ALBERT

Beschreibung: Looking beyond stratification: a model-based analysis of the biological drivers of oxygen depletion in the North Sea Biogeosciences Discussions, 12, 12543-12610, 2015 Author(s): F. Große, N. Greenwood, M. Kreus, H. J. Lenhart, D. Machoczek, J. Pätsch, L. A. Salt, and H. Thomas The problem of low oxygen conditions, often referred to as hypoxia, occurs regularly in the North Sea, a temperate European shelf sea. Stratification represents a major process regulating the seasonal dynamics of bottom oxygen. However, lowest oxygen conditions in the North Sea do not occur in the regions of strongest stratification. This suggests that stratification is an important prerequisite for hypoxia, but that the complex interaction between hydrodynamics and the biological processes drives its development. In this study we use the ecosystem model HAMSOM-ECOHAM5 to provide a general characteristic of the different North Sea oxygen regimes, and to quantify the impact of the different physical and biological factors driving the oxygen dynamics below the thermocline and in the bottom layer. We show that the North Sea can be subdivided into three different regimes in terms of oxygen dynamics: (1) a highly productive, non-stratified coastal regime, (2) a productive, seasonally stratified regime with a small sub-thermocline volume, and (3) a productive, seasonally stratified regime with a large sub-thermocline volume, with regime 2 being highly susceptible to hypoxic conditions. Our analysis of the different processes driving the oxygen development reveals that inter-annual variations in the oxygen conditions are caused by variations in primary production, while spatial differences can be attributed to differences in stratification and water depth. In addition, we show that benthic bacteria represent the main oxygen consumers in the bottom layer, consistently accounting for more than 50 % of the overall consumption. By providing these valuable insights, we show that ecosystem models can be a useful tool for the interpretation of observations and the estimation of the impact of anthropogenic drivers on the North Sea oxygen conditions.

Beschreibung: Estimating greenhouse gas emissions from travel – a GIS-based study Geographica Helvetica, 70, 185-192, 2015 Author(s): S. Kuonen Conferences, meetings and congresses are an important part of today's economic and scientific world. But the environmental impact, especially from greenhouse gas emissions associated with travel, can be extensive. Anthropogenic greenhouse gas (GHG) emissions account for the warming of the atmosphere and oceans. This study draws on the need to quantify and reduce greenhouse gas emissions associated with travel activities and aims to give suggestions for organizers and participants on possible ways to reduce greenhouse gas emissions, demonstrated on the example of the European Geography Association (EGEA) Annual Congress 2013 in Wasilkow, Poland. The lack of a comprehensive methodology for the estimation of greenhouse gas emissions from travel led to an outline of a methodology that uses geographic information systems (GIS) to calculate travel distances. The calculation of travel distances in GIS is adapted from actual transportation infrastructure, derived from the open-source platform OpenStreetMap. The methodology also aims to assess the possibilities to reduce GHG emissions by choosing different means of transportation and a more central conference location. The results of the participants of the EGEA congress, who shared their travel data for this study, show that the total travel distance adds up to 238 000 km, with average travel distance of 2429 km per participant. The travel activities of the participants in the study result in total GHG emissions of 39 300 kg CO 2 -eq including both outward and return trip. On average a participant caused GHG emissions of 401 kg CO 2 -eq. In addition, the analysis of the travel data showed differences in travel behaviour depending on the distance between conference site and point of origin. The findings on travel behaviour have then been used to give an estimation of total greenhouse gas emissions from travel for all participants of the conference, which result in a total amount of 79 711 kg CO 2 -eq. The potential for reducing greenhouse gas emissions by substituting short flights with train rides and car rides with bus and train rides is limited. Only 6 % of greenhouse gas emissions could be saved by applying these measures. Further considerable savings could only be made by substituting longer flights (32.6 %) or choosing a more central conference location (26.3 %).

Beschreibung: Uncertainties in calculating precipitation climatology in East Asia Hydrology and Earth System Sciences Discussions, 12, 7765-7783, 2015 Author(s): J. Kim and S. K. Park This study examines the uncertainty in calculating the fundamental climatological characteristics of precipitation in the East Asia region from multiple fine-resolution gridded analysis datasets based on in-situ rain gauge observations. Five observation-based gridded precipitation datasets are used to derive the long-term means, standard deviations in lieu of interannual variability and linear trends over the 28-year period from 1980 to 2007. Both the annual and summer (June–July–August) mean precipitation is examined. The agreement amongst these precipitation datasets are examined using multiple metrics including the signal-to-noise ratio (SNR) defined as the ratio between long-term means and the corresponding standard deviations, and Taylor diagrams which allows examinations of the pattern correlation, the standard deviation, and the centered root mean square error. It is found that the five gauge-based precipitation analysis datasets agree well in the long-term mean and interannual variability in most of the East Asia region including eastern China, Manchuria, South Korea, and Japan, which are densely populated and have fairly high density observation networks. The regions of large inter-dataset variations include Tibetan Plateau, Mongolia, northern Indo-China, and North Korea. The regions of large uncertainties are typically lightly populated and are characterized by severe terrain and/or extreme high elevations. Unlike the long-term mean and interannual variability, agreements between datasets in the linear trend is weak, both for the annual and summer mean values. In most of the East Asia region, the SNR for the linear trend is below 0.5, i.e., the inter-dataset variability exceeds the multi-data ensemble mean. The uncertainty in the spatial distribution of long-term means among these datasets occurs both in the spatial pattern and variability, but the uncertainty for the interannual variability and time trend is much larger in the variability than in the pattern correlation. Thus, care must be taken in using long-term trends calculated from gridded precipitation analysis data for climate studies over the East Asia region.

Beschreibung: Qualitative soil moisture assessment in semi-arid Africa – the role of experience and training on inter-rater reliability Hydrology and Earth System Sciences, 19, 3505-3516, 2015 Author(s): M. Rinderer, H. C. Komakech, D. Müller, G. L. B. Wiesenberg, and J. Seibert Soil and water management is particularly relevant in semi-arid regions to enhance agricultural productivity. During periods of water scarcity, soil moisture differences are important indicators of the soil water deficit and are traditionally used for allocating water resources among farmers of a village community. Here we present a simple, inexpensive soil wetness classification scheme based on qualitative indicators which one can see or touch on the soil surface. It incorporates the local farmers' knowledge on the best soil moisture conditions for seeding and brick making in the semi-arid environment of the study site near Arusha, Tanzania. The scheme was tested twice in 2014 with farmers, students and experts (April: 40 persons, June: 25 persons) for inter-rater reliability, bias of individuals and functional relation between qualitative and quantitative soil moisture values. During the test in April farmers assigned the same wetness class in 46 % of all cases, while students and experts agreed on about 60 % of all cases. Students who had been trained in how to apply the method gained higher inter-rater reliability than their colleagues with only a basic introduction. When repeating the test in June, participants were given improved instructions, organized in small subgroups, which resulted in a higher inter-rater reliability among farmers. In 66 % of all classifications, farmers assigned the same wetness class and the spread of class assignments was smaller. This study demonstrates that a wetness classification scheme based on qualitative indicators is a robust tool and can be applied successfully regardless of experience in crop growing and education level when an in-depth introduction and training is provided. The use of a simple and clear layout of the assessment form is important for reliable wetness class assignments.

Beschreibung: Nonlinear effects of locally heterogeneous hydraulic conductivity fields on regional stream–aquifer exchanges Hydrology and Earth System Sciences Discussions, 12, 7727-7764, 2015 Author(s): J. Zhu, C. L. Winter, and Z. Wang Computational experiments are performed to evaluate the effects of locally heterogeneous conductivity fields on regional exchanges of water between stream and aquifer systems in the Middle Heihe River Basin (MHRB) of northwestern China. The effects are found to be nonlinear in the sense that simulated discharges from aquifers to streams are systematically lower than discharges produced by a base model parameterized with relatively coarse effective conductivity. A similar, but weaker, effect is observed for stream leakage. The study is organized around three hypotheses: (H1) small-scale spatial variations of conductivity significantly affect regional exchanges of water between streams and aquifers in river basins, (H2) aggregating small-scale heterogeneities into regional effective parameters systematically biases estimates of stream–aquifer exchanges, and (H3) the biases result from slow-paths in groundwater flow that emerge due to small-scale heterogeneities. The hypotheses are evaluated by comparing stream–aquifer fluxes produced by the base model to fluxes simulated using realizations of the MHRB characterized by local (grid-scale) heterogeneity. Levels of local heterogeneity are manipulated as control variables by adjusting coefficients of variation. All models are implemented using the MODFLOW simulation environment, and the PEST tool is used to calibrate effective conductivities defined over 16 zones within the MHRB. The effective parameters are also used as expected values to develop log-normally distributed conductivity ( K ) fields on local grid scales. Stream-aquifer exchanges are simulated with K fields at both scales and then compared. Results show that the effects of small-scale heterogeneities significantly influence exchanges with simulations based on local-scale heterogeneities always producing discharges that are less than those produced by the base model. Although aquifer heterogeneities are uncorrelated at local scales, they appear to induce coherent slow-paths in groundwater fluxes that in turn reduce aquifer–stream exchanges. Since surface water–groundwater exchanges are critical hydrologic processes in basin-scale water budgets, these results also have implications for water resources management.

Beschreibung: Near–surface air temperature and snow skin temperature comparison from CREST-SAFE station data with MODIS land surface temperature data Hydrology and Earth System Sciences Discussions, 12, 7665-7687, 2015 Author(s): C. L. Pérez Díaz, T. Lakhankar, P. Romanov, J. Muñoz, R. Khanbilvardi, and Y. Yu Land Surface Temperature (LST) is a key variable (commonly studied to understand the hydrological cycle) that helps drive the energy balance and water exchange between the Earth's surface and its atmosphere. One observable constituent of much importance in the land surface water balance model is snow. Snow cover plays a critical role in the regional to global scale hydrological cycle because rain-on-snow with warm air temperatures accelerates rapid snow-melt, which is responsible for the majority of the spring floods. Accurate information on near-surface air temperature ( T -air) and snow skin temperature ( T -skin) helps us comprehend the energy and water balances in the Earth's hydrological cycle. T -skin is critical in estimating latent and sensible heat fluxes over snow covered areas because incoming and outgoing radiation fluxes from the snow mass and the air temperature above make it different from the average snowpack temperature. This study investigates the correlation between MODerate resolution Imaging Spectroradiometer (MODIS) LST data and observed T -air and T -skin data from NOAA-CREST-Snow Analysis and Field Experiment (CREST-SAFE) for the winters of 2013 and 2014. LST satellite validation is imperative because high-latitude regions are significantly affected by climate warming and there is a need to aid existing meteorological station networks with the spatially continuous measurements provided by satellites. Results indicate that near-surface air temperature correlates better than snow skin temperature with MODIS LST data. Additional findings show that there is a negative trend demonstrating that the air minus snow skin temperature difference is inversely proportional to cloud cover. To a lesser extent, it will be examined whether the surface properties at the site are representative for the LST properties within the instrument field of view.

Beschreibung: Does drought alter hydrological functions in forest soils? An infiltration experiment Hydrology and Earth System Sciences Discussions, 12, 7689-7725, 2015 Author(s): K. F. Gimbel, H. Puhlmann, and M. Weiler The water cycle is expected to change in future and severely affect precipitation patterns across central Europe and in other parts of the world, leading to more frequent and severe droughts. Usually, it is assumed that system properties, like soil properties, remain stable and will not be affected by drought events. To study if this assumption is appropriate, we address the effects of drought on the infiltration behavior of forest soils using dye tracer experiments on six sites in three regions across Germany, which were forced into drought conditions. The sites cover clayey, loamy and sandy textured soils. In each region, we compared a deciduous and a coniferous forest stand to address differences between the main tree species. The results of the dye tracer experiments show clear evidence for changes in infiltration behavior at the sites. The infiltration changed at the clayey plots from regular and homogeneous flow to fast preferential flow. Similar behavior was observed at the loamy plots, where large areas in the upper layers remained dry, displaying signs of strong water repellency. This was confirmed by WDPT tests, which revealed, in all except one plot, moderate to severe water repellency. Water repellency was also accountable for the change of regular infiltration to fingered flow in the sandy soils. The results of this study suggest that the "drought-history" or generally the climatic conditions in the past of a soil are more important than the actual antecedent soil moisture status regarding hydrophobicity and infiltration behavior; and also, that drought effects on infiltration need to be considered in hydrological models to obtain realistic predictions concerning water quality and quantity in runoff and groundwater recharge.

Beschreibung: Impact of model developments on present and future simulations of permafrost in a global land-surface model The Cryosphere, 9, 1505-1521, 2015 Author(s): S. E. Chadburn, E. J. Burke, R. L. H. Essery, J. Boike, M. Langer, M. Heikenfeld, P. M. Cox, and P. Friedlingstein There is a large amount of organic carbon stored in permafrost in the northern high latitudes, which may become vulnerable to microbial decomposition under future climate warming. In order to estimate this potential carbon–climate feedback it is necessary to correctly simulate the physical dynamics of permafrost within global Earth system models (ESMs) and to determine the rate at which it will thaw. Additional new processes within JULES, the land-surface scheme of the UK ESM (UKESM), include a representation of organic soils, moss and bedrock and a modification to the snow scheme; the sensitivity of permafrost to these new developments is investigated in this study. The impact of a higher vertical soil resolution and deeper soil column is also considered. Evaluation against a large group of sites shows the annual cycle of soil temperatures is approximately 25 % too large in the standard JULES version, but this error is corrected by the model improvements, in particular by deeper soil, organic soils, moss and the modified snow scheme. A comparison with active layer monitoring sites shows that the active layer is on average just over 1 m too deep in the standard model version, and this bias is reduced by 70 cm in the improved version. Increasing the soil vertical resolution allows the full range of active layer depths to be simulated; by contrast, with a poorly resolved soil at least 50 % of the permafrost area has a maximum thaw depth at the centre of the bottom soil layer. Thus all the model modifications are seen to improve the permafrost simulations. Historical permafrost area corresponds fairly well to observations in all simulations, covering an area between 14 and 19 million km 2 . Simulations under two future climate scenarios show a reduced sensitivity of permafrost degradation to temperature, with the near-surface permafrost loss per degree of warming reduced from 1.5 million km 2 °C −1 in the standard version of JULES to between 1.1 and 1.2 million km 2 °C −1 in the new model version. However, the near-surface permafrost area is still projected to approximately half by the end of the 21st century under the RCP8.5 scenario.

Beschreibung: Numerical simulations of the Cordilleran ice sheet through the last glacial cycle The Cryosphere Discussions, 9, 4147-4203, 2015 Author(s): J. Seguinot, I. Rogozhina, A. P. Stroeven, M. Margold, and J. Kleman Despite more than a century of geological observations, the Cordilleran ice sheet of North America remains poorly understood in terms of its former extent, volume and dynamics. Although geomorphological evidence is abundant, its complexity is such that whole ice-sheet reconstructions of advance and retreat patterns are lacking. Here we use a numerical ice sheet model calibrated against field-based evidence to attempt a quantitative reconstruction of the Cordilleran ice sheet history through the last glacial cycle. A series of simulations is driven by time-dependent temperature offsets from six proxy records located around the globe. Although this approach reveals large variations in model response to evolving climate forcing, all simulations produce two major glaciations during marine oxygen isotope stages 4 (61.9–56.5 ka) and 2 (23.2–16.8 ka). The timing of glaciation is better reproduced using temperature reconstructions from Greenland and Antarctic ice cores than from regional oceanic sediment cores. During most of the last glacial cycle, the modelled ice cover is discontinuous and restricted to high mountain areas. However, widespread precipitation over the Skeena Mountains favours the persistence of a central ice dome throughout the glacial cycle. It acts as a nucleation centre before the Last Glacial Maximum and hosts the last remains of Cordilleran ice until the middle Holocene (6.6–6.2 ka).

Beschreibung: Publication date: Available online 7 August 2015 Source: FEBS Open Bio Author(s): Kimberley J. Anderson, Aaron P. Russell, Victoria C. Foletta The function of the stress-responsive N-myc downstream-regulated gene 2 (NDRG2) in the control of myoblast growth, and the amino acids contributing to its function, are not well characterised. Here, we investigated the effect of increased NDRG2 levels on the proliferation, differentiation and apoptosis in skeletal muscle cells under basal and stress conditions. NDRG2 overexpression increased C2C12 myoblast proliferation and the expression of positive cell cycle regulators, cdk2, cyclin B and cyclin D, and phosphorylation of Rb, while the serine/threonine-deficient NDRG2, 3A-NDRG2, had less effect. The onset of differentiation was enhanced by NDRG2 as determined through the myogenic regulatory factor expression profiles and myocyte fusion index. However, the overall level of differentiation in myotubes was not different. While NDRG2 up-regulated caspase 3/7 activities during differentiation, no increase in apoptosis was measured by TUNEL assay or through cleavage of caspase 3 and PARP proteins. During H 2 O 2 treatment to induce oxidative stress, NDRG2 helped protect against the loss of proliferation and ER stress as measured by GRP78 expression with 3A-NDRG2 displaying less protection. NDRG2 also attenuated apoptosis by reducing cleavage of PARP and caspase 3 and expression of pro-apoptotic Bax while enhancing the pro-survival Bcl-2 and Bcl-xL levels. In contrast, Mcl-1 was not altered, and NDRG2 did not protect against palmitate-induced lipotoxicity. Our findings show that NDRG2 overexpression increases myoblast proliferation and caspase 3/7 activities without increasing overall differentiation. Furthermore, NDRG2 attenuates H 2 O 2 -induced oxidative stress and specific serine and threonine amino acid residues appear to contribute to its function in muscle cells.

Beschreibung: Optimizing the impact of temperature on bio-hydrogen production from food waste and its derivatives under no pH control using statistical modelling Biogeosciences Discussions, 12, 12823-12850, 2015 Author(s): A. Sattar, C. Arslan, C. Ji, S. Sattar, K. Yousaf, and S. Hashim The effect of temperature on bio-hydrogen production by co-digestion of sewerage sludge with food waste and its two derivatives, i.e. noodle waste and rice waste, was investigated by statistical modelling. Experimental results showed that increasing temperature from mesophilic (37 °C) to thermophilic (55 °C) was an effective mean for increasing bio-hydrogen production from food waste and noodle waste, but it caused a negative impact on bio-hydrogen production from rice waste. The maximum cumulative bio-hydrogen production of 650 mL was obtained from noodle waste under mesophilic temperature condition. Most of the production was observed during 48 h of incubation that continued till 72 h of incubation, and a decline in pH during this interval was 4.3 and 4.4 from a starting value of 7 under mesophilic and thermophilic conditions, respectively. Most of glucose consumption was also observed during 72 h of incubation and the maximum consumption was observed during the first 24 h, which was the same duration where the maximum pH drop occurred. The maximum hydrogen yields of 82.47 mL VS −1 , 131.38 mL COD −1 , and 44.90 mL glucose −1 were obtained from mesophilic food waste, thermophilic noodle waste and mesophilic rice waste respectively. The production of volatile fatty acids increased with an increase in time and temperature from food waste and noodle waste reactors whereas it decreased with temperature in rice waste reactors. The statistical modelling returned good results with high values of coefficient of determination ( R 2 ) for each waste type when it was opted for the study of cumulative hydrogen production, glucose consumption and volatile fatty acid production. The 3-D response surface plots developed by the statistical models helped a lot in developing better understanding of the impact of temperature and incubation time.

