An array of persistent chemical pollutants are present in the Arctic in both biota and abiotic compartments, including snow and ice. These chemicals include older legacy contaminants such as PCBs and DDT, well as an array of newer 'emerging' contaminants with contrasting physical-chemical properties. Rapid changes to the physical and biological environment in the Arctic are changing the pathways and fate of pollutants, making biological exposure and impact difficult to predict; indeed changes to the Arctic may be altering the biological exposure to contaminants and even exacerbating it. The purpose of this proposal is to provide a mechanistic and quantitative understanding on the role of sea ice (particularly first year sea ice - the dominant ice type in a warmer Arctic) in the accumulation and subsequent release of chemical contaminants to the base of the marine foodweb. Preliminary evidence indicates that some newer contaminants are present in sea ice at concentrations akin to temperate coastal seas and we need to know the reasons for this, plus the likely exposure to biota once contaminants are released during ice break up and melt at the end of winter. Elucidating this process and understanding the fate and behaviour of chemicals in marine ice and snow can help shape chemical management strategies at the global level, particularly if changes to the Arctic cryosphere are also altering nutirent availability in ice and surrounding seawater. The contaminant and nutrient processes to be observed in the Arctic will be supported by artificial sea ice experiments. We plan to investigate this topic using field and laboratory studies and use these to model effects on the lower marine foodweb, examining whether nutrient and contaminant availability are linked and their impact on sea ice habitat functioning.

Close to the Arctic front, Iceland with its ice sheet is a strategic accessible natural laboratory to study past and modern climate changes. Like in Greenland the Icelandic Ice Sheet (IIS) provides freshwater to the North Atlantic and modifies the circulation of its thermohaline currents. While the IIS margins are relatively well constrained offshore by marine or coastal evidences, little is known about its onshore characteristics and its rates of recession during the Holocene warmer periods. This study aims at filling this chronological gap of the IIS inland during the late Quaternary deglaciation using cosmogenic nuclides dating in northeast Iceland. Terrestrial evidences of the ice sheet past margins such as moraines, glacial outwash and kame terraces have been identified north of Vatnajökull where two complementary and independent cosmogenic exposure isotopes (36Cl and 3He) will be used to date these morphological markers of the IIS retreat. In doing so, we will constrain the chronology of the ice margins and test ice-sheet deglaciation models. The cosmogenic sampling strategy will consist of complementary surface boulders and 36Cl depth profiles of amalgamated cobbles originating from common lava flows and embedded in the morphological markers. All surface samples will be dated by both 36Cl and 3He surface exposure ages from Ca-rich plagioclases and from cogenetic pyroxene phenocrysts, respectively. The double dating with 36Cl and 3He and a control of the production mechanisms with the associated depth profiles will ensure that the cosmogenic ages are sound and effective in providing age constraints of the IIS deglaciation. Improved understanding of the IIS behaviour during periods of known rapid climate change will provide new tie-points for the calibration of the IIS models and will allow a better assessment of the volume and timing of terrestrial meltwater flux to the North Atlantic. This work will contribute to a better understanding of climate evolution in the North Hemisphere over the last 20 ka and, to a better understanding of the evolution of modern Ice sheets using analogue from the past.

Stem cells are pluripotent cells that can both proliferate indefinitely producing cells identical to them, and specialise into more mature cells types. In adults, stem cells have a repair function in case of damage; adult stem cells are currently used in medical therapy. The major limitation of adult stem cells' medical applications is their low availability, and the difficulty to expand them in culture. Such issues were thought to be overcome thanks to the astonishing discovery of reprogramming by the Nobel Prize-winning Shinya Yamanaka: differentiated (i.e. somatic) cells can be programmed back to a stem-like state, obtaining the so-called induced Pluripotent Stem Cells (iPSCs). iPSCs can be subsequently converted into any cell type, to be used for regenerative and personalised medicine purposes. In Japan, the first clinical trial using iPSC-derived cells in humans is on going to cure age-related macular degeneration. iPSC therapy still faces, however, major challenges: it is difficult to reprogram somatic cells and maintain iPSCs in the pluripotent state; also, iPSC differentiation is often inefficient. In this research, we aim at applying state-of-the-art Synthetic Biology and Control Engineering tools to automatize and optimise the manufacturing of iPSC-derived cells. We will prove, using mouse cell lines, that each of the 3 mentioned challenges can be addressed if, while providing inputs that trigger pluripotency or differentiation, cells are continuously observed and inputs are consequently "adjusted" to obtain the target phenotype. This closed-loop strategy will be implemented by means of microfluidics and microscopy, that allow monitoring in real-time living cells, comparing relevant cellular outputs to the target one and applying control algorithms that allow acting on the cells to minimise the error. While proving that, by "closing the loop", it is possible to automatically control stem cell fate, we will provide a platform that allows, at the end of the experiment, to retrieve from the microfluidics device the desired cell type with high efficiency and reproducibility.

