Das Projekt "Watershed sediment yield modelling for data scarce areas; a case study, Awash River Basin, Ethiopia" wird vom Umweltbundesamt gefördert und von Universität Stuttgart, Institut für Wasserbau durchgeführt. The main goal of the research was to device an alternative solution for watershed sediment yield modelling for data scarce areas where the existing physically based models can not be applicable. Awash River Basin in Ethiopia was selected as case study area. GIS data on soil, land use, precipitation, temperature, stream flow and suspended sediment yield was collected from the Federal Ministry of Water Resources of Ethiopia (FMWRE) and from the National Metrology Service Agency (NMSA) offices. Soil data obtained from FMWRE and Food and Agriculture Organization (FAO) world soil 1974 database was used for derivation of the soil erodibility factor (ERFAC) estimation equation. The ratio of silt to sand and clay content was considered as the governing factor for soil erodibility in developing the ERFAC equation. The SWAT2005 model was selected for calibration and validation of stream flow and sediment yield. A sensitivity analysis was carried out to prioritize model calibration parameters. From the sensitivity analysis, curve number II (CN2), soilwater available to plants (SOL-AWC) and ground water base flow factor (ALPHA-BF) were selected as major stream flow calibration parameters. Similarly CN2, SURLAG (surface lag), slope and sediment routing factor (SPCON) were taken as the major sediment calibration parameters. Parameters related to the soil properties and river channel characteristics were given special attention during the model calibration. Eleven years (1990-2000) stream flow and sediment data were used for model calibration and six years data (2001-2006) were used for model validation. Calibration has been done at three gauging stations located in the Awash River basin. The statistical indicators, Coefficient of determination (R2), Nash-Sutclife efficiency (NSE), Root mean square error observations standard deviation (RSR were applied to evaluate the calibration and validation results. The values of these indicators were used to ratethe performance of the model. Watershed geomorphologic and topographic factors were extracted from the SWAT2005 watershed configuration, using a GIS tool and empirical equations. The relative importance of the factors was determined using Pearsons correlation coefficient based on the sediment yield output obtained from the SWAT2005 model calibration. The results show that, the sediment yield is highly correlated with stream flow, watershed area and watershed slope. Based on the identified parameters and the SWAT2005 model output, an alternative sediment yield estimation equation was derived and checked for its validity.
Das Projekt "A5: Limitations to the growth of epiphytes and the productivity of associated methanogens in neotropical moist forests" wird vom Umweltbundesamt gefördert und von Universität Oldenburg, Institut für Biologie und Umweltwissenschaften, Arbeitsgruppe Funktionelle Ökologie der Pflanzen durchgeführt. Epiphytes play an important role in tropical forest ecosystem processes by influencing fluxes of water, carbon and nutrients. Tank bromeliads, a common group of epiphytes, also affect atmospheric CH4 budgets by hosting active communities of methanogens. At present, the limitations to epiphyte growth and the productivity of associated methanogens are poorly understood. The proposed study addresses two main questions: (1) To what extent are establishment and growth of epiphytes in undisturbed montane forest limited by nutrient availability? Epiphyte growth response to fertilisation with moderate doses of N, P, and NP will be monitored in late juveniles of selected vascular species from different functional and taxonomical groups. Additionally, epiphyte propagules (angiosperms, foliose lichens) will be sown experimentally to determine fertilisation effects on early establishment rates and seedling growth. (2) How do per capita and ecosystem-level CH4 emissions from bromeliad tanks change with elevation, and which factors limit the productivity of bromeliad methanogens? Data on per capita CH4 emissions and bromeliad densities will be taken along an elevational gradient of 250-3000 m asl. Furthermore, limitations to methanogens (water, carbon, nutrients, temperature) will be explored through in situ greenhouse experiments.
Das Projekt "Mechanisms of oxidative stress tolerance in rice and their application in the molecular breeding of genotypes adapted to stress environments" wird vom Umweltbundesamt gefördert und von Universität Bonn, Institut für Nutzpflanzenwissenschaften und Ressourcenschutz - Pflanzenernährung (Prof. Werner) durchgeführt. Abiotic environmental stresses are among the major factors limiting agricultural productivity in many developing countries. A common feature of various environmental stresses is the excessive accumulation of reactive oxygen species (ROS) in the leaf tissue leading to 'oxidative stress' and in turn visible leaf lesions, reduced growth, and in severe cases plant death. This project aims at identifying molecular mechanisms associated with oxidative stress tolerance in rice (Oryza sativa L.) under three different environmental conditions: (i) high tropospheric ozone concentration, (ii) zinc deficiency, and (iii) iron toxicity. This is achieved by dissecting naturally occurring genotypic variability in oxidative stress tolerance into distinct quantitative trait loci (QTL). Physiological mechanisms and genes underlying such tolerance QTL are identified by adopting an interdisciplinary approach including biochemical characterization of the antioxidant systems, transcriptome profiling, and experiments with gene knock-out mutants for candidate genes. Theoretical understanding of stress tolerance mechanisms obtained from laboratory experiments would be validated in field experiments together with international research institutions and partners in developing countries. At a later stage, the project strives to adopt emerging techniques in gene discovery such as single nucleotide polymorphism (SNP) based association mapping, and apply lessons learned from studying the 'model cereal crop' rice to other species such as barley (Hordeum vulgare L.). The project is expected to contribute to world-wide efforts in adapting crop production to stress environments by specifically advancing the understanding of oxidative stress tolerance.
