Steering protein adsorption at charged surfaces : electric fields and ionic screening

Protein adsorption at charged surfaces is a common process in the development of functional technological devices. Accurately reproducing the environment above the surface in simulations is essential for understanding how the adsorption process can be influenced and utilised. Here we present a simulation strategy that includes the electric field above the charged surface as well as the screening ions in solution, using standard molecular dynamics tools. With this approach we investigate the adsorption of Hen Egg White Lysozyme (HEWL) onto a model charged silica surface. We find that the screening effects of the ions slow down the adsorption process, giving the protein more time to find its optimal orientation as it adsorbs. Furthermore, we find that the concentrated ionic region directly above the surface helps to stabilise the protein structure in its adsorbed state. Together these effects imply that the adsorbed HEWL might retain its biological activity, with its active site exposed to solution rather than to the surface. Furthermore, this work shows how the steering effects of the electric field, coupled to the ionic screening, might be used to develop general strategies for surface functionalization through protein adsorption for technological applications

In Situ Diazotroph Population Dynamics Under Different Resource Ratios in the North Pacific Subtropical Gyre.

Major advances in understanding the diversity, distribution, and activity of marine N2-fixing microorganisms (diazotrophs) have been made in the past decades, however, large gaps in knowledge remain about the environmental controls on growth and mortality rates. In order to measure diazotroph net growth rates and microzooplankton grazing rates on diazotrophs, nutrient perturbation experiments and dilution grazing experiments were conducted using free-floating in situ incubation arrays in the vicinity of Station ALOHA in March 2016. Net growth rates for targeted diazotroph taxa as well as Prochlorococcus, Synechococcus and photosynthetic picoeukaryotes were determined under high (H) and low (L) nitrate:phosphate (NP) ratio conditions at four depths in the photic zone (25, 45, 75, and 100 m) using quantitative PCR and flow cytometry. Changes in the prokaryote community composition in response to HNP and LNP treatments were characterized using 16S rRNA variable region tag sequencing. Microzooplankton grazing rates on diazotrophs were measured using a modified dilution technique at two depths in the photic zone (15 and 125 m). Net growth rates for most of the targeted diazotrophs after 48 h were not stimulated as expected by LNP conditions, rather enhanced growth rates were often measured in HNP treatments. Interestingly, net growth rates of the uncultivated prymnesiophyte symbiont UCYN-A1 were stimulated in HNP treatments at 75 and 100 m, suggesting that N used for growth was acquired through continuing to fix N2 in the presence of nitrate. Net growth rates for UCYN-A1, UCYN-C, Crocosphaera sp. (UCYN-B) and the diatom symbiont Richelia (associated with Rhizosolenia) were uniformly high at 45 m (up to 1.6 ± 0.5 d-1), implying that all were growing optimally at the onset of the experiment at that depth. Differences in microzooplankton grazing rates on UCYN-A1 and UCYN-C in 15 m waters indicate that the grazer assemblage preyed preferentially on UCYN-A1. Deeper in the water column (125 m), both diazotrophs were grazed at substantial rates, suggesting grazing pressure may increase with depth in the photic zone. Constraining in situ diazotroph growth and mortality rates are important steps for improving parameterization for diazotrophs in global ecosystem models

Parallel-propagated frame along null geodesics in higher-dimensional black hole spacetimes

In [arXiv:0803.3259] the equations describing the parallel transport of orthonormal frames along timelike (spacelike) geodesics in a spacetime admitting a non-degenerate principal conformal Killing-Yano 2-form h were solved. The construction employed is based on studying the Darboux subspaces of the 2-form F obtained as a projection of h along the geodesic trajectory. In this paper we demonstrate that, although slightly modified, a similar construction is possible also in the case of null geodesics. In particular, we explicitly construct the parallel-transported frames along null geodesics in D=4,5,6 Kerr-NUT-(A)dS spacetimes. We further discuss the parallel transport along principal null directions in these spacetimes. Such directions coincide with the eigenvectors of the principal conformal Killing-Yano tensor. Finally, we show how to obtain a parallel-transported frame along null geodesics in the background of the 4D Plebanski-Demianski metric which admits only a conformal generalization of the Killing-Yano tensor.Comment: 17 pages, no figure

