Wave-modulated Arctic Air-sea eXchanges and Turbulence (WAAXT) is a project designed to improve our understanding of ocean boundary layer processes in a changing Arctic Ocean. Sea ice extent in the Arctic Ocean has been decreasing since the beginning of the satellite era, meaning that open-water, as opposed to under-ice, oceanographic processes are becoming increasingly important for Arctic dynamics. One of the most fundamental differences between the open and ice-covered oceans is the presence of surface waves. Surface waves and wave-driven processes drastically alter air-sea fluxes, upper-ocean turbulence, and the dominant dynamical balance in the upper ocean. WAAXT will be based on a series of field experiments to study the small-scale processes associated with this emerging wave climate, with a particular focus on near-surface turbulence. Three major effects of wave processes will be targeted: 1) Modification and suppression of ice formation by wave motions and the associated elevated near-surface turbulence. 2) Physical breakup of sea ice by wave motions, and the associated contributions to the modification of air-sea fluxes, upper-ocean structure, and melt rates. 3) Interactions between wave-driven turbulence, especially breaking and Langmuir circulations, with the unique salinity-based stratification in the Arctic basin. A key aspect of these processes is their horizontal variability, which will be captured using a multi-platform approach. Experimental work will begin in a natural laboratory in the Saint Lawrence Estuary and move to the Arctic as scientific and technical capacity is developed. The long-term goal for WAAXT is to produce the data and parameterizations needed to understand climate-scale feedbacks associated with the emerging wave climate in the Arctic basin.

The objective of ARCHPOL is to discover novel functional DNA polymerases in hyperthermophilic archaea and to examine the potential impact of relevant damaged nucleic acids onto their intrinsic properties. This interest is sustained by the limited number of DNA polymerases identified to date in the genome of the hyperthermophilic model, P. abyssi, posing the intriguing question of how this microorganism evolve to deal with a specific threshold of DNA damage without affecting cell growth and viability. Despite efficient DNA repair strategies employed to remove damaged nucleic acids, some of them persist. Palud. A et al recently published that DNA polymerases from P. abyssi develop unique and efficient features to counteract residual DNA lesions. In ARCHPOL, the functional analyses of conventional and damaged-induced DNA polymerases will be detailed in the presence of relevant damaged nucleic acids. This project aims at giving a clear picture of the involvement of DNA polymerases in damage tolerance in hyperthermophilic archaea that may provide useful information to further refined model of genomic maintenance in all living organisms. Unique and innovative methods will be applied to discover novel DNA polymerases and to identify the types and occurrence of damaged nucleic acids. A gas-lift bioreactor which offers the possibility to inflict genotoxic stresses will be used to produce the P. abyssi biomass. The types and rates of damaged nucleic acids will be assessed by cutting-edge analytic methods. Identification and captured of novel DNA polymerases will be obtained by implemented and original techniques. When required, relevant DNA damage will be introduced into DNA template and functional characterization of appropriate DNA polymerases will be investigated. As a consequence from basic fundamental research, ARCHPOL plans to develop valuable biochemical properties from P. abyssi polymerases that could be applied to various biotechnological applications. The current tendency in Polymerase chain Reaction (PCR) technology is to discover thermostable polymerases with broadened substrate spectra that could find applications in forensics and paleogenetics. In order to optimize the chances of success of ARCHPOL, which combines scientific and technological objectives, a highly competent and complementary team will be unified.

Oceans health is intimately linked to animal and human health in a One Health framework. Marine zoonotic diseases threaten animal and human health and well-being, ecosystem integrity and economic development of marine coastal systems. Coastal waters, where oysters are produced, are low inerty systems highly sensitive to contaminants, which can also accelerate the emergence of epidemics/epizootics and zoonotic diseases in marine ecosystems. Among them, copper is a widespread pollutant that acts as a major selective pressure influencing microorganism survival and evolution as it can be deadly for many bacteria. Vibrio aestuarianus subsp. francensis is an emerging pathogen that threatens European aquaculture since 2011. Recent work revealed that this bacterium is an oyster-restricted specialized pathogen. The IHPE laboratory has evidenced that an intimate relationship between virulence and copper resistance conferred by a pathogenicity island could be key in the adaptation of the subspecies to the oyster host. This proposal aims to evaluate the role of copper resistance in V. aestuarianus francensis adaptation to oyster, and to unveil the copper resistance molecular pathways underlying this key phenotype and infection outcome. Specifically, we will address the following questions: -Is copper resistance required for V. aestuarianus adaptation and virulence to its host? -What is the diversity of V. aestuarianus copper resistance mechanisms? -Does accumulated copper in oyster have an impact in the host-pathogen outcome? By investigating resistance to copper and virulence as interlinked phenotypes of pathogens and its impact on oyster immunity, we will bring knowledge on the way copper influences the pathogens´dynamics, driving their evolution and specialization in marine ecosystems, but also modulating host-pathogen interactions. Ultimately, the project should help shellfish farmers and policy-makers mitigate the effects of anthropogenic pollution on aquaculture services.

Over geological times, the evolution of carbon isotope compositions of carbonates (δ13Ccarb) in sedimentary record highlights many positive isotopic excursions (CIEs), reflecting significant perturbations of the carbon cycle in Earth surface environments. Although generally interpreted as a consequence of an increase of organic carbon burial in sediments, the lack of high organic carbon content, as well as the strong spatial and temporal variability, observed in many sedimentary successions recording CIEs challenge this postulate. Among other alternative hypothesis involving regional or local control, the potential influence of methanogenesis, i.e. the biological process of anaerobic organic matter degradation producing methane (CH4), has been raised; its ability to generate similar isotopic signatures has been demonstrated in modern analogue. Although the processes behind CIEs are questioned, providing more information about methanogenesis impact is challenging based on traditional isotopic tool like δ13Ccarb, as its isotopic effect on is similar to that of organic carbon burial increase. Recently, stable isotope compositions of metals used as enzymatic cofactors of CH4-related processes were investigated to explore their potential as biomarkers of methanogenesis. During the last decade, significant advances have been made on using Ni isotopes as tracers of methanogenesis but important challenges remain to better constrains both their potential and limit. In order to improve our understanding of CH4 cycle and its impact on Earth’s surface environments through geological times, we will investigate further the potential of Ni isotopes and its potential couplings with traditional stable isotope in various modern settings and past environments to enhance our ability to track and discriminate the influence of CH4-related processes through Earth’s history.