Effective dynamics of microorganisms that interact with their own trail

Like ants, some microorganisms are known to leave trails on surfaces to communicate. We explore how trail-mediated self-interaction could affect the behavior of individual microorganisms when diffusive spreading of the trail is negligible on the timescale of the microorganism using a simple phenomenological model for an actively moving particle and a finite-width trail. The effective dynamics of each microorganism takes on the form of a stochastic integral equation with the trail interaction appearing in the form of short-term memory. For moderate coupling strength below an emergent critical value, the dynamics exhibits effective diffusion in both orientation and position after a phase of superdiffusive reorientation. We report experimental verification of a seemingly counterintuitive perpendicular alignment mechanism that emerges from the model.Comment: new figure with experimental results; expanded appendi

Structural analysis of the GH43 enzyme Xsa43E from Butyrivibrio proteoclasticus

The rumen of dairy cattle can be thought of as a large, stable fermentation vat and as such it houses a large and diverse community of microorganisms. The bacterium Butyrivibrio proteoclasticus is a representative of a significant component of this microbial community. It is a xylan-degrading organism whose genome encodes a large number of open reading frames annotated as fibre-degrading enzymes. This suite of enzymes is essential for the organism to utilize the plant material within the rumen as a fuel source, facilitating its survival in this competitive environment. Xsa43E, a GH43 enzyme from B. proteoclasticus, has been structurally and functionally characterized. Here, the structure of selenomethionine-derived Xsa43E determined to 1.3 Å resolution using single-wavelength anomalous diffraction is reported. Xsa43E possesses the characteristic five-bladed β-propeller domain seen in all GH43 enzymes. GH43 enzymes can have a range of functions, and the functional characterization of Xsa43E shows it to be an arabinofuranosidase capable of cleaving arabinose side chains from short segments of xylan. Full functional and structural characterization of xylan-degrading enzymes will aid in creating an enzyme cocktail that can be used to completely degrade plant material into simple sugars. These molecules have a range of applications as starting materials for many industrial processes, including renewable alternatives to fossil fuels

Cascading Activation Revisited: How Audiences Contribute to News Agendas Using Social Media

Social media have become conduits through which audiences can challenge elites in media and politics. Recent updates to cascading activation, originally developed to explain how frames flowing from powerful figures gain public dominance, give greater theoretical scope for audiences to exert influence. Yet empirical understanding of how and in what circumstances this happens with respect to agenda-setting - another core media effect - is not well-developed, especially given the affordances of digital technologies. We address this gap by connecting theorization on cascades to developments in intermedia agenda-setting. Specifically, we analyze the dynamics surrounding the perceived reluctance by ARD-aktuell, the newsroom of Germany's public broadcasting consortium, to use its prime-time broadcast "Tagesschau" to report the arrest of a refugee accused of murdering a German woman in December 2016. By presenting finely grained timelines linking content analysis of 5,409 Facebook comments with Tagesschau editorial responses and parallel media coverage of this event, we contribute further conditions under which audience-informed cascades may occur: notably, when publicly funded news organizations are involved, and the issue at stake invokes both domestic and international aspects which sustain disagreement

A sex difference in the response of the rodent postsynaptic density to synGAP haploinsufficiency

SynGAP is a postsynaptic density (PSD) protein that binds to PDZ domains of the scaffold protein PSD-95. We previously reported that heterozygous deletion of Syngap1 in mice is correlated with increased steady-state levels of other key PSD proteins that bind PSD-95, although the level of PSD-95 remains constant (Walkup et al., 2016). For example, the ratio to PSD-95 of Transmembrane AMPA-Receptor-associated Proteins (TARPs), which mediate binding of AMPA-type glutamate receptors to PSD-95, was increased in young Syngap1+/- mice. Here we show that only females and not males show a highly significant correlation between an increase in TARP and a decrease in synGAP in the PSDs of Syngap1+/- rodents. The data reveal a sex difference in the adaptation of the PSD scaffold to synGAP haploinsufficiency

Bioinformatics-based assessment of the relevance of candidate genes for mutation discovery

The bioinformatics resources provide a wide range of tools that can be applied in different areas of mutation screening. The enormous and constantly increasing amount of genomic data obtained in plant-oriented molecular studies requires the development of efficient techniques for its processing. There is a wide range of bioinformatics tools which can aid in the course of mutation discovery. The following chapter focuses mainly on the application of different tools and resources to facilitate a Targeting-Induced Local Lesions in Genomes (TILLING) analysis. TILLING is a technique of reverse genetics that applies a traditional mutagenesis to create DNA libraries of mutagenised individuals that are then subjected to high-throughput screening for the identification of mutations. The bioinformatics tools have shown to be useful in supporting the process of candidate gene selection for mutation screening. The availability of bioinformatics software and experimental data repositories provides a powerful tool which enables a process of multi-database mining. The existing raw experimental data (genomics-related information, expression data, annotated ontologies) can be interpreted in terms of a new biological context. This may help in selecting the proper candidate gene for mutation discovery that is controlling the target phenotype. The mutation screening using a TILLING strategy requires a former knowledge of the full genomic sequence of the gene which is of interest. Depending on whether a fully sequenced genome of a particular species is available, different bioinformatics tools can facilitate this process. Specific tools can be also useful for the identification of possible gene paralogs which may mask the effect of mutated gene. Bioinformatics resources can also support the selection of gene fragments most prone to acquire a deleterious nucleotide change. Finally, there are available tools enabling a proper design of oligonucleotide primers for the amplification of a gene fragment for the purpose of mutation screening

