Rain-on-snow (ROS) events in the Arctic can lead to major impacts on the snow cover, cryosphere and environment. During the last decades, these events have significantly increased, mostly due to climate change. Here, we use outputs from the regional climate model MAR (version 3.14) driven by the ERA5 reanalysis at 10-km resolution over Greenland, in the period 1940-2023. MAR is used to simulate the climatological properties of summertime ROS events over Greenland, and their long-term changes over the period. The analyses also focused on the years after 1979, when reanalyses are more reliable. We found that both the spatial extension, the frequency, and rainfall amounts associated with ROS events all strongly increased, especially along the West and East coasts of Greenland. These changes either appeared, or strongly accelerated, during the last 40 yrs. We also analyzed the synoptic configurations conducive to major ROS events (the top 10% in terms of size and amounts). Poleward advection of moisture and heat generally prevails but shows non-negligible variability in their location, direction and strength of associated centers of action. About 10%-20% of those major ROS events correspond to atmospheric rivers, events that occur 1%-2% of the time but increase the probability of rainfall over Greenland by a factor 10 to nearly 40 locally, with respect to the climatology. Plain Language Summary The Arctic and Greenland are among the regions warming fastest on Earth. In summer, an increasing proportion of precipitation is liquid (rainfall), which causes snow to melt and leave ice unprotected. Here, we show that rain-on-snow events dramatically increased in frequency, size, and rainfall amounts. This increase is partly due to warming, turning snow to rain. Atmospheric circulations conducive to large rainfall amounts generally consist of southerly wind anomalies transporting moisture and heat polewards, among which 10%-20% correspond to "atmospheric rivers," corridors of particularly intense poleward transport. These results could help better understand the surface mass balance of the Greenland ice sheet.

The Svalbard Archipelago, located in the Arctic region of Norway, is extremely vulnerable to the climate change. With a current increase of 3 at 5°C in average air temperature and a change in precipitation with an increasing proportion of rain, certain negative consequences for the environment and ecosystem are inevitable. One of the most obvious signs of climate change in this region is the melting of ice, which is causing the Earth’s crust to deform. But there are other consequences, such as the loss of sea ice cover, changes in how sediment is transported and also changes in biodiversity.These phenomena are widely studied in this region. For example, deformation of the Earth’s crust is determined using 3D positioning data acquired by GNSS across Svalbard, particularly in Ny-Alesund. Since 2000, daily positioning time series show a strong upward component, with an average vertical velocity of between 8 to 13 mm/yr. This velocity is the Earth’s response to various episodes of glaciation and deglaciation in the past like the last glacial maximum or the Little Ice Age, and to the current melting of ice. This current melting has also been studied a lot at Ny-Alesund station, where glaciers are monitored to measure changes in ice height from one year to the next and calculate the glacier’s surface mass balance. This is the case for the Austre Lovenbreen, for which data has been available since 2007, showing record melting over the last ten years. The same is true for the study of the prodeltas evolution since 2009, which shows a stabilisation of almost all prodeltas since 2016.All these phenomena are largely studied separately, but our analysis consists of interpreting all this data in order to study the possible correlation between these observations which share the same cause: climate change. In our study, we ask how we can link measurements taken at the glacier or in the underwater sediment, along with space geodesy data, to better understand the ongoing geophysical processes that mark the transition between a glacial environment and paraglacial environment.

Glaciers lost 408 ± 132 Gt of mass during the hydrological year 2025, equivalent to 1.1 ± 0.4 mm sea-level rise. Since 1975, glacier mass loss has totalled 9,583 ± 1,211 Gt, equivalent to 26.4 ± 3.3 mm of sea-level rise, with six of the highest mass-loss years on record occurring in the past seven years.

