Benthic oxygen exchange over a heterogeneous Zostera noltei meadow in a temperate coastal ecosystem

Seagrass meadows support intense but highly variable benthic metabolic rates that still need to be better evaluated to determine an accurate trophic status. The present study assessed how seagrasses and associated benthic macrofauna control spatiotemporal changes in benthic oxygen exchanges within a temperate bay. Based on seasonal sampling over a complete year cycle, the diffusive oxygen uptake (DOU), community respiration (CR) and gross primary production (GPP) were measured in a Zostera noltei meadow within Arcachon Bay, taking into account its spatial heterogeneity. Oxygen fluxes were assessed in sediment cores, within which benthic macrofauna and seagrass abundances and biomasses were quantified. The presence of Z. noltei did not significantly affect the DOU. Seasonal changes in CR and GPP correlated strongly with temperature in the presence of Z. noltei. The characteristics of benthic macrofauna associated with Z. noltei only weakly affected seasonal changes in CR. High spatial changes in both GPP and CR were mainly driven by the aboveground biomass of Z. noltei. When extrapolated to the whole intertidal area of the bay, in spite of limitations, our results suggest (1) overall higher contributions to CR and GPP from the seagrass meadow than from bare sediments, even though alternative primary producers in bare sediments (likely microphytobenthos) contributed significantly during winter; (2) an annual decrease in CR and GPP of 35 and 41%, respectively, resulting from the decline in Z. noltei of 25% between 2005 and 2007; and (3) a strong seasonality in the magnitude of this decrease, which was high during autumn and low during winter.

Proteasomal Degradation of p53 by Human Papillomavirus E6 Oncoprotein Relies on the Structural Integrity of p53 Core Domain

The E6 oncoprotein produced by high-risk mucosal HPV stimulates ubiquitinylation and proteasome-dependent degradation of the tumour suppressor p53 via formation of a trimeric complex comprising E6, p53, and E6-AP. p53 is also degraded by its main cellular regulator MDM2. The main binding site of p53 to MDM2 is situated in the natively unfolded N-terminal region of p53. By contrast, the regions of p53 implicated in the degradation by viral E6 are not fully identified to date. Here we generated a series of mutations (Y103G, Y107G, T155A, T155V, T155D, L264A, L265A) targeting the central folded core domain of p53 within a region opposite to its DNA-binding site. We analysed by in vitro and in vivo assays the impact of these mutations on p53 degradation mediated by viral E6 oncoprotein. Whereas all mutants remained susceptible to MDM2-mediated degradation, several of them (Y103G, Y107G, T155D, L265A) became resistant to E6-mediated degradation, confirming previous works that pointed to the core domain as an essential region for the degradation of p53. In parallel, we systematically checked the impact of the mutations on the transactivation activity of p53 as well as on the conformation of p53, analysed by Nuclear Magnetic Resonance (NMR), circular dichroism (CD), and antibody probing. These measurements suggested that the conformational integrity of the core domain is an essential parameter for the degradation of p53 by E6, while it is not essential for the degradation of p53 by MDM2. Thus, the intracellular stability of a protein may or may not rely on its biophysical stability depending on the degradation pathway taken into consideration

The checkpoint Saccharomyces cerevisiae Rad9 protein contains a tandem tudor domain that recognizes DNA.

International audienceDNA damage checkpoints are signal transduction pathways that are activated after genotoxic insults to protect genomic integrity. At the site of DNA damage, 'mediator' proteins are in charge of recruiting 'signal transducers' to molecules 'sensing' the damage. Budding yeast Rad9, fission yeast Crb2 and metazoan 53BP1 are presented as mediators involved in the activation of checkpoint kinases. Here we show that, despite low sequence conservation, Rad9 exhibits a tandem tudor domain structurally close to those found in human/mouse 53BP1 and fission yeast Crb2. Moreover, this region is important for the resistance of Saccharomyces cerevisiae to different genotoxic stresses. It does not mediate direct binding to a histone H3 peptide dimethylated on K79, nor to a histone H4 peptide dimethylated on lysine 20, as was demonstrated for 53BP1. However, the tandem tudor region of Rad9 directly interacts with single-stranded DNA and double-stranded DNAs of various lengths and sequences through a positively charged region absent from 53BP1 and Crb2 but present in several yeast Rad9 homologs. Our results argue that the tandem tudor domains of Rad9, Crb2 and 53BP1 mediate chromatin binding next to double-strand breaks. However, their modes of chromatin recognition are different, suggesting that the corresponding interactions are differently regulated