Experiment-based Comparison of Prediction Methods for Pump Head Degradation with Viscous and Power-law Fluids

Although several methods are known to calculate pump performance with highly viscous and non-Newtonian fluids, research has not yet determined all the key parameters of these predictions. It is unclear how these parameters depend on the pump geometry and the delivered fluid rheology, which can vary widely in the chemical industry. In our study, the performance curves of a radial centrifugal pump with a viscous Newtonian glycerol solution and a non-Newtonian power-law fluid were experimentally compared. The head degradation of the pump was also presumed with the ANSI/HI and the Ofuchi methods, which are evident and commonly used for viscous Newtonian fluids, but not for non-Newtonians. The required constants were estimated based on experimental data for both models, and the Ofuchi method was adapted to power-law fluid. Based on our results, the Ofuchi method proved to apply for head degradation prediction with the examined power-law fluid. This work is licensed under a Creative Commons Attribution 4.0 International License

Pheromone glands in the click beetle genus Athous (Elateridae)

Sexualpheromone sind im gesamten Tierreich weit verbreitet. Vor allem Insekten nutzen diese Art der Partnerfindung. Im Vergleich zu vielen Insektenarten, bei welchen die Art der pheromonbildenden Drüsenzellen, ihre Lage im Körper sowie die chemische Zusammensetzung ihrer Pheromone identifiziert wurde (s. Review von Blomquist & Vogt 2003) ist bei Schnellkäfern (Elateridae) noch sehr wenig bekannt. Die verschiedenen mitteleuropäischen Schnellkäferarten lassen sich anhand ihrer Pheromonspeicherung in zwei unterschiedliche Gruppen unterteilen. Die Weibchen der Unterfamilie Elaterinae, besitzen im letzten von außen sichtbaren Abdominalsegment ein paariges Drüsenreservoir in welchem das produzierte Sexualpheromon gespeichert wird. Im Gegensatz dazu fehlt bei den Weibchen der übrigen Unterfamilien ein solches Pheromonreservoir und es ist unklar, wo bei diesen Arten die Pheromone produziert werden. Beobachtungen von Ivastschenko & Adamenko (1980) deuten darauf hin, dass sich bei diesen Arten die pheromonproduzierenden Zellen im Bereich der Intersegmentalmembran zwischen dem Abdominalsegment VIII und IX befinden. Um zu klären, ob die Pheromondrüsen tatsächlich in diesem Bereich zu finden sind, wurden im Rahmen der vorliegenden Arbeit die Intersegmentalmembranen bei Weibchen und Männchen von Athous haemorrhoidalis und A. subfuscus auf mögliche Drüsenzellvorkommen untersucht.Although it is well known, that click beetles (Elateridae) use pheromones to find their mating partners, only from 10 out of approximately 170 Elateridae species in Central Europe sexual pheromones have been identified. This was successful only with members of the subfamily Elaterinae, where females have an adenoid pheromone reservoir in the abdominal tip. However, all other subfamilies which represent the majority of all Central European click beetle species do not posses such a reservoir. In this study we examine the hypothesis that in these species pheromone glands have no reservoir and are situated on the intersegmental membrane between the 8th and 9th abdominal segment. Using REM, a large number of type III gland cells were found in this area in females of Athous haemorrhoidalis und A. subfuscus. In males these glands are absent. Together with literature data this strongly suggests that these glandular structures represent the source of the sexual pheromones in the genus Athous

Comercio de derechos de emisión, adopción de tecnología y heterogeneidad de industrias: un enfoque experimental

The economic and environmental gains expected from particular environmental policies based on allowances trading programs depend on how they are specifically implemented in the field. In this paper we focus on a tradable permit program based on a double auction market combined with an industry structure that presents heterogeneity in conventional abatement cost functions across firms, and allows for the possibility of adopting a new low emissions technology. Our results show that there is a direct relationship between the technological heterogeneity within an industry and the efficiency of firms behavior when investing in cleaner technologies and the efficiency of the market when reaping the potential benefits from trade by way of permits reallocationLos beneficios económicos y ambientales esperados de una determinada política medioambiental basada en el comer comercio de derechos de emisisón dependen de cómo éstos son implementados en el campo. En este artículo, analizamos el comercio de derechos de emisión a través de un mecanismo de subasta doble combinado con una estructura de la industria que presenta heterogeneidad en los costes de reducción de emisiones de las empresas, donde se permite además la adopción de una nueva tecnología más limpia. Nuestros resultados muestran que existe una relación directa entre la heteroogeneidad de la tecnología dentro de una industria, la eficiencia del comportamiento inversor de las empresas, así como la eficiencia del mecanismo de mercado para extraer los beneficios potenciales derivados de una reasignación de los permisos de emisió