cycles in the ocean, the exact impact on natural eukaryotic phytoplankton communities is still subject to much debate but is of significant importance to predict the outcome of global warming for some of the most important primary producers on earth. However, our preliminary unpublished data based on eukaryotic marine phytoplankton metatranscriptomes obtained from 1) North Pacific, 2) Central Equatorial Pacific, 3) Southern Ocean, 4) North Atlantic, and 5) the Arctic Ocean give first evidence that temperature is at least as important as nutrients and light for community structure and metabolism of marine microalgae in the global surface ocean. Especially diatom and dinoflagellate metabolism based on expressed genes across the 5 investigated marine habitats shows a high correlation with temperature and much less so with any of the measured nutrients. Translation of mRNA into proteins seems to be the most temperature dependent process in marine microalgae, indicated by a negative correlation between temperature and the abundance of ribosomal transcripts. Protein synthesis accounts for a remarkable ca. 75% of the cells total energy budget and ribosome content can be as high as 25% of total proteins in a cell. Thus, temperature might have a significant impact on the abundance of ribosomal proteins and maybe also on the total protein content in marine microalgae with consequences for marine food-webs and biogeochemical cycling of carbon and nitrogen in different latitudinal temperature zones of the surface ocean. For this research project, we have targeted one of the most temperature sensitive regions of the ocean: North Atlantic and Arctic Ocean. It is expected that many Arctic phytoplankton species won't be able to adapt to warming because the predicted environmental changes will occur on a time scale too fast for evolutionary processes to react. Thus, it is more likely that species that are well adapted to the low-temperature Arctic environment will be replaced by intruders from lower-latitude geographic areas outside the Arctic Circle, a process that already is underway. Thus, we are going to sample natural phytoplankton communities for metagenomics and metatranscriptomics on a transect from the southern North Sea to the high Arctic Ocean to investigate differences in community composition and metabolism of potential intruder communities from the North Atlantic in comparison to polar communities of the Arctic Ocean. We will also investigate whether increasing ribosomal transcripts under lower temperatures result in higher concentrations of ribosomal proteins in North Atlantic and Arctic diatom and dinoflagellate species by using antibodies and Western Blots. Potential consequences for biogeochemical cycling will be investigated by measuring cellular protein concentrations and particulate organic carbon and nitrogen under different temperatures in the selected microalgal species and natural communities sampled for sequencing. This project will provide first insights into how temperature changes will impact North Atlantic and Arctic marine microalgal community composition and metabolism.