Adult age of vascular plant species along an elevational land‐use and climate gradient

Trait variation across species plays a fundamental role in ecology and evolution, but quantitative analyses of key life‐history traits under natural conditions generally do not include a large number of species. In a comparative study, we analyzed interspecific variation in adult age as a minimum estimate of the lifespan of 708 vascular plant species along elevational gradients from 263–3175 m a.s.l. and compared this variation with predictions from r‐K selection theory and the metabolic theory of ecology (MTE). Age data based on annual ring counts of root collars and rhizomes were combined with a systematic sample of current species distributions in Switzerland (453 plots, each 1 km²). Elevation and temperature trends were investigated by regression analyses of the variation in adult age across species and species assemblages (median adult age) at the landscape level. We included climate, land use and geology as environmental predictors in multiple regressions and considered phylogeny by eigenvector filtering. We found a general increase in adult age towards higher elevations at the level of overall interspecific variation, and this trend was also detectable within individual plant families. Species generally had a shorter lifespan under warmer climates and, in agreement with r‐K prediction, in lowland agricultural landscapes. We found an exponential adult age–temperature relationship that is consistent with MTE. The estimate of the MTE parameter ‘activation energy’ for median adult age in multiple regression was 0.65 eV (95% CI 0.62–0.69 eV) which coincided with the predicted range of 0.60–0.70 eV. Our results imply that climate warming could accelerate species turnover rates by favoring short‐lived species over the whole range of life histories and species assemblages. Besides the strong temperature relationship, residual variability and confounding factors demonstrate the need for additional research about interactions between broad‐scale constraints and more local drivers of life‐history variation.     

Intrinsically Disordered and Aggregation Prone Regions Underlie β-Aggregation in S100 Proteins

S100 proteins are small dimeric calcium-binding proteins which control cell cycle, growth and differentiation via interactions with different target proteins. Intrinsic disorder is a hallmark among many signaling proteins and S100 proteins have been proposed to contain disorder-prone regions. Interestingly, some S100 proteins also form amyloids: S100A8/A9 forms fibrils in prostatic inclusions and S100A6 fibrillates in vitro and seeds SOD1 aggregation. Here we report a study designed to investigate whether β-aggregation is a feature extensive to more members of S100 family. In silico analysis of seven human S100 proteins revealed a direct correlation between aggregation and intrinsic disorder propensity scores, suggesting a relationship between these two independent properties. Averaged position-specific analysis and structural mapping showed that disorder-prone segments are contiguous to aggregation-prone regions and that whereas disorder is prominent on the hinge and target protein-interaction regions, segments with high aggregation propensity are found in ordered regions within the dimer interface. Acidic conditions likely destabilize the seven S100 studied by decreasing the shielding of aggregation-prone regions afforded by the quaternary structure. In agreement with the in silico analysis, hydrophobic moieties become accessible as indicated by strong ANS fluorescence. ATR-FTIR spectra support a structural inter-conversion from α-helices to intermolecular β-sheets, and prompt ThT-binding takes place with no noticeable lag phase. Dot blot analysis using amyloid conformational antibodies denotes a high diversity of conformers; subsequent analysis by TEM shows fibrils as dominant species. Altogether, our data suggests that β-aggregation and disorder-propensity are related properties in S100 proteins, and that the onset of aggregation is likely triggered by loss of protective tertiary and quaternary interactions.     

Zar geschlechtlichen Zuchtwahl der Sperlingsv?gel

Ohne Zusammenfassung     

„Arnica Doronicum Jacquin“ und ihre nächsten Verwandten

Ohne Zusammenfassung     

Neue Pflanzen aus Sokótra,Abdal Kuri und Semhah

Ohne Zusammenfassung     

Neue Pflanzen-Hybriden

Ohne Zusammenfassung     

Variationsanalytische untersuchungen an chydoriden

Ohne Zusammenfassung     

At the Desert's Green Edge: An Ethnobotany of the Gila River Pima.

At the Desert's Green Edge: An Ethnobotany of the Gila River Pima. Amadeo M. Rea. Tucson: University of Arizona Press, 1997. 430 pp.     

Comparison of ATP and Ergosterol as Indicators of Fungal Biomass Associated with Decomposing Leaves in Streams

ATP and ergosterol were compared as indicators of fungal biomass associated with leaves decomposing in laboratory microcosms and streams. In all studies, the sporulation rates of the fungi colonizing leaves were also determined to compare patterns of fungal reproductive activity with patterns of mycelial growth. During leaf degradation, ATP concentrations exhibited significant, positive correlations with ergosterol concentrations in the laboratory and when leaves had been air dried prior to being submerged in a stream. However, when freshly shed leaves were submerged in a stream, concentrations of ATP and ergosterol were negatively correlated during degradation. This appeared to be due to the persistence of leaf-derived ATP in freshly shed leaves during the first 1 to 2 weeks in the stream. Estimates of fungal biomass from ergosterol concentrations of leaf litter were one to three times those calculated from ATP concentrations. ATP, ergosterol, and sporulation data generally provided similar information about the fungi associated with decomposing leaves in streams during periods when fungi were growing. Ergosterol concentrations provide a more accurate indication of fungal biomass in situations in which other organisms make significant contributions to ATP pools.