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Validation and application of a method for polycyclic aromatic hydrocarbons (PAHS) analysis in marine sediments using APGC-MS/MS
No full textInternational audienceAccurate assessment of polycyclic aromatic hydrocarbon (PAH) pollution in marine sediments requires the establishment and validation of standard analytical techniques. In this work, a previously reported rapid, simple, inexpensive, effective, robust and safe (QuEChERS) alternative method for the determination of 16 PAHs in soils was modified and improved for application to marine sediments. The method involves QuEChERS extraction followed by atmospheric pressure gas chromatography coupled to tandem mass spectrometry. Validation was carried out according to the EURACHEM Guide using certified reference sediment material, evaluating selectivity, specificity, limits of detection and quantification, linearity, accuracy and precision. A good linear relationship (correlation coefficients ≥ 0.99) was observed in the range of 0.4–2500 µg/kg. The limits of detection and quantification ranged from 0.1 to 0.6 µg/kg and from 0.4 to 2.0 µg/kg, respectively. In terms of accuracy and precision, the results obtained were within acceptable limits based on the certificate of the reference material used during validation. The method was also used to assess the levels of PAHs in marine sediment samples from the Peruvian coast. We found PAH concentrations ranging from below the detection limit of the method up to 130.5 µg/kg. The developed method showed overall satisfactory results, supporting its applicability to marine sediments and its potential extension to other types of samples
Travail, télétravail et consommation d'alcool
No full textNational audienceContexte : L'étude s'intéresse au lien entre travail, télétravail (TT) et consommation d'alcool, en 2022. Méthodes : Étude épidémiologique transversale, descriptive, analytique, par auto-questionnaire rempli par les travailleurs intégrant l'AUDIT-C. Résultats : Sur 929 répondants (53,9 % de femmes, âge moyen de 37,67 ans), 11% ne s'estiment pas en bonne santé, 81,6 % consomment de l'alcool, 43,4 % ont un mésusage ou une possible dépendance. 48,4 % télétravaillent en moyenne 19 heures par semaine, 79,5% des télétravailleurs ont fait le choix du TT, 81,3 % s'estiment satisfaits de leurs conditions de TT. Il y a plus de situations de mésusage chez les répondants ayant une activité de TT par rapport aux travailleurs exclusivement en présentiel (p < 0,01), moins de mésusage si le TT a débuté avant mars 2020 (p<0,05), ceux en mésusage estiment que TT et travail sont responsables d'une majoration de leur consommation (p<0,001), ceux travaillant plus de 35 heures ont plus de mésusage (p<0,05), la consommation modérée est associée à une satisfaction professionnelle et le mésusage, à une insatisfaction (p<0,01). Discussion : Choisir le TT serait une tentative d'adaptation à une situation de travail jugée insatisfaisante, source potentielle de mésusage. Cette solution serait d'autant plus thérapeutique que le télétravail serait exclusif et ancien pour des raisons de bénéfice pour la santé d'une stabilité organisationnelle bienfaisante. Conclusion : Les conséquences du mésusage d'alcool sur la mortalité et la morbidité, impliquent autant de former les professionnels de santé en addictologie que de sensibiliser les entreprises à l'impact positif sur la santé de la prévention du risque psychosocial.</div
Regional and Seasonal Distribution of Arctic Low-Level Cloud Types and Their Relationship to Large-Scale Environmental Conditions
No full textInternational audienceLow-level clouds strongly influence the Arctic surface energy budget and hydrological cycle, yet their representation in climate models remains challenging due to limited observations and complex interactions between local processes and large-scale conditions. This study analyzes eight years (2007-2016) of active remote sensing observations from CALIPSO and CloudSat to investigate the regional and seasonal distribution of four types of low-level clouds: warm liquid, ice-only, mixed-phase clouds (MPCs), and unglaciated supercooled liquid clouds (USLCs). 51 % of Arctic clouds occur below 3 km.The statistical analysis of cloud-type frequencies shows that MPCs account for 17 %, ice-only clouds for 21 %, and USLCs for 12 %. This study provides the first satellite-based assessment of USLCs over the Arctic, revealing occurrences up to 20 % over marine regions during transition seasons. Multiple linear regressions are used to quantify the influence of key environmental drivers on the cloud type distribution. MPCs are linked to dynamically unstable conditions such as marine cold-air outbreaks, especially over open sea regions and during transition seasons. USLCs preferentially develop under stable and relatively dry mid-tropospheric environments as opposed to ice clouds. Cloud-surface coupling shows that, on average, 32 % of low-level clouds are coupled to the surface. In winter, USLCs are four times more frequently coupled with the open ocean than with sea ice, emphasizing the strong thermodynamic control of the underlying surface. These results provide new insight into Arctic cloud-phase variability and offer guidance for improving their representation in large-scale models