In the context of climate warming it is a common scientific goal to study and monitor surface and volume changes of glaciers and melting dynamics of its snow and ice. Therefore several measurement techniques exist to track permanently ice melting e.g. DGPS stations on glaciers, Smart stake, and snow and ice depth measurements via e.g. ultrasonic depth sensors to create time series of snow and ice loss or gain. None of the existing methods measure if actually liquid water is present and melting occurs, this is later concluded by interpretation of the geometric data. The capability of the laser sensor to do so via the reflectance value, in fact the received signal intensity, we consider as a big advantage and worth investigating further as a direct measure of snow or ice melt that helps not only to analyze glacier dynamics but is also important e.g. for providing reliable ground truth data for satellite remote sensing. When melting of snow and ice occurs, water changes the reflectance properties as due to absorption of the laser in water, only a portion of the laser is reflected. This allows determining if liquid water is present at the surface measured. We present the data collected in the last 2 melting seasons of the Austre Lovénbreen glacier near Ny Alesund, Svalbard. We show how we classify wet snow and wet ice hours with confidence and are able to compute melting rates. The single point measurement is put into context to area wide LiDAR measurements and melting dynamics of the glacier are analyzed. The data was verified against visual inspections from automatic cameras, data from an automatic weather station both located in the glacier catchment and ice melt was measured in close proximity with a SmartStake station.

The codon usage bias of the Zika virus (ZIKV) genome is skewed towards AA-ending codons, which are preferentially decoded by U34-modified cognate tRNAs. This contrasts with the human host’s preference for AG-ending codons, suggesting that ZIKV may exploit specific tRNA modifications to optimize protein synthesis within human cells. To test this hypothesis, we used codon-biased eGFP sensors and found that ZIKV infection transiently increased the expression of AA-biased GFP at the expense of AG-biased GFP. Mass spectrometry analysis further showed that ZIKV virus infection increases mcm5s2U34 tRNA modification content in host cells. In ELP1-deficient cells, which exhibit reduced U34 modifications, ZIKV replication was impaired. Enhancing U34 modification through using a small molecule known to restore ELP1 expression, rescued viral replication in these cells. Moreover, CRISPR/Cas9 and shRNA-mediated knockdown of key enzymes involved in U34 modification, ELP1, ALKBH8, and CTU1, significantly reduced ZIKV replication. Collectively, these results provide strong evidence that ZIKV reprograms the host tRNA epitranscriptome and exploits host cell tRNA modifications, particularly at the wobble position U34, to optimize translation of its own proteins and promote viral replication. ### Competing Interest Statement The authors have declared no competing interest.

In the Arctic, extreme weather conditions such as rain-on-snow events (ROS) make the monitoring of the snowpack with remote sensing techniques increasingly relevant and necessary. In recent years, remote sensing methods based on active radar images (SAR) are well described for mapping the spatial extent of ROS events in the terrestrial Arctic (Vickers, 2022; Bartsch, 2023). However, few methods are proposed to validate the relationship between ROS and elevation for such events over glaciers likely due to the lack of in-situ measurement networks in these high latitude areas. Svalbard provides several meteorological and snow monitoring sites, which is a great value for detecting the occurrence of these ROS events and validation of the remote sensing methods.The purpose of this study is to investigate the spatial and temporal effects of recent ROS events over the Brøgger peninsula (210 km2) in Svalbard (N 78°55’ / E 11° 55’), using remote sensing methods, local meteorological measurements and reanalyses. For each ROS event of the 2017-2023 time period, remote sensing SAR maps of wet snow (Nagler and Rott, 2000) are produced from images obtained with the TerraSAR-X (DLR) and RCM (CSA) high resolution sensors (5-m), respectively at X- and C-band frequency.The validation of the affected areas is based (i) on ERA5 reanalysis data used to estimate the altitude of the 0°C isoline and (ii) on a network of temperature sensors installed on the Austre Lovén glacier. SAR maps, ERA5 isoline, and in-situ data are in good agreement, resulting in altitude differences between 10 and 25 m for the transition of wet and dry snow, depending on the event.Although optical images availability is limited due to polar night and cloud cover during precipitation, it was further possible to use optical Planet images at high temporal and spatial resolution (3-m) to determine the ROS impact after the events on the properties of the snow cover. The decreasing signal of the red-edge and near-infrared bands indicate higher snow densities and a stronger wetness of the snowpack, which closely aligns with in-situ observations through snow stratigraphy.