Marine ecosystems are under pressure from a range of human activities as well climate change, and there is a need to develop more integrated plans to maximise their value to society in a sustainable way. These pressures are peaking in the polar regions, especially the Arctic, where the well documented progressive reductions in extent of sea-ice cover represent a rapid, massive and fundamental change in the environmental conditions to which the species which make up Arctic marine food webs have, for millennia, been adapted: it is possible that the pace of change in the Arctic is now more rapid than the pace at which life can evolve. We already know that the shrinking of ice-cover is resulting in increased primary production in the Arctic seas. However, the way and extent to which this increased production at the base of the food web propagates up to the higher trophic levels and charismatic megafauna such as whales, seals and polar bears, is extremely uncertain and hard to predict. Other features of the habitat than sea-ice such as currents and waves, seabed topography and sediments, and land-based freshwater and nutrient inputs, also dictate patterns of production and suitability for individual species. In this project we will employ mathematics and computer science to predict the likely flows of nutrient through the marine food web, from microbes to megafauna, as the physical environment in the Atlantic Arctic changes, as it is expected to do over the coming decades. The mathematics will be incorporated into computer models which describe the complex network of interactions between living components of the food web and the dissolved and particulate, inorganic and organic nutrients. This whole complex web is driven by the seasonal fluctuations in sunlight arriving at the sea surface, and coupled to the physical circulation and three-dimensional mixing of the marine environment by winds, tides and freshwater-driven currents, which transport all the components of the food web around in space. To accomplish this we need to summarize scientific information from across the whole range biology, chemistry and physics and represent it in our models. We start the project with the legacy of two different working models of marine ecosystems developed for temperate shelf seas, which include most of the basic elements that we need to model the food webs in the Barents Sea, Fram Strait, and the wider Atlantic-Arctic in this project. We will be working with researchers in all of the already-funded Changing Arctic Ocean projects to develop the models, so as to best represent the special features that are needed to simulate high-latitude ecosystems, especially the role of sea-ice on the ecology. By the end of the project we will be able to quantify the extent to which climate change may affect the potential fishery yields of fish and invertebrates from the Atlantic Arctic, and also the trade-offs that exploiting these resources may entail with respect to the culturally important abundances of Arctic megafauna which rely on fish and invertebrates for their survival.

The normal growth of all living entities depends on an adequate source of essential elements (e.g. C, N, S, P) and, in this respect, the Earth can be considered a closed system with the supply of essential elements being finite. Therefore, the recycling of these elements through the environment is fundamental to avoid exhaustion and microbes can be viewed as the 'engine room' that drive the component processes responsible for the recycling of these elements in the Earth's biogeochemical cycles. In cycling carbon, soil microbes utilise different organic and inorganic forms of carbon as energy and carbon sources resulting in the transfer carbon between environmental compartments. However, the carbon cycle does not operate on its own but it is closely metabolically linked with that of other essential elements either via the use of these as reductants and oxidants in energy transduction or via their incorporation into biomass (or release from decaying dead biomass) as part of multiple essential element- containing biomolecules (e.g proteins, DNA). Hence, the availability of carbon is a key factor in determining the transformations and cycling of other essential elements whilst the availability of other key elements control the rate at which microbes consume and respire carbon. Such biogeochemical cycle interactions can be illustrated by the soil microbial process of denitrification: the decomposition of organic carbon under low oxygen conditions through the respiration of nitrate resulting in the step-wise reduction of nitrate to dinitrogen gas (N2) with nitrous oxide (N2O) produced as an intermediate. A central goal in microbial ecology is to link biogeochemical processes to specific microbial taxa in the environment so that the role of microbial community structure can be better represented in predictive models. A suite of methods have been developed in the last decade in order achieve this goal without the need for cultivation and characterization of isolates but none of these offer the opportunity to quantify the interactions between biogeochemical cycles in a microbially-oriented way, for example, with respect to the use of a particular carbon source as a reductant to drive denitrification. Gaining the quantitative understanding of the interactions that is required to predict essential element fluxes and feedbacks under perturbed carbon cycle and environmental change scenarios is therefore method- limited. This project will provide proof-of-concept of a new method to quantify use of carbon by bacteria whilst transforming another essential element. The bacterial denitrification pathway will serve as a case study with a focus on the bacteria using carbon to reduce N2O to N2 (the final step in denitrification) due to the crucial role that this group play in regulating the atmospheric concentration of N2O, a potent greenhouse gas. The new method involves: (i) use of C isotopes to trace microbial C consumption; (ii) labelling actively N2O-reducing microbial cells with a fluorescent dye; (iii) sorting the fluorescent cells and quantifying the C isotope content. The proof of concept will be in simple experimental systems involving known N2O-reducing bacteria and soil microcosms incubated under conditions known to promote denitrification. As a case study, we will test a theory concerning the carbon source preference of the N2O-reducing bacteria.The project brings together the complimentary expertise of the investigators (use of C isotopes, fluorescence-labelling and sorting of bacteria, denitrification biogeochemistry) and the project partner (fluorescence labelling of bacteria active in biogeochemical cycling). We will use state-of-the art stable isotope techniques to quantify microbial N2O reduction and exploit advances in instrumentation for cell sorting that enables the accurate detection of bacterial cells extracted from soil.