Marine plastic litter is a global environmental problem (descriptor 10 of the EU Marine Strategy Framework Directive) since almost 10% of the 299 million tons of plastic produced worldwide gets accidentally or deliberately into the environment. The oceans are considered as the ultimate recipient of plastic litters. Plastics containing pro-oxidant additives called oxo-biodegradable (OXO) have been introduced onto the market (10% of the plastic bags in France are OXO) as material promising biodegradability, but their fate in marine waters is poorly investigated. The OXOMAR project gathers together the largest manufacturer of OXO in Europe (Symphony Environmental Technologies), a small or medium-sized enterprise specialized in valorization of academic researches on polymer ageing (CNEP), and three academic units (ICCF, LOMIC, IFREMER) specialized in chemistry of materials, marine microbiology and ecotoxicology. The objective of OXOMAR is to evaluate the abiotic (task 1) and biotic (task 2) degradation of OXO at sea, as well as its potential toxicity for marine organisms (task 3). This project present several novelties including: (i) the use of artificial ageing to evaluate the fate of OXO of different compositions (including an OXO-HYDRO hybrid polymer) in the Oceans related to abiotic environmental factors, (ii) the combination of innovative methodologies using stable isotope labelled 13C-OXO to deliver the first estimation of the OXO biodegradation rate at sea, together with the original identification of the bacteria performing this biodegradation, (iii) the evaluation of the possible toxicity of OXO by considering both the ingestion of micro-plastics and the leaching of pro-oxidant additives by using unprecedented set of marine organisms from various trophic levels, habitats and feeding behaviors. The evaluation of the fate of new formulations of plastics in the environment is a societal and environmental concern, which perfectly fits with the objective of the “Défi 1” (ORIENTATION 4). The potential for scientific breakthrough is very high in this project, since very few studies have been done so far on the fate of OXO in marine waters. The new research results obtained in this PRCE project will be mutually beneficial for the academic and industrial parts and for the market of OXO in general. For instance, “the impact of the use of oxo-biodegradable plastic carrier bags on the environment” has been identified as one of the priority of the European Council and Parliament for the reduction in consumption of plastic bags (Art. 20a (2) of Directive 2015-720).

Climate change has triggered fundamental modifications of marine biotopes in the Arctic Ocean (AO). The decrease in the extent of the ice pack during summer has led to a 20% increase in pan-Arctic primary production (PP) over the last decade. Phytoplankton blooms now occur earlier in several parts of the AO. In other parts, the structure of the phytoplankton community is shifting toward smaller species, typical of more oligotrophic conditions and some species found in warmer waters now migrate into the Arctic Ocean. Phytoplankton grow in the top tens of meters of both ice-free and ice-covered waters. The phytoplankton spring bloom (PSB) that develops at the ice-edge accounts for >50% of annual primary production in the AO, and is generally associated with both large energy transfer to higher trophic levels and export of carbon to the bottom. As well, the culture, health and economic capacity building of Northerners are closely associated with marine resources supported by the PSB. The Arctic PSB develops in the seasonally-covered ice zone (SIZ), the extent of which is expected to increase significantly during the next years, possibly over the whole AO as early as in 2030. How the PSB will actually evolve in this context is unknown. Will it span over the entire AO, and thereby make the AO ecosystems more productive? Will the ongoing modifications in physical properties of the AO rather limit the PSB and PP in general? How will biodiversity respond to and/or impact on those changes? To be able to answer these questions, it is necessary to understand in great detail and quantitatively the physical, chemical and biological processes involved in the preconditioning, development and decline of the PSB. Because this is a transient phenomenon occurring in a remote, complex and harsh environment, such a detailed understanding has not yet been achieved. The general objective of this research project is to understand the dynamics of the PSB and determine its role in the Arctic Ocean of tomorrow, including for human populations. More specifically, we want to 1) understand the key physical, chemical and biological processes that govern the PSB, 2) identify the key phytoplankton species involved in the PSB and model their growth under various environmental conditions, and 3) predict the fate of the PSB and related carbon transfer through the food web and toward the bottom sediments over the next decades. First, a PSB event will be monitored during 2015 in the Baffin Bay from its onset under melting sea ice in May to its conclusion within the seasonal ice zone in July. The distribution of relevant physical, chemical and biological properties will be described at various time and space scales using a fleet of profiling floats and gliders and an autonomous underwater vehicle, all equipped with a suite of physical and bio-optical sensors. Process studies will be conducted from an ice camp and then from a research icebreaker to document phytoplankton growth, nutrient assimilation and the transfer of carbon through the food web and toward the sediment. Second, key phytoplankton species will be isolated and grown in the laboratory under various conditions to model their response to environmental factors and to understand their succession during spring. Third, a coupled physical-biological model will be optimized for simulating the PSB in the Arctic Ocean and for predicting changes in phytoplankton communities and food web dynamics. In parallel, past and present trends in the intensity and spatial distribution of the PSB will be documented using a paleoceanography approach, and using remote sensing. Finally, interviews and bilateral discussion with local Inuit communities will enable the documentation of changing marine productivity from a social perspective and feed into a multi-scale integrated analysis of environment-human interactions.