Beschreibung: Statistical detection and modeling of the over-dispersion of winter storm occurrence Natural Hazards and Earth System Science, 15, 1757-1761, 2015 Author(s): M. Raschke In this communication, I improve the detection and modeling of the over-dispersion of winter storm occurrence. For this purpose, the generalized Poisson distribution and the Bayesian information criterion are introduced; the latter is used for statistical model selection. Moreover, I replace the frequently used dispersion statistics by an over-dispersion parameter which does not depend on the considered return period of storm events. These models and methods are applied in order to properly detect the over-dispersion in winter storm data for Germany, carrying out a joint estimation of the distribution models for different samples.

Beschreibung: Impacts of beaver dams on hydrologic and temperature regimes in a mountain stream Hydrology and Earth System Sciences, 19, 3541-3556, 2015 Author(s): M. Majerova, B. T. Neilson, N. M. Schmadel, J. M. Wheaton, and C. J. Snow Beaver dams affect hydrologic processes, channel complexity, and stream temperature in part by inundating riparian areas, influencing groundwater–surface water interactions, and changing fluvial processes within stream systems. We explored the impacts of beaver dams on hydrologic and temperature regimes at different spatial and temporal scales within a mountain stream in northern Utah over a 3-year period spanning pre- and post-beaver colonization. Using continuous stream discharge, stream temperature, synoptic tracer experiments, and groundwater elevation measurements, we documented pre-beaver conditions in the first year of the study. In the second year, we captured the initial effects of three beaver dams, while the third year included the effects of ten dams. After beaver colonization, reach-scale (~ 750 m in length) discharge observations showed a shift from slightly losing to gaining. However, at the smaller sub-reach scale (ranging from 56 to 185 m in length), the discharge gains and losses increased in variability due to more complex flow pathways with beaver dams forcing overland flow, increasing surface and subsurface storage, and increasing groundwater elevations. At the reach scale, temperatures were found to increase by 0.38 °C (3.8 %), which in part is explained by a 230 % increase in mean reach residence time. At the smallest, beaver dam scale (including upstream ponded area, beaver dam structure, and immediate downstream section), there were notable increases in the thermal heterogeneity where warmer and cooler niches were created. Through the quantification of hydrologic and thermal changes at different spatial and temporal scales, we document increased variability during post-beaver colonization and highlight the need to understand the impacts of beaver dams on stream ecosystems and their potential role in stream restoration.

Beschreibung: Does the Budyko curve reflect a maximum power state of hydrological systems? A backward analysis Hydrology and Earth System Sciences Discussions, 12, 7821-7842, 2015 Author(s): M. Westhoff, E. Zehe, P. Archambeau, and B. Dewals Almost all catchments plot within a small envelope around the Budyko curve. This apparent behaviour suggests that organizing principles may play a role in the evolution of catchments. In this paper we applied the thermodynamic principle of maximum power as the organizing principle. In a top-down approach we derived mathematical formulations of the relation between relative wetness and gradients driving runoff and evaporation for a simple one-box model. We did this in such a way that when the conductances are optimized with the maximum power principle, the steady state behaviour of the model leads exactly to a point on the Budyko curve. Subsequently we derived gradients that, under constant forcing, resulted in a Budyko curve following the asymptotes closely. With these gradients we explored the sensitivity of dry spells and dynamics in actual evaporation. Despite the simplicity of the model, catchment observations compare reasonably well with the Budyko curves derived with dynamics in rainfall and evaporation. This indicates that the maximum power principle may be used (i) to derive the Budyko curve and (ii) to move away from the empiricism in free parameters present in many Budyko functions. Future work should focus on better representing the boundary conditions of real catchments and eventually adding more complexity to the model.

Beschreibung: Impacts of land use change and climate variations on annual inflow into Miyun Reservoir, Beijing, China Hydrology and Earth System Sciences Discussions, 12, 7785-7819, 2015 Author(s): J. K. Zheng, G. Sun, W. H. Li, X. X. Yu, C. Zhang, Y. B. Gong, and L. H. Tu Miyun reservoir, the only surface water source for Beijing city, has experienced water supply decline in recent decades. Previous studies suggest that both land use change and climate contributes the changes of water supply in this critical watershed. However, the specific causes of the decline in Miyun reservoir are debatable in a non-stationary climate in the past four decades. The central objective of this study was to quantify the separate and collective contributions of land use change and climate variability to the decreasing inflow into Miyun reservoir during 1961–2008. Different from previous studies, this work objectively identified breakpoints by analyzing the long-term historical hydrometeorology and land cover records. To effectively study the different impacts of the climate variation and land cover change during different sub-periods, annual water balance model (AWB), climate elasticity model (CEM), and rainfall–runoff model (RRM) were employed to conduct attribution analysis synthetically. We found a significant decrease in annual streamflow ( p 〈 0.01), a significant positive trend in annual potential evapotranspiration ( p 〈 0.01), and an insignificant negative trend in annual precipitation ( p 〉 0.1) during 1961–2008. Combined with historical records, we identified two breakpoints as in 1983 and 1999 for the period 1961–2008 by the sequential Mann–Kendall Test and Double Mass Curve. Climate variability alone did not explain the decrease in inflow to Miyun reservoir. Reduction of water yield was closely related to increase in evapotranspiration rates due to the expansion of forestlands and reduction in cropland and grassland, and was likely exacerbated by increased water consumption for domestic and industrial uses in the basin. Our study found that the contribution to the observed streamflow decline from land use change fell from 64–92 % during 1984–1999 to 36–58 % during 2000–2008, whereas the contribution from climate variation climbed from 8–36 % during the 1984–1999 to 42–64 % during 2000–2008. Model uncertainty analysis further demonstrated that climate warming played a dominant role in streamflow reduction in the 2000s. We conclude that future climate change and variability will further challenge the goal of water supply of Miyun reservoir to meet water demand. A comprehensive watershed management strategy needs to consider the climate variations besides vegetation management.

Beschreibung: Stable isotope study of a new chondrichthyan fauna (Kimmeridgian, Porrentruy, Swiss Jura): an unusual freshwater-influenced isotopic composition for the hybodont shark Asteracanthus Biogeosciences Discussions, 12, 12899-12921, 2015 Author(s): L. Leuzinger, L. Kocsis, J.-P. Billon-Bruyat, S. Spezzaferri, and T. Vennemann Chondrichthyan teeth (sharks, rays and chimaeras) are mineralised in isotopic equilibrium with the surrounding water, and parameters such as water temperature and salinity can be inferred from the oxygen isotopic composition (δ 18 O p ) of their bioapatite. We analysed a new chondrichthyan assemblage, as well as teeth from bony fish (Pycnodontiformes). All specimens are from Kimmeridgian coastal marine deposits of the Swiss Jura (vicinity of Porrentruy, Ajoie district, NW Switzerland). While the overall faunal composition and the isotopic composition of bony fish are consistent with marine conditions, unusually low δ 18 O p values were measured for the hybodont shark Asteracanthus . These values are also lower compared to previously published data from older European Jurassic localities. Additional analyses on material from Solothurn (Kimmeridgian, NW Switzerland) also have comparable, low- 18 O isotopic compositions for Asteracanthus . The data are hence interpreted to represent a so far unique, freshwater-influenced isotopic composition for this shark that is classically considered as a marine genus. While reproduction in freshwater or brackish realms is established for other hybodonts, a similar behaviour for Asteracanthus is proposed here. Regular excursions into lower salinity waters can be linked to the age of the deposits and correspond to an ecological adaptation, most likely driven by the Kimmeridgian transgression and by the competition of the primitive shark Asteracanthus with the rapidly diversifying neoselachians (modern sharks).

Beschreibung: Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in CMIP5 models Biogeosciences Discussions, 12, 12851-12897, 2015 Author(s): W. Fu, J. Randerson, and J. K. Moore We examine climate change impacts on net primary production (NPP) and export production (sinking particulate flux; EP) with simulations from nine Earth System Models (ESMs) performed in the framework of the fifth Coupled Model Inter-comparison Project (CMIP5). Global NPP and EP are reduced considerably by the end of the century for the intense warming scenario of Representative Concentration Pathway (RCP) 8.5. Relative to the 1990s, global NPP in the 2090s is reduced by 2.3–16 % and EP by 7–18 %. The models with the largest increases in stratification (and largest relative reductions in NPP and EP) also show the largest positive biases in stratification for the contemporary period, suggesting some potential overestimation of climate impacts on NPP and EP. All of the CMIP5 models show an increase in stratification in response to surface ocean warming and freshening that is accompanied by decreases in NPP, EP, and surface macronutrient concentrations. There is considerable variability across models in the absolute magnitude of these fluxes, surface nutrient concentrations, and their perturbations by climate change, indicating large model uncertainties. The negative response of NPP and EP to stratification increases reflects a bottom-up control, as nutrient flux to the euphotic zone declines. Models with dynamic phytoplankton community structure show larger declines in EP than in NPP. This is driven by phytoplankton community composition shifts, with a reduced percentage of NPP by large phytoplankton under RCP 8.5, as smaller phytoplankton are favored under the increasing nutrient stress. Thus, projections of the NPP response to climate change in the CMIP5 models are critically dependent on the simulated phytoplankton community structure, the efficiency of the biological pump, and the resulting (highly variable) levels of regenerated production. Community composition is represented relatively simply in the CMIP5 models, and should be expanded to better capture the spatial patterns and the changes in export efficiency that are necessary for predicting climate impacts on NPP.

Beschreibung: Technical Note: A simple calculation algorithm to separate high-resolution CH 4 flux measurements into ebullition and diffusion-derived components Biogeosciences Discussions, 12, 12923-12945, 2015 Author(s): M. Hoffmann, M. Schulz-Hanke, J. Garcia Alba, N. Jurisch, U. Hagemann, T. Sachs, M. Sommer, and J. Augustin Processes driving the production, transformation and transport of methane (CH 4 ) in wetland ecosystems are highly complex. Thus, serious challenges are constitutes in terms of the mechanistic process understanding, the identification of potential environmental drivers and the calculation of reliable CH 4 emission estimates. We present a simple calculation algorithm to separate open-water CH 4 fluxes measured with automatic chambers into diffusion- and ebullition-derived components, which helps facilitating the identification of underlying dynamics and potential environmental drivers. Flux separation is based on ebullition related sudden concentration changes during single measurements. A variable ebullition filter is applied, using the lower and upper quartile and the interquartile range (IQR). Automation of data processing is achieved by using an established R-script, adjusted for the purpose of CH 4 flux calculation. The algorithm was tested using flux measurement data (July to September 2013) from a former fen grassland site, converted into a shallow lake as a result of rewetting ebullition and diffusion contributed 46 and 55 %, respectively, to total CH 4 emissions, which is comparable to those previously reported by literature. Moreover, the separation algorithm revealed a concealed shift in the diurnal trend of diffusive fluxes throughout the measurement period.

Beschreibung: Publication date: Available online 12 August 2015 Source: FEBS Open Bio Author(s): Yang Song, Yonghong Zhang, Haoxiang Jiang, Yanting Zhu, Lu Liu, Wei Feng, Lan Yang, Yibin Wang, Manxiang Li Activation of the Notch3 cascade is involved in the development of pulmonary arterial hypertension by stimulating the proliferation of vascular smooth muscle cells. However, the detailed molecular mechanisms underlying this effect are still unclear. The present study aims to address this issue. We demonstrated that over-expression of intracellular domain of the Notch3 receptor (NICD3) by adenovirus transfection dramatically induced proliferation of primary cultured pulmonary artery smooth muscle cells. This was accompanied with up-regulation of Hes1 protein and down-regulation of p27Kip1protein. More importantly, we observed that prior silencing of Hes1 with siRNA blocked NICD3 over-expression-induced p27Kip1 reduction and cell proliferation. The present study suggests that Hes1 lies downstream of NICD3 and particularly mediates Notch3 signaling-induced proliferation of pulmonary arterial smooth muscle cells by down-regulation of p27Kip1 expression.

Beschreibung: Publication date: Available online 11 August 2015 Source: FEBS Open Bio Author(s): Xueying Zhang, Yuanzhe Jin, Xiaohong Zhang, Mingming Lei, Yingzi Lin, Ian L. Megson, Jun Wei, Bo Yu A number of studies have reported an association between increased levels of antibodies against oxidized low-density lipoprotein (oxLDL) and cardiovascular disease, but the anti-oxLDL antibody has not been confirmed to serve as an effective biomarker for prediction of acute myocardial infarction (AMI). Apolipoprotein B 100 (ApoB 100 )-derived peptide fragments generated by proteolytic degradation and aldehyde modification are the major antigens in oxLDL, and so the present work was undertaken to detect circulating IgG for Apo-B 100 -derived peptide antigens. An in-house enzyme-linked immunosorbent assay (ELISA) was developed with eight ApoB 100 -derived peptide antigens (Ag1-Ag8) to detect circulating anti-ApoB 100 IgG levels in 267 patients with AMI and 201 control subjects. Binary logistic regression analysis revealed that circulating IgG for Ag1 was significantly higher in the patient group than the control group ( P 〈0.001) after adjustment for age, gender, smoking, hypertension, diabetes and circulating levels of cholesterol, HDL, LDL, ApoA and ApoB 100 . None of the other seven antigens detected an increase in IgG levels in AMI patients compared with control subjects. Spearman correlation analysis showed no correlation between IgG antibody for Ag1 and clinical characteristics. In conclusion, the linear peptide antigens derived from ApoB 100 may be suitable for the development of an ELISA antibody test for prediction of AMI, although further confirmation is still needed in large-scale clinical studies.

Beschreibung: Publication date: Available online 11 August 2015 Source: FEBS Open Bio Author(s): Yu-E. Hao, Dong-Fang He, Rong-Hua Yin, Hui Chen, Jian Wang, Shao-Xia Wang, Yi-Qun Zhan, Chang-Hui Ge, Chang-Yan Li, Miao Yu, Xiao-Ming Yang G protein-coupled receptor kinase interactor 2 (GIT2) is a signaling scaffold protein involved in regulation of cytoskeletal dynamics and the internalization of G protein-coupled receptors (GPCRs). The short-splice form of GIT2 is expressed in peripheral T cells and thymocytes. However, the functions of GIT2 in T cells have not yet been determined. We show that treatment with Con A in a model of polyclonal T-lymphocyte activation resulted in marked inhibitions in the intrahepatic infiltration of inflammatory cells, cytokine response and acute liver failure in Git2 -/- mice. CD4 + T cells from Git2 -/- mice showed significant impairment in proliferation, cytokine production and signal transduction upon TCR-stimulated activation. Our results suggested that GIT2 plays an important role in T-cell function in vivo and in vitro .

Beschreibung: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Alberto Pistocchi, Costanza Calzolari, Francesco Malucelli, Fabrizio Ungaro Study region The plains of Emilia Romagna, Italy. Study focus Urban expansion is among the main causes of increase in flood frequency and intensity in small rural catchments in Europe, and our study region is paradigmatic in this respect. We present here a regional screening-level assessment of soil sealing impacts in terms of increased flood peak discharges and flooding volumes on the secondary drainage network of the plains. We estimate flood peak discharges and flooding volumes through a simple kinematic model with runoff coefficients for the land use of 2008 and 1976. Additionally, we calculate an equivalent compensatory flood detention volume that would enable preserving flood peak discharges as prior to soil sealing (principle of “hydraulic invariance”). The proposed approach is simple and readily applicable to any region facing similar issues, for screening-level assessment of flood hazards over an extended stream network. New hydrological insights for the region The analysis highlights a significant increase in flood hazards throughout the secondary stream network. The impact. Widespread and relatively uniform, is more apparent in smaller catchments and in the case of more permeable soils. This demands retrofitting of the majority of the drainage network and/or significantly higher costs from flooding damages. The analysis suggests that costs of additional flooding after soil sealing may be higher than those of soil sealing impacts compensation through flood detention (hydraulic invariance).

Beschreibung: Nitrogen export from a boreal stream network following forest harvesting: seasonal nitrate removal and conservative export of organic forms Biogeosciences Discussions, 12, 12061-12089, 2015 Author(s): J. Schelker, R. Sponseller, E. Ring, L. Högbom, S. Löfgren, and H. Laudon Boreal streams are under pressure from large scale disturbance by forestry. Recent scenarios predict an increase in forest production in Scandinavia to meet market demands and to mitigate higher anthropogenic CO 2 emissions. Increased fertilization and shorter forest rotations are anticipated which will likely enhance the pressure on boreal streams in the near future. Among the major environmental impacts of forest harvesting is the increased mobilization of inorganic nitrogen (N), primarily as nitrate (NO 3 - ) into surface waters. But whereas NO 3 - inputs to first-order streams have been previously described, their downstream fate and impact is not well understood. We evaluated the downstream fate of N inputs in a boreal landscape that has been altered by forest harvests over a 10 year period to estimate the effects of multiple clear-cuts on aquatic N export in a boreal stream network. Small streams showed substantial leaching of NO 3 - in response to harvests with concentrations increasing by ~ 15 fold. NO 3 - concentrations at two sampling stations further downstream in the network were strongly seasonal and increased significantly in response to harvesting at the medium size, but not at the larger stream. Nitrate removal efficiency, E r , calculated as the percentage of "forestry derived" NO 3 - that was retained within the landscape using a mass balance model was highest during the snow melt season followed by the growing season, but declined continuously throughout the dormant season. In contrast, export of organic N from the landscape indicated little removal and was essentially conservative. Overall, net removal of NO 3 - between 2008 and 2011 accounted for ~ 70 % of the total NO 3 - mass exported from harvested patches distributed across the landscape. These results highlight the capacity and limitation of N-limited terrestrial and aquatic ecosystems to buffer inorganic N mobilization that arises from multiple clear-cuts within meso-scale boreal watersheds.

Beschreibung: Impacts on wave-driven harbour agitation due to climate change in Catalan ports Natural Hazards and Earth System Science, 15, 1695-1709, 2015 Author(s): J. P. Sierra, M. Casas-Prat, M. Virgili, C. Mösso, and A. Sánchez-Arcilla The objective of the present work is to analyse how changes in wave patterns due to the effect of climate change can affect harbour agitation (oscillations within the port due to wind waves). The study focuses on 13 harbours located on the Catalan coast (NW Mediterranean) using a methodology with general applicability. To obtain the patterns of agitation, a Boussinesq-type model is used, which is forced at the boundaries by present/future offshore wave conditions extracted from recently developed high-resolution wave projections in the NW Mediterranean. These wave projections were obtained with the SWAN model forced by present/future surface wind fields projected, respectively, by five different combinations of global and regional circulation models (GCMs and RCMs) for the A1B scenario. The results show a general slight reduction in the annual average agitation for most of the ports, except for the northernmost and southernmost areas of the region, where a slight increase is obtained. A seasonal analysis reveals that the tendency to decrease is accentuated in winter. However, the inter-model variability is large for both the winter and the annual analysis. Conversely, a general increase with a larger agreement among models is found during summer, which is the period with greater activity in most of the studied ports (marinas). A qualitative assessment of the factors of variability seems to indicate that the choice of GCM tends to affect the spatial pattern, whereas the choice of RCM induces a more homogeneous bias over the regional domain.

Beschreibung: Utilisation of CryoSat-2 SAR altimeter in operational ice charting The Cryosphere Discussions, 9, 4117-4145, 2015 Author(s): E. Rinne and M. Similä We present methods to utilise Cryosat-2 (CS-2) Synthetic Aperture (SAR) mode data in operational ice charting. We compare CS-2 data qualitatively to Synthetic Aperture Radar (SAR) mosaics over Barents and Kara seas. Furthermore, we compare the CS-2 to archived operational ice charts. We present distributions of four CS-2 waveform parameters for different ice types as presented in the ice charts. We go on to present an automatic classification method for CS-2 data which, after training with operational ice charts, is capable of determining open water from ice with a hit rate of 〉 90 %. The training data is dynamically updated every five days using the most recent 15 days CS-2 data and operative ice charts. This helps the adaption of the classifier to the evolving ice/snow conditions throughout winter. The classifier is also capable of detecting three different ice classes (thin and thick first year ice as well as old ice) with success rates good enough for the output to be usable to support operational ice charting. Finally, we present a near real time CS-2 product just plotting the waveform characteristics and conclude that even such a simple product is usable for some of the needs of ice charting.

