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Berlin Brandenburg

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  • 1
    Language: English
    In: Journal of Applied Ecology, 1 August 2011, Vol.48(4), pp.916-925
    Description: 1. Shoreline development and the associated loss of littoral habitats represent a pervasive alteration of the ecological integrity of lakes and have been identified as major drivers for the loss of littoral biodiversity world-wide. Little is known about the effects of shoreline development on the structure of, and energy transfer in, littoral food webs, even though this information is urgently needed for management and mitigation measures. 2. We measured macroinvertebrate biomass and analysed potential food resources using stable isotopes (δ¹³C, δ¹⁵N) and mixing models to compare the complexity and the trophic base of littoral food webs between undeveloped and developed shorelines in three North German lowland lakes. 3. The lower diversity of littoral habitats found at developed shorelines was associated with lower diversity of food resources and consumers. Consequently, the number of trophic links in food webs at developed shorelines was up to one order of magnitude lower as compared with undeveloped shorelines. 4. Mixing model analysis showed that consumer biomass at undeveloped shorelines was mainly derived from the particulate organic matter (FPOM) and coarse particulate organic matter of terrestrial origin (CPOM). The contribution of CPOM to consumer biomass was twofold lower at developed shorelines, and consumer biomass was mainly derived from FPOM and suspended particulate organic matter. 5. Synthesis and application. Shoreline development impacts the flow of organic matter within littoral food webs primarily through the reduction in littoral habitat diversity. These effects are exacerbated by clearcutting of the riparian vegetation, which disrupts cross-boundary couplings between the riparian and the littoral zone. Lakeshore conservation should focus on preserving the structural integrity of the littoral zone, while restoration of coarse woody debris, reed and root habitats can be a cost-efficient measure to improve degraded lakeshores. The local effects of shoreline development demonstrated in this study might lead to whole-lake effects, but future studies are needed to derive thresholds at which shoreline development has consequences for the structure and functioning of the entire ecosystem.
    Keywords: Vegetation and Community ecology
    ISSN: 00218901
    E-ISSN: 13652664
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  • 2
    In: Freshwater Biology, December 2012, Vol.57(12), pp.2425-2435
    Description: 1. Ship‐induced waves can affect the physical characteristics of lake and river shorelines, and laboratory studies have shown effects on littoral invertebrates. Here, we explored whether these effects could be observed under field conditions along a natural lake shore affected by wave sequences (trains) produced by boats. 2. Individuals of five invertebrate species (, , , , ) were exposed to waves with increasing shear stress in five habitats differing in structural complexity. 3. Detachment of invertebrates increased with increasing shear stress and was best modelled using sigmoid response curves. Habitat structural complexity mitigated the effects of shear stress, and detachment rate was influenced more by habitat type than by species. A threshold (90% of the individual invertebrates unaffected) stress level of 0.64 N m was found for a structurally complex reed habitat, compared to 0.37 N m for a simple sand habitat. 4. Shear stress associated with wave trains created by recreational boating at a distance of 35 m from the shore and at a speed of 11 km h resulted in 45% detachment of littoral invertebrates. Decreasing the boat‐to‐shore distance to 20 m increased wave shear stress by 30% and invertebrate detachments up to 75%. 5. Disturbance of littoral habitats and invertebrate assemblages are widespread in inland waters used for recreational and/or commercial navigation. Our findings show that the integrity of littoral zones of navigable surface waters could be much improved by implementing management measures such as physically protecting complex habitats with dense reed belts and tree roots, and reducing boat speeds and increasing their minimum shoreline distance.
    Keywords: Field Experiment ; Inland Navigation ; Invertebrate Detachment ; Shear Stress ; Structural Habitat Complexity
    ISSN: 0046-5070
    E-ISSN: 1365-2427
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  • 3
    Language: English
    In: Inorganic chemistry, 07 November 2011, Vol.50(21), pp.10682-92
    Description: Three copper(I) iodide clusters coordinated by different phosphine ligands formulated [Cu(4)I(4)(PPh(3))(4)] (1), [Cu(4)I(4)(Pcpent(3))(4)] (2), and [Cu(4)I(4)(PPh(2)Pr)(4)] (3) (PPh(3) = triphenylphosphine, Pcpent(3) = tricyclopentylphosphine, and PPh(2)Pr = diphenylpropylphosphine) have been synthesized and characterized by (1)H and (31)P NMR, elemental analysis and single crystal X-ray diffraction analysis. They crystallize in different space groups, namely, monoclinic P21/c, cubic Pa ̅3, and tetragonal I ̅42m for 1, 2, and 3, respectively. The photoluminescence properties of clusters 1 and 3 show reversible luminescence thermochromism with two highly intense emission bands whose intensities are temperature dependent. In accordance to Density Functional Theory (DFT) calculations, these two emission bands have been attributed to two different transitions, a cluster centered (CC) one and a mixed XMCT/XLCT one. Cluster 2 does not exhibit luminescence variation in temperature because of the lack of the latter transition. The absorption spectra of the three clusters have been also rationalized by time dependent DFT (TDDFT) calculations. A simplified model is suggested to represent the luminescence thermochromism attributed to the two different excited states in thermal equilibrium. In contrast with the pyridine derivatives, similar excitation profiles and low activation energy for these phosphine-based clusters reflect high coupling of the two emissive states. The effect of the Cu-Cu interactions on the emission properties of these clusters is also discussed. Especially, cluster 3 with long Cu-Cu contacts exhibits a controlled thermochromic luminescence which is to our knowledge, unknown for this family of copper iodide clusters. These phosphine-based clusters appear particularly interesting for the synthesis of original emissive materials.
