Kooperativer Bibliotheksverbund

Berlin Brandenburg


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  • 1
    In: Global Change Biology, August 2014, Vol.20(8), pp.2644-2662
    Description: The ational orest oil nventory () provides the reenhouse as eporting in ermany with a quantitative assessment of organic carbon () stocks and changes in forest soils. Carbon stocks of the organic layer and the mineral topsoil (30 cm) were estimated on the basis of ca. 1.800 plots sampled from 1987 to 1992 and resampled from 2006 to 2008 on a nationwide grid of 8 × 8 km. Organic layer stock estimates were attributed to surveyed forest stands and land cover data. Mineral soil stock estimates were linked with the distribution of dominant soil types according to the oil ap of ermany (1 : 1 000 000) and subsequently related to the forest area. It appears that the pool of the organic layer was largely depending on tree species and parent material, whereas the pool of the mineral soil varied among soil groups. We identified the organic layer pool as stable although was significantly sequestered under coniferous forest at lowland sites. The mineral soils, however, sequestered 0.41 Mg C ha yr. Carbon pool changes were supposed to depend on stand age and forest transformation as well as an enhanced biomass input. Carbon stock changes were clearly attributed to parent material and soil groups as sandy soils sequestered higher amounts of , whereas clayey and calcareous soils showed small gains and in some cases even losses of soil . We further showed that the largest part of the overall sample variance was not explained by fine‐earth stock variances, rather by the concentrations variance. The applied uncertainty analyses in this study link the variability of strata with measurement errors. In accordance to other studies for entral urope, the results showed that the applied method enabled a reliable nationwide quantification of the soil pool development for a certain period.
    Keywords: C/N Ratio ; Carbon Sequestration ; Carbon Stocks ; Forest Stand Type ; Mineral Soil ; Nation Forest Soil Inventory ; Organic Layer ; Soil Groups ; Soil Organic Matter ; Soil Survey ; Tree Species ; Uncertainties
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 2
    Language: English
    In: Journal of Plant Nutrition and Soil Science, April 2016, Vol.179(2), pp.129-135
    Description: Phosphorus is one of the major limiting factors of primary productivity in terrestrial ecosystems and, thus, the P demand of plants might be among the most important drivers of soil and ecosystem development. The P cycling in forest ecosystems seems an ideal example to illustrate the concept of ecosystem nutrition. Ecosystem nutrition combines and extents the traditional concepts of nutrient cycling and ecosystem ecology. The major extension is to consider also the loading and unloading of nutrient cycles and the impact of nutrient acquiring and recycling processes on overall ecosystem properties. Ecosystem nutrition aims to integrate nutrient related aspects at different scales and in different ecosystem compartments including all processes, interactions and feedbacks associated with the nutrition of an ecosystem. We review numerous previous studies dealing with P nutrition from this ecosystem nutrition perspective. The available information contributes to the description of basic ecosystem characteristics such as emergence, hierarchy, and robustness. In result, we were able to refine Odum's hypothesis on P nutrition strategies along ecosystem succession to substrate related ecosystem nutrition and development. We hypothesize that at sites rich in mineral‐bound P, plant and microbial communities tend to introduce P from primary minerals into the biogeochemical P cycle (acquiring systems), and hence the tightness of the P cycle is of minor relevance for ecosystem functioning. In contrast, tight P recycling is a crucial emergent property of forest ecosystems established at sites poor in mineral bound P (recycling systems). We conclude that the integration of knowledge on nutrient cycling, soil science, and ecosystem ecology into holistic ecosystem nutrition will provide an entirely new view on soil–plant–microbe interactions.
    Keywords: Ecosystem Properties ; P Recycling ; P Nutrition Strategy ; Forest Nutrition ; P Acquiring
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 3
    In: European Journal of Haematology, September 2016, Vol.97(3), pp.239-244
    Description: Byline: Nicole Degwert, Emily Latuske, Gabi Vohwinkel, Hauke Stamm, Marianne Klokow, Carsten Bokemeyer, Walter Fiedler, Jasmin Wellbrock Keywords: Acute myeloid leukaemia; hypoxia; drug resistance; deoxycytidine kinase; hypoxia-inducible factor 1 alpha Abstract Objectives Leukaemia initiating cells reside within specialised niches in the bone marrow where they undergo complex interactions with different stromal cell types. The bone marrow niche is characterised by a low oxygen content resulting in high expression of hypoxia-inducible factor 1 [alpha] in leukaemic cells conferring a negative prognosis to patients with acute myeloid leukaemia (AML). Methods and Results In the current study, we investigated the impact of hypoxic vs. normoxic conditions on the sensitivity of AML cell lines and primary AML blasts to cytarabine. AML cells cultured under 6% oxygen were significantly more resistant against cytarabine compared to cells cultured under normoxic conditions in proliferation and colony-formation assays. Interestingly upon cultivation under hypoxia, the expression of the cytarabine-activating enzyme deoxycytidine kinase was downregulated in all analysed AML cell lines and primary AML samples representing a possible mechanism for resistance to chemotherapy. Furthermore, the downregulation of deoxycytidine kinase could be associated with hypoxia-inducible factor 1 [alpha] as treatment with its inhibitor BAY87-2243 hampered the downregulation of deoxycytidine kinase expression under hypoxic conditions. Conclusions In conclusion, our data reveal that hypoxia-induced downregulation of deoxycytidine kinase represents one stroma-cell-independent mechanism of drug resistance to cytarabine in acute myeloid leukaemia. Article Note: Contributed equally to the work.
    Keywords: Acute Myeloid Leukaemia ; Hypoxia ; Drug Resistance ; Deoxycytidine Kinase ; Hypoxia‐Inducible Factor 1 Alpha
    ISSN: 0902-4441
    E-ISSN: 1600-0609
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