Contribution du mésozooplancton et des pelotes fécales à l’export de carbone : une approche par traits fonctionnels
No full textMarine mesozooplankton refers to marine animals measuring between 0.2 and 20 mm that are unable to fight against currents. They support the world's fisheries and play a key role in the biological carbon pump (PCB), exporting organic carbon to the interior of the ocean. This transfer is based in particular on the production of particles (faecal pellets, moults, carcasses) that form part of the marine snow that sediments. Fecal pellets make up most of this. In addition, some mesozooplankton species migrate vertically on a daily or seasonal basis, amplifying the intensity of the PCB. Recent methods, such as imaging and metabarcoding, complement traditional methods (plankton nets and binocular magnifying glasses for mesozooplankton, sediment traps for particles) and make it possible to study ecosystems using a functional trait approach. These are measurable individual characteristics that influence the selective value of organisms (ability to survive, grow and reproduce). They can be associated with ecological functions at ecosystem level, such as carbon export. In addition, models can be used to produce balances on the scale of the global ocean, based on information (e.g. parameters) obtained from data. In this context, the goal of this thesis is to study the role of mesozooplankton and the particles they produce in carbon export, using various analytical methods.In Chapter 1, I analyse imaging and metabarcoding data from mesozooplankton samples collected at the Bermuda Atlantic Time-series Study (BATS) site. I identify groups of highly correlated taxa (“modules”) formed by organisms that are more or less transparent. These variations in transparency can be attributed to physiological or ecological functions. The modules appear in different ecosystem dynamics (e.g. productive period, oligotrophic period) and their relative abundances vary according to the intensity of carbon export. A morphological space highlights size and transparency as traits influencing this export. In Chapter 2, I focus on the identification of cylindrical faecal pellets, typical of those produced by Arctic mesozooplankton, among the non-living particles imaged in situ in Baffin Bay (Arctic Ocean), during a period of high productivity, using the Underwater Vision Profiler. The 50,771 particles identified by their morphology probably correspond to pellets produced by the large copepods Calanus hyperboreus, amphipods or euphausiids, according to a comparison with reference data. This work highlights the relevance of in situ imaging approaches for quantifying the carbon fluxes associated with the production of faecal pellets in productive ecosystems. Finally, in Chapter 3, I review the role of faecal pellets in carbon export, based on a meta-analysis gathering 197 scientific articles. The abundance, biomass and contribution of faecal pellets to carbon fluxes are closely linked to ecosystem productivity. The sedimentation rate of faecal pellets is strongly correlated with their morphology but appears to be independent of depth. There is a need to better characterise the types of pellet studied and to measure several variables on the same sample in order to better understand their dynamics and propose more realistic parameter values. This thesis opens up perspectives for the joint analysis of imagery and metabarcoding data, in particular via co-occurrence networks, and proposes a characterisation of marine snow particles involved in carbon export using imagery.Le mésozooplancton marin désigne les animaux marins mesurant entre 0,2 et 20 mm ne pouvant lutter contre les courants, il soutient les pêcheries mondiales et joue un rôle clé dans la pompe à carbone biologique (PCB), en exportant du carbone organique vers l'intérieur de l'océan. Ce transfert repose notamment sur la production de particules (pelotes fécales, mues, carcasses) formant une partie de la neige marine qui sédimente. Les pelotes fécales en constituent la majeure partie. Par ailleurs, certaines espèces du mésozooplancton effectuent des migrations verticales, quotidiennes ou saisonnières, amplifiant l'intensité de la PCB. De récentes méthodes, telles que l'imagerie ou