Beschreibung: Relating seasonal dynamics of enhanced vegetation index to the recycling of water in two endorheic river basins in north-west China Hydrology and Earth System Sciences, 19, 3387-3403, 2015 Author(s): M. A. Matin and C. P.-A. Bourque This study associates the dynamics of enhanced vegetation index in lowland desert oases to the recycling of water in two endorheic (hydrologically closed) river basins in Gansu Province, north-west China, along a gradient of elevation zones and land cover types. Each river basin was subdivided into four elevation zones representative of (i) oasis plains and foothills, and (ii) low-, (iii) mid-, and (iv) high-mountain elevations. Comparison of monthly vegetation phenology with precipitation and snowmelt dynamics within the same basins over a 10-year period (2000–2009) suggested that the onset of the precipitation season (cumulative % precipitation 〉 7–8 %) in the mountains, typically in late April to early May, was triggered by the greening of vegetation and increased production of water vapour at the base of the mountains. Seasonal evolution of in-mountain precipitation correlated fairly well with the temporal variation in oasis-vegetation coverage and phenology characterised by monthly enhanced vegetation index, yielding coefficients of determination of 0.65 and 0.85 for the two basins. Convergent cross-mapping of related time series indicated bi-directional causality (feedback) between the two variables. Comparisons between same-zone monthly precipitation amounts and enhanced vegetation index provided weaker correlations. Start of the growing season in the oases was shown to coincide with favourable spring warming and discharge of meltwater from low- to mid-elevations of the Qilian Mountains (zones 1 and 2) in mid-to-late March. In terms of plant requirement for water, mid-seasonal development of oasis vegetation was seen to be controlled to a greater extent by the production of rain in the mountains. Comparison of water volumes associated with in-basin production of rainfall and snowmelt with that associated with evaporation seemed to suggest that about 90 % of the available liquid water (i.e. mostly in the form of direct rainfall and snowmelt in the mountains) was recycled locally.

Beschreibung: Investigating suspended sediment dynamics in contrasting agricultural catchments using ex situ turbidity-based suspended sediment monitoring Hydrology and Earth System Sciences, 19, 3349-3363, 2015 Author(s): S. C. Sherriff, J. S. Rowan, A. R. Melland, P. Jordan, O. Fenton, and D. Ó hUallacháin Soil erosion and suspended sediment (SS) pose risks to chemical and ecological water quality. Agricultural activities may accelerate erosional fluxes from bare, poached or compacted soils, and enhance connectivity through modified channels and artificial drainage networks. Storm-event fluxes dominate SS transport in agricultural catchments; therefore, high temporal-resolution monitoring approaches are required, but can be expensive and technically challenging. Here, the performance of in situ turbidity sensors, conventionally installed submerged at the river bankside, is compared with installations where river water is delivered to sensors ex situ, i.e. within instrument kiosks on the riverbank, at two experimental catchments (Grassland B and Arable B). The in situ and ex situ installations gave comparable results when calibrated against storm-period, depth-integrated SS data, with total loads at Grassland B estimated at 12 800 and 15 400 t, and 22 600 and 24 900 t at Arable B, respectively. The absence of spurious turbidity readings relating to bankside debris around the in situ sensor and its greater security make the ex situ sensor more robust. The ex situ approach was then used to characterise SS dynamics and fluxes in five intensively managed agricultural catchments in Ireland which feature a range of landscape characteristics and land use pressures. Average annual suspended sediment concentration (SSC) was below the Freshwater Fish Directive (78/659/EEC) guideline of 25 mg L −1 , and the continuous hourly record demonstrated that exceedance occurred less than 12 % of the observation year. Soil drainage class and proportion of arable land were key controls determining flux rates, but all catchments reported a high degree of inter-annual variability associated with variable precipitation patterns compared to the long-term average. Poorly drained soils had greater sensitivity to runoff and soil erosion, particularly in catchments with periods of bare soils. Well drained soils were less sensitive to erosion even on arable land; however, under extreme rainfall conditions, all bare soils remain a high sediment loss risk. Analysis of storm-period and seasonal dynamics (over the long term) using high-resolution monitoring would be beneficial to further explore the impact of landscape, climate and land use characteristics on SS export.

Beschreibung: Landscape heterogeneity drives contrasting concentration–discharge relationships in shale headwater catchments Hydrology and Earth System Sciences, 19, 3333-3347, 2015 Author(s): E. M. Herndon, A. L. Dere, P. L. Sullivan, D. Norris, B. Reynolds, and S. L. Brantley Solute concentrations in stream water vary with discharge in patterns that record complex feedbacks between hydrologic and biogeochemical processes. In a comparison of three shale-underlain headwater catchments located in Pennsylvania, USA (the forested Shale Hills Critical Zone Observatory), and Wales, UK (the peatland-dominated Upper Hafren and forest-dominated Upper Hore catchments in the Plynlimon forest), dissimilar concentration–discharge ( C – Q ) behaviors are best explained by contrasting landscape distributions of soil solution chemistry – especially dissolved organic carbon (DOC) – that have been established by patterns of vegetation and soil organic matter (SOM). Specifically, elements that are concentrated in organic-rich soils due to biotic cycling (Mn, Ca, K) or that form strong complexes with DOC (Fe, Al) are spatially heterogeneous in pore waters because organic matter is heterogeneously distributed across the catchments. These solutes exhibit non-chemostatic behavior in the streams, and solute concentrations either decrease (Shale Hills) or increase (Plynlimon) with increasing discharge. In contrast, solutes that are concentrated in soil minerals and form only weak complexes with DOC (Na, Mg, Si) are spatially homogeneous in pore waters across each catchment. These solutes are chemostatic in that their stream concentrations vary little with stream discharge, likely because these solutes are released quickly from exchange sites in the soils during rainfall events. Furthermore, concentration–discharge relationships of non-chemostatic solutes changed following tree harvest in the Upper Hore catchment in Plynlimon, while no changes were observed for chemostatic solutes, underscoring the role of vegetation in regulating the concentrations of certain elements in the stream. These results indicate that differences in the hydrologic connectivity of organic-rich soils to the stream drive differences in concentration behavior between catchments. As such, in catchments where SOM is dominantly in lowlands (e.g., Shale Hills), we infer that non-chemostatic elements associated with organic matter are released to the stream early during rainfall events, whereas in catchments where SOM is dominantly in uplands (e.g., Plynlimon), these non-chemostatic elements are released later during rainfall events. The distribution of SOM across the landscape is thus a key component for predictive models of solute transport in headwater catchments.

Beschreibung: Future changes in flash flood frequency and intensity of the Tha Di River (Thailand) based on rainfall–runoff modeling and advanced delta change scaling Hydrology and Earth System Sciences Discussions, 12, 7327-7352, 2015 Author(s): S. Hilgert, A. Wagner, and S. Fuchs As a consequence of climate change, extreme and flood-causing precipitation events are expected to increase in magnitude and frequency, especially in today's high-precipitation areas. During the north-east monsoon seasons, Nakhon Si Thammarat in southern Thailand is flash-flooded every 2.22 years on average. This study investigates frequency and intensity of harmful discharges of the Tha Di River regarding the IPCC emission scenarios A2 and B2. The regional climate model (RCM) PRECIS was transformed using the advanced delta change (ADC) method. The hydrologic response model HBV-Light was calibrated to the catchment and supplied with ADC-scaled daily precipitation and temperature data for 2010–2089. Under the A2 (B2) scenario, the flood threshold exceedance frequency on average increases by 133 % (decreases by 10 %), average flood intensity increases by 3 % (decreases by 2 %) and the annual top five discharge peaks intensities increase by 46 % (decrease by 5 %). Yearly precipitation sums increase by 30 % (10 %) towards the end of the century. The A2 scenario predicts a precipitation increase during the rainy season, which intensifies flood events; while increases projected exclusively for the dry season are not expected to cause floods. Retention volume demand of past events was calculated to be up to 12 × 10 6 m 3 . Flood risks are staying at high levels under the B2 scenario or increase dramatically under the A2 scenario. Results show that the RCM scaling process is inflicted with systematic biases but is crucial to investigate small, mountainous catchments. Improvement of scaling techniques should therefore accompany the development towards high-resolution climate models.

Beschreibung: A pan-African medium-range ensemble flood forecast system Hydrology and Earth System Sciences, 19, 3365-3385, 2015 Author(s): V. Thiemig, B. Bisselink, F. Pappenberger, and J. Thielen The African Flood Forecasting System (AFFS) is a probabilistic flood forecast system for medium- to large-scale African river basins, with lead times of up to 15 days. The key components are the hydrological model LISFLOOD, the African GIS database, the meteorological ensemble predictions by the ECMWF (European Centre for Medium-Ranged Weather Forecasts) and critical hydrological thresholds. In this paper, the predictive capability is investigated in a hindcast mode, by reproducing hydrological predictions for the year 2003 when important floods were observed. Results were verified by ground measurements of 36 sub-catchments as well as by reports of various flood archives. Results showed that AFFS detected around 70 % of the reported flood events correctly. In particular, the system showed good performance in predicting riverine flood events of long duration (〉 1 week) and large affected areas (〉 10 000 km 2 ) well in advance, whereas AFFS showed limitations for small-scale and short duration flood events. The case study for the flood event in March 2003 in the Sabi Basin (Zimbabwe) illustrated the good performance of AFFS in forecasting timing and severity of the floods, gave an example of the clear and concise output products, and showed that the system is capable of producing flood warnings even in ungauged river basins. Hence, from a technical perspective, AFFS shows a large potential as an operational pan-African flood forecasting system, although issues related to the practical implication will still need to be investigated.

Beschreibung: Publication date: Available online 3 August 2015 Source: FEBS Open Bio Author(s): Johan Vande Voorde, Peter Vervaeke, Sandra Liekens, Jan Balzarini Mycoplasmas may colonize tumour tissue in patients. The cytostatic activity of gemcitabine was dramatically decreased in Mycoplasma hyorhinis -infected tumour cell cultures compared with non-infected tumour cell cultures. This mycoplasma-driven drug deamination could be prevented by exogenous administration of the cytidine deaminase (CDA) inhibitor tetrahydrouridine, but also by the natural nucleosides or by a purine nucleoside phosphorylase inhibitor. The M. hyorhinis -encoded CDA Hyor gene was cloned, expressed as a recombinant protein and purified. CDA Hyor was found to be more catalytically active than its human equivalent and efficiently deaminates (inactivates) cytosine-based anticancer drugs. CDA Hyor expression at the tumour site may result in selective drug inactivation and suboptimal therapeutic efficiency.

Beschreibung: A comprehensive filtering scheme for high-resolution estimation of the water balance components from high-precision lysimeters Hydrology and Earth System Sciences, 19, 3405-3418, 2015 Author(s): M. Hannes, U. Wollschläger, F. Schrader, W. Durner, S. Gebler, T. Pütz, J. Fank, G. von Unold, and H.-J. Vogel Large weighing lysimeters are currently the most precise method to directly measure all components of the terrestrial water balance in parallel via the built-in weighing system. As lysimeters are exposed to several external forces such as management practices or wind influencing the weighing data, the calculated fluxes of precipitation and evapotranspiration can be altered considerably without having applied appropriate corrections to the raw data. Therefore, adequate filtering schemes for obtaining most accurate estimates of the water balance components are required. In this study, we use data from the TERENO (TERrestrial ENvironmental Observatories) SoilCan research site in Bad Lauchstädt to develop a comprehensive filtering procedure for high-precision lysimeter data, which is designed to deal with various kinds of possible errors starting from the elimination of large disturbances in the raw data resulting e.g., from management practices all the way to the reduction of noise caused e.g., by moderate wind. Furthermore, we analyze the influence of averaging times and thresholds required by some of the filtering steps on the calculated water balance and investigate the ability of two adaptive filtering methods (the adaptive window and adaptive threshold filter (AWAT filter; Peters et al., 2014), and a new synchro filter applicable to the data from a set of several lysimeters) to further reduce the filtering error. Finally, we take advantage of the data sets of all 18 lysimeters running in parallel at the Bad Lauchstädt site to evaluate the performance and accuracy of the proposed filtering scheme. For the tested time interval of 2 months, we show that the estimation of the water balance with high temporal resolution and good accuracy is possible. The filtering code can be downloaded from the journal website as Supplement to this publication.

Beschreibung: Assimilation of Antarctic velocity observations provides evidence for uncharted pinning points The Cryosphere, 9, 1427-1443, 2015 Author(s): J. J. Fürst, G. Durand, F. Gillet-Chaulet, N. Merino, L. Tavard, J. Mouginot, N. Gourmelen, and O. Gagliardini In ice flow modelling, the use of control methods to assimilate the dynamic and geometric state of an ice body has become common practice. These methods have primarily focussed on inverting for one of the two least known properties in glaciology, namely the basal friction coefficient or the ice viscosity parameter. Here, we present an approach to infer both properties simultaneously for the whole of the Antarctic ice sheet. After the assimilation, the root-mean-square deviation between modelled and observed surface velocities attains 8.7 m a −1 for the entire domain, with a slightly higher value of 14.0 m a −1 for the ice shelves. An exception in terms of the velocity mismatch is the Thwaites Glacier Ice Shelf, where the RMS value is almost 70 m a −1 . The reason is that the underlying Bedmap2 geometry ignores the presence of an ice rise, which exerts major control on the dynamics of the eastern part of the ice shelf. On these grounds, we suggest an approach to account for pinning points not included in Bedmap2 by locally allowing an optimisation of basal friction during the inversion. In this way, the velocity mismatch on the ice shelf of Thwaites Glacier is more than halved. A characteristic velocity mismatch pattern emerges for unaccounted pinning points close to the marine shelf front. This pattern is exploited to manually identify seven uncharted features around Antarctica that exert significant resistance to the shelf flow. Potential pinning points are detected on Fimbul, West, Shackleton, Nickerson and Venable ice shelves. As pinning points can provide substantial resistance to shelf flow, with considerable consequences if they became ungrounded in the future, the model community is in need of detailed bathymetry there. Our data assimilation points to some of these dynamically important features not present in Bedmap2 and implicitly quantifies their relevance.

Beschreibung: Long-term coastal-polynya dynamics in the Southern Weddell Sea from MODIS thermal-infrared imagery The Cryosphere Discussions, 9, 3959-3993, 2015 Author(s): S. Paul, S. Willmes, and G. Heinemann Based upon high-resolution thermal-infrared Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite imagery in combination with ERA-Interim atmospheric reanalysis data, we derived long-term polynya parameters such as polynya area, thin-ice thickness distribution and ice-production rates from daily cloud-cover corrected thin-ice thickness composites. Our study is based on a thirteen year investigation period (2002–2014) for the austral winter (1 April to 30 September) in the Antarctic Southern Weddell Sea. The focus lies on coastal polynyas which are important hot spots for new-ice formation, bottom-water formation and heat/moisture release into the atmosphere. MODIS has the capability to resolve even very narrow coastal polynyas. Its major disadvantage is the sensor limitation due to cloud cover. We make use of a newly developed and adapted spatial feature reconstruction scheme to account for cloud-covered areas. We find the sea-ice areas in front of Ronne and Brunt Ice Shelf to be the most active with an annual average polynya area of 3018 ± 1298 and 3516 ± 1420 km 2 as well as an accumulated volume ice production of 31 ± 13 and 31 ± 12 km 3 , respectively. For the remaining four regions, estimates amount to 421 ± 294 km 2 and 4 ± 3 km 3 (Antarctic Peninsula), 1148 ± 432 km 2 and 12 ± 5 km 3 (Iceberg A23A), 901 ± 703 km 2 and 10 ± 8 km 3 (Filchner Ice Shelf) as well as 499 ± 277 km 2 and 5 ± 2 km 3 (Coats Land). Our findings are discussed in comparison to recent studies based on coupled sea-ice/ocean models and passive-microwave satellite imagery, each investigating different parts of the Southern Weddell Sea.

Beschreibung: Climatic controls and climate proxy potential of Lewis Glacier, Mt Kenya The Cryosphere Discussions, 9, 3887-3924, 2015 Author(s): R. Prinz, L. I. Nicholson, T. Mölg, W. Gurgiser, and G. Kaser The Lewis Glacier on Mt Kenya is one of the best studied tropical glaciers and has experienced considerable retreat since a maximum extent in the late 19th century (L19). From distributed mass and energy balance modelling, this study evaluates the current sensitivity of the surface mass and energy balance to climatic drivers, explores climate conditions under which the L19 maximum extent might have sustained, and discusses the potential for using the glacier retreat to quantify climate change. Multiyear meteorological measurements at 4828 m provide data for input, optimization and evaluation of a spatially distributed glacier mass balance model to quantify the exchanges of energy and mass at the glacier–atmosphere interface. Currently the glacier loses mass due to the imbalance between insufficient accumulation and enhanced melt, because radiative energy gains cannot be compensated by turbulent energy sinks. Exchanging model input data with synthetic climate scenarios, which were sampled from the meteorological measurements and account for coupled climatic variable perturbations, reveal that the current mass balance is most sensitive to changes in atmospheric moisture (via its impact on solid precipitation, cloudiness and surface albedo). Positive mass balances result from scenarios with an increase of annual (seasonal) accumulation of 30 % (100 %), compared to values observed today, without significant changes in air temperature required. Scenarios with lower air temperatures are drier and associated with lower accumulation and increased net radiation due to reduced cloudiness and albedo. If the scenarios currently producing positive mass balances are applied to the L19 extent, negative mass balances are the result, meaning that the conditions required to sustain the glacier in its L19 extent are not reflected in today's observations. Alternatively, a balanced mass budget for the L19 extent can be explained by changing model parameters that imply a distinctly different coupling between the glacier's local surface-air layer and its surrounding boundary-layer. This result underlines the difficulty of deriving paleoclimates for larger glacier extents on the basis of modern measurements of small glaciers.

Beschreibung: Towards predictive data-driven simulations of wildfire spread – Part II: Ensemble Kalman Filter for the state estimation of a front-tracking simulator of wildfire spread Natural Hazards and Earth System Science, 15, 1721-1739, 2015 Author(s): M. C. Rochoux, C. Emery, S. Ricci, B. Cuenot, and A. Trouvé This paper is the second part in a series of two articles, which aims at presenting a data-driven modeling strategy for forecasting wildfire spread scenarios based on the assimilation of the observed fire front location and on the sequential correction of model parameters or model state. This model relies on an estimation of the local rate of fire spread (ROS) as a function of environmental conditions based on Rothermel's semi-empirical formulation, in order to propagate the fire front with an Eulerian front-tracking simulator. In Part I, a data assimilation (DA) system based on an ensemble Kalman filter (EnKF) was implemented to provide a spatially uniform correction of biomass fuel and wind parameters and thereby, produce an improved forecast of the wildfire behavior (addressing uncertainties in the input parameters of the ROS model only). In Part II, the objective of the EnKF algorithm is to sequentially update the two-dimensional coordinates of the markers along the discretized fire front, in order to provide a spatially distributed correction of the fire front location and thereby, a more reliable initial condition for further model time-integration (addressing all sources of uncertainties in the ROS model). The resulting prototype data-driven wildfire spread simulator is first evaluated in a series of verification tests using synthetically generated observations; tests include representative cases with spatially varying biomass properties and temporally varying wind conditions. In order to properly account for uncertainties during the EnKF update step and to accurately represent error correlations along the fireline, it is shown that members of the EnKF ensemble must be generated through variations in estimates of the fire's initial location as well as through variations in the parameters of the ROS model. The performance of the prototype simulator based on state estimation (SE) or parameter estimation (PE) is then evaluated by comparison with data taken from a reduced-scale controlled grassland fire experiment. Results indicate that data-driven simulations are capable of correcting inaccurate predictions of the fire front location and of subsequently providing an optimized forecast of the wildfire behavior at future lead times. The complementary benefits of both PE and SE approaches, in terms of analysis and forecast performance, are also emphasized. In particular, it is found that the size of the assimilation window must be specified adequately with the persistence of the model initial condition and/or with the temporal and spatial variability of the environmental conditions in order to track sudden changes in wildfire behavior. The present prototype data-driven forecast system is still at an early stage of development. In this regard, this preliminary investigation provides valuable information on how to combine observations with a fire spread model in an efficient way, as well as guidelines to design the future system evolution in order to meet the operational requirements of wildfire spread monitoring.

