The distinct roles of the nucleus and nucleus-cytoskeleton connections in three-dimensional cell migration

Cells often migrate in vivo in an extracellular matrix that is intrinsically three-dimensional (3D) and the role of actin filament architecture in 3D cell migration is less well understood. Here we show that, while recently identified linkers of nucleoskeleton to cytoskeleton (LINC) complexes play a minimal role in conventional 2D migration, they play a critical role in regulating the organization of a subset of actin filament bundles – the perinuclear actin cap - connected to the nucleus through Nesprin2giant and Nesprin3 in cells in 3D collagen I matrix. Actin cap fibers prolong the nucleus and mediate the formation of pseudopodial protrusions, which drive matrix traction and 3D cell migration. Disruption of LINC complexes disorganizes the actin cap, which impairs 3D cell migration. A simple mechanical model explains why LINC complexes and the perinuclear actin cap are essential in 3D migration by providing mechanical support to the formation of pseudopodial protrusions

ExoClock Project III: 450 new exoplanet ephemerides from ground and space observations

The ExoClock project has been created with the aim of increasing the efficiency of the Ariel mission. It will achieve this by continuously monitoring and updating the ephemerides of Ariel candidates over an extended period, in order to produce a consistent catalogue of reliable and precise ephemerides. This work presents a homogenous catalogue of updated ephemerides for 450 planets, generated by the integration of $\sim$18000 data points from multiple sources. These sources include observations from ground-based telescopes (ExoClock network and ETD), mid-time values from the literature and light-curves from space telescopes (Kepler/K2 and TESS). With all the above, we manage to collect observations for half of the post-discovery years (median), with data that have a median uncertainty less than one minute. In comparison with literature, the ephemerides generated by the project are more precise and less biased. More than 40\% of the initial literature ephemerides had to be updated to reach the goals of the project, as they were either of low precision or drifting. Moreover, the integrated approach of the project enables both the monitoring of the majority of the Ariel candidates (95\%), and also the identification of missing data. The dedicated ExoClock network effectively supports this task by contributing additional observations when a gap in the data is identified. These results highlight the need for continuous monitoring to increase the observing coverage of the candidate planets. Finally, the extended observing coverage of planets allows us to detect trends (TTVs - Transit Timing Variations) for a sample of 19 planets. All products, data, and codes used in this work are open and accessible to the wider scientific community.Comment: Recommended for publication to ApJS (reviewer's comments implemented). Main body: 13 pages, total: 77 pages, 7 figures, 7 tables. Data available at http://doi.org/10.17605/OSF.IO/P298

ExoClock Project. III. 450 New Exoplanet Ephemerides from Ground and Space Observations

The ExoClock project has been created to increase the efficiency of the Ariel mission. It will achieve this by continuously monitoring and updating the ephemerides of Ariel candidates, in order to produce a consistent catalog of reliable and precise ephemerides. This work presents a homogenous catalog of updated ephemerides for 450 planets, generated by the integration of ∼18,000 data points from multiple sources. These sources include observations from ground-based telescopes (the ExoClock network and the Exoplanet Transit Database), midtime values from the literature, and light curves from space telescopes (Kepler, K2, and TESS). With all the above, we manage to collect observations for half of the postdiscovery years (median), with data that have a median uncertainty less than 1 minute. In comparison with the literature, the ephemerides generated by the project are more precise and less biased. More than 40% of the initial literature ephemerides had to be updated to reach the goals of the project, as they were either of low precision or drifting. Moreover, the integrated approach of the project enables both the monitoring of the majority of the Ariel candidates (95%), and also the identification of missing data. These results highlight the need for continuous monitoring to increase the observing coverage of the candidate planets. Finally, the extended observing coverage of planets allows us to detect trends (transit-timing variations) for a sample of 19 planets. All the products, data, and codes used in this work are open and accessible to the wider scientific community

