Telomeres are nucleoprotein structures at the ends of linear chromosomes. In humans, they consist of TTAGGG repeats, which are bound by dedicated proteins such as the shelterin complex. This complex blocks unwanted DNA damage repair at telomeres, e.g. by suppressing non-homologous end joining (NHEJ) through its subunit TRF2. We here describe ZNF524, a zinc finger protein that directly binds telomeric repeats with nanomolar affinity and reveal the base-specific sequence recognition by co-crystallization with telomeric DNA. ZNF524 localizes to telomeres and specifically maintains the presence of the TRF2/RAP1 subcomplex at telomeres without affecting other shelterin members. Loss of ZNF524 concomitantly results in an increase in DNA damage signaling and recombination events. Overall, ZNF524 is a direct telomere-binding protein involved in the maintenance of telomere integrity.

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<p>Methane is emitted during the production and transportation of fossil fuels. Methane emissions result also from intensive livestock farming and agricultural practices as well as by the decay of organic waste. The leakage throughout the extraction, processing and transportation of natural gas releases methane straight into the atmosphere. Due to the damage to the Nord Stream gas pipelines on 26 September 2022 leaks have appeared close to the Danish island of Bornholm in the Baltic Sea, which releases large amounts of methane in the pipeline into the atmosphere within just a few days. In our study, we simulated the transport of methane plume in Nord Stream case by using DWD’s regional Icosahedral Nonhydrostatic (ICON) model with its transport scheme ART (Aerosols and Reactive Trace gases) extension.</p> <p>The model is run for Limited Area Mode (LAM) with a horizontal spatial resolution of 6.5 km and 60 model levels. As source strength of methane emissions were used the estimates which were calculated by the German Federal Environmental Agency (Umwelt Bundesamt). An assumption, that a constant 700 kg/s of gas had been leaking since September 26 was used for the hourly model run to simulate the methane plume between September 26 and October 1 2022.</p> <p>The model results had been compared to the potential methane signals of Nord Stream leaks detected at Integrated Carbon Observation System (ICOS) stations. According to our simulations, we found a good fit with respect to ICOS observations for the stations Hyltemossa, Birkenes and Norunda. Further analysis has been conducted to look at vertical profiles at different heights and also into correlation coefficients between the model and observations.</p> <p>In this Nord Stream case, our simulation demonstrates modelling capabilities of the ICON-ART model and its associated quantitative assessment of methane emissions.</p> <p>This work has been funded by the German Federal Ministry for Digital and Transport programme for Development and Implementation of Copernicus services for public needs within the HoTC project.</p>

<p>We conducted CH<sub>4 </sub>simulations for Europe by using the ICON (<strong>ICO</strong>sahedral <strong>N</strong>on-hydrostatic)-ART (<strong>A</strong>erosols and <strong>R</strong>eactive <strong>T</strong>race gases) model and emissions from EDGAR.</p><p>With respect to the forecast of CH<sub>4</sub> in Limited Area Mode (Europe, 6.5 x 6.5 km), the model requires as accurate as possible initial and boundary atmospheric conditions. While the intial data denote here the state of the atmosphere at the start of the model run, the boundary conditions shall denote the data in the lateral boundary zone where the model is forced by the meteorological and CH<sub>4 </sub>concentration data out side the domain.</p><p>The meteorological conditions can be obtained, for example,  from both the DWD's operational numerical weather prediction output or from Copernicus. The Copernicus Atmosphere Monitoring Service (CAMS) provides the necessary boundary CH<sub>4 </sub>data for the ICON-ART run in Limited Area Mode. The  CH<sub>4</sub> initial concentrations can be obtained from Copernicus or from a previous ICON-ART simulation run (e.g., the 24 h CH4 forecast from the previous day).</p><p>This way, ICON-ART in Limited Area Mode (LAM) allows for a flexible choice of boundary data and respective sensitivity testing. </p><p>To combine the meteorological data of the ICON with the CH<sub>4</sub> concentration data of CAMS as forcing data at the boundary, the CAMS data has to be provided on the same horizontal grid and the same vertical model levels as the ICON data. Since CAMS uses a vertical coordinate of a hybrid sigma-pressure system, the data has, in addition to the horizontal interpolation, to be interpolated vertically to the height based SLEVE coordinate system of ICON.</p><p>Also, the EDGAR emission datasets are interpolated to the target ICON grid. Both interpolations are characterized with respect introducing uncertainties.</p><p>Thirdly, variation in meteorological conditions is simulated by running ensembles in the ICON-ART LAM.</p><p>In this work, the ICON-ART CH<sub>4</sub> simulation setup forced by ICON meteorology and CAMS CH<sub>4</sub> boundary data is shown to be a useful method to simulate the CH<sub>4</sub> atmospheric concentrations at the regional scale and for the purposes of regional atmospheric inversions.</p><p>This work has been supported by the project Prototype system for a Copernicus CO<sub>2</sub> service (COCO2).</p><p> </p>