Beschreibung: Multiscale evaluation of the standardized precipitation index as a groundwater drought indicator Hydrology and Earth System Sciences Discussions, 12, 7405-7436, 2015 Author(s): R. Kumar, J. L. Musuuza, A. F. Van Loon, A. J. Teuling, R. Barthel, J. Ten Broek, J. Mai, L. Samaniego, and S. Attinger The lack of comprehensive groundwater observations at regional and global scales has promoted the use of alternative proxies and indices to quantify and predict groundwater droughts. Among them, the Standardized Precipitation Index (SPI) is commonly used to characterize droughts in different compartments of the hydro-meteorological system. In this study, we explore the suitability of the SPI to characterize local and regional scale groundwater droughts using observations at more than 2000 groundwater wells in geologically different areas in Germany and the Netherlands. A multiscale evaluation of the SPI is performed using the station data and their corresponding 0.5° gridded estimates to analyze the local and regional behavior of groundwater droughts, respectively. The standardized anomalies in the groundwater heads (SGI) were correlated against SPIs obtained using different accumulation periods. The accumulation periods to achieve maximum correlation exhibited high spatial variability (ranges 3 to 36 months) at both scales, leading to the conclusion that an a priori selection of the accumulation period (for computing the SPI) would result in inadequate characterization of groundwater droughts. The application of the uniform accumulation periods over the entire domain significantly reduced the correlation between SPI and SGI (≈ 21–66 %) indicating the limited applicability of SPI as a proxy for groundwater droughts even at long accumulation times. Furthermore, the low scores of the hit rate (0.3–0.6) and high false alarm ratio (0.4–0.7) at the majority of the wells and grid cells demonstrated the low reliability of groundwater drought predictions using the SPI. The findings of this study highlight the pitfalls of using the SPI as a groundwater drought indicator at both local and regional scales, and stress the need for more groundwater observations and accounting for regional hydrogeological characteristics in groundwater drought monitoring.

Beschreibung: Publication date: July 2015 Source: Global Ecology and Conservation, Volume 4 Author(s): David M.P. Jacoby, John M. Casselman, Vicki Crook, Mari-Beth DeLucia, Hyojin Ahn, Kenzo Kaifu, Tagried Kurwie, Pierre Sasal, Anders M.C. Silfvergrip, Kevin G. Smith, Kazuo Uchida, Alan M. Walker, Matthew J. Gollock With broad distributions, diadromous fishes can be exposed to multiple threats at different stages of development. For the primarily catadromous eels of the family Anguillidae, there is growing international concern for the population abundance and escapement trends of some of these species and yet incomplete knowledge of their remarkable life-histories hampers management and conservation. Anguillids experience a suite of pressures that include habitat loss/modification, migration barriers, pollution, parasitism, exploitation, and fluctuating oceanic conditions that likely have synergistic and regionally variable impacts, even within species. In beginning to redress this rather fragmented picture, we evaluated the extinction risk of these species using the IUCN Red List of Threatened Species Categories and Criteria to infer population-wide trends from catch and monitoring data. Here we consolidate and build upon these species assessments by presenting an overview of the current state of global eel data and conservation, categorising the knowledge gaps and geographic regions where resources are needed and discussing future recommendations to improve our understanding of anguillids. We find stark disparity between the quality and length of data available to assess population trends and conservation priorities in temperate and tropical anguillids. Of the 13 species assessed, four were listed as ‘Threatened’ (Vulnerable, Endangered or Critically Endangered); four were Near Threatened, three were Data Deficient and two were deemed Least Concern. Comparing with other diadromous species, we examine the multiple threats that impact eels during their different life-history stages, highlighting the challenges of applying the Red List Categories and Criteria to geographically-expansive, catadromous and panmictic groups of species.

Beschreibung: Comparing the Ensemble and Extended Kalman Filters for in situ soil moisture assimilation with contrasting soil conditions Hydrology and Earth System Sciences Discussions, 12, 7353-7403, 2015 Author(s): D. Fairbairn, A. L. Barbu, J.-F. Mahfouf, J.-C. Calvet, and E. Gelati Two data assimilation methods are compared for their ability to produce a deterministic soil moisture analysis on the Météo-France land surface model: (i) SEKF, a Simplified Extended Kalman Filter, which uses a climatological background-error covariance, (ii) EnSRF, the Ensemble Square Root Filter, which uses an ensemble background-error covariance and approximates random forcing errors stochastically. The accuracy of the deterministic analysis is measured on 12 sites with in situ observations and various soil textures in Southwest France (SMOSMANIA network). In the experiments with real observations, the two methods perform similarly and improve on the open loop. Both methods suffer from incorrect linear assumptions which are particularly degrading to the analysis during water-stressed conditions: the EnSRF by a dry bias and the SEKF by an over-sensitivity of the model Jacobian between the surface and the root zone layers. These problems are less severe for sandy soils than clay soils because sandy soils are less sensitive to perturbations in the initial conditions. A simple bias correction technique is tested on the EnSRF. Although this reduces the bias, it also suppresses the ensemble spread, which degrades the analysis performance. However, the EnSRF flow-dependent background-error covariance evidently captures seasonal variability in the soil moisture errors and should exploit planned improvements in the model physics. Synthetic experiments demonstrate that when there is only a random component in the precipitation forcing errors, the correct stochastic representation of these errors enables the EnSRF to perform better than the SEKF. But in the real experiments the same rainfall error specification does not improve the EnSRF analysis. It is likely that the actual rainfall errors are underestimated and that other sources of errors could limit the usefulness of this information. More comprehensive ways of representing the rainfall errors are suggested, which might improve the EnSRF performance.

Beschreibung: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): M.A. Sarr, O. Seidou, Y. Tramblay, S. El Adlouni Study region The study considers six precipitation stations located in Senegal, West Africa. Senegal is located in the Sahel, an area that is threatened by climate variability and change. Both droughts and extreme rainfall have been an issue in recent years. Study focus Two different statistical downscaling techniques were applied to the outputs of four regional climate models at six selected precipitation stations in Senegal. First, the delta-change method was applied to the mean annual precipitation as well as the 5, 10, 20, 50 and 100-year return period daily precipitation events. Second, a quantile–quantile transformation (QQ) was used to downscale the monthly distributions of precipitation simulated by regional climate models (RCMs). The 5, 10, 20, 50 and 100-year daily precipitation events were afterward calculated. All extreme events were calculated assuming that maximum annual daily precipitations follow the generalized extreme value (GEV) distribution. The two-sided Kolmogorov–Smirnov (KS) test was finally used to assess the performance of the quantile–quantile transformation as well as the GEV distribution fit for the annual maximum daily precipitation. New hydrological insights for the region Results show that the two downscaling techniques generally agree on the direction of the change when applied to the outputs of same RCM, but some cases lead to very different projections of the direction and magnitude of the change. Projected changes indicate a decline in mean precipitation except for one RCM over one region in Senegal. Projected changes in extreme precipitations are not consistent across stations and return periods. The choice of the downscaling technique has more effect on the estimation of extreme daily precipitations of return period equal or greater than ten years than the choice of the climate models.

Beschreibung: Morphological dynamics of an englacial channel Hydrology and Earth System Sciences Discussions, 12, 7615-7664, 2015 Author(s): G. Vatne and T. D. L. Irvine-Fynn Despite an interest in the hydraulic functioning of supraglacial and englacial channels over the last four decades, the processes and forms of such ice-bounded streams have remained poorly documented. Recent glaciological research has demonstrated the potential significance of so-called "cut and closure" streams, where englacial or subglacial flowpaths are created from the long-term incision of supraglacial channels. These flowpaths are reported to exhibit step-pool morphology, comprising knickpoints and/or knickzones, albeit exaggerated in dimensions in comparison to their supraglacial channel counterparts. However, little is known of the development of such channels' morphology. Here, we examine the spatial organization of step-pools and the upstream migration of steps, many of which form knickzones, with repeated surveys over a 10 year period in an englacial conduit in cold-based Austre Brøggerbreen, Svalbard. The observations show upstream knickpoint recession to be the dominant process for channel evolution. This is paralleled by an increase in average step height and conduit gradient over time. Characteristic channel reach types and step-riser forms are consistently observed in each of the morphological surveys reported. We suggest that the formation of steps has a hydrodynamic origin, where step-pool geometry is more efficient for energy dissipation than meanders, and that the englacial channel system is one in rapid transition rather than in dynamic equilibrium. The evolution and recession of knickzones reported here result in the formation of a 37 m moulin, suggesting over time the englacial channel may evolve towards a stable end-point characterised by a singular vertical descent to the local hydraulic base level. In light of this, our observations highlight the need to further examine the adjustment processes in cut-and-closure channels to better understand their coupling to supraglacial meltwater sources and role and potential significance in cold-based glacier hydrology and ice dynamics.

Beschreibung: Scenario based approach for multiple source Tsunami Hazard assessment for Sines, Portugal Natural Hazards and Earth System Sciences Discussions, 3, 4663-4693, 2015 Author(s): M. Wronna, R. Omira, and M. A. Baptista In this paper, we present a scenario-based approach for tsunami hazard assessment for the city and harbour of Sines – Portugal, one of the test-sites of project ASTARTE. Sines holds one of the most important deep-water ports which contains oil-bearing, petrochemical, liquid bulk, coal and container terminals. The port and its industrial infrastructures are facing the ocean southwest towards the main seismogenic sources. This work considers two different seismic zones: the Southwest Iberian Margin and the Gloria Fault. Within these two regions, we selected a total of six scenarios to assess the tsunami impact at the test site. The tsunami simulations are computed using NSWING a Non-linear Shallow Water Model With Nested Grids. In this study, the static effect of tides is analysed for three different tidal stages MLLW (mean lower low water), MSL (mean sea level) and MHHW (mean higher high water). For each scenario, inundation is described by maximum values of wave height, flow depth, drawback, runup and inundation distance. Synthetic waveforms are computed at virtual tide gauges at specific locations outside and inside the harbour. The final results describe the impact at Sines test site considering the single scenarios at mean sea level, the aggregate scenario and the influence of the tide on the aggregate scenario. The results confirm the composite of Horseshoe and Marques Pombal fault as the worst case scenario. It governs the aggregate scenario with about 60 % and inundates an area of 3.5 km 2 .

Beschreibung: The impact of near-surface soil moisture assimilation at subseasonal, seasonal, and inter-annual time scales Hydrology and Earth System Sciences Discussions, 12, 7971-8004, 2015 Author(s): C. Draper and R. Reichle Nine years of Advanced Microwave Scanning Radiometer – Earth Observing System (AMSR-E) soil moisture retrievals are assimilated into the Catchment land surface model at four locations in the US. The assimilation is evaluated using the unbiased Mean Square Error (ubMSE) relative to watershed-scale in situ observations, with the ubMSE separated into contributions from the subseasonal (SM short ), mean seasonal (SM seas ) and inter-annual (SM long ) soil moisture dynamics. For near-surface soil moisture, the average ubMSE for Catchment without assimilation was (1.8 × 10 −3 m 3 m −3 ) 2 , of which 19 % was in SM long , 26 % in SM seas , and 55 % in SM short . The AMSR-E assimilation significantly reduced the total ubMSE at every site, with an average reduction of 33 %. Of this ubMSE reduction, 37 % occurred in SM long , 24 % in SM seas , and 38 % in SM short . For root-zone soil moisture, in situ observations were available at one site only, and the near-surface and root-zone results were very similar at this site. These results suggest that, in addition to the well-reported improvements in SM short , assimilating a sufficiently long soil moisture data record can also improve the model representation of important long term events, such as droughts. The improved agreement between the modeled and in situ SM seas is harder to interpret, given that mean seasonal cycle errors are systematic, and systematic errors are not typically targeted by (bias-blind) data assimilation. Finally, the use of one year subsets of the AMSR-E and Catchment soil moisture for estimating the observation-bias correction (rescaling) parameters is investigated. It is concluded that when only one year of data is available, the associated uncertainty in the rescaling parameters should not greatly reduce the average benefit gained from data assimilation, but locally and in extreme years there is a risk of increased errors.

Beschreibung: Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate The Cryosphere, 9, 1579-1600, 2015 Author(s): S. L. Cornford, D. F. Martin, A. J. Payne, E. G. Ng, A. M. Le Brocq, R. M. Gladstone, T. L. Edwards, S. R. Shannon, C. Agosta, M. R. van den Broeke, H. H. Hellmer, G. Krinner, S. R. M. Ligtenberg, R. Timmermann, and D. G. Vaughan We use the BISICLES adaptive mesh ice sheet model to carry out one, two, and three century simulations of the fast-flowing ice streams of the West Antarctic Ice Sheet, deploying sub-kilometer resolution around the grounding line since coarser resolution results in substantial underestimation of the response. Each of the simulations begins with a geometry and velocity close to present-day observations, and evolves according to variation in meteoric ice accumulation rates and oceanic ice shelf melt rates. Future changes in accumulation and melt rates range from no change, through anomalies computed by atmosphere and ocean models driven by the E1 and A1B emissions scenarios, to spatially uniform melt rate anomalies that remove most of the ice shelves over a few centuries. We find that variation in the resulting ice dynamics is dominated by the choice of initial conditions and ice shelf melt rate and mesh resolution, although ice accumulation affects the net change in volume above flotation to a similar degree. Given sufficient melt rates, we compute grounding line retreat over hundreds of kilometers in every major ice stream, but the ocean models do not predict such melt rates outside of the Amundsen Sea Embayment until after 2100. Within the Amundsen Sea Embayment the largest single source of variability is the onset of sustained retreat in Thwaites Glacier, which can triple the rate of eustatic sea level rise.

Beschreibung: Hydroxy fatty acids in fresh snow samples from northern Japan: long-range atmospheric transport of Gram-negative bacteria by Asian winter monsoon Biogeosciences Discussions, 12, 13375-13397, 2015 Author(s): P. Tyagi, S. Yamamoto, and K. Kawamura Hydroxy fatty acids (FAs) in fresh snow from Sapporo, one of the heaviest snowfall regions in the world, have been studied to ascertain the airborne bacterial endotoxin concentrations and their biomass. The presence of β-hydroxy FAs (C 9 –C 28 ), constituents of Gram-negative bacteria (GNB), suggests long-range transport of soil microbes. Likewise, the occurrence of α- and ω-hydroxy FAs (C 9 –C 30 and C 9 –C 28 , respectively) in snow reveals their contribution from epicuticular waxes and soil microorganisms. Estimated endotoxin and GNB mass can aid in assessing their possible impacts on the diversity and functioning of aquatic and terrestrial ecosystems, as well as lethal effects on pedestrians through dispersal of microbes. Air mass back trajectories together with hydroxy FAs unveil their sources from Siberia, Russian Far East and North China by the Asian monsoon. This study highlights the role of fresh snow that reduces the human health risk of GNB and endotoxin by scavenging from the air.

Beschreibung: A method for predicting the factor of safety of an infinite slope based on the depth ratio of the wetting front induced by rainfall infiltration Natural Hazards and Earth System Science, 15, 1835-1849, 2015 Author(s): B.-G. Chae, J.-H. Lee, H.-J. Park, and J. Choi Most landslides in Korea are classified as shallow landslides with an average depth of less than 2 m. These shallow landslides are associated with the advance of a wetting front in the unsaturated soil due to rainfall infiltration, which results in an increase in water content and a reduction in the matric suction in the soil. Therefore, this study presents a modified equation of infinite slope stability analysis based on the concept of the saturation depth ratio to analyze the slope stability change associated with the rainfall on a slope. A rainfall infiltration test in unsaturated soil was performed using a column to develop an understanding of the effect of the saturation depth ratio following rainfall infiltration. The results indicated that the rainfall infiltration velocity due to the increase in rainfall in the soil layer was faster when the rainfall intensity increased. In addition, the rainfall infiltration velocity tends to decrease with increases in the unit weight of soil. The proposed model was applied to assess its feasibility and to develop a regional landslide susceptibility map using a geographic information system (GIS). For that purpose, spatial databases for input parameters were constructed and landslide locations were obtained. In order to validate the proposed approach, the results of the proposed approach were compared with the landslide inventory using a ROC (receiver operating characteristics) graph. In addition, the results of the proposed approach were compared with the previous approach used: a steady-state hydrological model. Consequently, the approach proposed in this study displayed satisfactory performance in classifying landslide susceptibility and showed better performance than the steady-state approach.

Beschreibung: Regional trends and controlling factors of fatal landslides in Latin America and the Caribbean Natural Hazards and Earth System Science, 15, 1821-1833, 2015 Author(s): S. A. Sepúlveda and D. N. Petley A new data set of landslides that caused loss of life in Latin America and the Caribbean in the 10-year period from 2004 and 2013 inclusive has been compiled, providing new insight into the impact of landslides in this key part of the world. This data set indicates that in the 10-year period a total of 11 631 people lost their lives across the region in 611 landslides. The geographical distribution of the landslides is highly heterogeneous, with areas of high incidence in parts of the Caribbean (most notably Haiti), Central America, Colombia, and southeast Brazil. There is significant interannual variation in the number of landslides, with the El Niño/La Niña cycle emerging as a key control. Our analysis suggests that on a continental scale the mapped factors that best explain the observed distribution are topography, annual precipitation and population density. On a national basis we have compared the occurrence of fatality-inducing landslide occurrence with the production of locally authored research articles, demonstrating that there is a landslide research deficit in Latin America and the Caribbean. Understanding better the mechanisms, distribution causes and triggers of landslides in Latin America and the Caribbean must be an essential first step towards managing the hazard.

Beschreibung: Publication date: Available online 19 August 2015 Source: FEBS Open Bio Author(s): Ajay Srivastava Malignant pleural mesothelioma (MPM) is an aggressive form of thoracic cancer with poor prognosis. While some studies have identified the molecular alterations associated with MPM, little is known about their role in MPM. For example, fragile X mental retardation ( FMR ) gene is up-regulated in MPM but its role in MPM is unknown. Here, utilizing Drosophila genetics, I investigate the possible role FMR may be playing in MPM. I provide evidence which suggests that FMR may contribute to tumorigenesis by up-regulating a matrix metalloprotease (MMP) and by degrading the basement membrane (BM), both important for tumor metastasis. I also demonstrate a novel link between FMR and the JNK pathway and suggest that the effects of FMR in MPM could in part be mediated by up-regulation of the JNK pathway.

