Advances and visions in large-scale hydrological modelling: findings from the 11th Workshop on Large-Scale Hydrological Modelling

Large-scale hydrological modelling has become increasingly wide-spread during the last decade. An annual workshop series on large-scale hydrological modelling has provided, since 1997, a forum to the German-speaking community for discussing recent developments and achievements in this research area. In this paper we present the findings from the 2007 workshop which focused on advances and visions in large-scale hydrological modelling. We identify the state of the art, difficulties and research perspectives with respect to the themes "sensitivity of model results", "integrated modelling" and "coupling of processes in hydrosphere, atmosphere and biosphere". Some achievements in large-scale hydrological modelling during the last ten years are presented together with a selection of remaining challenges for the future

E2F8 is a nonreceptor activator of heterotrimeric G proteins

BACKGROUND: Heterotrimeric G proteins are important for numerous signaling events in eukaryotes, serving primarily to transduce signals that are initiated by G protein-coupled receptors. It has recently become clear that nonreceptor activators can regulate the level of heterotrimeric G protein signaling and, in some cases, drive cycles of receptor-independent G protein activation. In this study, we used a yeast expression cloning strategy to identify novel nonreceptor activators of heterotrimeric G proteins in a human adipocyte cDNA library. RESULTS: The human transcription factor E2F8 was found to activate heterotrimeric G proteins, suggesting a specific biological role for this recently described member of the E2F family. Epistasis studies showed that E2F8 acted at the level of G proteins and was specific for Gα(i )over Gpa1. E2F8 augmented receptor-driven signaling, but also activated G proteins in the absence of a receptor. The GTPase-activating protein RGS4 antagonized the effect of E2F8, showing that E2F8's effect on Gα involved nucleotide turnover. The entire E2F8 protein was required for full activity, but the majority of the signaling activity appeared to reside in the first 200 residues. CONCLUSION: In yeast, E2F8 is a guanine nucleotide exchange factor (GEF) for the α subunit of heterotrimeric G proteins. The molecular mechanism and biological significance of this effect remain to be determined

Improved regional scale processes reflected in projected hydrological changes over large European catchments

For the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC), the recent version of the coupled atmosphere/ocean general circulation model (GCM) of the Max Planck Institute for Meteorology has been used to conduct an ensemble of transient climate simulations. These simulations comprise three control simulations for the past century covering the period 1860-2000, and nine simulations for the future climate(2001-2100) using greenhouse gas (GHG) and aerosol concentrations according to the three IPCC scenarios B1, A1B and A2. For each scenario three simulations were performed. The global simulations were dynamically downscaled over Europe using the regional climate model (RCM) REMO at 0.44A degrees horizontal resolution (about 50 km), whereas the physics packages of the GCM and RCM largely agree. The regional simulations comprise the three control simulations (1950-2000), the three A1B simulations and one simulation for B1 as well as for A2 (2001-2100). In our study we concentrate on the climate change signals in the hydrological cycle and the 2 m temperature by comparing the mean projected climate at the end of the twenty-first century (2071-2100) to a control period representing current climate (1961-1990). The robustness of the climate change signal projected by the GCM and RCM is analysed focussing on the large European catchments of Baltic Sea (land only), Danube and Rhine. In this respect, a robust climate change signal designates a projected change that sticks out of the noise of natural climate variability. Catchments and seasons are identified where the climate change signal in the components of the hydrological cycle is robust, and where this signal has a larger uncertainty. Notable differences in the robustness of the climate change signals between the GCM and RCM simulations are related to a stronger warming projected by the GCM in the winter over the Baltic Sea catchment and in the summer over the Danube and Rhine catchments. Our results indicate that the main explanation for these differences is that the finer resolution of the RCM leads to a better representation of local scale processes at the surface that feed back to the atmosphere, i.e. an improved representation of the land sea contrast and related moisture transport processes over the Baltic Sea catchment, and an improved representation of soil moisture feedbacks to the atmosphere over the Danube and Rhine catchments. [References: 41

A conserved filamentous assembly underlies the structure of the meiotic chromosome axis.