We address the evolution of a proglacial hydrographic network under the influence of icings over a small Arctic glacier forefield in the context of glacier retreat. The newly deglaciated area allows glacial rivers to carve new channels as fine-grained sediment is exposed. The main glacier outlet flow from one channel to another is controlled by icings over the years. The research methodology involves analyzing optical camera images for qualitative observations of morphological evolutions and LiDAR data for quantitative estimates of the icings' volume as well as riverbed profiles. Ground penetrating radar (GPR) is used to investigate the internal structure of icings and its possible influence on runoff streams. Based on the seasonal persistence of icings and their spatial extent, we observe that icings act as dams channelling the main glacier outlet between canyons carved in the deglaciated areas and, when lasting long enough, even define long-term outflow paths. The internal structure of icings suggests that upstream, deep icings are permeable to water flow while downstream dense, shallow icings act as watertight obstacles, contributing to their dam effect.

Simultaneous heat waves occurred on March 2022 in both Antarctic and Arctic regions. The impact of this extreme weather event is investigated from the perspective of a north-facing polar glacier in the Br & oslash;gger Peninsula of Svalbard, Arctic Norway. Original measurement systems including timelapse cameras and an automated ablation stake acquiring the ice melt with hourly resolution were deployed for a couple of years during and after the event. The results of these measurements demonstrate that the liquid precipitation accompanying the warm event led to a significant impact on the snowpack structure. It resulted in an earlier snowpack disappearance. Consequently, the glacier surface was exposed earlier, resulting in ice melting earlier than it did in 2023, which is considered as a reference state. This in turn contributed to a more negative mass balance. This study highlights the strong negative influence of winter liquid precipitation on glacier mass balance.

In the context of glacier retreat and increased precipitations, Arctic glacier basin slopes are subject to stress leading to visible transformations. In this work, subsurface features of a small Arctic glacier basin slopes are mapped using ground-penetrating RADAR. In combination with surface topography data, eight transects were surveyed ranging from the areas furthest from the current glacier extent to the areas still in contact with the glacier. This allowed for a reconstitution of the successive stages ice-cored slopes go through when glaciers retreat. It appears that slopes evolve from thick debris-covered ice bodies connected with the glacier, to residual ice and ice/debris mixes covered in debris. At the same time, surface morphology of the slopes shifts from homogeneous ice-cored slope gradients to more complex talus-type slopes at the end of the process. The stages of these evolutions are in compliance with former glacier extents. The main driving factors of the slopes successive stages are the constant slope adjustments linked to debris movements, and the melting of ice cores. All these factors are exacerbated by the warmer and wetter conditions they are subject to. Ground penetrating RADAR maps of ice buried under debris flowing downhill slopes surrounding an Arctic glacier demonstrate how maximum past glacier extent can be deduced from the maximum buried ice altitude. This buried ice is connected to the main glacier ice body and vanishes as older slopes disconnected for longer from the main glacier are investigated. The glacier is hence considered to extend well beyond the visual exposed ice area but also under the surrounding slopes. image

