Subcellular trafficking of the Arabidopsis auxin influx carrier AUX1 uses a novel pathway distinct from PIN1

The directional flow of the plant hormone auxin mediates multiple developmental processes, including patterning and tropisms. Apical and basal plasma membrane localization of AUXIN-RESISTANT1 (AUX1) and PIN-FORMED1 (PIN1) auxin transport components underpins the directionality of intercellular auxin flow in Arabidopsis thaliana roots. Here, we examined the mechanism of polar trafficking of AUX1. Real-time live cell analysis along with subcellular markers revealed that AUX1 resides at the apical plasma membrane of protophloem cells and at highly dynamic subpopulations of Golgi apparatus and endosomes in all cell types. Plasma membrane and intracellular pools of AUX1 are interconnected by actin-dependent constitutive trafficking, which is not sensitive to the vesicle trafficking inhibitor brefeldin A. AUX1 subcellular dynamics are not influenced by the auxin influx inhibitor NOA but are blocked by the auxin efflux inhibitors TIBA and PBA. Furthermore, auxin transport inhibitors and interference with the sterol composition of membranes disrupt polar AUX1 distribution at the plasma membrane. Compared with PIN1 trafficking, AUX1 dynamics display different sensitivities to trafficking inhibitors and are independent of the endosomal trafficking regulator ARF GEF GNOM. Hence, AUX1 uses a novel trafficking pathway in plants that is distinct from PIN trafficking, providing an additional mechanism for the fine regulation of auxin transport

The vicious circle and infection intensity: The case of Trypanosoma microti in field vole populations

Objective: In natural populations, infection and condition may act synergistically to trigger a vicious circle: poor condition predisposes to host infections, which further reduce condition, and so on. If this vicious circle originates from a reduced resistance to infection, it will not only result in greater proneness to becoming infected of those that are in poorer condition, but it may also cause infections of higher intensity. Here, we investigate the temporal relationship between host condition and intensity of infection by a specific pathogen using as a system the dynamics of the protozoan Trypanosoma microti in field vole (Microtus agrestis) populations. Methods and results: With two years of longitudinal data from three monthly-sampled populations, we evaluated if individuals acquiring a high intensity of infection previously had lower haematological indicators of condition (red blood cells [RBCs] and lymphocyte counts) than those that acquired lower infection intensities. Also, the association of these indicators with past and present trypanosome blood levels was investigated. The individuals that developed high levels of parasitaemia were those that previously had low lymphocyte counts. Greater intensity of infection corresponded with lower RBCs only in low to moderate weight females, and no effect of intensity of infection on lymphocyte counts was observed. However, delayed effects of high trypanosome intensity were seen on both RBCs and lymphocytes. Conclusions: The vicious circle may also result in high infection intensity: individuals in poor condition are not only more likely to become infected by one pathogen; they may also be the most important source of infection for that and for other pathogens, and thus key protagonists for parasite dynamics.Fil: Beldomenico, Pablo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; ArgentinaFil: Telfer, Sandra. University of Liverpool; Reino UnidoFil: Gebert, Stephanie. University of Liverpool; Reino UnidoFil: Lukomski, Lukasz. University of Liverpool; Reino UnidoFil: Bennett, Malcolm. University of Liverpool; Reino UnidoFil: Begon, Michael. University of Liverpool; Reino Unid

Crosstalk between gibberellin signaling and iron uptake in plants: an Achilles’ heel for modern cereal varieties?

Plants utilize sophisticated morphological and physiological mechanisms to acquire iron from soil. In this issue of Developmental Cell, Wild et al. (2016) find that the hormone signal gibberellic acid is key in integrating these responses, raising questions about the impact of altering GA responses in modern cereal varieties on iron acquisition

Root Development: Cytokinin Transport Matters, Too!

SummaryUnlike the plant hormone auxin, the mechanism and function of cytokinin transport is poorly characterised. Two new studies now demonstrate that cytokinins transported from shoot to roots via the phloem are critical for creating mutually exclusive auxin and cytokinin signalling domains that control root vascular patterning

One gene, many proteins: mapping cell-specific alternative splicing in plants

Pre-mRNA alternative splicing (AS) generates protein variants from a single gene that can create novel regulatory opportunities. In this issue of Developmental Cell, Li et al. (2016) present a high-resolution expression map of AS events in Arabidopsis root tissues, giving insight into cell-type- and stage-specific AS mechanisms in plants

