Altered spatio-temporal dynamics of RNase H2 complex assembly at replication and repair sites in Aicardi-Goutières syndrome.

Ribonuclease H2 plays an essential role for genome stability as it removes ribonucleotides misincorporated into genomic DNA by replicative polymerases and resolves RNA/DNA hybrids. Biallelic mutations in the genes encoding the three RNase H2 subunits cause Aicardi-Goutières syndrome (AGS), an early-onset inflammatory encephalopathy that phenotypically overlaps with the autoimmune disorder systemic lupus erythematosus. Here we studied the intracellular dynamics of RNase H2 in living cells during DNA replication and in response to DNA damage using confocal time-lapse imaging and fluorescence cross-correlation spectroscopy. We demonstrate that the RNase H2 complex is assembled in the cytosol and imported into the nucleus in an RNase H2B-dependent manner. RNase H2 is not only recruited to DNA replication foci, but also to sites of PCNA-dependent DNA repair. By fluorescence recovery after photobleaching, we demonstrate a high mobility and fast exchange of RNase H2 at sites of DNA repair and replication. We provide evidence that recruitment of RNase H2 is not only PCNA-dependent, mediated by an interaction of the B subunit with PCNA, but also PCNA-independent mediated via the catalytic domain of the A subunit. We found that AGS-associated mutations alter complex formation, recruitment efficiency and exchange kinetics at sites of DNA replication and repair suggesting that impaired ribonucleotide removal contributes to AGS pathogenesis.

Large-scale impact of climate change vs. land-use change on future biome shifts in Latin America.

Climate change and land-use change are two major drivers of biome shifts causing habitat and biodiversity loss. What is missing is a continental-scale future projection of the estimated relative impacts of both drivers on biome shifts over the course of this century. Here, we provide such a projection for the biodiverse region of Latin America under four socio-economic development scenarios. We find that across all scenarios 5-6% of the total area will undergo biome shifts that can be attributed to climate change until 2099. The relative impact of climate change on biome shifts may overtake land-use change even under an optimistic climate scenario, if land-use expansion is halted by the mid-century. We suggest that constraining land-use change and preserving the remaining natural vegetation early during this century creates opportunities to mitigate climate-change impacts during the second half of this century. Our results may guide the evaluation of socio-economic scenarios in terms of their potential for biome conservation under global change.

Role of Water in Phase Transformations and Crystallization of Ferrihydrite and Hematite.

The oxides, hydroxides, and oxo-hydroxides of iron belong to the most abundant materials on earth. They also feature a wide range of practical applications. In many environments, they can undergo facile phase transformations and crystallization processes. Water appears to play a critical role in many of these processes. Despite numerous attempts, the role of water has not been fully revealed yet. We present a new approach to study the influence of water in the crystallization and phase transformations of iron oxides. The approach employs model-type iron oxide films that comprise a defined homogeneous nanostructure. The films are exposed to air containing different amounts of water reaching up to pressures of 10 bar. Ex situ analysis via scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and X-ray diffraction is combined with operando near-ambient pressure X-ray photoelectron spectroscopy to follow water-induced changes in hematite and ferrihydrite. Water proves to be critical for the nucleation of hematite domains in ferrihydrite, the resulting crystallite orientation, and the underlying crystallization mechanism.

Oxygen Evolution Catalysts Based on Ir-Ti Mixed Oxides with Templated Mesopore Structure: Impact of Ir on Activity and Conductivity.

The efficient generation of hydrogen via water electrolysis requires highly active oxygen evolution catalysts. Among the active metals, iridium oxide provides the best compromise in terms of activity and stability. The limited availability and usage in other applications demands an efficient utilization of this precious metal. Forming mixed oxides with titania promises improved Ir utilization, but often at the cost of a low catalyst surface area. Moreover, the role of Ir in establishing a sufficiently conductive mixed oxide has not been elucidated so far. We report a new approach for the synthesis of Ir/TiOx mixed-oxide catalysts with defined template-controlled mesoporous structure, low crystallinity, and superior oxygen evolution reaction (OER) activity. The highly accessible pore system provides excellent Ir dispersion and avoids transport limitations. A controlled variation of the oxides Ir content reveals the importance of the catalysts electrical conductivity: at least 0.1 S m-1 are required to avoid limitations owing to slow electron transport. For sufficiently conductive oxides a clear linear correlation between Ir surface sites and OER currents can be established, where all accessible Ir sites equally contribute to the reaction. The optimized catalysts outperform Ir/TiOx materials reported in literature by about a factor of at least four.