The accelerated melting of the Antarctic ice sheet due to global warming profoundly influences adjacent marine ecosystems. The delivery of fresh water from the ice sheet potentially represents a new source of key nutrients, including iron (Fe), a micronutrient known to limit phytoplankton primary production and the biological pump of CO2 in the Southern Ocean. But the bioavailability of Fe, provided mainly in the form of colloids and particles by glacial ice, is poorly understood. The main objectives of PIANO are to elucidate the role of marine prokaryotes as key engineers in the transformation of Fe delivered by Antarctic ice sheet melting and its consequences on their interactions with phytoplankton. PIANO aims to elucidate 1- the processes by which prokaryotes transform and acquire glacial Fe 2- the response of phytoplankton to Fe processed by prokaryotes and 3- the nature and strength of the Fe-mediated prokaryote-phytoplankton interactions. To fill these knowledge gaps the multidisciplinary team of PIANO will combine experimental observations using model organisms of prokaryotes and phytoplankton, a mechanistic model, and in situ observations throughout one year at a coastal Antarctic site influenced by ice melting. This latter will be achieved by the deployment of two innovative autonomous samplers. The identification of the pathways involved in the acquisition of glacial Fe by prokaryotes and the resulting interactions with phytoplankton together with the seasonal in situ dynamics of the respective genes and transcripts will provide original insights to the metabolic routes and microbial taxa involved in this key process. PIANO will thereby provide a better understanding of a key mechanism likely to influence the Southern Ocean ecological trajectory under climate change conditions.

Regulatory T cells (Treg), most notably those developing very early on (in the mouse during the neonatal period), play a central role in the control of immune-responses and thus prevent immunopathologies such as autoimmune diseases and chronic inflammation. Our recent data show that in NOD mice, the main experimental type I diabetes (T1D)-model, the T1D susceptibility locus Idd5.1 contributes to an exceptionally high frequency of PD1-expressing cells among Treg developing during the neonatal period. We showed that these neonatal PD1(pos) Treg are very autoreactive and strongly recirculate from the periphery back to the thymus. Based on these observations, we postulate that 1) PD1 expression by neonatal Treg impairs their suppressive activity and/or 2) that these very autoreactive Treg, upon recirculation back to the thymus, disturb induction of T cell-tolerance in the thymus, thus contributing to the development of T1D. WP1: We will first investigate how particularly high levels of PD1-expressing Treg develop in the neonatal NOD thymus. We will identify the gene (among the four located in Idd5.1) that controls PD1 expression and decipher the molecular mechanisms involved. Our recent data show that PI3Kdelta controls PD1-expression by neonatal Treg and we will study the upstream and downstream mechanisms involved, including identification of transcription factors. WP2 & 3: We will then extensively characterise the in vivo (clonal) dynamics of neonatal PD1(pos) Treg in pre-diabetic and diabetic NOD mice and compare them to those of neonatal PD1(neg) Treg. Based on the to-be-acquired multi-omics data, we will construct mathematical models to better describe and understand neonatal PD1(pos) Treg-behaviour in vivo. To assess the potential involvement of neonatal PD1(pos) Treg in susceptibility to T1D, we will construct NOD mice in which neonatal PD1+ Treg are absent, analyse immune-activation and monitor T1D development. Since we found that neonatal PD1+ Treg strongly recirculate back to the thymus, we will also analyse their capacity to obstruct T cell-tolerance induction in the thymus, potentially involved in T1D-development. To assess a potential effect of PD1 on neonatal Treg function (e.g. inhibition, modulation of metabolism), we will ablate its expression exclusively on neonatal Treg and study homing, activation, differentiation, and metabolism of Treg, and T1D development of the mice. WP4: Since the locus controlling part of the PD1-phenotype of neonatal Treg in NOD mice (Idd5.1) has an orthologue in humans also controlling T1D-susceptibility (IDDM12), we feel that abnormalities of the earliest Treg developing in humans may be involved in human T1D. In preparation for a clinical research program on early Treg development in T1D-patients, we will set up in vitro mouse foetal thymus organ cultures in which human Treg develop from (non-mobilised) peripheral blood stem-cells from young adult donors. Our project, which is based on a large body of solid but still unpublished data, will thus provide a better understanding of the complex role of inherited functional defects of Tregs in the aetiology of T1D in NOD mice. It may thus have repercussions for development of Treg-based or Treg-targeting immunotherapies against T1D in humans.

Summary Microalgae are a highly diverse bio-resource and feature a large variety of value-added compounds, which remains almost untapped today. For example, long chain polyunsaturated fatty acids (Omega 3), carotenoids pigments and exopolysaccharides are started to be used in food, cosmetics and health industries but challenges remains to reach their full potential of use. Besides, many other compounds of economic interest have been recently identified in microalgae. The full economic valorization of these compounds requires to knock down two main technical barriers: the selection of microalgae lines overexpressing the compound(s) of interest and the high scale industrial culture of these lines in closed and controlled photobioreactors. To overcome these challenges, the OTARI labcom project will associate two highly complementary partners recognized by the academic and industrial communities. The laboratory of microbial oceanography lab, UMR7621 Université Pierre et Marie Curie and CNRS has a unique expertise in the selection and genetic engineering and has developed and patented a microalgal system of expression. Microphyt is a company which has developed original photobioreactors at pilot and industrial scales for the production of microalgae. The objective of OTARI is to develop and implement a microalgae factory for the production of value-added coumpounds for well-being, food and health industries.