Affective response to physical activity as an intermediate phenotype

Over the past seventy years, biomedical and epidemiological research has shown that regular physical activity (PA) is critical for physical and mental health. Despite this knowledge, physical inactivity is the fourth leading risk factor for global mortality, accounting for 9% (5.3 million) of premature deaths annually. We suggest this mismatch between knowing about the risks of PA and engaging in regular PA can be reconciled by focusing less on expected health benefits of PA and more on how people feel during PA. Specifically, in this position paper, we argue that affective response (feeling good versus bad) to PA is an intermediate phenotype that can explain significant variance in PA behavior and is, in turn, a function of genetic variability. In making this argument, we first review empirical evidence showing that affective response to PA predicts future physical activity behavior. Second, we systematically review research on single nucleotide morphisms (SNPs) that are associated with affective response to PA. Investigating affective response to PA as an intermediate phenotype will allow future researchers to move beyond asking “What SNPs are associated with PA?“, and begin asking “How do these SNPs influence PA?“, thus ultimately optimizing the translation of knowledge gained from genomic data to intervention development

Relative effects on stratospheric ozone of halogenated methanes and ethanes of social and industrial interest

Four atmospheric modeling groups have calculated relative effects of several halocarbons (chlorofluorocarbons (CFC's)-11, 12, 113, 114, and 115; hydrochlorofluorocarbons (HCFC's) 22, 123, 124, 141b, and 142b; hydrofluorocarbons (HFC's) 125, 134a, 143a, and 152a, carbon tetrachloride; and methyl chloroform) on stratospheric ozone. Effects on stratospheric ozone were calculated for each compound and normalized relative to the effect of CFC-11. These models include the representations for homogeneous physical and chemical processes in the middle atmosphere but do no account for either heterogeneous chemistry or polar dynamics which are important in the spring time loss of ozone over Antarctica. Relative calculated effects using a range of models compare reasonably well. Within the limits of the uncertainties of these model results, compounds now under consideration as functional replacements for fully halogenated compounds have modeled stratospheric ozone reductions of 10 percent or less of that of CFC-11. Sensitivity analyses examined the sensitivity of relative calculated effects to levels of other trace gases, assumed transport in the models, and latitudinal and seasonal local dependencies. Relative effects on polar ozone are discussed in the context of evolving information on the special processes affecting ozone, especially during polar winter-springtime. Lastly, the time dependency of relative effects were calculated

Assessment of wind speeds along the damage path of the Alonsa, Manitoba EF4 tornado on 3 August 2018

Given the impracticality of attempting to directly measure wind speeds in tornadoes, wind speed estimation typically relies on the assessment of damage to structures and vegetation using classifications described in the Enhanced Fujita (EF) Scale. The advent of technology enabling the collection of large amounts of data, including detailed ground, drone, and aerial imagery, has led to a growth in research on non-conventional approaches for estimating tornado wind speeds. Research methods focused on defining the tornadic wind field based on forensic analysis of damage observations have shown promise for improving tornado assessments in a quantitative manner. In this study, novel methods for collecting forensic data following tornadoes are presented. Data from the Alonsa, MB tornado are applied to estimating the wind field along the damage path using treefall pattern analysis and threshold debris flight speed calculations. Comparison of the resulting wind speed estimates show reasonable agreement, with maximum speeds from both methods in the EF5 range. These research methods yield higher wind speeds than the maximum value obtained from the conventional EF-Scale assessment, which is in the low-end of the EF4 range based on a wood-frame house with sub-standard construction that was swept entirely from its foundation. Further work is still needed to make these methods operational for routine tornado intensity estimates

Conservation of Glomerular Organization in the Main Olfactory Bulb of Anuran Larvae

The glomerular array in the olfactory bulb of many vertebrates is segregated into molecularly and anatomically distinct clusters linked to different olfactory functions. In anurans, glomerular clustering is so far only described in Xenopus laevis. We traced olfactory projections to the bulb in tadpoles belonging to six distantly related anuran species in four families (Pipidae, Hylidae, Bufonidae, Dendrobatidae) and found that glomerular clustering is remarkably conserved. The general bauplan consists of four unequally sized glomerular clusters with minor inter-species variation. During metamorphosis, the olfactory system undergoes extensive remodeling. Tracings in metamorphotic and juvenile Dendrobates tinctorius and Xenopus tropicalis suggest a higher degree of variation in the glomerular organization after metamorphosis is complete. Our study highlights, that the anatomical organization of glomeruli in the main olfactory bulb (MOB) is highly conserved, despite an extensive ecomorphological diversification among anuran tadpoles, which suggests underlying developmental constraints.Fil: Weiss, Lukas. Justus Liebig Universitat Giessen; AlemaniaFil: Jungblut, Lucas David. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Pozzi, Andrea Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: O´Connell, Lauren A.. University of Stanford; Estados UnidosFil: Hassenklöver, Thomas. Justus Liebig Universitat Giessen; AlemaniaFil: Manzini, Ivan. Justus Liebig Universitat Giessen; Alemani

