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

Building directly on our preliminary unpublished data and a funded sequencing grant (Joint Genome Institute, US) that will substantially support this project, we will combine environmental metagenomics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 However, our preliminary unpublished data based on eukaryotic marine phytoplankton metatranscriptomes obtained from 1) North Pacific, 2) Central Equatorial Pacific, 3) Southern Ocean, 4) North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.

This project is primarily driven by the need to address a fundamental gap in the knowledge of how temperature impacts community composition and especially metabolism of marine eukaryotic phytoplankton (microalgae). These data are key for a mechanistic understanding of how warming of the surface ocean will influence marine biogeochemcial cycling. Unpublished work presented in this grant application has already led to two invitations to international conferences (SGM and the 5th European Phycological Congress) and a manuscript currently is under in-depth review at 'Science'. Our previous work in the field of marine microalgae has led to 'Nature', 'Science' and PNAS papers including worldwide coverage on the internet, in news papers, magazines and radio (e.g. recent interview on 'Rundfunk Berlin Brandenburg', rrb). Thus, our work has impact and we are well versed in disseminating it to wide audiences and will continue to exploit this strong starting position.

In addition to conventional routes: journals, science meetings and the web, we will continue to use other local channels to bring our work to wider audiences. These routes will build on the "Beacon of Public Engagement" award "CueEast" (Community University Engagement East) to UEA and partners; see http://www.uea.ac.uk/ssf/cue-east. The Beacon Scheme is strongly supported by NERC and BBSRC. We will also be involved in "SAW" (Science Art and Writing - http://www.sawtrust.org/; PLoS Biology 2008 6; e211).

We plan the following activities to deliver impact to various beneficiaries:
1) In National Science Week, we participate in hands-on exhibitions of 'Norfolk Science-Past and Present' at the Norwich Castle Museum. We will also contribute to a showcase in the 'Norwich Forum' where PhD students and young PDRAs present their work in form of posters and presentations to the public. This event is organized by the Post Graduate Research office at UEA and takes place once a year for 3 days to disseminate current unpublished research to the public.
2) Science, Art and Writing Projects (SAW) will be set up each year at local primary schools by Mock and Moulton. These will involve visits and talks about the importance of marine microalgae for life on our planet. Experiments will be carried out to isolate microalgae from sea water. For both the diatoms and dinoflagellates, we will exemplify their extraordinary, diverse and sometimes unearthly appearance.
3) A recently setup ITEAM explores commercial opportunities for a significant discovery in the field of diatom growth regulation. An ITEAM is a group of 7 PhD students who engage with industrial partners in order to explore opportunities for commercialization. Mock is the scientific advisor for the UEA ITEAM. We will continue with this approach for novel discoveries with commercial potential made by this project.
4) Mock is directly engaged with two different companies for the commercialization of algae and their products for several different end users. These engagements are based on discovering a gene in diatoms that enhances growth (patent pending in the US). Synthetic Genomics (US) (Imad Ajjawi, PhD) and Supreme Biotechnology Inc. (Mr. Tony Dowd) have approached Mock to setup collaborative projects. Currently both companies explore the biotechnological potential of a new transgenic diatom strain and the 'growth-enhancer' gene for biofuel production and pigment synthesis.
5) Importantly, Mock is also involved in work to overexpress genes from diverse diatoms involved in lipid metabolism in higher plants (BBSRC IBTI Club PhD studentship with Prof. Johnathan Napier, Rothamsted Research) therefore he is in a great position to translate discoveries from the proposed work towards development of new strains of transgenic crops. It is very likely that this project will identify novel genes involved in algal lipid metabolism by sequencing metagenomes from many unknown microalgal species.