ABSTRACT Chikungunya virus (CHIKV) is a mosquito-borne pathogen responsible for an acute musculoskeletal disease in humans. Replication of the viral RNA genome occurs in specialized membranous replication organelles (ROs) or spherules, which contain the viral replication complex. Initially generated by RNA synthesis-associated plasma membrane deformation, alphavirus ROs are generally rapidly endocytosed to produce type I cytopathic vacuoles (CPV-I), from which nascent RNAs are extruded for cytoplasmic translation. By contrast, CHIKV ROs are poorly internalized, raising the question of their fate and functionality at the late stage of infection. Here, using in situ cryogenic-electron microscopy approaches, we investigate the outcome of CHIKV ROs and associated replication machinery in infected human cells. We evidence the late persistence of CHIKV ROs at the plasma membrane with a crowned protein complex at the spherule neck similar to the recently resolved replication complex. The unexpectedly heterogeneous and large diameter of these compartments suggests a continuous, dynamic growth of these organelles beyond the replication of a single RNA genome. Ultrastructural analysis of surrounding cytoplasmic regions supports that outgrown CHIKV ROs remain dynamically active in viral RNA synthesis and export to the cell cytosol for protein translation. Interestingly, rare ROs with a homogeneous diameter are also marginally internalized in CPV-I near honeycomb-like arrangements of unknown function, which are absent in uninfected controls, thereby suggesting a temporal regulation of this internalization. Altogether, this study sheds new light on the dynamic pattern of CHIKV ROs and associated viral replication at the interface with cell membranes in infected cells. IMPORTANCE The Chikungunya virus (CHIKV) is a positive-stranded RNA virus that requires specialized membranous replication organelles (ROs) for its genome replication. Our knowledge of this viral cycle stage is still incomplete, notably regarding the fate and functional dynamics of CHIKV ROs in infected cells. Here, we show that CHIKV ROs are maintained at the plasma membrane beyond the first viral cycle, continuing to grow and be dynamically active both in viral RNA replication and in its export to the cell cytosol, where translation occurs in proximity to ROs. This contrasts with the homogeneous diameter of ROs during internalization in cytoplasmic vacuoles, which are often associated with honeycomb-like arrangements of unknown function, suggesting a regulated mechanism. This study sheds new light on the dynamics and fate of CHIKV ROs in human cells and, consequently, on our understanding of the Chikungunya viral cycle.

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Landslide processes are one of the dominant agents of erosion and sediment transport on sediment-mantled slopes in arctic environments. Increased landslide activity is anticipated as climate change is projected to decrease mountain slope stability. High-Arctic environments, such as Svalbard, serve as crucial observatories for investigating current and future slope dynamics within a changing climate, particularly due to arctic amplification effects. Despite the significance of Arctic regions, empirical evidence in high latitudes is often lacking. This scarcity can be attributed to the absence of long-term, high-resolution terrain data with sufficient temporal resolution to assess the impact of meteorological boundary conditions on landscapes altered by climate change. However, addressing this gap in empirical evidence is essential for understanding the complex interplay between meteorological variables and debris slide and debris flow evolution in Arctic environments. This study presents a unique high-resolution remote sensing dataset within a high-Arctic glacier basin acquired over a 10-year period. Through the combination of terrestrial laser-scanning and an autonomous camera network, we were able to investigate the impact of meteorological boundary conditions on the trigger mechanisms of translational debris slides and debris flows and unravel paraglacial slope evolution following recent glacier retreat on the example of the Austre Lovenbreen glacier basin (Svalbard, Norway). Translational debris slides accounted for approximately 96 % (N = 147) of the total sediment flux observed, with debris flows (N = 21) acting as a secondary agent of sediment transport. The debris slide activity significantly increased between 2011 and 2021. Heavy rainfall events primarily influence the frequency and magnitude of debris slides during the hydrological summer, while the duration and intensity of the thawing period serve as the principal control for their initiation. Furthermore, a 2-year recurrence period for major debris flows (>= 400 m3) was found, which is about 2.5 to 5 times shorter than previous estimates for the last few decades on Svalbard. In conclusion, this study highlights the impact of meteorological factors on debris slide frequency and magnitude within high-Arctic glacier basins, shedding light on the dynamics of paraglacial slope modification in Arctic environments affected by climate change.