The meiotic chromosome axis plays key roles in meiotic chromosome organization and recombination, yet the underlying protein components of this structure are highly diverged. Here, we show that 'axis core proteins' from budding yeast (Red1), mammals (SYCP2/SYCP3), and plants (ASY3/ASY4) are evolutionarily related and play equivalent roles in chromosome axis assembly. We first identify 'closure motifs' in each complex that recruit meiotic HORMADs, the master regulators of meiotic recombination. We next find that axis core proteins form homotetrameric (Red1) or heterotetrameric (SYCP2:SYCP3 and ASY3:ASY4) coiled-coil assemblies that further oligomerize into micron-length filaments. Thus, the meiotic chromosome axis core in fungi, mammals, and plants shares a common molecular architecture, and likely also plays conserved roles in meiotic chromosome axis assembly and recombination control

Case study for the assessment of the biogeophysical effects of a potential afforestation in Europe

BACKGROUND: A regional-scale sensitivity study has been carried out to investigate the climatic effects of forest cover change in Europe. Applying REMO (regional climate model of the Max Planck Institute for Meteorology), the projected temperature and precipitation tendencies have been analysed for summer, based on the results of the A2 IPCC-SRES emission scenario simulation. For the end of the 21st century it has been studied, whether the assumed forest cover increase could reduce the effects of the greenhouse gas concentration change. RESULTS: Based on the simulation results, biogeophysical effects of the hypothetic potential afforestation may lead to cooler and moister conditions during summer in most parts of the temperate zone. The largest relative effects of forest cover increase can be expected in northern Germany, Poland and Ukraine, which is 15-20% of the climate change signal for temperature and more than 50% for precipitation. In northern Germany and France, potential afforestation may enhance the effects of emission change, resulting in more severe heavy precipitation events. The probability of dry days and warm temperature extremes would decrease. CONCLUSIONS: Large contiguous forest blocks can have distinctive biogeophysical effect on the climate on regional and local scale. In certain regions of the temperate zone, climate change signal due to greenhouse gas emission can be reduced by afforestation due to the dominant evaporative cooling effect during summer. Results of this case study with a hypothetical land cover change can contribute to the assessment of the role of forests in adapting to climate change. Thus they can build an important basis of the future forest policy

A common founding clone with TP53 and PTEN mutations gives rise to a concurrent germ cell tumor and acute megakaryoblastic leukemia

We report the findings from a patient who presented with a concurrent mediastinal germ cell tumor (GCT) and acute myeloid leukemia (AML). Bone marrow pathology was consistent with a diagnosis of acute megakaryoblastic leukemia (AML M7), and biopsy of an anterior mediastinal mass was consistent with a nonseminomatous GCT. Prior studies have described associations between hematological malignancies, including AML M7 and nonseminomatous GCTs, and it was recently suggested that a common founding clone initiated both cancers. We performed enhanced exome sequencing on the GCT and the AML M7 from our patient to define the clonal relationship between the two cancers. We found that both samples contained somatic mutations in PTEN (C136R missense) and TP53 (R213 frameshift). The mutations in PTEN and TP53 were present at ∼100% variant allele frequency (VAF) in both tumors. In addition, we detected and validated five other shared somatic mutations. The copy-number analysis of the AML exome data revealed an amplification of Chromosome 12p. We also identified a heterozygous germline variant in FANCA (S858R), which is known to be associated with Fanconi anemia but is of uncertain significance here. In summary, our data not only support a common founding clone for these cancers but also suggest that a specific set of distinct genomic alterations (in PTEN and TP53) underlies the rare association between GCT and AML. This association is likely linked to the treatment resistance and extremely poor outcome of these patients. We cannot resolve the clonal evolution of these tumors given limitations of our data

Expression of the ggpPS gene for glucosylglycerol biosynthesis from Azotobacter vinelandii improves the salt tolerance of Arabidopsis thaliana

Many organisms accumulate compatible solutes in response to salt or desiccation stress. Moderate halotolerant cyanobacteria and some heterotrophic bacteria synthesize the compatible solute glucosylglycerol (GG) as their main protective compound. In order to analyse the potential of GG to improve salt tolerance of higher plants, the model plant Arabidopsis thaliana was transformed with the ggpPS gene from the γ-proteobacterium Azotobacter vinelandii coding for a combined GG-phosphate synthase/phosphatase. The heterologous expression of the ggpPS gene led to the accumulation of high amounts of GG. Three independent Arabidopsis lines showing different GG contents were characterized in growth experiments. Plants containing a low (1–2 μmol g−1 FM) GG content in leaves showed no altered growth performance under control conditions but an increased salt tolerance, whereas plants accumulating a moderate (2–8 μmol g−1 FM) or a high GG content (around 17 μmol g−1 FM) showed growth retardation and no improvement of salt resistance. These results indicate that the synthesis of the compatible solute GG has a beneficial effect on plant stress tolerance as long as it is accumulated to an extent that does not negatively interfere with plant metabolism