le métabarcoding, complètent les méthodes traditionnelles (filets à plancton et loupe binoculaire pour le mésozooplancton, pièges à sédiments pour les particules) et permettent d'aborder l'étude des écosystèmes à travers une approche par traits fonctionnels. Ce sont des caractéristiques individuelles mesurables influençant la valeur sélective des organismes (capacité à survivre, croître et se reproduire). Ils peuvent être associés à des fonctions écologiques à l'échelle de l'écosystème, telles que l'export de carbone. En complément, l'utilisation de modèles permet de réaliser des bilans à l'échelle de l'océan global, en se basant sur des informations (e.g., paramètres) obtenues depuis les données. Dans ce contexte, l'objectif de cette thèse est d'étudier le rôle du mésozooplancton et des particules qu'il produit dans l'export de carbone, en mobilisant diverses méthodes d'analyses. Dans le Chapitre 1, j'analyse des données d'imagerie et de métabarcoding issues d'échantillons de mésozooplancton collectés sur le site de Bermuda Atlantic Time-serie Study (BATS). J'identifie des groupes de taxons fortement corrélés (“modules”) constitués d'organismes plus ou moins transparents. Ces variations de transparence peuvent être attribuées à des fonctions physiologiques ou écologiques. Les modules apparaissent dans des dynamiques d'écosystème différentes (e.g., période productive, période oligotrophe) et leurs abondances relatives varient selon l'intensité de l'export de carbone. Un espace morphologique met en évidence la taille et la transparence comme traits influençant cet export. Dans le Chapitre 2, je m'intéresse à l'identification de pelotes fécales cylindriques, typiques de celles produites par le mésozooplancton arctique, parmi les particules non-vivantes imagées in situ dans la Baie de Baffin (Océan Arctique), en période de forte productivité, grâce à l'Underwater Vision Profiler. Les 50 771 particules identifiées par leur morphologie correspondent probablement à des pelotes produites par les grands copépodes Calanus hyperboreus, les amphipodes ou les euphausiacés, selon une comparaison avec des données de référence. Ce travail met en lumière la pertinence des approches d'imagerie in situ pour quantifier les flux de carbone associés à la production de pelotes fécales dans les écosystèmes productifs. Enfin, dans le Chapitre 3, je dresse un état des lieux du rôle des pelotes fécales dans l'export de carbone, à partir d'une méta-analyse rassemblant 197 articles scientifiques. Ainsi, l'abondance, la biomasse et la contribution des pelotes fécales dans les flux de carbone sont étroitement liées à la productivité des écosystèmes. La vitesse de sédimentation des pelotes fécales est fortement corrélée à leur morphologie mais semble être indépendante de la profondeur. Il est nécessaire de mieux caractériser les types de pelotes étudiés et de mesurer plusieurs variables sur un même échantillon pour mieux comprendre leur dynamique et proposer des valeurs de paramètres plus réalistes. Cette thèse ouvre des perspectives pour l'analyse croisée des données d'imagerie et de métabarcoding, notamment via les réseaux de co-occurrence, et propose une caractérisation des particules de neige marine impliquées dans l'export de carbone grâce à l'imagerie
Weakened stratification across the Eurasian Basin enables enhanced vertical spreading of Atlantic Water
No full textInternational audienceOcean stratification plays a crucial role in regulating heat fluxes from the ocean to the sea ice and atmosphere. In the Arctic Ocean, a layer of fresh and cold Polar Water near the surface isolates warm and saline Atlantic Water (AW) due to a strong halocline. While the stratification in the eastern Eurasian Basin halocline is known to have weakened since the 2000s, we here investigate the variability of stratification over the full AW depth range at basin scale. We analyze 40 years of in situ hydrographic data to track changes in stratification across the entire Eurasian Basin and introduce a conceptual dynamical model to explain the underlying mechanisms. Our results show that the most pronounced temperature and salinity variability occurs in the ∼100 m thick thermocline, which separates warm AW at depth from the colder, fresher halocline above. This variability is driven by warm, saline anomalies lasting for a few years entering through Fram Strait and propagating along the boundary current, superimposed on long-term trends. Our combined observational and modeling approach reveals that thermocline stratification has weakened by up to 50% in many regions, enhancing the potential for upward diffusive fluxes of heat and salt toward the base of the halocline. Plain Language SummaryOcean stratification plays a key role in determining the response of the Arctic Ocean to climate