Beschreibung: A numerical study of the early stages of a tropical cyclogenesis in relation to the MJO Natural Hazards and Earth System Sciences Discussions, 3, 4919-4935, 2015 Author(s): J. Guerbette, M. Plu, C. Barthe, and J.-F. Mahfouf The role of an active phase of the Madden–Julian Oscillation (MJO) on the evolution of a mesoscale convective systems (MCS) leading to a tropical depression is investigated in the South-West Indian Ocean during the Dynamics of the Madden–Julian Oscillation (DYNAMO) field experiment, with a numerical limited-area atmospheric model. A mesoscale vortex is followed in the low-troposphere from the initiation of the active MJO phase. It is shown that the interaction of the vortex with the Equatorial jet associated with the MJO plays an important role on the vortex development. As the vortex encounters the southern part of the low-level jet, it undergoes intensification that is explained by the barotropic conversion of kinetic energy from the low-level jet to the vortex.

Beschreibung: Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core The Cryosphere, 9, 1633-1648, 2015 Author(s): J.-L. Tison, M. de Angelis, G. Littot, E. Wolff, H. Fischer, M. Hansson, M. Bigler, R. Udisti, A. Wegner, J. Jouzel, B. Stenni, S. Johnsen, V. Masson-Delmotte, A. Landais, V. Lipenkov, L. Loulergue, J.-M. Barnola, J.-R. Petit, B. Delmonte, G. Dreyfus, D. Dahl-Jensen, G. Durand, B. Bereiter, A. Schilt, R. Spahni, K. Pol, R. Lorrain, R. Souchez, and D. Samyn An important share of paleoclimatic information is buried within the lowermost layers of deep ice cores. Because improving our records further back in time is one of the main challenges in the near future, it is essential to judge how deep these records remain unaltered, since the proximity of the bedrock is likely to interfere both with the recorded temporal sequence and the ice properties. In this paper, we present a multiparametric study (δD-δ 18 O ice , δ 18 O atm , total air content, CO 2 , CH 4 , N 2 O, dust, high-resolution chemistry, ice texture) of the bottom 60 m of the EPICA (European Project for Ice Coring in Antarctica) Dome C ice core from central Antarctica. These bottom layers were subdivided into two distinct facies: the lower 12 m showing visible solid inclusions (basal dispersed ice facies) and the upper 48 m, which we will refer to as the "basal clean ice facies". Some of the data are consistent with a pristine paleoclimatic signal, others show clear anomalies. It is demonstrated that neither large-scale bottom refreezing of subglacial water, nor mixing (be it internal or with a local basal end term from a previous/initial ice sheet configuration) can explain the observed bottom-ice properties. We focus on the high-resolution chemical profiles and on the available remote sensing data on the subglacial topography of the site to propose a mechanism by which relative stretching of the bottom-ice sheet layers is made possible, due to the progressively confining effect of subglacial valley sides. This stress field change, combined with bottom-ice temperature close to the pressure melting point, induces accelerated migration recrystallization, which results in spatial chemical sorting of the impurities, depending on their state (dissolved vs. solid) and if they are involved or not in salt formation. This chemical sorting effect is responsible for the progressive build-up of the visible solid aggregates that therefore mainly originate "from within", and not from incorporation processes of debris from the ice sheet's substrate. We further discuss how the proposed mechanism is compatible with the other ice properties described. We conclude that the paleoclimatic signal is only marginally affected in terms of global ice properties at the bottom of EPICA Dome C, but that the timescale was considerably distorted by mechanical stretching of MIS20 due to the increasing influence of the subglacial topography, a process that might have started well above the bottom ice. A clear paleoclimatic signal can therefore not be inferred from the deeper part of the EPICA Dome C ice core. Our work suggests that the existence of a flat monotonic ice–bedrock interface, extending for several times the ice thickness, would be a crucial factor in choosing a future "oldest ice" drilling location in Antarctica.

Beschreibung: Nitrogen cycling in the subsurface biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic Biogeosciences Discussions, 12, 13545-13591, 2015 Author(s): S. D. Wankel, C. Buchwald, W. Ziebis, C. B. Wenk, and M. F. Lehmann Nitrogen (N) is a key component of fundamental biomolecules. Hence, the cycling and availability of N is a central factor governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO 3 − ) from a site in the oligotrophic North Atlantic (IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO 3 − accumulates far above bottom seawater concentrations (∼ 21 μM) throughout the sediment column (up to ∼ 50 μM) down to the oceanic basement as deep as 90 mbsf, reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ 15 N and δ 18 O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion–reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO 3 − isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide isotope evidence for expanded zones of co-ocurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ 15 N and δ 18 O of newly produced nitrate (δ 15 N NTR and δ 18 O NTR ), as well as the isotope effect for denitrification ( 15 ϵ DNF ), parameters with high relevance to global ocean models of N cycling. Estimated values of δ 15 N NTR were generally lower than previously reported δ 15 N values for sinking PON in this region. We suggest that these values can be related to sedimentary N-fixation and remineralization of the newly fixed organic N. Values of δ 18 O NTR generally ranged between −2.8 and 0.0 ‰, consistent with recent estimates based on lab cultures of nitrifying bacteria. Notably, some δ 18 O NTR values were elevated, suggesting incorporation of 18 O-enriched dissolved oxygen during nitrification, and possibly indicating a tight coupling of NH 4 + and NO 2 − oxidation in this metabolically sluggish environment. Our findings indicate that the production of organic matter by in situ autotrophy (e.g., nitrification, nitrogen fixation) supply a large fraction of the biomass and organic substrate for heterotrophy in these sediments, supplementing the small organic matter pool derived from the overlying euphotic zone. This work sheds new light on an active nitrogen cycle operating, despite exceedingly low carbon inputs, in the deep sedimentary biosphere.

Beschreibung: Spring bloom onset in the Nordic Seas Biogeosciences Discussions, 12, 13631-13673, 2015 Author(s): A. Mignot, R. Ferrari, and K. A. Mork The North Atlantic spring bloom is a massive annual growth event of marine phytoplankton, tiny free-floating algae that form the base of the ocean's food web and generates a large fraction of the global primary production of organic matter. The conditions that trigger the onset of the spring bloom in the Nordic Seas, at the northern edge of the North Atlantic, are studied using in-situ data from five bio-optical floats released above the Arctic Circle. It is often assumed that spring blooms start as soon as phytoplankton cells daily irradiance is sufficiently abundant that division rates exceed losses. The bio-optical float data instead suggest the tantalizing hypothesis that Nordic Seas blooms start when the photoperiod, the number of daily light hours experienced by phytoplankton, exceeds a critical value, independently of division rates. This bloom behavior may be explained by realizing that photosynthesis is impossible during polar nights and phytoplankton enters in a dormant stage in winter, only to be awaken by a photoperiodic trigger. While the first accumulation of biomass recorded by the bio-optical floats is consistent with the photoperiod hypothesis, it is possible that some biomass accumulation started before the critical photoperiod but at levels too low to be detected by the fluorometers. Thus more precise observations are needed to test the photoperiod hypothesis.

Beschreibung: Impact of debris cover on glacier ablation and atmosphere–glacier feedbacks in the Karakoram The Cryosphere, 9, 1617-1632, 2015 Author(s): E. Collier, F. Maussion, L. I. Nicholson, T. Mölg, W. W. Immerzeel, and A. B. G. Bush The Karakoram range of the Hindu-Kush Himalaya is characterized by both extensive glaciation and a widespread prevalence of surficial debris cover on the glaciers. Surface debris exerts a strong control on glacier surface-energy and mass fluxes and, by modifying surface boundary conditions, has the potential to alter atmosphere–glacier feedbacks. To date, the influence of debris on Karakoram glaciers has only been directly assessed by a small number of glaciological measurements over short periods. Here, we include supraglacial debris in a high-resolution, interactively coupled atmosphere–glacier modeling system. To investigate glaciological and meteorological changes that arise due to the presence of debris, we perform two simulations using the coupled model from 1 May to 1 October 2004: one that treats all glacier surfaces as debris-free and one that introduces a simplified specification for the debris thickness. The basin-averaged impact of debris is a reduction in ablation of ~ 14 %, although the difference exceeds 5 m w.e. on the lowest-altitude glacier tongues. The relatively modest reduction in basin-mean mass loss results in part from non-negligible sub-debris melt rates under thicker covers and from compensating increases in melt under thinner debris, and may help to explain the lack of distinct differences in recent elevation changes between clean and debris-covered ice. The presence of debris also strongly alters the surface boundary condition and thus heat exchanges with the atmosphere; near-surface meteorological fields at lower elevations and their vertical gradients; and the atmospheric boundary layer development. These findings are relevant for glacio-hydrological studies on debris-covered glaciers and contribute towards an improved understanding of glacier behavior in the Karakoram.

Beschreibung: Publication date: Available online 20 August 2015 Source: Cell Reports Author(s): Bettina Schreiner, Elisa Romanelli, Pawel Liberski, Barbara Ingold-Heppner, Bettina Sobottka-Brillout, Tom Hartwig, Vijay Chandrasekar, Helge Johannssen, Hanns Ulrich Zeilhofer, Adriano Aguzzi, Frank Heppner, Martin Kerschensteiner, Burkhard Becher Although the importance of reactive astrocytes during CNS pathology is well established, the function of astroglia in adult CNS homeostasis is less well understood. With the use of conditional, astrocyte-restricted protein synthesis termination, we found that selective paralysis of GFAP + astrocytes in vivo led to rapid neuronal cell loss and severe motor deficits. This occurred while structural astroglial support still persisted and in the absence of any major microvascular damage. Whereas loss of astrocyte function did lead to microglial activation, this had no impact on the neuronal loss and clinical decline. Neuronal injury was caused by oxidative stress resulting from the reduced redox scavenging capability of dysfunctional astrocytes and could be prevented by the in vivo treatment with scavengers of reactive oxygen and nitrogen species (ROS/RNS). Our results suggest that the subpopulation of GFAP + astrocytes maintain neuronal health by controlling redox homeostasis in the adult CNS. Graphical abstract Teaser Schreiner et al. examine the functional contribution of astrocytes to tissue homeostasis in the adult CNS and identify the redox-scavenging capacity of GFAP + astrocytes as a key factor for neuronal health in vivo. The importance of the metabolic integrity of the glia-neuron interface highlights potential therapies for the treatment of neurodegenerative diseases.

Beschreibung: Publication date: Available online 20 August 2015 Source: Cell Reports Author(s): Priya Srikanth, Karam Han, Dana G. Callahan, Eugenia Makovkina, Christina R. Muratore, Matthew A. Lalli, Honglin Zhou, Justin D. Boyd, Kenneth S. Kosik, Dennis J. Selkoe, Tracy L. Young-Pearse Genetic and clinical association studies have identified disrupted in schizophrenia 1 ( DISC1 ) as a candidate risk gene for major mental illness. DISC1 is interrupted by a balanced chr(1;11) translocation in a Scottish family in which the translocation predisposes to psychiatric disorders. We investigate the consequences of DISC1 interruption in human neural cells using TALENs or CRISPR-Cas9 to target the DISC1 locus. We show that disruption of DISC1 near the site of the translocation results in decreased DISC1 protein levels because of nonsense-mediated decay of long splice variants. This results in an increased level of canonical Wnt signaling in neural progenitor cells and altered expression of fate markers such as Foxg1 and Tbr2. These gene expression changes are rescued by antagonizing Wnt signaling in a critical developmental window, supporting the hypothesis that DISC1-dependent suppression of basal Wnt signaling influences the distribution of cell types generated during cortical development. Graphical abstract Teaser Srikanth et al. report the generation of isogenic hiPSC lines with engineered mutations in two locations within the DISC1 gene. This disease-relevant disruption shows a loss of long isoforms, which, in turn, affects neural progenitor cell proliferation, baseline WNT signaling, and the expression of NPC fate markers such as FoxG1 and Tbr2.

Beschreibung: Publication date: Available online 20 August 2015 Source: Cell Reports Author(s): Ivana Vonkova, Antoine-Emmanuel Saliba, Samy Deghou, Kanchan Anand, Stefano Ceschia, Tobias Doerks, Augustinus Galih, Karl G. Kugler, Kenji Maeda, Vladimir Rybin, Vera van Noort, Jan Ellenberg, Peer Bork, Anne-Claude Gavin Many cellular processes involve the recruitment of proteins to specific membranes, which are decorated with distinctive lipids that act as docking sites. The phosphoinositides form signaling hubs, and we examine mechanisms underlying recruitment. We applied a physiological, quantitative, liposome microarray-based assay to measure the membrane-binding properties of 91 pleckstrin homology (PH) domains, the most common phosphoinositide-binding target. 10,514 experiments quantified the role of phosphoinositides in membrane recruitment. For most domains examined, the observed binding specificity implied cooperativity with additional signaling lipids. Analyses of PH domains with similar lipid-binding profiles identified a conserved motif, mutations in which—including some found in human cancers—induced discrete changes in binding affinities in vitro and protein mislocalization in vivo. The data set reveals cooperativity as a key mechanism for membrane recruitment and, by enabling the interpretation of disease-associated mutations, suggests avenues for the design of small molecules targeting PH domains. Graphical abstract Teaser Vonkova et al. systematically quantify the lipid-binding properties of 91 pleckstrin homology (PH) domains using a physiological, quantitative, liposome microarray-based assay. The data set reveals that cooperativity between lipids is a key mechanism for membrane recruitment of PH domains.

Beschreibung: Publication date: Available online 20 August 2015 Source: Cell Reports Author(s): Ju-Hyun Lee, Mary Kate McBrayer, Devin M. Wolfe, Luke J. Haslett, Asok Kumar, Yutaka Sato, Pearl P.Y. Lie, Panaiyur Mohan, Erin E. Coffey, Uday Kompella, Claire H. Mitchell, Emyr Lloyd-Evans, Ralph A. Nixon Presenilin 1 (PS1) deletion or Alzheimer’s disease (AD)-linked mutations disrupt lysosomal acidification and proteolysis, which inhibits autophagy. Here, we establish that this phenotype stems from impaired glycosylation and instability of vATPase V0a1 subunit, causing deficient lysosomal vATPase assembly and function. We further demonstrate that elevated lysosomal pH in Presenilin 1 knockout (PS1KO) cells induces abnormal Ca 2+ efflux from lysosomes mediated by TRPML1 and elevates cytosolic Ca 2+ . In WT cells, blocking vATPase activity or knockdown of either PS1 or the V0a1 subunit of vATPase reproduces all of these abnormalities. Normalizing lysosomal pH in PS1KO cells using acidic nanoparticles restores normal lysosomal proteolysis, autophagy, and Ca 2+ homeostasis, but correcting lysosomal Ca 2+ deficits alone neither re-acidifies lysosomes nor reverses proteolytic and autophagic deficits. Our results indicate that vATPase deficiency in PS1 loss-of-function states causes lysosomal/autophagy deficits and contributes to abnormal cellular Ca 2+ homeostasis, thus linking two AD-related pathogenic processes through a common molecular mechanism. Graphical abstract Teaser Lee et al. present evidence establishing that Presenilin 1 loss of function elevates lysosomal pH via loss of V0a1 vATPase subunits. Besides disrupting autophagy, elevated lysosomal pH hyperactivates the TRPML1 calcium channel, causing increased lysosomal calcium efflux and cytosolic calcium elevation, thus linking two AD-related presenilin phenotypes to vATPase deficiency.

Beschreibung: Publication date: Available online 20 August 2015 Source: Cell Reports Author(s): Soraia Barão, Annette Gärtner, Eduardo Leyva-Díaz, Galina Demyanenko, Sebastian Munck, Tine Vanhoutvin, Lujia Zhou, Melitta Schachner, Guillermina López-Bendito, Patricia F. Maness, Bart De Strooper ΒACE1 is the major drug target for Alzheimer’s disease, but we know surprisingly little about its normal function in the CNS. Here, we show that this protease is critically involved in semaphorin 3A (Sema3A)-mediated axonal guidance processes in thalamic and hippocampal neurons. An active membrane-bound proteolytic CHL1 fragment is generated by BACE1 upon Sema3A binding. This fragment relays the Sema3A signal via ezrin-radixin-moesin (ERM) proteins to the neuronal cytoskeleton. APH1B-γ-secretase-mediated degradation of this fragment stops the Sema3A-induced collapse and sensitizes the growth cone for the next axonal guidance cue. Thus, we reveal a cycle of proteolytic activity underlying growth cone collapse and restoration used by axons to find their correct trajectory in the brain. Our data also suggest that BACE1 and γ-secretase inhibition have physiologically opposite effects in this process, supporting the idea that combination therapy might attenuate some of the side effects associated with these drugs. Graphical abstract Teaser Barão et al. show that the Alzheimer’s-disease-related proteases, BACE1 and APH1B-γ-secretase, control axonal guidance by regulating growth cone dynamics. BACE1 cleaves CHL1, inducing growth cone collapse. Subsequently, γ-secretase activity stops the collapse and axonal growth resumes. Therefore, testing of inhibitors of these proteases in humans should proceed with caution.

Beschreibung: Publication date: Available online 20 August 2015 Source: Cell Reports Author(s): Alexander Harms, Frédéric Valentin Stanger, Patrick Daniel Scheu, Imke Greet de Jong, Arnaud Goepfert, Timo Glatter, Kenn Gerdes, Tilman Schirmer, Christoph Dehio Toxin-antitoxin (TA) modules are ubiquitous molecular switches controlling bacterial growth via the release of toxins that inhibit cell proliferation. Most of these toxins interfere with protein translation, but a growing variety of other mechanisms hints at a diversity that is not yet fully appreciated. Here, we characterize a group of FIC domain proteins as toxins of the conserved and abundant FicTA family of TA modules, and we reveal that they act by suspending control of cellular DNA topology. We show that FicTs are enzymes that adenylylate DNA gyrase and topoisomerase IV, the essential bacterial type IIA topoisomerases, at their ATP-binding site. This modification inactivates both targets by blocking their ATPase activity, and, consequently, causes reversible growth arrest due to the knotting, catenation, and relaxation of cellular DNA. Our results give insight into the regulation of DNA topology and highlight the remarkable plasticity of FIC domain proteins. Graphical abstract Teaser Harms et al. reveal that the FicTA toxin-antitoxin module acts via adenylylation of DNA gyrase and topoisomerase IV. This modification inactivates both targets by blocking the ATPase activity that is central to their enzymatic functions, and it reversibly inhibits bacterial growth via the knotting, catenation, and relaxation of cellular DNA.

Beschreibung: Unusual biogenic calcite structures in two shallow lakes, James Ross Island, Antarctica Biogeosciences Discussions, 12, 13593-13629, 2015 Author(s): J. Elster, L. Nedbalová, R. Vodrážka, K. Láska, J. Haloda, and J. Komárek The floors of two shallow endorheic lakes, located on volcanic surfaces on James Ross Island, are covered with calcareous organosedimentary structures. Their biological and chemical composition, lake water characteristics, and seasonal variability of the thermal regime are introduced. The lakes are frozen down to the bottom eight-nine months per year and their water chemistry is characterized by low conductivity and neutral to slightly alkaline pH. The photosynthetic microbial mat is composed of filamentous cyanobacteria and microalgae that are considered to be Antarctic endemic species. The mucilaginous black biofilm is covered by green spots formed by a green microalga and the macroscopic structures are packed together with fine material. Thin sections consist of rock substrate, soft biofilm, calcite spicules and mineral grains originating from different sources. The morphology of the spicules is typical of calcium carbonate monocrystals having a layered structure and worn surface, which reflect growth and degradation processes. The spicules chemical composition and structure correspond to pure calcite. Lakes age, altitude, morphometry, geomorphological and hydrological stability, including low sedimentation rates, together with thermal regime predispose the existence of this community. We hypothesize that the precipitation of calcite is connected with the photosynthetic activity of the green microalgae that were not recorded in any other lake in the region. This study has shown that the unique community producing biogenic calcite spicules is quite different to any yet described.