Alphavirus infection induces dramatic remodeling of host cellular membranes, producing filopodia-like and intercellular extensions. The formation of filopodia-like extensions has been primarily assigned to the replication protein nsP1, which binds and reshapes the host plasma membrane when expressed alone. While reported decades ago, the molecular mechanisms behind nsP1 membrane deformation remain unknown. Using mammalian epithelial cells and Chikungunya virus (CHIKV) as models, we characterized nsP1-induced membrane deformations as highly dynamic actin-rich lamellipodia and filopodia-like extensions. Through pharmacological inhibition and genetic invalidation, we identified the critical contribution of the Rac1 GTPase and its downstream effectors PAK1 and the actin nucleator Arp2 in nsP1-induced membrane deformation. An intact Rac1-PAK1-Arp2 signaling axis was also required for optimal CHIKV genome replication. Therefore, our results designate the Rac1-PAK1-Arp2 pathway as an essential signaling node for CHIKV infection and establish a parallel requirement for host factors involved in nsP1-induced plasma membrane reshaping and assembly of a functional replication complex.IMPORTANCEThe alphavirus nsP1 protein dramatically remodels host cellular membranes, resulting in the formation of filopodia-like extensions. Although described decades ago, the molecular mechanisms controlling these membrane deformations and their functional importance remain elusive. Our study provides mechanistic insight, uncovering the critical role of the Rac1 GTPase, along with its downstream effectors PAK1 and the actin nucleator Arp2, in the nsP1-associated phenotype. Furthermore, we demonstrate that the Rac1-PAK1-Arp2 pathway is essential for optimal CHIKV genome replication. Our findings establish a parallel in the cellular mechanisms governing nsP1-induced plasma membrane reshaping and the production of a functional replication complex in infected cells.

The snowpack evolution during the melt season on an Arctic glacier is assessed using ground-based oblique-view cameras, spaceborne imaging and spaceborne RADAR. The repeated and systematic Synthetic Aperture RADAR (SAR) imaging by the European Space Agency’s Sentinel-1 spaceborne RADARs allows for all-weather, all-illumination condition monitoring of the snow-covered fraction of the glacier and hence assessing its water production potential. A comparison of the RADAR reflectivity with optical and multispectral imaging highlights the difference between the observed quantities—water content in the former, albedo in the latter—and the complementarity for understanding the snow melt processes. This work highlights the temporal inertia between the visible spring melting of the snowpack and the snow metamorphism. It was found that the snowpack exhibits that approximately 30 days before it starts to fade.

Landslide processes are one of the dominant agents of erosion and sediment transport in alpine terrain, which often pose a significant risk to communities and infrastructure around the world. Climate change generates a wide range of processes such as glacier retreat, permafrost degradation or changing precipitation patterns, which are projected to decrease the stability of mountain slopes and thus will lead to increased landslide activity. However, the empirical evidence is lacking as meteorological boundary conditions altered by climate change, may have different and often contrasting effects on landslide formation and activity. As a result of the Arctic amplification, high-arctic environments are an important field laboratory for investigating current and future landslide processes.The ongoing paraglacial response of sediment-mantled slopes through landslide processes has been assessed and mapped around the globe. However, investigations on the impact of meteorological factors on shallow landslide formation modifying sediment-mantled slopes in the surroundings of retreating glaciers is in many cases not possible due to the lack of long-term high-resolution terrain data. The Austre Lovénbreen glacier basin in Svalbard (Norway) is a particularly relevant location to study the modification of slopes through landslides, as the area has been affected by the recent global warming characterized by the greatest temperature increase during the last three decades.The objectives of this study are i) to provide data utilizing multi-temporal high-resolution terrestrial laser scans of the glacier and the surrounding slopes, ii) identify and quantify landslide processes found on sediment-mantled slopes, iii) investigate failure mechanisms and derive a conceptual model describing the adaptation of the periglacial talus slopes to the retreat of the glacier and iv) investigate the driving factors for the temporal and spatial evolution of landslides in the Austre Lovénbreen Basin.The Austre Lovénbreen glacier basin represents a highly dynamic environment, which is in an unstable state, caused by the rapid retreat of the glacier and by climatic conditions. We show that, in contrast to the established literature, shallow debris slides are the primary source of sediment transport on steep sediment-mantled slopes in a high-arctic environment and that meteorological parameters control their spatial and temporal evolution.