change. Earlier studies have shown that the halocline, which protects sea ice from warmer water underneath, has become less stable in the eastern Eurasian Basin since the 2000s. The full range of changes down to the deeper, warmer, and saltier Atlantic Water (AW) layer has, however, been little studied. In this study, data from the past 35 years is analyzed to track stratification changes. We find that the temperature and salinity have varied the most in the so-called thermocline, which separates the warmer AW below from the colder, fresher halocline above. The changes in stratification are driven by both short-term anomalies of warm, saline water entering through Fram Strait and by a long-term warming and salinity increase. In many parts of the Eurasian Basin, the thermocline has become up to 50% less stable, making it easier for heat and salt to move upwards to the base of the halocline. Using a conceptual model, we propose a mechanism linking temperature and salinity changes to the stratification of the water column
Elucidating the landscape of genome-wide chromatin interaction sites of the lncRNA TUG1 in bovine cell lines and liver tissue
No full textInternational audienceLong-noncoding RNA (lncRNA) interact with DNA, RNA and proteins to regulate the epigenome and fundamental biological processes. In the bovine genome, the nature and mechanisms of lncRNA interactions with specific chromatin regions are unexplored yet. Here, we aimed to unravel the chromatin interaction sites of the evolutionary conserved lncRNA TUG1 in the bovine genome using ChIRP-seq (chromatin isolation by RNA precipitation) in two popular bovine cell lines (MDBK, MAC-T) and liver tissue. About half of the genome-wide TUG1 chromatin occupancy in the genome (3225, 3587 and 3,977 interaction sites in MDBK, MAC-T and liver, respectively) was associated with protein-coding genes. Observation of numerous concordant TUG1 chromatin interaction sites between MDBK and MAC-T cells and liver tissue was consistent with the known ubiquitous expression of TUG1. Analysis of overlaps between ChIRP-seq peaks and ATAC-seq peaks in MDBK and MAC-T cells pinpointed TUG1 chromatin interaction sites relevant for modulating chromatin accessibility
[Poster]#2259 Serum interleukin-8 concentrations, associated factors, and associated cardiovascular risk in patients with moderate-to-advanced chronic kidney disease
No full textInternational audienceBackground and Aims Chronic kidney disease (CKD) is associated to increased inflammation and elevated cytokine levels. Interleukins, a group of cytokines, play a crucial role in immune system development and activity, serving as key effectors and signalling molecules. In CKD patients, pro-inflammatory interleukins tend to be elevated. While interleukin 6 (IL-6) has been extensively studied in the context of CKD, other interleukins, such as interleukin 8 (IL-8), deserve further attention. IL-8 is a chemoattractant cytokine primarily involved in neutrophil activation, which is produced by a wide range of cell types, mainly monocytes and macrophages. IL-8 is produced early in the inflammatory response but can persist for prolonged periods, even days or weeks. Despite experimental data suggesting its potential harmful effects, notably in cardiovascular disease, IL-8 has been poorly studied in patients with CKD. Thus, the objectives of the present study were to (i) describe the serum IL-8 concentration in patients at various CKD stages, (ii) assess the correlation between the estimated glomerular filtration rate (eGFR) and IL-8 concentration, (iii) identify the factors associated with IL-8 levels, and (iv) explore the association between IL-8 levels and the risk of major adverse cardiovascular event (MACE). Method CKD-REIN is a French, prospective, nationally representative cohort of 3,033 patients with stage 3 to 5 CKD (eGFR <60 mL/min/1.73 m²), recruited from 40 nephrology facilities. Participants were neither on maintenance dialysis nor had received a kidney transplant, and were followed-up for 5 years. Baseline IL-8 serum concentrations were measured centrally using an ELISA method. Since IL-8 concentration was not normally distributed in this population, it was log-transformed for analysis. IL-8 levels were compared across CKD stages using analysis of variance. Multivariate linear regression was performed to identify factors associated with serum IL-8 concentrations (log-transformed). Cox proportional hazards model was used to estimate hazard ratio (HR) for the first major adverse cardiovascular event (MACE, defined as a composite of nonfatal stroke, nonfatal myocardial infarction, hospitalization for heart failure, and cardiovascular death). The models were adjusted for baseline comorbidities, laboratory data and medications. Results Among the 2,389 patients