Growth-induced mass flows in fungal networks

Cord-forming fungi form extensive networks that continuously adapt to maintain an efficient transport system. As osmotically driven water uptake is often distal from the tips, and aqueous fluids are incompressible, we propose that growth induces mass flows across the mycelium, whether or not there are intrahyphal concentration gradients. We imaged the temporal evolution of networks formed by Phanerochaete velutina, and at each stage calculated the unique set of currents that account for the observed changes in cord volume, while minimizing the work required to overcome viscous drag. Predicted speeds were in reasonable agreement with experimental data, and the pressure gradients needed to produce these flows are small. Furthermore, cords that were predicted to carry fast-moving or large currents were significantly more likely to increase in size than cords with slow-moving or small currents. The incompressibility of the fluids within fungi means there is a rapid global response to local fluid movements. Hence velocity of fluid flow is a local signal that conveys quasi-global information about the role of a cord within the mycelium. We suggest that fluid incompressibility and the coupling of growth and mass flow are critical physical features that enable the development of efficient, adaptive biological transport networks.     

Edovum puttleri [Hym.: Eulophidae]: Biological activity and responses to normal and frozen eggs ofLeptinotarsa decemlineata [Col.: Chrysomelidae]

Biological control of eggplant pests in general, and (CPB)Leptinotarsa decemlineata (Say) in particular, is highly problematic.Edovum puttleri Grissell, an exotic egg parasitoid which has been found potentially effective, is being reared to this end. Frozen CPB eggs (?18°C) proved to be accepted and suitable for parasitization byE. puttleri. However, when given a choice between 20 frozen and 20 normal eggs every 2 days, the females exhibited a significant preference for the latter. Parasitization and host predation patterns related to female age are described by 2 opposing fourth-order polynomial functions. Parasitization increased up to day 10, followed by progressive decline. Average life span per female was 31.10±.58, with a recorded maximum of 56 days. High predatory behaviour of older females, which showed a decrease in parasitization, was observed in these experimental conditions.     

A mathematical model for fibro-proliferative wound healing disorders

The normal process of dermal wound healing fails in some cases, due to fibro-proliferative disorders such as keloid and hypertrophic scars. These types of abnormal healing may be regarded as pathologically excessive responses to wounding in terms of fibroblastic cell profiles and their inflammatory growth-factor mediators. Biologically, these conditions are poorly understood and current medical treatments are thus unreliable. In this paper, the authors apply an existing deterministic mathematical model for fibroplasia and wound contraction in adult mammalian dermis (Olsenet al., J. theor. Biol. 177, 113–128, 1995) to investigate key clinical problems concerning these healing disorders. A caricature model is proposed which retains the fundamental cellular and chemical components of the full model, in order to analyse the spatiotemporal dynamics of the initiation, progression, cessation and regression of fibro-contractive diseases in relation to normal healing. This model accounts for fibroblastic cell migration, proliferation and death and growth-factor diffusion, production by cells and tissue removal/decay. Explicit results are obtained in terms of the model processes and parameters. The rate of cellular production of the chemical is shown to be critical to the development of a stable pathological state. Further, cessation and/or regression of the disease depend on appropriate spatiotemporally varying forms for this production rate, which can be understood in terms of the bistability of the normal dermal and pathological steady states—a central property of the model, which is evident from stability and bifurcation analyses. The work predicts novel, biologically realistic and testable pathogenic and control mechanisms, the understanding of which will lead toward more effective strategies for clinical therapy of fibro-proliferative disorders.     

Existence and uniqueness of a sharp travelling wave in degenerate non-linear diffusion Fisher-KPP equations

In this paper we use a dynamical systems approach to prove the existence of a unique critical value c ^* of the speed c for which the degenerate density-dependent diffusion equation u _ct = [D(u)u _x ] _x + g(u) has: 1. no travelling wave solutions for 0 < c < c ^*, 2. a travelling wave solution u(x, t) = (x - c ^* t) of sharp type satisfying (– ) = 1, () = 0 ^*; '(^*–) = – c ^*/D'(0), '(^*+) = 0 and 3. a continuum of travelling wave solutions of monotone decreasing front type for each c > c ^*. These fronts satisfy the boundary conditions (– ) = 1, '(– ) = (+ ) = '(+ ) = 0. We illustrate our analytical results with some numerical solutions.     