Testing socio-cultural valuation methods of ecosystem services to explain land use preferences.

Socio-cultural valuation still emerges as a methodological field in ecosystem service (ES) research and until now lacks consistent formalisation and balanced application in ES assessments. In this study, we examine the explanatory value of ES values for land use preferences. We use 563 responses to a survey about the Pentland Hills regional park in Scotland. Specifically, we aim to (1) identify clusters of land use preferences by using a novel visualisation tool, (2) test if socio-cultural values of ESs or (3) user characteristics are linked with land use preferences, and (4) determine whether both socio-cultural values of ESs and user characteristics can predict land use preferences. Our results suggest that there are five groups of people with different land use preferences, ranging from forest and nature enthusiasts to traditionalists, multi-functionalists and recreation seekers. Rating and weighting of ESs and user characteristics were associated with different clusters. Neither socio-cultural values nor user characteristics were suitable predictors for land use preferences. While several studies have explored land use preferences by identifying socio-cultural values in the past, our findings imply that in this case study ES values inform about general perceptions but do not replace the assessment of land use preferences.

Microbial diversity and composition of the sediment in the drinking water reservoir Saidenbach (Saxonia, Germany).

Sediments contain a huge number and diversity of microorganisms that are important for the flux of material and are pivotal to all major biogeochemical cycles. Sediments of reservoirs are affected by a wide spectrum of allochthous and autochthonous influences providing versatile environments along the flow of water within the reservoir. Here we report on the microbial diversity in sediments of the mesotrophic drinking water reservoir Saidenbach, Germany, featuring a pronounced longitudinal gradient in sediment composition in the reservoir system. Three sampling sites were selected along the gradient, and the microbial communities in two sediment depths were characterized using catalysed reporter deposition fluorescence in situ hybridization (CARD-FISH) and a bar-coded pyrosequencing approach. Multivariate statistic was used to reveal relationships between sequence diversity and the environmental conditions. The microbial communities were tremendously diverse with a Shannon index of diversity (H') ranging from 6.7 to 7.1. 18,986 sequences could be classified into 37 phyla including candidate divisions, but the full extent of genetic diversity was not captured. While CARD-FISH gave an overview about the community composition, more detailed information was gained by pyrosequencing. Bacteria were more abundant than Archaea. The dominating phylum in all samples was Proteobacteria, especially Betaproteobacteria and Deltaproteobacteria. Furthermore, sequences of Bacteroidetes, Verrucomicrobia, Acidobacteria, Chlorobi, Nitrospira, Spirochaetes, Gammaproteobacteria, Alphaproteobacteria, Chloroflexi, and Gemmatimonadetes were found. The site ammonium concentration, water content and organic matter content revealed to be strongest environmental predictors explaining the observed significant differences in the community composition between sampling sites.

A phenomenological approach shows a high coherence of warming patterns in dimictic aquatic systems across latitude.

To predict the coherence in local responses to large-scale climatic forcing among aquatic systems, we developed a generalized approach to compare long-term data of dimictic water bodies based on phenomenologically defined hydrographic events. These climate-sensitive phases (inverse stratification, spring overturn, early thermal stratification, summer stagnation) were classified in a dual code (cold/warm) based on threshold temperatures. Accounting for a latitudinal gradient in seasonal timing of phases derived from gradients in cumulative irradiation (2.2 days per degree latitude), we found a high spatial and temporal coherence in warm-cold patterns for six lakes (84 %) and the Baltic Sea (78 %), even when using the same thresholds for all sites. Similarity to CW-codes for the North Sea still was up to 72 %. The approach allows prediction of phase-specific warming trends and resulting instantaneous or time-delayed ecological responses. Exemplarily, we show that warming during early thermal stratification controls food-web-mediated effects on key species during summer.