Transfert du radiocésium présent dans du foin contaminé par les retombées de Tchernobyl à des brebis gestantes et à leurs produits à différents âges

Quatre brebis gestantes ont reçu du foin contaminé par les retombées de l'accident de Tchernobyl, pendant environ 1 mois avant et un mois après le part. Le niveau de contamination (134Cs et 137Cs) des mères et des agneaux a été déterminé par comptage in toto ; la quantité de lait ingérée par les agneaux a été estimée par leur gain de poids journalier. Entre J10 et J30 après le part, la valeur moyenne des transferts a été de 4,7 ± 1,4 % pour le lait et 7,9 ± 1,7 % pour la viande. A la naissance, la charge corporelle moyenne des agneaux était égale à 3,2 ± 0,8 % celle de mère ; le coefficient moyen de rétention du césium ingéré était au sevrage (J30) de 39 ± 6 % pour les agneaux et de 27,3 ± 3,2 % pour les brebis. La période de décontamination spontanée était pour les agneaux après le sevrage d'environ 14,5 jours (courbe monoexponentielle) et d'environ 26 jours pour la composante longue de la courbe bi-exponentielle chez les brebis. Les transferts à la viande, les paramètres de charge et de décontamination spontanée ont été également étudiés : 1) chez 4 agneaux de 1 à 3 mois après le sevrage, 2) chez 3 jeunes animaux âgés de 9 à 10 mois. Les valeurs des différents paramètres du transit du césium chez les nouveaux-nés et chez les jeunes animaux sont discutées en rapport avec la gestion d'un accident de contamination

Bio-organic self-assembled DNA nanostructures and their use in the mitigation of the activation of microglia in neuroinflammation

Neuroinflammation, which is characterized by the activation of microglial cells, is a hallmark of ALS and most other neurodegenerative diseases. In the early phases of chronic neurodegenerative diseases, microglia assume an M2 phenotype, which is neuroprotective, while in advanced phases, they activate to an M1 phenotype which is neurotoxic. The mechanism by which activation spreads among microglial cells is not fully understood yet, but it is known that the exchange of proteins and microRNA is involved and exosomes are play a role in this process1. Studies have shown that activation of microglia stimulates the release of exosomes, altering their composition and function. As some miRNAs are upregulated in neuroinflammation, these could turn up to be transported in higher number and participate to the spreading of neuroinflammation to otherwise resting microglia. After demonstrating that microglia can naturally take up tetrahedron-shaped DNA nanostructures2 even without the need for any transfection agent, we designed and realized several types of modular DNA-based self-assembled nanostructures that can bear functional elements and labelling moieties (such as fluorophores). We engineered these self-assembled nanostructures by incorporating functional components that target and cleave specific miRNAs involved in the activation of microglia (like miR-34a). We observed the uptake of nanostructures by the cells and a reduction of the activation, by quantitating its molecular markers. Mir-34a, otherwise upregulated in activated microglia, was reduced after nanostructure treatment. The self-assembled tetrahedral DNA nanostructures proved a valuable shuttle for delivering specific functional elements to live mammalian cells without being intrinsically toxic. A variety of different organic or biological functional units can be loaded on them for future extensions of their application and the preparation of candidate drugs or theranostics by design. References: [1] F. Massenzio, , E. Peña-Altamira, S. Petralla, M. Virgili, G. Zuccheri, A. Miti, E. Polazzi, I. Mengoni , D. Piffaretti, B. Monti, Biochim Biophys Acta Mol Basis Dis. 2018, 1864, 3771-3785. [2] C. Bergamini, P. Angelini, K. J. Rhoden, A. M. Porcelli, R., G. Zuccheri, Methods, 2014, 67, 185-9

Les accès veineux de longue durée.

The authors summarize the technique of placement of long term venous access systems. The complications encountered are described. As an example, the experience of the Institut Jules Bordet in this field is presented.SCOPUS: ar.jinfo:eu-repo/semantics/publishe