Das Projekt "Regulation of nitrogen storage and mobilization in the annual life cycle of poplar" wird vom Umweltbundesamt gefördert und von Universität Freiburg, Institut für Forstbotanik und Baumphysiologie durchgeführt. Nitrogen nutrition is a major growth limiting factor for trees and, therefore, nitrogen uptake and assimilation are highly regulated. Recently it was shown that beside reduced nitrogen compounds, e.g. glutamine, phytohormones such as cytokinins regulate nitrate uptake. The central aim of this project is to test the hypothesis that two antagonistic regulatory pathways are involved in the adaptation of N uptake by the roots to the N-demand of trees: (1) The enrichment of particular amino compounds serves as signal for the repression of nitrogen uptake and (2) the enrichment of cytokinins increases the expression of genes involved in nitrogen uptake and assimilation. A combination of molecular and physiological methods with computer modelling will be used to assess the regulation of N-metabolism by reduced N-compounds and cytokinins in poplar and their cycling within the plant.
Das Projekt "Spatial heterogeneity and substrate availability as limiting factors for subsoil C-turnover" wird vom Umweltbundesamt gefördert und von Universität Bochum, Geographisches Institut durchgeführt. In subsoils, organic matter (SOM) concentrations and microbial densities are much lower than in topsoils and most likely highly heterogeneously distributed. We therefore hypothesize, that the spatial separation between consumers (microorganisms) and their substrates (SOM) is an important limiting factor for carbon turnover in subsoils. Further, we expect microbial activity to occur mainly in few hot spots, such as the rhizosphere or flow paths where fresh substrate inputs are rapidly mineralized. In a first step, the spatial distribution of enzyme and microbial activities in top- and subsoils will be determined in order to identify hot spots and relate this to apparent 14C age, SOM composition, microbial community composition and soil properties, as determined by the other projects within the research unit. In a further step it will be determined, if microbial activity and SOM turnover is limited by substrate availability in spatially distinct soil microsites. By relating this data to root distribution and preferential flow paths we will contribute to the understanding of stabilizing and destabilizing processes of subsoil organic matter. As it is unclear, at which spatial scale these differentiating processes are effective, the analysis of spatial variability will cover the dm to the mm scale. As spatial segregation between consumers and substrates will depend on the pore and aggregate architecture of the soil, the role of the physical integrity of these structures on SOM turnover will also be investigated in laboratory experiments.
Das Projekt "Natural product lead discovery at the microgram scale - an integrated approach" wird vom Umweltbundesamt gefördert und von Universität Basel, Department Pharmazeutische Biologie durchgeführt. Natural products remain an important source for drugs and a source of inspiration for medicinal chemists for the design of synthetic drugs and probes for the study of biological functions. The contribution of academic laboratories in natural products discovery has been substantial. The limiting factor of pharmaceutical natural product research has been with the tedious process of purification and identification of the lead molecules from the highly complex crude extract. Recent technological advances enable now a miniaturization of the screening and discovery process for natural product leads. The proposal here is for the purchase of a 500 MHz NMR spectrometer specifically equipped for the measurement of mass limited samples. It includes a recently commercialized 1 mm probe and autosampler and is capable of recording 1D and 2D NMR spectra with microgram (20-100 myg) amounts of natural products and synthetic drug-like molecules. The spectrometer is configured to fit into the technology platforms and the workflows of the Drug Screening Group of the Swiss Tropical Institute and the Institute of Pharmaceutical Biology. The instrument shall be used for various interdisciplinary projects of the two principal applicants and for a consortium which is being established. The major use will be for HPLC-based lead discovery in the area of Alzheimer's disease, Malaria, and neglected tropical diseases. The instrument will also be employed for metabolic fingerprinting of selected plants and phytomedicines. A third application will be in the analysis of compound libraries from external sources which are screened by the applicants in the context of the principal projects. An NMR instrument with this configuration is currently not in operation at a Swiss university. It is the missing link in a technology platform established at the laboratories of the two applicants. This platform should enable a paradigm shift in the way how natural product leads are identified, namely by miniaturizing the entire process of screening, separation and lead identification to the microgram level. A significant gain in efficiency of the discovery process and, thus, in research productivity, both qualitative and quantitative, is anticipated. The equipment will also be of interest to all those scientists in the biomedical sciences who need structural information from mass limited samples such as, for example drug metabolites.