Beschreibung: Publication date: Available online 20 August 2015 Source: Cell Reports Author(s): Takaharu Kanno, Davide G. Berta, Camilla Sjögren The structural maintenance of chromosome (SMC) protein complexes cohesin and condensin and the Smc5/6 complex (Smc5/6) are crucial for chromosome dynamics and stability. All contain essential ATPase domains, and cohesin and condensin interact with chromosomes through topological entrapment of DNA. However, how Smc5/6 binds DNA and chromosomes has remained largely unknown. Here, we show that purified Smc5/6 binds DNA through a mechanism that requires ATP hydrolysis by the complex and circular DNA to be established. This also promotes topoisomerase 2-dependent catenation of plasmids, suggesting that Smc5/6 interconnects two DNA molecules using ATP-regulated topological entrapment of DNA, similar to cohesin. We also show that a complex containing an Smc6 mutant that is defective in ATP binding fails to interact with DNA and chromosomes and leads to cell death with concomitant accumulation of DNA damage when overexpressed. Taken together, these results indicate that Smc5/6 executes its cellular functions through ATP-regulated intermolecular DNA linking. Graphical abstract Teaser Kanno et al. have found that Smc5/6 interacts with DNA by two different mechanisms. One is based on electrostatic interactions that require ATP binding to Smc6. The other leads to topological entrapment and demands ATP hydrolysis by the complex. The results show that Smc5/6 is an ATP-dependent intermolecular DNA linker.

Beschreibung: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): J.S. Lessels, T.F.A. Bishop Study region South eastern Australia. Study focus This region is characterised with rainfall events that are associated with large exports of nutrients and sediments. Many water quality monitoring schemes use a form of event-based sampling to quantify these exports. Previous water quality studies that have evaluated different sampling schemes often rely on continuously monitored water quality data. However, many catchment authorities only have access to limited historical data which consists of event-based and monthly routine samples. Therefore there is a need to develop a method that assesses the importance of sampling events using information from limited historical data. This work presents a simulation based approach using unconditional simulation based on historical stream discharge. Such an approach offers site-specific information on optimal sampling schemes. A linear mixed model is used to model the relationship between total phosphorus and stream discharge and the auto-correlation of total phosphorus. New hydrological insights for the region The inclusion of event-based sampling improved annual load estimates of all sites with a maximum RMSE difference of 16.11 tonnes between event-based and routine sampling. Based on the accuracy of annual loads, event-based sampling was found to be more important in catchments with a large relief and high annual rainfall in this region. Using this approach, different sampling schemes can be compared based on limited historical data.

Beschreibung: Drought assessment in the Dongliao River basin: traditional approaches vs. generalized drought assessment index based on water resources systems Natural Hazards and Earth System Science, 15, 1889-1906, 2015 Author(s): B. S. Weng, D. H. Yan, H. Wang, J. H. Liu, Z. Y. Yang, T. L. Qin, and J. Yin Drought is firstly a resource issue, and with its development it evolves into a disaster issue. Drought events usually occur in a determinate but a random manner. Drought has become one of the major factors to affect sustainable socioeconomic development. In this paper, we propose the generalized drought assessment index (GDAI) based on water resources systems for assessing drought events. The GDAI considers water supply and water demand using a distributed hydrological model. We demonstrate the use of the proposed index in the Dongliao River basin in northeastern China. The results simulated by the GDAI are compared to observed drought disaster records in the Dongliao River basin. In addition, the temporal distribution of drought events and the spatial distribution of drought frequency from the GDAI are compared with the traditional approaches in general (i.e., standard precipitation index, Palmer drought severity index and rate of water deficit index). Then, generalized drought times, generalized drought duration, and generalized drought severity were calculated by theory of runs. Application of said runs at various drought levels (i.e., mild drought, moderate drought, severe drought, and extreme drought) during the period 1960–2010 shows that the centers of gravity of them all distribute in the middle reaches of Dongliao River basin, and change with time. The proposed methodology may help water managers in water-stressed regions to quantify the impact of drought, and consequently, to make decisions for coping with drought.

Beschreibung: The electrical self-potential method is a non-intrusive snow-hydrological sensor The Cryosphere Discussions, 9, 4437-4457, 2015 Author(s): S. S. Thompson, B. Kulessa, R. L. H. Essery, and M. P. Lüthi Our ability to measure, quantify and assimilate hydrological properties and processes of snow in operational models is disproportionally poor compared to the significance of seasonal snowmelt as a global water resource and major risk factor in flood and avalanche forecasting. Encouraged by recent theoretical, modelling and laboratory work, we show here that the diurnal evolution of aerially-distributed self-potential magnitudes closely track those of bulk meltwater fluxes in melting in-situ snowpacks at Rhone and Jungfraujoch glaciers, Switzerland. Numerical modelling infers temporally-evolving liquid water contents in the snowpacks on successive days in close agreement with snow-pit measurements. Muting previous concerns, the governing physical and chemical properties of snow and meltwater became temporally invariant for modelling purposes. Because measurement procedure is straightforward and readily automated for continuous monitoring over significant spatial scales, we conclude that the self-potential geophysical method is a highly-promising non-intrusive snow-hydrological sensor for measurement practice, modelling and operational snow forecasting.

Beschreibung: A rainfall design method for spatial flood risk assessment: considering multiple flood sources Hydrology and Earth System Sciences Discussions, 12, 8005-8033, 2015 Author(s): X. Jiang and H. Tatano Information about the spatial distribution of flood risk is important for integrated urban flood risk management. Focusing on urban areas, spatial flood risk assessment must reflect all risk information derived from multiple flood sources: rivers, drainage, coastal flooding etc. that may affect the area. However, conventional flood risk assessment deals with each flood source independently, which leads to an underestimation of flood risk in the floodplain. Even in floodplains that have no risk from coastal flooding, flooding from river channels and inundation caused by insufficient drainage capacity should be considered simultaneously. For integrated flood risk management, it is necessary to establish a methodology to estimate flood risk distribution across a floodplain. In this paper, a rainfall design method for spatial flood risk assessment, which considers the joint effects of multiple flood sources, is proposed. The concept of critical rainfall duration determined by the concentration time of flooding is introduced to connect response characteristics of different flood sources with rainfall. A copula method is then adopted to capture the correlation of rainfall amount with different critical rainfall durations. Rainfall events are designed taking advantage of the copula structure of correlation and marginal distribution of rainfall amounts within different critical rainfall durations. A case study in the Otsu River Basin, Osaka prefecture, Japan was conducted to demonstrate this methodology.

Beschreibung: Tilt error in cryospheric surface radiation measurements at high latitudes: a model study The Cryosphere Discussions, 9, 4355-4376, 2015 Author(s): W. S. Bogren, J. F. Burkhart, and A. Kylling We have evaluated the magnitude and makeup of error in cryospheric radiation observations due to small sensor misalignment in in-situ measurements of solar irradiance. This error is examined through simulation of diffuse and direct irradiance arriving at a detector with a cosine-response foreoptic. Emphasis is placed on assessing total error over the solar shortwave spectrum from 250 to 4500 nm, as well as supporting investigation over other relevant shortwave spectral ranges. The total measurement error introduced by sensor tilt is dominated by the direct component. For a typical high latitude albedo measurement with a solar zenith angle of 60°, a sensor tilted by 1, 3, and 5° can respectively introduce up to 2.6, 7.7, and 12.8 % error into the measured irradiance and similar errors in the derived albedo. Depending on the daily range of solar azimuth and zenith angles, significant measurement error can persist also in integrated daily irradiance and albedo.

Beschreibung: Publication date: 18 August 2015 Source: Cell Reports, Volume 12, Issue 7 Author(s): Marvin L. Meistrich, Gunapala Shetty In this issue of Cell Reports , DeFalco et al. (2015) characterize a novel macrophage population associated with the peritubular lamina of mouse testes. These macrophages may create a niche not for the self-renewal of stem cells but rather the induction of their differentiation.

Beschreibung: Hydroelastic analysis of ice shelves under long wave excitation Natural Hazards and Earth System Science, 15, 1851-1857, 2015 Author(s): T. K. Papathanasiou, A. E. Karperaki, E. E. Theotokoglou, and K. A. Belibassakis The transient hydroelastic response of an ice shelf under long wave excitation is analysed by means of the finite element method. The simple model, presented in this work, is used for the simulation of the generated kinematic and stress fields in an ice shelf, when the latter interacts with a tsunami wave. The ice shelf, being of large length compared to its thickness, is modelled as an elastic Euler-Bernoulli beam, constrained at the grounding line. The hydrodynamic field is represented by the linearised shallow water equations. The numerical solution is based on the development of a special hydroelastic finite element for the system of governing of equations. Motivated by the 2011 Sulzberger Ice Shelf (SIS) calving event and its correlation with the Honshu Tsunami, the SIS stable configuration is studied. The extreme values of the bending moment distribution in both space and time are examined. Finally, the location of these extrema is investigated for different values of ice shelf thickness and tsunami wave length.

Beschreibung: Pre-earthquake magnetic pulses Natural Hazards and Earth System Science, 15, 1873-1880, 2015 Author(s): J. Scoville, J. Heraud, and F. Freund A semiconductor model of rocks is shown to describe unipolar magnetic pulses, a phenomenon that has been observed prior to earthquakes. These pulses are suspected to be generated deep in the Earth's crust, in and around the hypocentral volume, days or even weeks before earthquakes. Their extremely long wavelength allows them to pass through kilometers of rock. Interestingly, when the sources of these pulses are triangulated, the locations coincide with the epicenters of future earthquakes. We couple a drift-diffusion semiconductor model to a magnetic field in order to describe the electromagnetic effects associated with electrical currents flowing within rocks. The resulting system of equations is solved numerically and it is seen that a volume of rock may act as a diode that produces transient currents when it switches bias. These unidirectional currents are expected to produce transient unipolar magnetic pulses similar in form, amplitude, and duration to those observed before earthquakes, and this suggests that the pulses could be the result of geophysical semiconductor processes.

Beschreibung: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Hayet Chihi, Ghislain de Marsily, Habib Belayouni, Houcine Yahyaoui Study region “Jeffara de Medenine” aquifer system in south-eastern Tunisia. Study focus This study investigates the role of fault structures in the distribution of hydrogeochemical facies and groundwater compartmentalization for the aquifer system. New hydrological insights for the region The proposed methodology, including seismic structural study, hierarchical cluster analysis and geostatistical methods, allowed an efficient multi-element characterization of the spatial patterns of the structural elements in the aquifers and of the hydrogeological parameters used in a spatial cross-correlation to explore the dependence of the geochemical properties in each “geochemical population” on the hosting structural compartment to delineate the different geochemical compartments. The tectonic studies showed that the lateral extent of the aquifers is controlled by normal faults. The multivariate statistical analysis revealed a strong spatial coherence between hydrogeochemical facies clustering and the reservoir compartments at both large and small scales. The kriged maps of major-ion concentrations and of total dissolved solids in the aquifers were then analyzed and compared with the reservoir facies distribution for each compartment, the geometric characteristics of the aquifer, and the piezometric level trends. This allowed to characterize the hydraulic behavior of the Medenine fault and to understand the underlying physical and chemical processes having led to the spatial distribution of the geochemical properties, and thus, the hydrogeochemical functioning of the aquifers.

Beschreibung: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Marnie L. Atkins, Isaac R. Santos, Damien T. Maher Study region This study investigates dissolved methane distribution in groundwater from the Richmond River Catchment (New South Wales, Australia) before proposed coal seam gas (CSG, or coal bed methane) development. Study focus Unconventional gas exploration has rapidly expanded in recent years. However, the impact of these operations on groundwater systems is poorly understood. A total of 91 groundwater samples were analyzed from 6 geological units. Our observations act as regional baseline research prior to CSG extraction and may assist with long term impact assessment. New hydrological insights for the region Methane was found in all geological units ranging between 0.26 and 4427 μg L −1 (median 10.68 μg L −1 ). Median methane concentrations were highest in chloride-type groundwater (13.26 μg L −1 , n = 58) while bicarbonate-type groundwater had lower concentrations (3.71 μg L −1 ). Groundwater from alluvial sediments had significantly higher median methane concentrations (91.46 μg L −1 ) than groundwater from both the basalt aquifers (0.7 μg L −1 ) and bedrock aquifers (4.63 μg L −1 ); indicating geology was a major driver of methane distribution. Methane carbon stable isotope ratios ranged from –90.9‰ to –29.5‰, suggesting a biogenic origin with some methane oxidation. No significant correlations were observed between methane concentrations and redox indicators (nitrate, manganese, iron and sulphate) except between iron and methane in the Lismore Basalt ( r 2 = 0.66, p 〈 0.001), implying redox conditions were not the main predictor of methane distribution.

Beschreibung: Characterizing Leaf Area Index (LAI) and Vertical Foliage Profile (VFP) over the United States Biogeosciences Discussions, 12, 13675-13710, 2015 Author(s): H. Tang, S. Ganguly, G. Zhang, M. A. Hofton, R. F. Nelson, and R. Dubayah Leaf area index (LAI) and vertical foliage profile (VFP) are among the important canopy structural variables. Recent advances in lidar remote sensing technology have demonstrated the capability of accurately mapping LAI and VFP over large areas. The primary objective of this study was to derive and validate a LAI and VFP product over the contiguous United States using spaceborne waveform lidar data. This product was derived at the footprint level from the Geoscience Laser Altimeter System (GLAS) using a biophysical model. We validated GLAS derived LAI and VFP across major forest biomes using airborne waveform lidar. The comparison results showed that GLAS retrievals of total LAI were generally accurate with little bias ( r 2 = 0.67, bias = −0.13, RMSE = 0.75). The derivations of GLAS retrievals of VFP within layers was not as accurate overall ( r 2 = 0.36, bias = −0.04, RMSE = 0.26), and these varied as a function of height, increasing from understory to overstory −0 to 5 m layer: r 2 = 0.04, bias = 0.09, RMSE = 0.31; 10 to 15 m layer: r 2 = 0.53, bias = −0.08, RMSE = 0.22; and 15 to 20 m layer: r 2 = 0.66, bias =−0.05, RMSE = 0.20. Significant relationships were also found between GLAS LAI products and different environmental factors, in particular elevation and annual precipitation. In summary, our results provide a unique insight into vertical canopy structure distribution across North American ecosystems. This data set is a first step towards a baseline of canopy structure needed for evaluating climate and land use induced forest changes at continental scale in the future and should help deepen our understanding of the role of vertical canopy structure on terrestrial ecosystem processes across varying scales.

Beschreibung: Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya) The Cryosphere Discussions, 9, 4407-4436, 2015 Author(s): A. Spolaor, T. Opel, J. R. McConnell, O. J. Maselli, G. Spreen, C. Varin, T. Kirchgeorg, D. Fritzsche, and P. Vallelonga The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere-ocean heat and gas exchange. Here we present a reconstruction of AD 1950 to 1998 sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The halogens bromine (Br) and iodine (I) are strongly influenced by sea ice processes. Bromine reacts with the sea ice surface in auto-catalyzing "Bromine explosion" events causing an enrichment of the Br / Na ratio and the bromine excess (Br exc ) in snow compared to that in seawater. Iodine is emitted from algal communities growing under sea ice. The results suggest a connection between Br exc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. These two halogens are therefore good candidates for extended reconstructions of past sea ice changes in the Arctic.

Beschreibung: Application of the 15 N-Gas Flux method for measuring in situ N 2 and N 2 O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique Biogeosciences Discussions, 12, 12653-12689, 2015 Author(s): F. Sgouridis, S. Ullah, and A. Stott Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N 2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15 N tracer approaches can provide in situ measurements of both N 2 and N 2 O simultaneously, but their use has been limited to fertilised agro-ecosystems due to the need for large 15 N additions in order to detect 15 N 2 production against the high atmospheric N 2 . For 15 N-N 2 analyses, we have used an "in house" laboratory designed and manufactured N 2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS). The N 2 prep unit has gas purification steps, a copper based reduction furnace, and allows the analysis of small gas injection volumes (4 μL) for 15 N-N 2 analysis. For the analysis of N 2 O, an automated Tracegas Pre-concentrator (Isoprime Ltd) coupled to an IRMS was used to measure the 15 N-N 2 O (4 mL gas injection volume). Consequently, the coefficient of variation for the determination of isotope ratios for N 2 in air and in standard N 2 O (0.5 ppm) was better than 0.5 %. The 15 N Gas-Flux method was adapted for application in natural and semi-natural land use types (peatlands, forests and grasslands) by lowering the 15 N tracer application rate to 0.04–0.5 kg 15 N ha −1 . For our chamber design (volume / surface = 8:1) and a 20 h incubation period, the minimum detectable flux rates were 4 μg N m −2 h −1 and 0.2 ng N m −2 h −1 for the N 2 and N 2 O fluxes respectively. The N 2 flux ranged between 2.4 and 416.6 μg N m −2 h −1 , and the grassland soils showed on average 3 and 14 times higher denitrification rates than the woodland and organic soils respectively. The N 2 O flux was on average 20 to 200 times lower than the N 2 flux, while the denitrification product ratio (N 2 O/N 2 + N 2 O) was low, ranging between 0.03 and 13 %. Total denitrification rates measured by the acetylene inhibition technique under the same field conditions correlated ( r = 0.58) with the denitrification rates measured under the 15 N Gas-Flux method but were underestimated by a factor of 4 and this was attributed to the incomplete inhibition of N 2 O reduction to N 2 under relatively high soil moisture content. The results show that the 15 N Gas-Flux method can be used for quantifying N 2 and N 2 O production rates in natural terrestrial ecosystems, thus significantly improving our ability to constrain ecosystem N budgets.

Beschreibung: The 9 September 2010 torrential rain and flash flood in the Dragone catchment, Atrani, Amalfi Coast (Southern Italy) Natural Hazards and Earth System Sciences Discussions, 3, 4715-4751, 2015 Author(s): C. Violante, G. Braca, E. Esposito, and G. Tranfaglia In this paper we use a multi-hazard approach to analyse the 9 September 2010 flash-flood occurred in the Dragone basin, a 9 km 2 catchment located along the Amalfi rocky coastal range, Southern Italy. In this area, alluvial-fan-flooding is the most frequent and destructive geologic hazards since Roman time. Sudden torrent of waters (flash flood) are caused by high-intensity and very localized cloudbursts of short duration inducing slope erosion and sediment delivery from slope-to-stream. The elevated bed load transport produces fast-moving hyperconcentrated flows with significant catastrophic implications for communities living at stream mouth. The 9 September 2010 rainstorm event lasted 1 h with an intensity rainfall peak nearly to 120 mm h −1 . High topographic relief of the Amalfi coastal range and positive anomalies of the coastal waters conditioned the character of the convective system. Based on geological data and post-event field evidence and surveys, as well as homemade-videos, and eyewitness accounts the consequent flash-flood mobilized some 25 000 m 3 of materials with a total (water and sediment) peak flow of 80 m 3 s −1 . The estimated peak discharge of only clear water was about 65 m 3 s −1 . This leads to a sediment bulking factor of 1.2 that corresponds to a flow with velocities similar to those of water during a flood.