Impact of early statin therapy on development of atrial fibrillation at the acute stage of myocardial infarction: data from the FAST-MI register

Background Atrial fibrillation developing at the acute stage of myocardial infarction is associated with untoward clinical outcomes. The aim of this study was to determine correlations between early statin therapy and atrial fibrillation in acute myocardial infarction.Methods Patients (3396) with sinus rhythm developing acute myocardial infarction were enrolled in the French registry of Acute ST-elevation and non-ST-elevation Myocardial Infarction (FAST-MI). Results Atrial fibrillation developed in 7.0% of patients without and 3.9% of patients with early (≤48 h of admission) statin therapy (p<0.001). Multivariable analysis, including the propensity score for early statin treatment, showed that statin therapy was associated with reduced risk of atrial fibrillation (OR 0.64; 95% CI 0.45 to 0.92, p=0.017). Compared to patients without early statin therapy, the OR for atrial fibrillation were 0.72 (0.49 to 1.04, p=0.080), 0.52 (0.28 to 0.95, p=0.034) and 0.40 (0.18 to 0.92, p=0.030) in patients on conventional, intermediate and high doses respectively. Conclusions This study is the first to document a correlation between early statin therapy and atrial fibrillation at the early stage of acute myocardial infarction

CDC25B associates with a centrin 2-containing complex and is involved in maintaining centrosome integrity

Background information. CDC25 (cell division cycle 25) phosphatases function as activators of CDK (cyclin-dependent kinase)–cyclin complexes to regulate progression through the CDC. We have recently identified a pool of CDC25B at the centrosome of interphase cells that plays a role in regulating centrosome numbers

Automatized lung disease quantification in patients with COVID-19 as a predictive tool to assess hospitalization severity

peer reviewedThe pandemic of COVID-19 led to a dramatic situation in hospitals, where staff had to deal with a huge number of patients in respiratory distress. To alleviate the workload of radiologists, we implemented an artificial intelligence (AI) - based analysis named CACOVID-CT, to automatically assess disease severity on chest CT scans obtained from those patients. We retrospectively studied CT scans obtained from 476 patients admitted at the University Hospital of Liege with a COVID-19 disease. We quantified the percentage of COVID-19 affected lung area (% AA) and the CT severity score (total CT-SS). These quantitative measurements were used to investigate the overall prognosis and patient outcome: hospital length of stay (LOS), ICU admission, ICU LOS, mechanical ventilation, and in-hospital death. Both CT-SS and % AA were highly correlated with the hospital LOS, the risk of ICU admission, the risk of mechanical ventilation and the risk of in-hospital death. Thus, CAD4COVID-CT analysis proved to be a useful tool in detecting patients with higher hospitalization severity risk. It will help for management of the patients flow. The software measured the extent of lung damage with great efficiency, thus relieving the workload of radiologists

Plant-dominated assemblage and invertebrates from the lower Cenomanian of Jaunay-Clan, western France

International audienceTwo fossil localities are reported on the "LGV SEA" railroad from the Lower Cenomanianof Jaunay-Clan (JC), near Poitiers, western France. The laminated mudstones yielded plantfossils including ferns (Cladophlebis, Osmundophyllum, Ruffordia goeppertii, Sphenopteris),conifers (Brachyphyllum, Dammarophyllum, Pagiophyllum), and terrestrial and aquaticfreshwater angiosperms (Eucalyptolaurus depreii, Ploufolia). They are associated with acoleopteran insect that shows systematic affinities to the modern subfamily Chrysomeli-nae (Chrysomelidae). This assemblage suggests connections with arborescent vegetationgrowing in calm freshwater environment. Brackish to marine invertebrates also occurand include a dakoticancroid crab (Brachyura, Podotremata, Dakoticancroidea) and a fewbivalves (Brachidontes). They suggest brackish episodes during pond sedimentation in acoastal environment. Lastly, vertebrates are represented by an isolated feather