Ethanol Specifically Inhibits NMDA Receptors with Affinity for Ifenprodil in the Low Micromolar Range in Cultured Cerebellar Granule Cells

Abstract: The effect of ethanol on the intracellular Ca²⁺ concentration response to NMDA in rat cerebellar granule cells grown in low or high KCI concentrations has been studied using image analysis. The cells grown in low KCI displayed high sensitivity for glycine. The subtype-selective antagonist ifenprodil inhibited the response with high (in the low micromolar range) and low (in the high micromolar range) potency. Ethanol affected the high-potency component in these cultures. In cells grown in high KCI the glycine sensitivity was lower, and a low potency for ifenprodil (high micromolar) dominated. These cells were not significantly sensitive to ethanol. The results indicate that the component displaying potency for ifenprodil in the low micromolar range with properties of the NR2B subunit is the target for ethanol action on the NMDA receptor.     

Role of Chlamydia trachomatis and HLA-B27 in sexually acquired reactive arthritis.

Inflammatory arthritis, tendinitis, and fasciitis after non-specific urethritis ("sexually acquired reactive arthritis" (SARA)) was studied prospectively in 531 men with non-specific urethritis, with particular reference to the frequency of isolation of Chlamydia trachomatis and the presence of HLA-B27. Satisfactory cultures were obtained from the urethral swabs from 384 patients; and HLA typing was performed on 482, of whom 30 (6%) were HLA-B27-positive. Arthritis developed in 16 patients, and five of the 14 (36%) with satisfactory cultures were positive for C trachomatis; 135 of the patients without arthritis were also positive for C trachomatis, an identical proportion. Seven of the 15 patients (40%) with arthritis who were HLA-typed were HLA-B27-positive. Six of the 30 patients with HLA-B27 developed peripheral arthritis in contrast to only nine of the 452 patients lacking the antigen, suggesting a tenfold increase susceptibility. C trachomatis, however, was no more prevalent in cultures from HLA-B27-positive men than from the others. Thus carriage of C trachomatis is unlikely to be influenced by HLA-B27. C trachomatis may be an important pathogen in some cases of SARA but does not appear to be an exclusive trigger factor for this condition.     

Sex pheromone components of the leafroller moth Pandemis cerasana

Female-tip washings of the leafroller moth, Pandemis cerasana, were found to contain (E)-11-tetradecenyl acetate, (Z)-11-tetradecenyl acetate, (E)-11-tetradecenol, (Z)-11-tetradecenol and tetradecyl acetate, based on chemical analysis and electroantennogram tests. The relative amounts of these compounds in the gland were ca. 64:21:10:3:2 in the order named. Only (E)-11 and (Z)-11-tetradecenyl acetate were required for attraction of males to trap dispensed in the ratio 3:1, respectively.     

Climatic Factors Influencing the Anthrax Outbreak of 2016 in Siberia,Russia

In 2016, an outbreak of anthrax killing thousands of reindeer and affecting dozens of humans occurred on the Yamal peninsula, Northwest Siberia, after 70 years of epidemiological situation without outbreaks. The trigger of the outbreak has been ascribed to the activation of spores due to permafrost thaw that was accelerated during the summer heat wave. The focus of our study is on the dynamics of local environmental factors in connection with the observed anthrax revival. We show that permafrost was thawing rapidly for already 6 years before the outbreak. During 2011–2016, relatively warm years were followed by cold years with a thick snow cover, preventing freezing of the soil. Furthermore, the spread of anthrax was likely intensified by an extremely dry summer of 2016. Concurrent with the long-term decreasing trend in the regional annual precipitation, the rainfall in July 2016 was less than 10% of its 30-year mean value. We conclude that epidemiological situation of anthrax in the previously contaminated Arctic regions requires monitoring of climatic factors such as warming and precipitation extremes.