Beschreibung: Natural variability in the surface ocean carbonate ion concentration Biogeosciences Discussions, 12, 13123-13157, 2015 Author(s): N. S. Lovenduski, M. C. Long, and K. Lindsay We investigate variability in the surface ocean carbonate ion concentration ([CO 3 2− ]) on the basis of a long control simulation with a fully-coupled Earth System Model. The simulation is run with a prescribed, pre-industrial atmospheric CO 2 concentration for 1000 years, permitting investigation of natural [CO 3 2− ] variability on interannual to multi-decadal timescales. We find high interannual variability in surface [CO 3 2− ] in the tropical Pacific and at the boundaries between the subtropical and subpolar gyres in the Northern Hemisphere, and relatively low interannual variability in the centers of the subtropical gyres and in the Southern Ocean. Statistical analysis of modeled [CO 3 2− ] variance and autocorrelation suggests that significant anthropogenic trends in the saturation state of aragonite (Ω aragonite ) are already or nearly detectable at the sustained, open-ocean timeseries sites, whereas several decades of observations are required to detect anthropogenic trends in Ω aragonite in the tropical Pacific, North Pacific, and North Atlantic. The detection timescale for anthropogenic trends in pH is shorter than that for Ω aragonite , due to smaller noise-to-signal ratios and lower autocorrelation in pH. In the tropical Pacific, the leading mode of surface [CO 3 2− ] variability is primarily driven by variations in the vertical advection of dissolved inorganic carbon (DIC) in association with El Niño–Southern Oscillation. In the North Pacific, surface [CO 3 2− ] variability is caused by circulation-driven variations in surface DIC and strongly correlated with the Pacific Decadal Oscillation, with peak spectral power at 20–30 year periods. North Atlantic [CO 3 2− ] variability is also driven by variations in surface DIC, and exhibits weak correlations with both the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation. As the scientific community seeks to detect the anthropogenic influence on ocean carbonate chemistry, these results will aid the interpretation of trends calculated from spatially- and temporally-sparse observations.

Beschreibung: Technical Note: Testing an improved index for analysing storm nutrient hysteresis Hydrology and Earth System Sciences Discussions, 12, 7875-7892, 2015 Author(s): C. E. M. Lloyd, J. E. Freer, P. J. Johnes, and A. L. Collins Analysis of hydrochemical behaviour in extreme flow events can provide new insights into the process controls on nutrient transport in catchments. The examination of storm behaviours using hysteresis analysis has increased in recent years, partly due to the increased availability of high temporal resolution datasets for discharge and nutrient parameters. A number of these analyses involve the use of an index to describe the characteristics of a hysteresis loop in order to compare different storm behaviours both within and between catchments. This technical note reviews the methods for calculation of the hysteresis index (HI) and explores a new more effective methodology. Each method is systematically tested and the impact of the chosen calculation on the results is examined. Recommendations are made regarding the most effective method of calculating a HI which can be used for comparing data between storms and between different parameters and catchments.

Beschreibung: Mediterranean cyclone characteristics related to precipitation occurrence in Crete, Greece Natural Hazards and Earth System Science, 15, 1807-1819, 2015 Author(s): V. Iordanidou, A. G. Koutroulis, and I. K. Tsanis The characteristics of the cyclone tracks that caused precipitation events of variable intensity for the period 1979–2011 over the island of Crete are presented. The data set used for cyclone identification is the 0.5° × 0.5°, 30 years European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim mean sea-level pressure. Cyclone characteristics are calculated with the aid of the Melbourne University algorithm (MS scheme). Daily precipitation data from a dense gauging network over the island of Crete are also used for the classification of the precipitation events in terms of rain accumulation (intensity). Daily precipitation is classified in three categories and the associated cyclones are chosen according to their distance from Crete island. The seasonal and annual cycle of the physical characteristics of the cyclone tracks are investigated with respect to the cyclones' relative position to the island of Crete. It was found that cyclones affecting Crete most frequently approach from the western side of the island and the actual cyclone centers associated with precipitation events are usually located northwest and southeast of the Crete domain. Cyclone-induced rainfall increases in function to cyclones' depth, radius and propagation velocity increase as well as cyclones' pressure decrease. Spring cyclones that affect Crete with rainfall present lower pressures and higher cyclone propagation velocity in contrast to the ones associated with winter and autumn precipitation events. The examination of the relation between cyclone characteristics and precipitation occurrence provides valuable information related to forecasting potential and management of the water resources and the rainfall extremes.

Beschreibung: Spatial and temporal trends in summertime climate and water quality indicators in the coastal embayments of Buzzards Bay, Massachusetts Biogeosciences Discussions, 12, 13159-13192, 2015 Author(s): J. E. Rheuban, S. C. Williamson, J. E. Costa, D. M. Glover, R. W. Jakuba, D. C. McCorkle, C. Neill, T. Williams, and S. C. Doney Degradation of coastal ecosystems by eutrophication is largely defined by nitrogen loading from land via surface and groundwater flows. However, indicators of water quality are highly variable due to a myriad of other drivers, including temperature and precipitation. To evaluate these drivers, we examined spatial and temporal trends in a 22 year record of summer water quality data from 122 stations in 17 embayments within Buzzards Bay, MA (USA), collected through a citizen science monitoring program managed by Buzzards Bay Coalition. To identify spatial patterns across Buzzards Bay's embayments, we used a principle component and factor analysis and found that rotated factor loadings indicated little correlation between inorganic nutrients and organic matter and chlorophyll a (Chl a ) concentration. Factor scores showed that embayment geomorphology in addition to nutrient loading was a strong driver of water quality, where embayments with surface water inputs showed larger biological impacts than embayments dominated by groundwater influx. A linear regression analysis of annual summertime water quality indicators over time revealed that from 1992 to 2013, most embayments (15 of 17) exhibited an increase in temperature (mean rate of 0.082 ± 0.025 (SD) °C yr −1 ) and Chl a (mean rate of 0.0171 ± 0.0088 log 10 (Chl a ; mg m −3 ) yr −1 , equivalent to a 4.0 % increase per year). However, only 7 embayments exhibited an increase in total nitrogen (TN) concentration (mean rate 0.32 ± 0.47 (SD) μM yr −1 ). Average summertime log 10 (TN) and log 10 (Chl a ) were correlated with an indication that yield of Chl a per unit total nitrogen increased with time suggesting the estuarine response to TN may have changed because of other stressors such as warming, altered precipitation patterns, or changing light levels. These findings affirm that nitrogen loading and physical aspects of embayments are essential in explaining observed ecosystem response. However, climate-related stressors may also need to be considered by managers because increased temperature and precipitation may worsen water quality and partially offset benefits achieved by reducing nitrogen loading.

Beschreibung: Publication date: Available online 13 August 2015 Source: Cell Reports Author(s): Kavita R. Sharma, Brittany L. Enzmann, Yvonne Schmidt, Dani Moore, Graeme R. Jones, Jane Parker, Shelley L. Berger, Danny Reinberg, Laurence J. Zwiebel, Bernhard Breit, Jürgen Liebig, Anandasankar Ray The sophisticated organization of eusocial insect societies is largely based on the regulation of complex behaviors by hydrocarbon pheromones present on the cuticle. We used electrophysiology to investigate the detection of cuticular hydrocarbons (CHCs) by female-specific olfactory sensilla basiconica on the antenna of Camponotus floridanus ants through the utilization of one of the largest family of odorant receptors characterized so far in insects. These sensilla, each of which contains multiple olfactory receptor neurons, are differentially sensitive to CHCs and allow them to be classified into three broad groups that collectively detect every hydrocarbon tested, including queen and worker-enriched CHCs. This broad-spectrum sensitivity is conserved in a related species, Camponotus laevigatus , allowing these ants to detect CHCs from both nestmates and non-nestmates. Behavioral assays demonstrate that these ants are excellent at discriminating CHCs detected by the antenna, including enantiomers of a candidate queen pheromone that regulates the reproductive division of labor. Graphical abstract Teaser Sharma et al. show that ants can detect a number of hydrocarbons present on the cuticle, therefore recognizing different castes such as workers and queens from their own colony as well as different colonies. They also show that ants are able to smell and discriminate minor differences among hydrocarbons.

Beschreibung: Publication date: Available online 13 August 2015 Source: Cell Reports Author(s): Sanjeev Kumar, Jing Liu, Paul Pang, A. Michaela Krautzberger, Antoine Reginensi, Haruhiko Akiyama, Andreas Schedl, Benjamin D. Humphreys, Andrew P. McMahon After acute kidney injury (AKI), surviving cells within the nephron proliferate and repair. We identify Sox9 as an acute epithelial stress response in renal regeneration. Translational profiling after AKI revealed a rapid upregulation of Sox9 within proximal tubule (PT) cells, the nephron cell type most vulnerable to AKI. Descendants of Sox9 + cells generate the bulk of the nephron during development and regenerate functional PT epithelium after AKI-induced reactivation of Sox9 after renal injury. After restoration of renal function post-AKI, persistent Sox9 expression highlights regions of unresolved damage within injured nephrons. Inactivation of Sox9 in PT cells pre-injury indicates that Sox9 is required for the normal course of post-AKI recovery. These findings link Sox9 to cell intrinsic mechanisms regulating development and repair of the mammalian nephron. Graphical abstract Teaser Surviving tubular epithelial cells repair the nephron after acute kidney injury (AKI). Kumar et al. identify Sox9 activation as a rapid response to AKI within repairing cells of the damaged proximal tubule segment. Sox9 activation is required for a normal repair process.

Beschreibung: Publication date: Available online 13 August 2015 Source: Cell Reports Author(s): Rheinallt M. Jones, Chirayu Desai, Trevor M. Darby, Liping Luo, Alexandra A. Wolfarth, Christopher D. Scharer, Courtney S. Ardita, April R. Reedy, Erin S. Keebaugh, Andrew S. Neish An optimal gut microbiota influences many beneficial processes in the metazoan host. However, the molecular mechanisms that mediate and function in symbiont-induced host responses have not yet been fully characterized. Here, we report that cellular ROS enzymatically generated in response to contact with lactobacilli in both mice and Drosophila has salutary effects against exogenous insults to the intestinal epithelium via the activation of Nrf2 responsive cytoprotective genes. These data show that the xenobiotic-inducible Nrf2 pathway participates as a signaling conduit between the prokaryotic symbiont and the eukaryotic host. Indeed, our data imply that the capacity of lactobacilli to induce redox signaling in epithelial cells is a highly conserved hormetic adaptation to impel cellular conditioning to exogenous biotic stimuli. These data also highlight the role the microbiota plays in eukaryotic cytoprotective pathways and may have significant implications in the characterization of a eubiotic microbiota. Graphical abstract Teaser Jones et al. report that the commensal gut bacterial taxa lactobacilli are able to mediate beneficial cytoprotective effects in the gut of both flies and mice. These highly conserved events are mediated by ROS-dependent activation of the Nrf2 xenobiotic pathway and conserved effector genes.

Beschreibung: Publication date: Available online 13 August 2015 Source: Cell Reports Author(s): Neel Mehta, Arthur H. Cheng, Cheng-Kang Chiang, Lucia Mendoza-Viveros, Harrod H. Ling, Abhilasha Patel, Bo Xu, Daniel Figeys, Hai-Ying M. Cheng The pacemaker properties of the suprachiasmatic nucleus (SCN) circadian clock are shaped by mechanisms that influence the expression and behavior of clock proteins. Here, we reveal that G-protein-coupled receptor kinase 2 (GRK2) modulates the period, amplitude, and entrainment characteristics of the SCN. Grk2 -deficient mice show phase-dependent alterations in light-induced entrainment, slower recovery from jetlag, and longer behavioral rhythms. Grk2 ablation perturbs intrinsic rhythmic properties of the SCN, increasing amplitude and decreasing period. At the cellular level, GRK2 suppresses the transcription of the mPeriod1 gene and the trafficking of PERIOD1 and PERIOD2 proteins to the nucleus. Moreover, GRK2 can physically interact with PERIOD1/2 and promote PERIOD2 phosphorylation at Ser545, effects that may underlie its ability to regulate PERIOD1/2 trafficking. Together, our findings identify GRK2 as an important modulator of circadian clock speed, amplitude, and entrainment by controlling PERIOD at the transcriptional and post-translational levels. Graphical abstract Teaser Mehta et al. demonstrate the importance of GRK2 in regulating both the pace of the circadian clock and its response to environmental time cues (i.e., light). GRK2 functionally interacts with the molecular clock at the transcriptional and post-translational levels, dampening mPeriod1 gene transcription and suppressing nuclear trafficking of PERIOD1/2 proteins.

Beschreibung: Publication date: Available online 13 August 2015 Source: Cell Reports Author(s): Juan F. Linares, Angeles Duran, Miguel Reina-Campos, Pedro Aza-Blanc, Alex Campos, Jorge Moscat, Maria T. Diaz-Meco The mTORC1 complex is central to the cellular response to changes in nutrient availability. The signaling adaptor p62 contributes to mTORC1 activation in response to amino acids and interacts with TRAF6, which is required for the translocation of mTORC1 to the lysosome and the subsequent K63 polyubiquitination and activation of mTOR. However, the signal initiating these p62-driven processes was previously unknown. Here, we show that p62 is phosphorylated via a cascade that includes MEK3/6 and p38δ and is driven by the PB1-containing kinase MEKK3. This phosphorylation results in the recruitment of TRAF6 to p62, the ubiquitination and activation of mTOR, and the regulation of autophagy and cell proliferation. Genetic inactivation of MEKK3 or p38δ mimics that of p62 in that it leads to inhibited growth of PTEN-deficient prostate organoids. Analysis of human prostate cancer samples showed upregulation of these three components of the pathway, which correlated with enhanced mTORC1 activation. Graphical abstract Teaser Linares et al. identify a kinase cascade that regulates the phosphorylation of the signal adaptor p62 in response to amino acids to control mTORC1 activation. This nutrient-sensing mechanism is relevant for autophagy regulation and tumor growth.

Beschreibung: Soil storage influences climate–evapotranspiration interactions in three western United States catchments Hydrology and Earth System Sciences Discussions, 12, 7893-7931, 2015 Author(s): E. S. Garcia and C. L. Tague In the winter-wet, summer-dry forests of the western United States, total annual evapotranspiration (ET) varies with precipitation and temperature. Geologically mediated drainage and storage properties, however, may strongly influence these relationships between climate and ET. We use a physically based process model to evaluate how soil available water capacity (AWC) and rates of drainage influence model estimates of ET-climate relationships for three snow-dominated, mountainous catchments with differing precipitation regimes. Model estimates show that total annual precipitation is a primary control on inter-annual variation in ET across all catchments and that the timing of recharge is a second order control. Low soil AWC, however, increases the sensitivity of annual ET to these climate drivers by three to five times in our two study basins with drier summers. ET–climate relationships in our Colorado basin receiving summer precipitation are more stable across subsurface drainage and storage characteristics. Climate driver-ET relationships are most sensitive to soil AWC and soil drainage parameters related to lateral redistribution in the relatively dry Sierra site that receives little summer precipitation. Our results demonstrate that uncertainty in geophysically mediated storage and drainage properties can strongly influence model estimates of watershed scale ET responses to climate variation and climate change. This sensitivity to uncertainty in geophysical properties is particularly true for sites receiving little summer precipitation. A parallel interpretation of this parameter sensitivity is that spatial variation in soil properties are likely to lead to substantial within-watershed plot scale differences in forest water use and drought stress.

Beschreibung: Carbon dynamics in highly heterotrophic subarctic thaw ponds Biogeosciences Discussions, 12, 11707-11749, 2015 Author(s): T. Roiha, I. Laurion, and M. Rautio Global warming has accelerated the formation of permafrost thaw ponds in several subarctic and arctic regions. These ponds are net heterotrophic as evidenced by their greenhouse gas (GHG) supersaturation levels (CO 2 and CH 4 ), and generally receive large terrestrial carbon inputs from the thawing and eroding permafrost. We measured seasonal and vertical variations in the concentration and type of dissolved organic matter (DOM) in five subarctic thaw (thermokarst) ponds in northern Quebec, and explored how environmental gradients influenced heterotrophic and phototrophic biomass and productivity. Late winter DOM had low aromaticity indicating reduced inputs of terrestrial carbon, while the high concentration of dissolved organic carbon (DOC) suggests that some production of non-chromophoric dissolved compounds by the microbial food web took place under the ice cover. Summer DOM had a strong terrestrial signature, but was also characterized with significant inputs of algal-derived carbon, especially at the pond surface. During late winter, bacterial production was low (maximum of 0.8 mg C m −3 d −1 ) and was largely based on free-living bacterioplankton (58 %). Bacterial production in summer was high (up to 58 mg C m −3 d −1 ), dominated by particle-attached bacteria (67 %), and strongly correlated to the amount of terrestrial carbon. Primary production was restricted to summer surface waters due to strong light limitation deeper in the water column or in winter. The phototrophic biomass was equal to the heterotrophic biomass, but as the algae were mostly composed of mixotrophic species, most probably they used bacteria rather than solar energy in such shaded ponds. According to the δ 13 C analyses, non-algal carbon supported 51 % of winter and 37 % of summer biomass of the phantom midge larvae, Chaoborus sp., that are at the top of the trophic chain. Our results point to a strong heterotrophic energy pathway in these thaw pond ecosystems, where bacterioplankton dominates the production of new carbon in both summer and winter.

Beschreibung: Probabilistic hurricane-induced storm surge hazard assessment in Guadeloupe, Lesser Antilles Natural Hazards and Earth System Science, 15, 1711-1720, 2015 Author(s): Y. Krien, B. Dudon, J. Roger, and N. Zahibo Current storm surge hazard maps in the French West Indies are essentially based on simple statistical methods using limited historical data and early low-resolution models which do not take the effect of waves into account. In this paper, we infer new 100-year and 1000-year surge levels in Guadeloupe from the numerical modelling of storm surges induced by a large set of synthetic events that are in statistical agreement with features of historical hurricanes in the North Atlantic Basin between 1980 and 2011. Computations are performed using the wave-current coupled model ADCIRC–SWAN with high grid resolutions (up to 40–60 m) in the coastal and wave dissipation areas. This model is validated against observations during past events such as hurricane HUGO (1989). Results are generally found to be in reasonable agreement with past studies in areas where surge is essentially wind-driven, but found to differ significantly in coastal regions where the transfer of momentum from waves to the water column constitutes a non-negligible part of the total surge. The methodology, which can be applied to other islands in the Lesser Antilles, allows storm surge level maps to be obtained that can be of major interest for coastal planners and decision makers in terms of risk management.

Beschreibung: Teaching disaster preparedness via a mobile device: a study of Auckland Civil Defence's Smartphone Application Natural Hazards and Earth System Sciences Discussions, 3, 4555-4583, 2015 Author(s): O. Kulemeka This content analysis study examined whether a disaster preparedness education smartphone application created by a New Zealand city matches what experts say are effective ways of teaching disaster preparedness and teaching via an app. The app was assessed to ascertain if it excelled as a platform for learning, communicated effectively, addressed factors that can hinder people from preparing, and provided information for special needs populations. Results show that the app addressed most factors that hinder preparedness, provided information for some special needs populations, excelled as a platform for learning, and communicated effectively. The app's weaknesses include the fact that it lacked targeted information for low-income residents. The findings provide insight on how organizations can effectively use apps to teach disaster preparedness. The author passed away before the publication of this discussion paper. Therefore, a final revised paper is not foreseen.

