Chemoreceptor Evolution in Hymenoptera and Its Implications for the Evolution of Eusociality.

Eusocial insects, mostly Hymenoptera, have evolved unique colonial lifestyles that rely on the perception of social context mainly through pheromones, and chemoreceptors are hypothesized to have played important adaptive roles in the evolution of sociality. However, because chemoreceptor repertoires have been characterized in few social insects and their solitary relatives, a comprehensive examination of this hypothesis has not been possible. Here, we annotate ∼3,000 odorant and gustatory receptors in recently sequenced Hymenoptera genomes and systematically compare >4,000 chemoreceptors from 13 hymenopterans, representing one solitary lineage (wasps) and three independently evolved eusocial lineages (ants and two bees). We observe a strong general tendency for chemoreceptors to expand in Hymenoptera, whereas the specifics of gene gains/losses are highly diverse between lineages. We also find more frequent positive selection on chemoreceptors in a facultative eusocial bee and in the common ancestor of ants compared with solitary wasps. Our results suggest that the frequent expansions of chemoreceptors have facilitated the transition to eusociality. Divergent expression patterns of odorant receptors between honeybee and ants further indicate differential roles of chemoreceptors in parallel trajectories of social evolution

Chemosensory sensitivity reflects reproductive status in the ant Harpegnathos saltator.

Insects communicate with pheromones using sensitive antennal sensilla. Although trace amounts of pheromones can be detected by many insects, context-dependent increased costs of high sensitivity might lead to plasticity in sensillum responsiveness. We have functionally characterized basiconic sensilla of the ant Harpegnathos saltator for responses to general odors in comparison to cuticular hydrocarbons which can act as fertility signals emitted by the principal reproductive(s) of a colony to inhibit reproduction by worker colony members. When released from inhibition workers may become reproductive gamergates. We observed plasticity in olfactory sensitivity after transition to reproductive status with significant reductions in electrophysiological responses to several long-chained cuticular hydrocarbons. Although gamergates lived on average five times longer than non-reproductive workers, the shift to reproductive status rather than age differences matched the pattern of changes in olfactory sensitivity. Decreasing sensillum responsiveness to cuticular hydrocarbons could potentially reduce mutually inhibitory or self-inhibitory effects on gamergate reproduction

Production of Hybrid Tubular Metal-Fiber-Preforms: Material Characterization of Braided Hoses with a Binder

Hybrid shafts or rods, where the area of load introduction is metallic (e.g. steel or aluminium) and the area of load transfer is made of fibre reinforced plastics (FRP), are an established concept for lightweight parts. Besides the monolithic FRP and the metallic areas, the overlap area of both materials is particularly important. Such parts can beneficially be produced by the use of liquid composite moulding (LCM), where the bonding process takes place during the resin curing. This is called intrinsic hybridization. Beforehand it is crucial to produce a near-net-shape preform in which the metallic end fittings for the load introduction are already integrated. To manufacture such parts constantly with a high quality, a process model of the joining by draping the braided preform is necessary. In this paper an approach for the production of hybrid preforms made of braided hoses and metallic fittings is presented in order to develop a process model. The process starts with a cylindrical multi-layer preform made of braided hoses, in which the layers are bonded by a thermoplastic binder powder. The decisive process step is the draping of the preform onto the metallic fitting. For this forming step, the material characterization of the hybrid preform plays an important role. Several material tests to determine the textile parameters of the preform are therefore evaluated and performed. Finally, the results of these tests are presented and discussed

A semi-implicit Hall-MHD solver using whistler wave preconditioning

The dispersive character of the Hall-MHD solutions, in particular the whistler waves, is a strong restriction to numerical treatments of this system. Numerical stability demands a time step dependence of the form $\Delta t\propto (\Delta x)^2$ for explicit calculations. A new semi--implicit scheme for integrating the induction equation is proposed and applied to a reconnection problem. It it based on a fix point iteration with a physically motivated preconditioning. Due to its convergence properties, short wavelengths converge faster than long ones, thus it can be used as a smoother in a nonlinear multigrid method

High Resolution inline Topography of Iron in p-Doped Multicrystalline Bricks by MDP

AbstractThe iron density is one crucial parameter to verify the quality of the material. Brick measurements enable to check the material quality right at the beginning of the production line. This paper presents contact less high resolution inline topographic measurements of the iron density in multicrystalline silicon bricks by MDP (microwave detected photoconductivity). The measurement procedure is fully automatic and takes less than 5min a brick. The data obtained were compared to QSSPC (quasi steady state photoconductivity) measurements, however, with a loss in spatial resolution. Furthermore, passivated wafers were prepared from the bricks after the measurements and investigated individually. The consistency of all the data is remarkable

A Parallel Mesh-Adaptive Framework for Hyperbolic Conservation Laws

We report on the development of a computational framework for the parallel, mesh-adaptive solution of systems of hyperbolic conservation laws like the time-dependent Euler equations in compressible gas dynamics or Magneto-Hydrodynamics (MHD) and similar models in plasma physics. Local mesh refinement is realized by the recursive bisection of grid blocks along each spatial dimension, implemented numerical schemes include standard finite-differences as well as shock-capturing central schemes, both in connection with Runge-Kutta type integrators. Parallel execution is achieved through a configurable hybrid of POSIX-multi-threading and MPI-distribution with dynamic load balancing. One- two- and three-dimensional test computations for the Euler equations have been carried out and show good parallel scaling behavior. The Racoon framework is currently used to study the formation of singularities in plasmas and fluids.Comment: late submissio

Serum response factor is crucial for actin cytoskeletal organization and focal adhesion assembly in embryonic stem cells

The activity of serum response factor (SRF), an essential transcription factor in mouse gastrulation, is regulated by changes in actin dynamics. Using Srf(−/−) embryonic stem (ES) cells, we demonstrate that SRF deficiency causes impairments in ES cell spreading, adhesion, and migration. These defects correlate with defective formation of cytoskeletal structures, namely actin stress fibers and focal adhesion (FA) plaques. The FA proteins FA kinase (FAK), β1-integrin, talin, zyxin, and vinculin were downregulated and/or mislocalized in ES cells lacking SRF, leading to inefficient activation of the FA signaling kinase FAK. Reduced overall actin expression levels in Srf(−/−) ES cells were accompanied by an offset treadmilling equilibrium, resulting in lowered F-actin levels. Expression of active RhoA-V14 rescued F-actin synthesis but not stress fiber formation. Introduction of constitutively active SRF-VP16 into Srf(−/−) ES cells, on the other hand, strongly induced expression of FA components and F-actin synthesis, leading to a dramatic reorganization of actin filaments into stress fibers and lamellipodia. Thus, using ES cell genetics, we demonstrate for the first time the importance of SRF for the formation of actin-directed cytoskeletal structures that determine cell spreading, adhesion, and migration. Our findings suggest an involvement of SRF in cell migratory processes in multicellular organisms

Geologie und Bergbaufolgen im Steinkohlerevier Lugau/Oelsnitz

Autoren des Landesamtes für Umwelt, Landwirtschaft und Geologie, des Oberbergamtes, beauftragter Firmen und Hochschulen stellen in 12 Fachbeiträgen die Ergebnisse der bergbaufolgebezogenen Untersuchungen im ehemaligen Steinkohlerevier Lugau/Oelsnitz vor. Redaktionsschluss: 30.06.201