Chikungunya virus (CHIKV) is a mosquito-borne pathogen responsible for an acute musculo-skeletal disease in humans. The viral RNA genome replication occurs in membrane spherules named replication organelles (ROs). In this work, we investigate the native structural organization of CHIKV ROs in their cellular context using in situ cryogenic-electron microscopy approaches at late replication stage. We observed previously unreported diameter heterogeneity of ROs at the plasma membrane of infected human cells. CHIKV ROs were only marginally detected in cytopathic vacuoles where they are homogeneous in size, suggesting a finely regulated internalization process. Our data show that ROs maintained at the plasma membrane beyond the first viral cycle are dynamically active both in viral RNA replication, in its export to the cell cytosol, but also in the production of viral proteins. We suggest that late CHIKV ROs have an amplifying role or represent an alternative pathway in the production of infectious viral particles. All these observations bring new insight into the CHIKV life cycle in human cells.

<p>Arctic snow cover dynamics exhibit modification in terms of extent and duration due to recent changes in climate, i.e. increasing temperatures and changing precipitation patterns, i.e. winter rain-on-snow events (WROS). Remote sensing methods based on active radar images (SAR) have demonstrated a significant advantage for snow monitoring, (i) capturing physical and dielectric properties, (ii) overcoming the weakness of optical images limited by cloud cover and polar night.</p> <p>The aim of this study is dedicated to the analysis of the spatial and temporal variability of snow cover in the Ny-Ålesund area on the BrØgger peninsula, Svalbard (N 78°55’ / E 11° 55’). In-situ snow measurements from two automated weather stations (Ny-Ålesund, and Bayelva), regular snowpits around the village and in spring on the Austre Loéven, were compared with the spaceborne dataset.</p> <p>The RADARSAT Constellation Mission (RCM) is comprised of three satellites into closely coordinated orbits operating in C-band (5.4 GHz, 5.5 cm). The high temporal (4-day repeat cycle) and spatial resolution of the sensors in Quad-Pol mode (9-m) or Compact-Pol mode (5-m) provide a helpful performance for detecting the spatial variability of snow properties. RCM data are also compared to images of the TerraSAR-X satellite (DLR, Germany) operated in X-band (9.6 GHz, 3.1 cm) at 5-m spatial resolution. Both RCM QP mode and TSX data were acquired with medium incidence angles (33° to 39°) providing better snow penetration for volume backscattering. The RCM CP data were only available under low (23°) and high (53°) beam angles.</p> <p>The following two snow properties were analyzed:</p> <p>WROS detection: the focus was set on the 16-17 March 2022 event (+ 5.5 °C, 62 mm). RCM data at cross-polarization VH or HV can clearly detect the impact of rain on snow, indicating an intensity drop of -10 dB, even on the glacier at high elevation.</p> <p>Snow depth retrieval: the study covers spring 2021 (March-June) and the complete winter season 2021-2022 (November-June).</p> <p>- Concerning QP mode, better correlation between snow depth and SAR backscattering is observed by the cross-pol VH component, retrieving more volume backscattering information than co-pol configuration or total backscattering power (Span). We observe also that descending orbit images (06 :30 AM) provide a better correlation with snow depth than ascending orbit (15 :30 PM) data.</p> <p>- Concerning CP mode and Span (RH+RV), the low incidence images (23°) do not match the snow depth observations due to main surface backscattering, contrariwise the high incidence images correlate better with in-situ observations. The analyses of the Stokes vector elements showed a satisfying correlation for the <em>g3</em> element and the Relative Phase polarimetric decomposition.</p> <p>Finally, a comparison of Span temporal values between RCM at C-band and TSX at X-band indicates similar time profiles, but clearly lower values of -5 to -10 dB at the C-band.</p>