    Keywords: Chemical Sciences ; Material Chemistry ; Thermochromic Luminescence ; Iodide ; Copper ; Ligands ; Phosphine ; Chemistry;
    ISSN: 00201669
    E-ISSN: 1520-510X
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  • 4
    Language: English
    In: Inorganic chemistry, 16 January 2012, Vol.51(2), pp.794-8
    Description: A copper iodide cluster bearing reactive silanol groups exhibits thermochromic luminescence properties sensitive to its chemical environment and is thus a suitable building block for the synthesis of optically active materials.
    Keywords: Chemical Sciences ; Material Chemistry ; Thermochromic Materials ; Iodide ; Luminescence ; Silanol Groups ; Chemistry;
    ISSN: 00201669
    E-ISSN: 1520-510X
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  • 5
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 07 July 2015, Vol.112(27), pp.8290-5
    Description: The survival of commensal bacteria requires them to evade host peptidases. Gram-negative bacteria from the human gut microbiome encode a relative of the human endopeptidase inhibitor, α2-macroglobulin (α2M). Escherichia coli α2M (ECAM) is a ∼ 180-kDa multidomain membrane-anchored pan-peptidase inhibitor, which is cleaved by host endopeptidases in an accessible bait region. Structural studies by electron microscopy and crystallography reveal that this cleavage causes major structural rearrangement of more than half the 13-domain structure from a native to a compact induced form. It also exposes a reactive thioester bond, which covalently traps the peptidase. Subsequently, peptidase-laden ECAM is shed from the membrane and may dimerize. Trapped peptidases are still active except against very large substrates, so inhibition potentially prevents damage of large cell envelope components, but not host digestion. Mechanistically, these results document a novel monomeric "snap trap."
    Keywords: X-Ray Crystal Structure ; Conformational Rearrangement ; Cryo-Electron Microscopy ; Gut Microbiome ; Protein Inhibitor ; Endopeptidases -- Metabolism ; Escherichia Coli Proteins -- Metabolism ; Protease Inhibitors -- Metabolism ; Alpha-Macroglobulins -- Metabolism
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 6
    Language: English
    In: Journal of Clinical Child & Adolescent Psychology, 28 February 2011, Vol.40(2), pp.266-280
    Description: Despite the nosological distinction between bipolar disorder and schizophrenia, there is increasing evidence that these conditions share phenomenological characteristics. To examine the similarities in their patterns of cognitive impairment, we conducted a meta-analysis from 12 studies of Early...
    Keywords: Social Welfare & Social Work ; Psychology
    ISSN: 1537-4416
    E-ISSN: 1537-4424
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  • 7
    In: American Journal of Botany, February 2008, Vol.95(2), pp.258-262
    Description: Survival and fecundity are basic components of demography and therefore have a strong influence on population dynamics. These two key parameters and their relationship are crucial to understand the evolution of life histories. It remains, however, to be empirically established how life span, fecundity, and population dynamics are linked in different organism groups. We conducted a comparative study based on demographic data sets of 55 populations of 23 perennial herbs for which structured demographic models and among‐year natural variation in demographic attributes were available. Life span (from 4 to 128 yr old), estimated by using an algorithm, was inversely correlated with the deviance of the population growth rate from equilibrium as well as with among‐year population fluctuations. Temporal variability was greater for short‐lived species than for the long‐lived ones because fecundity was more variable than survival and relatively more important for population dynamics for the short‐lived species. The relationship between life span and population stability suggests that selection for longevity may have played an important role in the life history evolution of plants because of its ability to buffer temporal fluctuations in population size.
