Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Applications de la transduction des protéines (transfert de TPr-Met pour la transplantation cellulaire)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Platinum Complexes Can Bind to Telomeres by Coordination

It is suggested that several compounds, including G-quadruplex ligands, can target telomeres, inducing their uncapping and, ultimately, cell death. However, it has never been demonstrated whether such ligands can bind directly and quantitatively to telomeres. Here, we employed the property of platinum and platinum-G-quadruplex complexes to target G-rich sequences to investigate and quantify their covalent binding to telomeres. Using inductively coupled plasma mass spectrometry, surprisingly, we found that, in cellulo, in the presence of cisplatin, a di-functional platinum complex, telomeric DNA was platinated 13-times less than genomic DNA in cellulo, as compared to in vitro data. On the contrary, the amount of mono-functional platinum complexes (Pt-ttpy and Pt-tpy) bound either to telomeric or to genomic DNA was similar and occurred in a G-quadruplex independent-manner. Importantly, the quantification revealed that the low level of cisplatin bound to telomeric DNA could not be the direct physical cause of TRF2 displacement from telomeres. Altogether, our data suggest that platinum complexes can affect telomeres both directly and indirectly

Linking of Antitumor trans NHC-Pt(II) Complexes to G-Quadruplex DNA Ligand for Telomeric Targeting

International audienceG-quadruplex structures (G4) are promising anticancer-ous targets. A great number of small molecules targeting these structures have already been identified through biophysical methods. In cellulo, some of them are able to target either telomeric DNA and/or some sequences involved in oncogene promotors, both resulting in cancer cell death. However, only a few of them are able to bind to these structures G4 irreversibly. Here we combine within the same molecule the G4-binding agent PDC (pyridodicarboxamide) with a N-heterocyclic carbene−platinum complex NHC-Pt already identified for its antitumor properties. The resulting conjugate platinum complex NHC-Pt-PDC stabilizes strongly G-quadruplex structures in vitro, with affinity slightly affected as compared to PDC. In addition, we show that the new conjugate binds preferentially and irreversibly the quadruplex form of the human telomeric sequence with a profile in a way different from that of NHC-Pt thereby indicating that the platination reaction is oriented by stacking of the PDC moiety onto the G4-structure. In cellulo, NHC-Pt-PDC induces a significant loss of TRF2 from telomeres that is considerably more important than the effect of its two components alone, PDC and NHC-Pt, respectively

Linking of Antitumor <i>trans</i> NHC-Pt(II) Complexes to G‑Quadruplex DNA Ligand for Telomeric Targeting

G-quadruplex structures (G4) are promising anticancerous targets. A great number of small molecules targeting these structures have already been identified through biophysical methods. In cellulo, some of them are able to target either telomeric DNA and/or some sequences involved in oncogene promotors, both resulting in cancer cell death. However, only a few of them are able to bind to these structures G4 irreversibly. Here we combine within the same molecule the G4-binding agent <b>PDC</b> (pyridodicarboxamide) with a <i>N</i>-heterocyclic carbene–platinum complex <b>NHC-Pt</b> already identified for its antitumor properties. The resulting conjugate platinum complex <b>NHC-Pt-PDC</b> stabilizes strongly G-quadruplex structures in vitro, with affinity slightly affected as compared to <b>PDC</b>. In addition, we show that the new conjugate binds preferentially and irreversibly the quadruplex form of the human telomeric sequence with a profile in a way different from that of <b>NHC-Pt</b> thereby indicating that the platination reaction is oriented by stacking of the <b>PDC</b> moiety onto the G4-structure. In cellulo, <b>NHC-Pt-PDC</b> induces a significant loss of TRF2 from telomeres that is considerably more important than the effect of its two components alone, <b>PDC</b> and <b>NHC-Pt</b>, respectively

Overview: Quasi-Lagrangian observations of Arctic air mass transformations -Introduction and initial results of the HALO-(AC) 3 aircraft campaign

International audienceThe global warming is amplified in the Arctic. To collect data that help to constrain weather and climate models, which often do not realistically represent the enhanced Arctic warming, the HALO-(AC)³ aircraft campaign was conducted in March and April 2022 over the Norwegian and Greenland Seas, the Fram Strait, and the central Arctic Ocean. Observations were made over areas of open ocean, the marginal sea ice zone, and the central Arctic sea ice. Two low-flying and one long-range, high-altitude research aircraft have been employed. Whenever possible, the three aircraft were flown in collocated formation. The campaign focused on one specific challenge posed by the models: The reasonable representation of transformations of air masses during their meridional transport into (northward by moist and warm air intrusions, WAIs) and out of (southward via marine cold air outbreaks, CAOs) the Arctic. To observe the air mass transformations, a quasi-Lagrangian flight strategy using trajectory calculations was realized enabling to sample the moving air mass parcels twice along their trajectories. Eight distinct WAI and 12 CAO cases were probed extensively. From the quasi-Lagrangian measurements, we have derived the diabatic heating and moistening of the moving air masses during CAOs and WAIs, the development of cloud macrophysical and microphysical properties along the southward pathways of the air masses during CAOs, and the moisture budget of WAIs. As an example result, we have obtained typical values of the surface-driven diabatic heating between 1–3 K h-1 and of the near-surface moistening between 0.05–0.3 g kg-1 h-1 within the lowest about 0.5 km. From the observations of WAIs, a weak diabatic cooling of up to 0.4 K h-1 and a moisture loss of up to 0.1 g kg-1 h-1 from the ground to about 5 km altitude were derived. In addition, we discuss the frequency of occurrence of the different thermodynamic phases of Arctic low-level clouds, the interaction of Arctic cirrus with sea ice, water vapor, and aerosol particles, and the characteristic microphysical and chemical properties of Arctic aerosol particles. Finally, we provide proof of a concept to measure mesoscale divergence and subsidence in the Arctic using data from dropsondes released during circular flight patterns