Evidence of Balanced Diversity at the Chicken Interleukin 4 Receptor Alpha Chain Locus

Background: The comparative analysis of genome sequences emerging for several avian species with thefully sequenced chicken genome enables the genome-wide investigation of selective processes infunctionally important chicken genes. In particular, because of pathogenic challenges it is expected thatgenes involved in the chicken immune system are subject to particularly strong adaptive pressure.Signatures of selection detected by inter-species comparison may then be investigated at the populationlevel in global chicken populations to highlight potentially relevant functional polymorphisms.Results: Comparative evolutionary analysis of chicken (Gallus gallus) and zebra finch (Taeniopygia guttata)genes identified interleukin 4 receptor alpha-chain (IL-4Rα), a key cytokine receptor as a candidate with asignificant excess of substitutions at nonsynonymous sites, suggestive of adaptive evolution. Resequencingand detailed population genetic analysis of this gene in diverse village chickens from Asia and Africa,commercial broilers, and in outgroup species red jungle fowl (JF), grey JF, Ceylon JF, green JF, grey francolinand bamboo partridge, suggested elevated and balanced diversity across all populations at this gene, actingto preserve different high-frequency alleles at two nonsynonymous sites.Conclusion: Haplotype networks indicate that red JF is the primary contributor of diversity at chickenIL-4Rα: the signature of variation observed here may be due to the effects of domestication, admixtureand introgression, which produce high diversity. However, this gene is a key cytokine-binding receptor inthe immune system, so balancing selection related to the host response to pathogens cannot be excluded

Age Moderates the Effect of Self-Paced Exercise on Exercise Adherence among Overweight Adults

Objective: The present study tested the hypothesis that the effect of self-paced exercise on adherence to exercise programs is more pronounced with increasing age. Method: Fifty-nine low-active overweight adults (18-65 years) were encouraged to walk 30 to 60 min/day and randomized to either self-paced (n = 30) or prescribed moderate-intensity (n = 29) conditions. Results: The effect of study condition was moderated by age (main effect: b = 6.14, SE = 2.54, p = .02; Condition × Age: b = −11.55, SE = 3.77, p \u3c .01), such that among participants \u3e50 years, those in the self-paced condition exercised 6 more min/day than participants in the prescribed moderate-intensity condition (p = .02), whereas among participants \u3c50 \u3eyears, those in the self-paced condition exercised 5.4 fewer min/day compared with those in the moderate-intensity condition (p = .05). Affective response to physical activity did not mediate the moderating effect of age. Discussion: As age increases, adults may be more likely to adhere to self-paced versus prescribed moderate-intensity exercise

The Northern Tornadoes Project - Uncovering Canada’s True Tornado Climatology

Canada is a vast country with most of its population located along its southern border. Large areas are sparsely populated and/or heavily forested, and severe weather reports are rare when thunderstorms occur there. Thus, it has been difficult to accurately assess the true tornado climatology and risk. It is also important to establish a reliable baseline for tornado-related climate change studies. The Northern Tornadoes Project (NTP), led by Western University, is an ambitious multidisciplinary initiative aimed at detecting and documenting every tornado that occurs across Canada. A team of meteorologists and wind engineers collects research-quality data during each damage investigation, via thorough ground surveys and high-resolution satellite, aircraft and drone imaging. Crowdsourcing through social media is also key to tracking down events. In addition, NTP conducts research to improve our ability to detect and accurately assess tornadoes that affect forests, cropland and grassland. An open data website allows sharing of resulting data sets and analyses. Pilot investigations were carried out during the warm seasons of 2017 and 2018, with the scope expanding from the detection of any tornadoes in heavily forested regions of central Canada in 2017 to the detection of all EF1+ tornadoes in Ontario plus all significant events outside of Ontario in 2018. The 2019 season was the first full campaign, systemically collecting research-quality tornado data across the entire country. To date, the Project has found 89 tornadoes that otherwise would not have been identified, and increased the national tornado count in 2019 by 78%. © 2020 American Meteorological Societ