    Keywords: Demography ; Elasticity ; Life‐Cycle Components ; Life History Evolution ; Matrix Models ; Perennial Herbs ; Population Growth Rate ; Temporal Variability
    ISSN: 0002-9122
    E-ISSN: 1537-2197
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  • 8
    Language: English
    In: Journal of the American Chemical Society, 13 August 2014, Vol.136(32), pp.11311-20
    Description: An in-depth study of mechanochromic and thermochromic luminescent copper iodide clusters exhibiting structural polymorphism is reported and gives new insights into the origin of the mechanochromic luminescence properties. The two different crystalline polymorphs exhibit distinct luminescence properties with one being green emissive and the other one being yellow emissive. Upon mechanical grinding, only one of the polymorphs exhibits great modification of its emission from green to yellow. Interestingly, the photophysical properties of the resulting partially amorphous crushed compound are closed to those of the other yellow polymorph. Comparative structural and optical analyses of the different phases including a solution of clusters permit us to establish a correlation between the Cu-Cu bond distances and the luminescence properties. In addition, the local structure of the [Cu4I4P4] cluster cores has been probed by (31)P and (65)Cu solid-state NMR analysis, which readily indicates that the grinding process modifies the phosphorus and copper atoms environments. The mechanochromic phenomenon is thus explained by the disruption of the crystal packing within intermolecular interactions inducing shortening of the Cu-Cu bond distances in the [Cu4I4] cluster core and eventually modification of the emissive state. These results definitely establish the role of cuprophilic interactions in the mechanochromism of copper iodide clusters. More generally, this study constitutes a step further into the understanding of the mechanism involved in the mechanochromic luminescent properties of metal-based compounds.
    Keywords: Chemical Sciences/Material Chemistry ; Chimie/Matériaux;
    ISSN: 00027863
    E-ISSN: 1520-5126
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  • 9
    Language: English
    In: Journal of the American Chemical Society, 18 August 2010, Vol.132(32), pp.10967-9
    Description: The mechanochromic and thermochromic luminescence properties of a molecular copper(I) iodide cluster formulated [Cu(4)I(4)(PPh(2)(CH(2)CH=CH(2)))(4)] are reported. Upon mechanical grinding in a mortar, its solid-state emission properties are drastically modified as well as its thermochromic behavior. This reversible phenomenon has been attributed to distortions in the crystal packing leading to modifications of the intermolecular interactions and thus of the [Cu(4)I(4)] cluster core geometry. Notably, modification of the Cu-Cu interactions seems to be involved in this phenomenon directly affecting the emissive properties of the cluster.
    Keywords: Luminescent Measurements ; Mechanical Phenomena ; Temperature ; Copper -- Chemistry ; Iodides -- Chemistry
    ISSN: 00027863
    E-ISSN: 1520-5126
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  • 10
    Language: English
    In: The Journal of biological chemistry, 30 June 2017, Vol.292(26), pp.10883-10898
    Description: Enduring host-microbiome relationships are based on adaptive strategies within a particular ecological niche. is a dysbiotic member of the human oral microbiome that inhabits periodontal pockets and contributes to chronic periodontitis. To counteract endopeptidases from the host or microbial competitors, possesses a serpin-type proteinase inhibitor called miropin. Although serpins from animals, plants, and viruses have been widely studied, those from prokaryotes have received only limited attention. Here we show that miropin uses the serpin-type suicidal mechanism. We found that, similar to a snap trap, the protein transits from a metastable native form to a relaxed triggered or induced form after cleavage of a reactive-site target bond in an exposed reactive-center loop. The prey peptidase becomes covalently attached to the inhibitor, is dragged 75 Å apart, and is irreversibly inhibited. This coincides with a large conformational rearrangement of miropin, which inserts the segment upstream of the cleavage site as an extra β-strand in a central β-sheet. Standard serpins possess a single target bond and inhibit selected endopeptidases of particular specificity and class. In contrast, miropin uniquely blocked many serine and cysteine endopeptidases of disparate architecture and substrate specificity owing to several potential target bonds within the reactive-center loop and to plasticity in accommodating extra β-strands of variable length. Phylogenetic studies revealed a patchy distribution of bacterial serpins incompatible with a vertical descent model. This finding suggests that miropin was acquired from the host through horizontal gene transfer, perhaps facilitated by the long and intimate association of with the human gingiva.
    Keywords: Inhibition Mechanism ; Inhibitor ; Molecular Biology ; Peptidase ; Periodontal Disease ; Protease ; Protease Inhibitor ; Protein Structure ; Proteinase ; Proteolysis ; Dysbiosis ; Microbiota ; Bacterial Proteins -- Chemistry ; Gingiva -- Microbiology ; Peptide Hydrolases -- Chemistry ; Serpins -- Chemistry ; Tannerella Forsythia -- Chemistry
    E-ISSN: 1083-351X
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