Microbial communities comprise the majority of the biomass in the oceans and drive nutrient and energy cycling, thereby supporting also the polar ecosystems. The Arctic Ocean ecosystem is expected to undergo major climate change related transformations in the coming decades. Recent data indicate that the future Arctic Ocean will experience a shift at the base of the food web towards small-sized phytoplankton, which will lower the efficiency of the Arctic ecosystem. Viruses are expected to be important mortality agents specifically for these smaller-sized phytoplankton, thereby stimulating the microbial food web, diminishing transfer of organic matter to higher trophic levels and reducing the biologically-driven CO2 sequestration in the deep ocean. The proposed project will study temporal variation in Arctic marine microbial interaction, and more specifically the importance of viral lysis over grazing, in relation to host community composition. Additionally, we will study the influence of fine sediments in glacier outflow on virus-host interactions. In order to clarify the effect of changing environmental conditions on the microbial interactions in these ecologically important waters, the influence of combined environmental changes (e.g. temperature and salinity, light) will be studied using 2 small-sized phytoplankton model species in the presence and absence of host-specific viruses. This timely study is primed to deliver essential data for ecosystem modeling, provide a solid base for future studies, and contribute to predictions of ecological relevant shifts in key players and ecosystem productivity as a result of global climate change.

Life leads to death, which is arguably the sole universal characteristic of life. The association between the rate of living and the rate of dying has fascinated biologists for a century, but the principal causes of ageing in humans and other organisms are still not resolved. Life span and rates of senescence vary distinctly, even between closely related species of similar size. Yet, for many organisms an intriguing relation between metabolic rate and lifespan is observed: when summed over lifetime, the metabolic rate per unit body mass is remarkably constant. This relation spans a wide range of organisms from yeast to elephant, and includes humans. Also within species, metabolism seems to be causally related with ageing, since caloric (or dietary) restriction typically enhances life expectancy. Despite intense research efforts, the nature of the relationship between metabolism and ageing remains enigmatic. By establishing a Systems Biology Centre called Energy Metabolism and Ageing (SBC-EMA), we will apply a systems biology approach to shed new light on metabolism, ageing, and their interaction. The metabolic rate of an organism is the result of the complex interplay of biochemical and physiological processes acting at various levels of organisation (mitochondria, cells, tissues, organs). Similarly, the physiological and molecular deterioration that characterizes ageing reflects the failure of networks of interacting cells, tissues and organs. Hence, by their very nature both metabolism and ageing require a systems biology approach in order to achieve a full understanding of their nature and their interaction. To unravel the complex relationship between energy metabolism and lifespan, SBC-EMA will combine large-scale data generation efforts with both data-driven top-down approaches and hypothesis-driven bottom-up approaches. In the first phase of its development, the Centre will focus on two model systems: the yeast Saccharomyces cerevisiae and mice Mus musculus. Metabolism and ageing in unicellular yeast and mice shows many similarities as well as differences, but the existence of a universal relation between metabolic rate and ageing suggests that key mechanisms underlying the ageing process are conserved from microorganisms to humans. We aim to discover these general mechanisms and this is an important motivation to study mouse and yeast next to each other. Yeast allows detailed investigations at the level of cells and organelles and they age rapidly. Moreover, a plethora of ?omics? information and techniques is already available, also within the University of Groningen, and metabolic and signalling pathways have been well characterised. Mice will be used to generate and test hypotheses involving intercellular and inter-organ relationships that are critical in higher organisms including humans. By applying similar manipulations (caloric restriction) in two model systems, we will simultaneously study intracellular (yeast) and higher-order (mice) processes in unprecedented detail with the aim to uncover the fundamental ageing processes shared by all life. This proposal is a joint research initiative of two faculties of the University of Groningen, the Faculty of Mathematics and the Natural Sciences (FMNS) and the Faculty of Medical Sciences (FMS). To achieve our ambitious goal, SBC-EMA brings together leading groups from both faculties, with expertise ranging from biochemistry, (molecular) biology, physiology and medicine to mathematics, statistics, bioinformatics and theoretical biology. The research theme of SBC-EMA builds on a rich history in both energetics and ageing research in both faculties. The University of Groningen has identified Healthy Ageing as one of its central research themes, and has founded the European Research Institute on the Biology of Ageing (ERIBA), which will focus on fundamental aspects of the biology of ageing. SBC-EMA will be physically and scientifically embedded within ERIBA together with other facilities like the Groningen Genomics Coordination Centre. By creating first-class infrastructure and by their recruitment policy, the University already demonstrates its commitment to systems biology. They also show a commitment to this proposal by providing 12 PhD student positions in addition to the positions requested in this proposal. SBC-EMA will be a vibrant Centre where scientists with diverse backgrounds will meet and collaborate on a daily basis to understand the fundamentals of ageing. Although research in SBC-EMA is predominantly fundamental, the topic of (healthy) ageing is of major societal relevance. Our research program on yeast and mice will therefore interact closely with Lifelines (and the complementary Systems Genetics endeavours), which will become the largest longitudinal population study in the Netherlands, involving more than 150,000 individuals. SBC-EMA will also have considerable scientific and educational outreach, by making data and results available to the scientific community, by developing user-friendly systems biology software, and by launching attractive systems biology courses for graduate and postgraduate students.

Despite phytoplankton, viruses and zooplankton grazers being key players in aquatic ecosystems, only sparse knowledge exists of their seasonal and interactive role in the Antarctic waters. Given the global interest in the Antarctic Peninsula for its ecological importance to the food web, and for the climate change-induced environmental changes occurring there, it is timely to study the following barely explored objectives: (1) the temporal dynamics of phytoplankton, viruses and zooplankton in the coastal waters of the western Antarctic Peninsula, (2) determine viral lysis rates of phytoplankton and compare to micro- and mesozooplankton grazing, (3) examine to what extent viral infection affects the lipid composition of phytoplankton in field and laboratory and (4) establish how changing phytoplankton community structure and biochemical composition controls the lipid composition and overwintering strategies of dominant calanoid copepods. This project will be the first synergistic study on important interactive processes in the waters of the Antarctic Peninsula that are experiencing rapid environmental change. The temporal, comparative and integrative character of this study that spans trophic levels is unique, and will significantly advance our comprehension of aquatic food webs in a changing world.