included, 66% were men, with a median age of 68 [Q1–Q3: 60–76] years, and a mean (SD) eGFR of 34.8 (13.4) mL/min/1.73 m². The median serum IL-8 concentration was 12.2 [Q1–Q3: 8.0-17.7] pg/mL. IL-8 concentrations were significantly inversely correlated with eGFR (r=−0.21, P < 0.001). IL-8 levels varied across CKD stages, with higher concentrations observed in advanced stages (P < 0.001). Serum IL-8 concentration was independently and positively associated with decreasing eGFR, diabetes, history of cardiovascular disease, anaemia, C-reactive protein (CRP) levels, and proton pump inhibitor use. It was negatively associated with serum albumin. CRP (eβCRP = 1.01), eGFR (eβeGFR = 0.99), albumin (eβalbumin = 0.98), and diabetes (eβdiabetes = 1.16) were the strongest predictors of IL-8 levels. The risk of MACE increased with higher baseline serum IL-8 concentrations (HR [95% Confidence Interval] for 1-unit change in log(IL-8), 1.30 [1.09; 1.56]), after adjusting for age, sex, smoking status, history of diabetes, cardiovascular disease, anaemia, eGFR, pulse pressure, body mass index, C-reactive protein, serum albumin, serum urea, urinary albumin-to-creatinine ratio, and baseline prescriptions for proton pump inhibitors, diuretics, statins, and antithrombotic agents. Conclusion Decline of kidney function was associated with an increase in serum IL-8 levels in patients with moderate-to-advanced CKD. Higher levels of IL-8 were associated to higher risk of MACE, independently of eGFR. These results suggest that IL-8 may serve as a potential biomarker for cardiovascular risk in CKD patients. Further studies are needed to evaluate whether targeting IL-8 could mitigate the risk of cardiovascular outcomes in CKD
Copper and iron orchestrate cell-state transitions in cancer and immunity
No full textInternational audienc
Travailler en gare. Ajustements corporels et adaptations émotionnelles des agent·es de la gare
No full textInternational audienceWhat hardships do railway station workers face in their daily work, and how do they adapt? This article presents the findings of a collective ethnographic study conducted among maintenance staff, security personnel, and ticket inspectors working in a railway station. We offer a cross-sectional analysis of the daily adaptations these three categories of workers employ to cope with the challenges they encounter. Our analysis reveals that these adaptations occur on three levels: accommodating physical suffering and the most arduous tasks, defusing or reversing power dynamics in violent interactions with station users, and distancing themselves from the meaning of their work. However, bodily adjustments and emotional adaptations also vary depending on workers’ social characteristics, career trajectories, job positions, and potential professional mobility.¿Cuáles son las dificultades que enfrentan cotidianamente quienes trabajan en las estaciones de tren? ¿Cómo el personal se adapta a dichas condiciones? Este artículo presenta los resultados de una investigación etnográfica colectiva realizada con agentes de limpieza, seguridad y controladores. Proponemos un análisis comparado de las adaptaciones que estas tres categorías de trabajadores desarrollan en su trabajo cotidiano. Mostramos que estas se desarrollan en tres niveles: adaptarse al sufrimiento físico y a las tareas consideradas más penosas, desactivar o revertir las relaciones de dominación que se despliegan en las interacciones violentas con los usuarios de la estación, y distanciarse del significado que reviste el trabajo. Pero los ajustes corporales y las adaptaciones emocionales de los trabajadores también presentan matices según sus características sociales, sus trayectorias, sus puestos y las probabilidades de movilidad profesional asociadas.Quelles sont les pénibilités au travail éprouvées par celles et ceux qui œuvrent quotidiennement dans la gare ? Comment le personnel en gare s’y adapte-t-il ? Cet article présente les résultats d’une enquête ethnographique collective conduite auprès d’agents d’entretien, de la sécurité et de contrôleurs qui travaillent en gare. Nous proposons une analyse croisée des adaptations quotidiennes aux difficultés que ces trois catégories de travailleurs rencontrent dans leur travail quotidien. Nous montrons qu’elles se jouent à trois niveaux : s’accommoder aux souffrances physiques et aux tâches jugées les plus pénibles, désamorcer ou renverser les rapports de domination qui se déploient dans les interactions violentes avec les usagers de la gare, et mettre à distance le sens que revêt le travail. Mais les ajustements corporels et les adaptations émotionnelles des travailleurs présentent aussi des nuances selon leurs caractéristiques sociales, leurs trajectoires, leurs postes et les possibles mobilités professionnelles associées