Beschreibung: Phototrophic pigment diversity and picophytoplankton abundance in permafrost thaw lakes Biogeosciences Discussions, 12, 12121-12156, 2015 Author(s): A. Przytulska, J. Comte, S. Crevecoeur, C. Lovejoy, I. Laurion, and W. F. Vincent Permafrost thaw lakes (thermokarst lakes) are widely distributed across the northern landscape, and are known to be biogeochemically active sites that emit large amounts of carbon to the atmosphere as CH 4 and CO 2 . However, the abundance and composition of the photosynthetic communities that consume CO 2 have been little explored in this ecosystem type. In order to identify the major groups of phototrophic organisms and their controlling variables, we sampled 12 permafrost thaw lakes along a permafrost degradation gradient in northern Québec, Canada. Additional samples were taken from 5 rock-basin reference lakes in the region to determine if the thaw waters differed in limnological properties and phototrophs. Phytoplankton community structure was determined by high performance liquid chromatography analysis of their photoprotective and photosynthetic pigments, and autotrophic picoplankton concentrations were assessed by flow cytometry. One of the black colored lakes located in a andscape of rapidly degrading palsas (permafrost mounds) was selected for high-throughput 18S rRNA sequencing to help interpret the pigment and cytometry data. The results showed that the limnological properties of the thaw lakes differed significantly from the reference lakes, and were more highly stratified. However, both waterbody types contained similarly diverse phytoplankton groups, with dominance of the pigment assemblages by fucoxanthin-containing taxa, as well as chlorophytes, cryptophytes and cyanobacteria. Chlorophyll a concentrations (Chl a ) were correlated with total phosphorus (TP), and both were significantly higher in the thaw lakes (overall means of 3.3 μg Chl a L −1 and 34 μg TP L −1 ) relative to the reference lakes (2.0 μg Chl a L −1 and 8.2 μg TP L −1 ). Stepwise multiple regression of Chl a against the other algal pigments showed that it was largely a function of lutein, fucoxanthin and peridinin ( R 2 = 0.78). The bottom waters of two of the thaw lakes also contained high concentrations of bacteriochlorophyll d , showing the presence of green photosynthetic sulphur bacteria. The molecular analyses indicated a relatively minor contribution of diatoms, while chrysophytes, dinoflagellates and chlorophytes were well represented; the heterotrophic eukaryote fraction was dominated by numerous ciliate taxa, and also included Heliozoa, Rhizaria, chytrids and flagellates. Autotrophic picoplankton occurred in cell concentrations up to 8.8 × 10 5 mL −1 (picocyanobacteria) and 4.6 × 10 5 mL −1 (picoeukaryotes). Both groups of picophytoplankton were positively correlated with total phytoplankton abundance, as measured by Chl a ; picocyanobacteria were inversely correlated with dissolved organic carbon, while picoeukaryotes were correlated with conductivity. Despite their net heterotrophic character, subarctic thaw lakes are rich habitats for diverse phototrophic communities.

Beschreibung: Publication date: 4 August 2015 Source: Cell Reports, Volume 12, Issue 5 Author(s): Obinna Chijioke, Anne Müller, Regina Feederle, Mario Henrique M. Barros, Carsten Krieg, Vanessa Emmel, Emanuela Marcenaro, Carol S. Leung, Olga Antsiferova, Vanessa Landtwing, Walter Bossart, Alessandro Moretta, Rocio Hassan, Onur Boyman, Gerald Niedobitek, Henri-Jacques Delecluse, Riccarda Capaul, Christian Münz

Beschreibung: The Global Network of Isotopes in Rivers (GNIR): integration of water isotopes in watershed observation and riverine research Hydrology and Earth System Sciences, 19, 3419-3431, 2015 Author(s): J. Halder, S. Terzer, L. I. Wassenaar, L. J. Araguás-Araguás, and P. K. Aggarwal We introduce a new online global database of riverine water stable isotopes (Global Network of Isotopes in Rivers, GNIR) and evaluate its longer-term data holdings. Overall, 218 GNIR river stations were clustered into three different groups based on the seasonal variation in their isotopic composition, which was closely coupled to precipitation and snowmelt water runoff regimes. Sinusoidal fit functions revealed phases within each grouping and deviations from the sinusoidal functions revealed important river alterations or hydrological processes in these watersheds. The seasonal isotopic amplitude of δ 18 O in rivers averaged 2.5 ‰, and did not increase as a function of latitude, like it does for global precipitation. Low seasonal isotopic amplitudes in rivers suggest the prevalence of mixing and storage such as occurs via lakes, reservoirs, and groundwater. The application of a catchment-constrained regionalized cluster-based water isotope prediction model (CC-RCWIP) allowed for direct comparison between the expected isotopic compositions for the upstream catchment precipitation with the measured isotopic composition of river discharge at observation stations. The catchment-constrained model revealed a strong global isotopic correlation between average rainfall and river discharge ( R 2 = 0.88) and the study demonstrated that the seasonal isotopic composition and variation of river water can be predicted. Deviations in data from model-predicted values suggest there are important natural or anthropogenic catchment processes like evaporation, damming, and water storage in the upstream catchment.

Beschreibung: Sub-daily runoff simulations with parameters inferred at the daily time scale Hydrology and Earth System Sciences Discussions, 12, 7437-7467, 2015 Author(s): J. E. Reynolds, S. Halldin, C. Y. Xu, J. Seibert, and A. Kauffeldt Concentration times in small and medium-sized watersheds (~ 100–1000 km 2 ) are commonly less than 24 h. Flood-forecasting models then require data at sub-daily time scales, but time-series of input and runoff data with sufficient lengths are often only available at the daily time scale, especially in developing countries. This has led to a search for time-scale relationships to infer parameter values at the time scales where they are needed from the time scales where they are available. In this study, time-scale dependencies in the HBV-light conceptual hydrological model were assessed within the generalized likelihood uncertainty estimation (GLUE) approach. It was hypothesised that the existence of such dependencies is a result of the numerical method or time-stepping scheme used in the models rather than a real time-scale-data dependence. Parameter values inferred showed a clear dependence on time scale when the explicit Euler method was used for modelling at the same time steps as the time scale of the input data (1–24 h). However, the dependence almost fully disappeared when the explicit Euler method was used for modelling in 1 h time steps internally irrespectively of the time scale of the input data. In other words, it was found that when an adequate time-stepping scheme was implemented, parameter sets inferred at one time scale (e.g., daily) could be used directly for runoff simulations at other time scales (e.g., 3 or 6 h) without any time scaling and this approach only resulted in a small (if any) model performance decrease, in terms of Nash–Sutcliffe and volume-error efficiencies. The overall results of this study indicated that as soon as sub-daily driving data can be secured, flood forecasting in watersheds with sub-daily concentration times is possible with model-parameter values inferred from long time series of daily data, as long as an appropriate numerical method is used.

Beschreibung: Inversion kinematics at deep-seated gravity slope deformations: a paleoseismological perspective Natural Hazards and Earth System Sciences Discussions, 3, 4585-4617, 2015 Author(s): F. Pasquarè Mariotto and A. Tibaldi We compare data from three deep-seated gravity slope deformations (DSGSDs) where paleoseismological techniques were applied in artificial trenches. At all trenches, located in metamorphic rocks of the Italian Alps, there is evidence of extensional deformation given by normal movements along slip planes dipping downhill or uphill, and/or fissures, as expected in gravitational failure. However, we document and illustrate – with the aid of trenching – the evidence of reverse movements. The reverse slips occurred mostly along the same planes along which normal slip occurred, and produced drag folds in unconsolidated Holocene sediments as well as the superimposition of substrate rocks on Holocene sediments. Since trenches are located in different positions with respect to the slope affected by the DSGSD, it is possible to suggest that reverse slip might occur both at the toe portions of DSGSDs and in their central-upper portions. When the age relationships between the two deformation kinematics can be sorted out, they clearly indicate that reverse slips postdate normal ones. Our data suggest that during the development of long-lived DSGSDs, inversion kinematics may occur in different sectors of the unstable rock mass. The inversion is interpreted as either due to locking of the frontal blocks of a DSGSD, or the relative decrease in the rate of downward movement in the frontal blocks with respect to the rear blocks.

Beschreibung: Mapping snow depth from manned aircraft on landscape scales at centimeter resolution using structure-from-motion photogrammetry The Cryosphere, 9, 1445-1463, 2015 Author(s): M. Nolan, C. Larsen, and M. Sturm Airborne photogrammetry is undergoing a renaissance: lower-cost equipment, more powerful software, and simplified methods have significantly lowered the barriers to entry and now allow repeat mapping of cryospheric dynamics at spatial resolutions and temporal frequencies that were previously too expensive to consider. Here we apply these advancements to the measurement of snow depth from manned aircraft. Our main airborne hardware consists of a consumer-grade digital camera directly coupled to a dual-frequency GPS; no inertial motion unit (IMU) or on-board computer is required, such that system hardware and software costs less than USD 30 000, exclusive of aircraft. The photogrammetric processing is done using a commercially available implementation of the structure from motion (SfM) algorithm. The system is simple enough that it can be operated by the pilot without additional assistance and the technique creates directly georeferenced maps without ground control, further reducing overall costs. To map snow depth, we made digital elevation models (DEMs) during snow-free and snow-covered conditions, then subtracted these to create difference DEMs (dDEMs). We assessed the accuracy (real-world geolocation) and precision (repeatability) of our DEMs through comparisons to ground control points and to time series of our own DEMs. We validated these assessments through comparisons to DEMs made by airborne lidar and by a similar photogrammetric system. We empirically determined that our DEMs have a geolocation accuracy of ±30 cm and a repeatability of ±8 cm (both 95 % confidence). We then validated our dDEMs against more than 6000 hand-probed snow depth measurements at 3 separate test areas in Alaska covering a wide-variety of terrain and snow types. These areas ranged from 5 to 40 km 2 and had ground sample distances of 6 to 20 cm. We found that depths produced from the dDEMs matched probe depths with a 10 cm standard deviation, and were statistically identical at 95 % confidence. Due to the precision of this technique, other real changes on the ground such as frost heave, vegetative compaction by snow, and even footprints become sources of error in the measurement of thin snow packs ( 〈 20 cm). The ability to directly measure such small changes over entire landscapes eliminates the need to extrapolate limited field measurements. The fact that this mapping can be done at substantially lower costs than current methods may transform the way we approach studying change in the cryosphere.

Beschreibung: Analysis of three-dimensional groundwater flow toward a radial collector well in a finite-extent unconfined aquifer Hydrology and Earth System Sciences Discussions, 12, 7503-7540, 2015 Author(s): C.-S. Huang, J.-J. Chen, and H.-D. Yeh This study develops a three-dimensional mathematical model for describing transient hydraulic head distributions due to pumping at a radial collector well (RCW) in a rectangular confined or unconfined aquifer bounded by two parallel streams and no-flow boundaries. The governing equation with a point-sink term is employed. A first-order free surface equation delineating the water table decline induced by the well is considered. The head solution for the point sink is derived by applying the methods of double-integral transform and Laplace transform. The head solution for a RCW is obtained by integrating the point-sink solution along the laterals of the RCW and then dividing the integration result by the sum of lateral lengths. On the basis of Darcy's law and head distributions along the streams, the solution for the stream depletion rate (SDR) can also be developed. With the aid of the head and SDR solutions, the sensitivity analysis can then be performed to explore the response of the hydraulic head to the change in a specific parameter such as the horizontal and vertical hydraulic conductivities, streambed permeability, specific storage, specific yield, lateral length and well depth. Spatial head distributions subject to the anisotropy of aquifer hydraulic conductivities are analyzed. A quantitative criterion is provided to identify whether groundwater flow at a specific region is 3-D or 2-D without the vertical component. In addition, another criterion is also given to allow the neglect of vertical flow effect on SDR. Conventional 2-D flow models can be used to provide accurate head and SDR predictions if satisfying these two criteria.

Beschreibung: Diagnosing the seasonal land–atmosphere correspondence over northern Australia: dependence on soil moisture state and correspondence strength definition Hydrology and Earth System Sciences, 19, 3433-3447, 2015 Author(s): M. Decker, A. Pitman, and J. Evans The similarity of the temporal variations of land and atmospheric states during the onset (September) through to the peak (February) of the wet season over northern Australia is statistically diagnosed using ensembles of offline land surface model simulations that produce a range of different background soil moisture states. We derive the temporal correspondence between variations in the soil moisture and the planetary boundary layer via a statistical measure of rank correlation. The simulated evaporative fraction and the boundary layer are shown to be strongly correlated during both SON (September–October–November) and DJF (December–January–February) despite the differing background soil moisture states between the two seasons and among the ensemble members. The sign and magnitude of the boundary layer–surface layer soil moisture association during the onset of the wet season (SON) differs from the correlation between the evaporative fraction and boundary layer from the same season, and from the correlation between the surface soil moisture and boundary layer association during DJF. The patterns and magnitude of the surface flux–boundary layer correspondence are not captured when the relationship is diagnosed using the surface layer soil moisture alone. The conflicting results arise because the surface layer soil moisture lacks strong correlation with the atmosphere during the monsoon onset because the evapotranspiration is dominated by transpiration. Our results indicate that accurately diagnosing the correspondence and therefore coupling strength in seasonally dry regions, such as northern Australia, requires root zone soil moisture to be included.

Beschreibung: Publication date: Available online 6 August 2015 Source: Cell Reports Author(s): Matthew T. Maurano, Hao Wang, Sam John, Anthony Shafer, Theresa Canfield, Kristen Lee, John A. Stamatoyannopoulos Although DNA methylation is commonly invoked as a mechanism for transcriptional repression, the extent to which it actively silences transcription factor (TF) occupancy sites in vivo is unknown. To study the role of DNA methylation in the active modulation of TF binding, we quantified the effect of DNA methylation depletion on the genomic occupancy patterns of CTCF, an abundant TF with known methylation sensitivity that is capable of autonomous binding to its target sites in chromatin. Here, we show that the vast majority (>98.5%) of the tens of thousands of unoccupied, methylated CTCF recognition sequences remain unbound upon abrogation of DNA methylation. The small fraction of sites that show methylation-dependent binding in vivo are in turn characterized by highly variable CTCF occupancy across cell types. Our results suggest that DNA methylation is not a primary groundskeeper of genomic TF landscapes, but rather a specialized mechanism for stabilizing intrinsically labile sites. Graphical abstract Teaser Alterations of DNA methylation in malignancy and development are frequently interpreted as affecting transcriptional activity. Maurano et al. find that, upon genomic abrogation of DNA methylation, binding of the canonically methylation-sensitive transcriptional regulator CTCF is largely unaffected. Their results suggest that a limited set of methylation-sensitive CTCF sites are variable across cell types and that key sequence and chromatin features predict methylation sensitivity of CTCF binding.

Beschreibung: Publication date: Available online 6 August 2015 Source: Cell Reports Author(s): Swea-Ling Khaw, Chua Min-Wen, Cheng-Gee Koh, Bing Lim, Ng Shyh-Chang Oocyte factors not only drive somatic cell nuclear transfer reprogramming but also augment the efficiency and quality of induced pluripotent stem cell (iPSC) reprogramming. Here, we show that the oocyte-enriched factors Tcl1 and Tcl1b1 significantly enhance reprogramming efficiency. Clonal analysis of pluripotency biomarkers further show that the Tcl1 oocyte factors improve the quality of reprogramming. Mechanistically, we find that the enhancement effect of Tcl1b1 depends on Akt, one of its putative targets. In contrast, Tcl1 suppresses the mitochondrial polynucleotide phosphorylase (PnPase) to promote reprogramming. Knockdown of PnPase rescues the inhibitory effect from Tcl1 knockdown during reprogramming, whereas PnPase overexpression abrogates the enhancement from Tcl1 overexpression. We further demonstrate that Tcl1 suppresses PnPase’s mitochondrial localization to inhibit mitochondrial biogenesis and oxidation phosphorylation, thus remodeling the metabolome. Hence, we identified the Tcl1-PnPase pathway as a critical mitochondrial switch during reprogramming. Graphical abstract Teaser Khaw et al. identify the oocyte Tcl1-PnPase pathway as a critical mitochondrial switch during reprogramming into iPSCs. They find that Tcl1 suppresses the mitochondrial localization of PNPase, thus inhibiting mitochondrial biogenesis and oxidation phosphorylation.

Beschreibung: Publication date: Available online 6 August 2015 Source: Cell Reports Author(s): Xinfang Huang, Jingjing Li, Stephanie Dorta-Estremera, Jeremy Di Domizio, Scott M. Anthony, Stephanie S. Watowich, Daniel Popkin, Zheng Liu, Philip Brohawn, Yihong Yao, Kimberly S. Schluns, Lewis L. Lanier, Wei Cao Here, we examine the mechanism by which plasmacytoid dendritic cells (pDCs) and type I interferons promote humoral autoimmunity. In an amyloid-induced experimental autoimmune model, neutrophil depletion enhanced anti-nuclear antibody development, which correlated with heightened IFN-γ production by natural killer (NK) cells. IFN-α/β produced by pDCs activated NK cells via IL-15 induction. Neutrophils released reactive oxygen species (ROS), which negatively modulated the levels of IL-15, thereby inhibiting IFN-γ production. Mice deficient in NADPH oxidase 2 produced increased amounts of IFN-γ and developed augmented titers of autoantibodies. Both the pDC-IFN-α/β pathway and IFN-γ were indispensable in stimulating humoral autoimmunity. Male NZB/W F1 mice expressed higher levels of superoxide than their female lupus-prone siblings, and depletion of neutrophils resulted in spontaneous NK cell and autoimmune B cell activation. Our findings suggest a regulatory role for neutrophils in vivo and highlight the importance of an NK-IFN-γ axis downstream of the pDC-IFN-α/β pathway in systemic autoimmunity. Graphical abstract Teaser Huang et al. find that IFN-α/β produced by plasmacytoid dendritic cells (pDCs) stimulates NK cells to secrete IFN-γ, which is essential for the development of autoantibodies. ROS-producing neutrophils negatively regulate this NK-IFN-γ pathway and control autoimmune progression in lupus-prone mice.

Beschreibung: Effects of cultivation and reforestation on suspended sediment concentrations: a case study in a mountainous catchment in China Hydrology and Earth System Sciences Discussions, 12, 7583-7614, 2015 Author(s): N. F. Fang, F. X. Chen, H. Y. Zhang, Y. X. Wang, and Z. H. Shi Understanding how sediment concentrations vary with land use/cover is critical for evaluating the current and future impacts of human activities on river systems. This paper presents suspended sediment concentration (SSC) dynamics and the relationship between SSC and discharge ( Q ) in the 8973 km 2 Du catchment and its sub-catchment (4635 km 2 ). In the Du catchment and its sub-catchment, 4235 and 3980 paired Q -SSC samples, respectively, were collected over 30 years. Under the influence of the "Household Contract Responsibility System" and Grain-for-Green projects in China, three periods were designated, the original period (1980s), cultivation period (1990s), and reforestation period (2000s). The results of a Mann–Kendall test showed that rainfall slightly increased during the study years; however, the annual discharge and sediment load significantly decreased. The annual suspended sediment yield of the Du catchment varied between 4 and 332 kg s −1 , and that of the sub-catchment varied between 2 and 135 kg s −1 . The SSCs in the catchment and sub-catchment fluctuated between 1 and 22 400 g m −3 and between 1 and 31 800 g m −3 , respectively. The mean SSC of the Du catchment was relatively stable during the three periods (±83 g m −3 ). ANOVA indicated that the SSC did not significantly change under cultivation for low and moderate flows, but was significantly different under high flow during reforestation of the Du catchment. The SSC in the sub-catchment was more variable, and the mean-SSC in the sub-catchment varied from 1058 g m −3 in the 1980s to 1256 g m −3 in the 1990s and 891 g m −3 in the 2000s. Reforestation significantly decreased the SSCs during low and moderate flows, whereas cultivation increased the SSCs during high flow. The sediment rating curves showed a stable relationship between the SSC and Q in the Du catchment during the three periods. However, the SSC- Q of the sub-catchment exhibited scattered relationships during the original and cultivation periods and a more linear relationship during the reforestation period.