Plant biology: building barriers... in roots

The Casparian strip is an important barrier regulating water and nutrient uptake into root tissues. New research reveals two peptide signals and their co-receptors play critical roles patterning and maintaining barrier integrity

Fractional boundary value problems: Analysis and numerical methods

This is the author's PDF of an article published in Fractional calculus and applied analysis 2011. The original publication is available at www.springerlink.comThis journal article discusses nonlinear boundary value problems.Fundacao para a Ciencia e Tecnologi

Evaluating the role of surgical sterilisation in canine rabies control: A systematic review of impact and outcomes

© 2020 Collinson et al. Current recommendations for the elimination of canine-mediated human rabies focus on mass dog vaccination as the most feasible and cost-effective strategy. However, attempts to control rabies are often combined with canine surgical sterilisation programmes. The added value of sterilisation is widely debated. A systematic review was undertaken to compare the outcomes and impact of vaccination and sterilisation programmes with vaccination only programmes. A systematic search of three electronic databases (CAB Abstracts, Med-line and Global Health) and grey literature was performed. From 8696 abstracts found, 5554 unique studies were identified, and 16 studies met the inclusion criteria. Eight described vaccination only programmes and eight described vaccination and sterilisation programmes. Indicators of impact measured were dog bites and/or doses of post-exposure prophylaxis administered; numbers of dog and/or human rabies cases; dog population demographic changes; changes in health and welfare of dogs, and indicators related to human behaviour change. The studies were contextually very diverse, programmes being implemented were complex, and there was variation in measurement and reporting of key indicators. There-fore, it was difficult to compare the two types of intervention, and impossible to make an evaluation of the role of sterilisation, using this evidence. Given the large number of vaccination and sterilisation programmes conducted globally, the lack of studies available for review highlights a gap in data collection or reporting, essential for impact assessment. There are several knowledge gaps concerning the impact of the sterilisation component alone, as well as subsequent effects on rabies transmission and control. Prospective studies comparing the outcomes and impact of the two interventions would be required in order to establish any additional contribution of sterilisation, as well as the underlying mechanisms driving any changes. In the absence of such evidence, the priority for rabies control objectives should be implementation of mass vaccination, as currently recommended by the World Health Organisation

Hybrid vertex-midline modelling of elongated plant organs

We describe a method for the simulation of the growth of elongated plant organs, such as seedling roots. By combining a midline representation of the organ on a tissue scale and a vertex-based representation on the cell scale, we obtain a multiscale method, which is able to both simulate organ growth and incorporate cell-scale processes. Equations for the evolution of the midline are obtained, which depend on the cell-wall properties of individual cells through appropriate averages over the vertex-based representation. The evolution of the organ midline is used to deform the cellular-scale representation. This permits the investigation of the regulation of organ growth through the cell-scale transport of the plant hormone auxin. The utility of this method is demonstrated in simulating the early stages of the response of a root to gravity, using a vertex-based template acquired from confocal imaging. Asymmetries in the concentrations of auxin between the upper and lower sides of the root lead to bending of the root midline, reflecting a gravitropic response

The Effect of Foam Rolling for Three Consecutive Days on Muscular Efficiency and Range of Motion

Background Foam rolling (FR) has been shown to alleviate some symptoms of exercise-induced muscle damage and has been suggested to increase range of motion (ROM) without negatively impacting strength. However, it is unclear what neuromuscular effects, if any, mediate these changes. Methods In a randomized, crossover design, 16 healthy active males completed 2 min of rest or FR of the knee extensors on three consecutive days. Mechanical properties of vastus lateralis (VL) and rectus femoris (RF) were assessed via Tensiomyography. Knee extension maximal voluntary contraction (MVC) and knee flexion ROM were also assessed, and surface electromyography amplitude (RMS) was recorded during a submaximal isometric contraction (50% of MVC). Measures were performed before and after (0, 15, and 30 min) FR or rest. Results MVC was reduced on subsequent days in the rest condition compared to FR (p = 0.002, pη2 = 0.04); ROM was not different across time or condition (p = 0.193, pη2 = 0.01). Stiffness characteristics of the VL were different on the third day of FR (p = 0.002, pη2 = 0.03). RMS was statistically reduced 0, 15, and 30 min after FR compared to rest (p = 0.006, pη2 = 0.03; p = 0.003, pη2 = 0.04; p = 0.002, pη2 = 0.04). Conclusions Following FR, MVC was elevated compared to rest and RMS was transiently reduced during a submaximal task. Excitation efficiency of the involved muscles may have been enhanced by FR, which protected against the decline in MVC which was observed with rest