Das Projekt "Recovery from drought stress: Are the processes of plant's capacity to adapt and survive under climate-driven environmental extremes underestimated?" wird vom Umweltbundesamt gefördert und von Departament de Qimica Universitat de les Illes Balears durchgeführt. With regard to climate-driven environmental changes in Europe during the next decades (heatwaves and extended drought periods) the understanding of how plants may adapt to these environmental constraints and ensure their survival awaits further attention. Moreover, besides well studied responses of plants to various drought intensities, the capacity of recovery from drought and its velocity and rate will become an important issue for plant species across Europe. As there is a scarcity of studies in the field of recovery from drought, this project is designed to unravel its underlying physiological processes by a systematic analysis of photosynthetic and respiratory traits of several Mediterranean species during recovery from various drought intensities. The time frame of drought within a vegetation period may additionally affect the capacity of drought tolerance and rate of recovery, as well as growth and survival. Main Results and Conclusions The rate of photosynthetic restoration after drought-induced suppression depends on the intensity of drought, as recovery of all examined plant species has always been more rapid after mild or moderate drought (one to three days) than after severe drought (more than three days). Differences appeared among species, as annual species (Nicotiana sylvestris, Glycine max) recovered more rapidly from severe drought than perennial ones (Vitis vinifery, Cistus albidus, Quercus ilex). However, perennials followed a more conservative strategy during drought progression by loosing less water than the annual plants (which reached severe stress more rapidly but recovered also quicker after the short drought period). Limitation of photosynthetic recovery during the re-watering phase was driven by a delayed stomatal opening and impaired internal CO2 diffusion, namely the mesophyll conductance (gm). The gm has been found to be an important factor in limiting photosynthesis during drought and after subsequent re-watering, which further supports the idea of an important role of gm in photosynthetic regulation during stress and the necessity of further studies on its regulation under climatic variables. The impact of other climatic variables than water stress on gm could be assumed by comparing tobacco plants under different growth conditions. Besides the role of gm, the interaction of photosynthesis and respiration during drought and recovery has been shown to be important and highly flexible, as impaired respiratory chain was overcome by enhanced cytochrome pathway activity and hence higher total respiration. This adjustment might help to match the cellular ATP demand and maintain the cell redox balance, thus resulting in a similar response of photosynthesis to drought and re-watering.
Das Projekt "Bioactive natural products - linking chemical and biological information for lead discovery, preliminary SAR and assessment of undesired pharmacological properties" wird vom Umweltbundesamt gefördert und von Universität Basel, Department Pharmazeutische Biologie durchgeführt. Small molecule natural products are a prolific source of inspiration for the development of new drugs, and essential tools in basic biomedical research as probes of biological functions. The contribution of academic laboratories in natural products discovery has been essential. The limiting factor of traditional approaches in bioactivity-directed natural product research has been the tedious process of purification and identification of active molecules from a highly complex extract matrix. Recent technological advances enable substantial improvements in efficiency via a consequential miniaturization of the screening and discovery process, and automation of certain process steps. The aim of the project is to discover small molecule natural products leads from plants and fungi acting against clinically relevant and/or emerging targets in important disease areas. The targets have been selected on the basis of specific criteria, such as (i) novelty and importance of target; (ii) lack of specific/selective inhibitors; (iii) need for enhancement of structural diversity of ligands; (iv) difficulty/impossibility to use rational drug discovery approaches; (v) access to animal models. Indications include CNS (selective GABA-A receptor agonists), inflammation and cancer (modulation of angiogenesis and lymphangiogenesis, inhibition of PI3 kinases). In addition, a screening for hERG channel inhibition will be carried out as the currently most critical anti-target in drug discovery & development. An extract library and a technology platform for the miniaturized discovery of natural products will be used. The library consists of currently 1000 plant and fungal extracts. An ethnomedicine-based focussed sub-library will be specifically tested for GABAA receptor agonistic properties. All process steps in the screening and consecutive lead identification are miniaturized, in part automated, and based on the 96-well microtiter footprint. Most of the assays are via external collaborations, and some assays involving cell signalling are established in-house. Prioritized extracts are submitted to HPLC-based activity profiling with microtiter-based fractionation of column effluent, and simultaneous on-line spectroscopic (PDA, ion-trap ESI and APCI-MS, and ESI-TOF) analysis. Compound dereplication and identification is supported by off-line microprobe NMR spectroscopy. Around the active target molecules, structurally related compounds will be characterized to generate small 'virtual' libraries for preliminary structure activity relationships. Calculation of physico-chemical data and secondary bioassays will characterize leads, and shortlisted compounds will be tested in vivo for proof of concept. For this purpose, compounds of interest are isolated in a targeted manner in amounts of up to several hundred mg.
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