Rational Parameter Rays of The Multibrot Sets

We prove a structure theorem for the multibrot sets, which are the higher degree analogues of the Mandelbrot set, and give a complete picture of the landing behavior of the rational parameter rays and the bifurcation phenomenon. Our proof is inspired by previous works of Schleicher and Milnor on the combinatorics of the Mandelbrot set; in particular, we make essential use of combinatorial tools such as orbit portraits and kneading sequences. However, we avoid the standard global counting arguments in our proof and replace them by local analytic arguments to show that the parabolic and the Misiurewicz parameters are landing points of rational parameter rays

Distribution and population structure of the anther smut Microbotryum silenes-acaulis parasitizing an arctic-alpine plant

BGPI : équipe 5International audienceCold-adapted organisms with current arctic-alpine distributions have persisted during the last glaciation in multiple ice-free refugia, leaving footprints in their population structure that contrast with temperate plants and animals. However, pathogens that live within hosts having arctic-alpine distributions have been little studied. Here, we therefore investigated the geographical range and population structure of a fungus parasitizing an arctic-alpine plant. A total of 1437 herbarium specimens of the plant Silene acaulis were examined, and the anther smut pathogen Microbotryum silenes-acaulis was present throughout the host's geographical range. There was significantly greater incidence of anther smut disease in more northern latitudes and where the host locations were less dense, indicating a major influence of environmental factors and/or host demographic structure on the pathogen distribution. Genetic analyses with seven microsatellite markers on recent collections of 195 M. silenes-acaulis individuals revealed three main genetic clusters, in North America, northern Europe and southern Europe, likely corresponding to differentiation in distinct refugia during the last glaciation. The lower genetic diversity in northern Europe indicates postglacial recolonization northwards from southern refugia. This study combining herbarium surveys and population genetics thus uniquely reveals the effects of climate and environmental factors on a plant pathogen species with an arctic-alpine distribution. \\textcopyright\ 2015 John Wiley \&\ Sons Ltd

Data from: Distribution and population structure of the anther smut fungus Microbotryum silenes-acaulis parasitizing an arctic-alpine plant

Cold-adapted organisms with current arctic-alpine distributions have persisted during the last glaciation in multiple ice-free refugia, leaving footprints in their population structure that contrast with temperate plants and animals. However, pathogens that live within hosts having arctic-alpine distributions have been little studied. Here, we therefore investigated the geographical range and population structure of a fungus parasitizing an arctic-alpine plant. A total of 1437 herbarium specimens of the plant Silene acaulis were examined, and the anther smut pathogen Microbotryum silenes-acaulis was present throughout the host’s geographic range. There was significantly greater incidence of anther smut disease in more northern latitudes and where the host locations were less dense, indicating a major influence of environmental factors and/or host demographic structure on the pathogen distribution. Genetic analyses with seven microsatellite markers on recent collections of 195 M. silenes-acaulis individuals revealed three main genetic clusters, in North America, northern Europe and southern Europe, likely corresponding to differentiation in distinct refugia during the last glaciation. The lower genetic diversity in northern Europe indicates postglacial recolonization northwards from southern refugia. This study combining herbarium surveys and population genetics thus uniquely reveals the effects of climate and environmental factors on a plant pathogen species with an arctic-alpine distribution

Pressure-dependent electronic structure calculations using integral equation-based solvation models

Recent methodological progress in quantum-chemical calculations using the "embedded cluster reference interaction site model" (EC-RISM) integral equation theory is reviewed in the context of applying it as a solvation model for calculating pressure-dependent thermodynamic and spectroscopic properties of molecules immersed in water. The methodology is based on self-consistent calculations of electronic and solvation structure around dissolved molecules where pressure enters the equations via an appropriately chosen solvent response function and the pure solvent density. Besides specification of a dispersion-repulsion force field for solute-solvent interactions, the EC-RISM approach derives the electrostatic interaction contributions directly from the wave function. We further develop and apply the method to a variety of benchmark cases for which computational or experimental reference data are either available in the literature or are generated specifically for this purpose in this work. Starting with an enhancement to predict hydration free energies at non-ambient pressures, which is the basis for pressure-dependent molecular population estimation, we demonstrate the performance on the calculation of the autoionization constant of water. Spectroscopic problems are addressed by studying the biologically relevant small osmolyte TMAO (trimethylamine N-oxide). Pressure-dependent NMR shifts are predicted and compared to experiments taking into account proper computational referencing methods that extend earlier work. The experimentally observed IR blue-shifts of certain vibrational bands of TMAO as well as of the cyanide anion are reproduced by novel methodology that allows for weighing equilibrium and non-equilibrium solvent relaxation effects. Taken together, the model systems investigated allow for an assessment of the reliability of the EC-RISM approach for studying pressure-dependent biophysical processes

Herbaria-Collections

Results from herbaria collection of specimens of the plant Silene acaulis partially infected with the pathogen Microbotryum silenes-acaulis. Data has been recorded between 2001 to 2013 from the following herbaria: U.S. Forest Service Herbarium (USFS), New York Botanical Garden (NY), Museum National d'Histoire Naturelle (P), Oregon State University (OSC), University of California, Berkeley (UC), University of Iowa and Iowa State University (ISC), University of Minnesota (MIN), University Washington (WTU), Washington State University (WS), British Museum of Natural History (BM)

Microsatellite-Data

Microsatellite data file resulting from genotyping of 255 individuals of Microbotryum silenes-acaulis with 23 markers. Second sheet represents the Structure Input File for the global data set (195 Individuals) analysed with 16 previously developed markers. Third sheet represents the Structure Input File for the Norway/Svalbard Set (110 Individuals) analysed with seven newly-developed markers

A pair of noncompeting neutralizing human monoclonal antibodies protecting from disease in a SARS-CoV-2 infection model

TRIANNI mice carry an entire set of human immunoglobulin V region gene segments and are a powerful tool to rapidly isolate human monoclonal antibodies. After immunizing these mice with DNA encoding the spike protein of SARS-CoV-2 and boosting with spike protein, we identified 29 hybridoma antibodies that reacted with the SARS-CoV-2 spike protein. Nine antibodies neutralize SARS-CoV-2 infection at IC50 values in the subnanomolar range. ELISA-binding studies and DNA sequence analyses revealed one cluster of three clonally related neutralizing antibodies that target the receptor-binding domain and compete with the cellular receptor hACE2. A second cluster of six clonally related neutralizing antibodies bind to the N-terminal domain of the spike protein without competing with the binding of hACE2 or cluster 1 antibodies. SARS-CoV-2 mutants selected for resistance to an antibody from one cluster are still neutralized by an antibody from the other cluster. Antibodies from both clusters markedly reduced viral spread in mice transgenic for human ACE2 and protected the animals from SARS-CoV-2-induced weight loss. The two clusters of potent noncompeting SARS-CoV-2 neutralizing antibodies provide potential candidates for therapy and prophylaxis of COVID-19. The study further supports transgenic animals with a human immunoglobulin gene repertoire as a powerful platform in pandemic preparedness initiatives