Genome-wide screens are powerful approaches to unravel new regulators of viral infections. Here, we used a CRISPR/Cas9 screen to reveal new HIV-1 inhibitors. This approach led us to identify the RNA helicase DDX42 as an intrinsic antiviral inhibitor. DDX42 was previously described as a non-processive helicase, able to bind RNA secondary structures such as G-quadruplexes, with no clearly defined function ascribed. Our data show that depletion of endogenous DDX42 significantly increased HIV-1 DNA accumulation and infection in cell lines and primary cells. DDX42 overexpression inhibited HIV-1, whereas a dominant-negative mutant increased infection. Importantly, DDX42 also restricted retrotransposition of LINE-1, infection with other retroviruses and positive-strand RNA viruses, including CHIKV and SARS-CoV-2. However, DDX42 did not inhibit infection with three negative-strand RNA viruses, arguing against a general, unspecific effect on target cells, which was confirmed by RNA-seq analysis. DDX42 was found in the vicinity of viral elements by proximity ligation assays, and cross-linking RNA immunoprecipitation confirmed a specific interaction of DDX42 with RNAs from sensitive viruses. This strongly suggested a direct mode of action of DDX42 on viral ribonucleoprotein complexes. Taken together, our results show for the first time a new and important role of DDX42 in intrinsic antiviral immunity.

Ras-GTPase-activating SH3 domain-binding-proteins 1 (G3BP1) and 2 (G3BP2) are multifunctional RNA-binding proteins involved in stress granule nucleation, previously identified as essential cofactors of Old World alphaviruses. They are recruited to viral replication complexes formed by the Chikungunya virus (CHIKV), Semliki Forest virus (SFV), and Sindbis virus (SINV) via an interaction with a duplicated FGxF motif conserved in the hypervariable domain (HVD) of virus-encoded nsP3. According to mutagenesis studies, this FGxF duplication is strictly required for G3BP binding and optimal viral growth. Contrasting with this scenario, nsP3 encoded by Mayaro virus (MAYV), an arthritogenic virus grouped with Old World alphaviruses, contains a single canonical FGxF sequence. In light of this unusual feature, we questioned MAYV nsP3/G3BPs relationships. We report that G3BP1 and G3BP2 are both required for MAYV growth in human cells and bind nsP3 protein. In infected cells, they are recruited to nsP3-containing cytosolic foci and active replication complexes. Unexpectedly, deletion of the single FGxF sequence in MAYV nsP3 did not abolish these phenotypes. Using mutagenesis and in silico modeling, we identify an upstream FGAP amino acid sequence as an additional MAYV nsP3/G3BP interaction motif required for optimal viral infectivity. These results, therefore, highlight a non-conventional G3BP binding sequence in MAYV nsP3.

The global climate shift currently underway has significant impacts on both the quality and quantity of snow precipitation. This directly influences the spatial variability of the snowpack as well as cumulative snow height. Contemporary glacier retreat reorganizes periglacial morphology: while the glacier area decreases, the moraine area increases. The latter is becoming a new water storage potential that is almost as important as the glacier itself, but with considerably more complex topography. Hence, this work fills one of the missing variables of the hydrological budget equation of an arctic glacier basin by providing an estimate of the snow water equivalent (SWE) of the moraine contribution. Such a result is achieved by investigating Structure from Motion (SfM) image processing that is applied to pictures collected from an Unmanned Aerial Vehicle (UAV) as a method for producing snow depth maps over the proglacial moraine area. Several UAV campaigns were carried out on a small glacial basin in Spitsbergen (Arctic): the measurements were made at the maximum snow accumulation season (late April), while the reference topography maps were acquired at the end of the hydrological year (late September) when the moraine is mostly free of snow. The snow depth is determined from Digital Surface Model (DSM) subtraction. Utilizing dedicated and natural ground control points for relative positioning of the DSMs, the relative DSM georeferencing with sub-meter accuracy removes the main source of uncertainty when assessing snow depth. For areas where snow is deposited on bare rock surfaces, the correlation between avalanche probe in-situ snow depth measurements and DSM differences is excellent. Differences in ice covered areas between the two measurement techniques are attributed to the different quantities measured: while the former only measures snow accumulation, the latter includes all of the ice accumulation during winter through which the probe cannot penetrate, in addition to the snow cover. When such inconsistencies are observed, icing thicknesses are the source of the discrepancy that is observed between avalanche probe snow cover depth measurements and differences of DSMs.