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991.
Magnus Röding Leander Lacroix Annika Krona Tobias Gebäck Niklas Lorén 《Biophysical journal》2019,116(7):1348-1361
We introduce a new, to our knowledge, numerical model based on spectral methods for analysis of fluorescence recovery after photobleaching data. The model covers pure diffusion and diffusion and binding (reaction-diffusion) with immobile binding sites, as well as arbitrary bleach region shapes. Fitting of the model is supported using both conventional recovery-curve-based estimation and pixel-based estimation, in which all individual pixels in the data are utilized. The model explicitly accounts for multiple bleach frames, diffusion (and binding) during bleaching, and bleaching during imaging. To our knowledge, no other fluorescence recovery after photobleaching framework incorporates all these model features and estimation methods. We thoroughly validate the model by comparison to stochastic simulations of particle dynamics and find it to be highly accurate. We perform simulation studies to compare recovery-curve-based estimation and pixel-based estimation in realistic settings and show that pixel-based estimation is the better method for parameter estimation as well as for distinguishing pure diffusion from diffusion and binding. We show that accounting for multiple bleach frames is important and that the effect of neglecting this is qualitatively different for the two estimation methods. We perform a simple experimental validation showing that pixel-based estimation provides better agreement with literature values than recovery-curve-based estimation and that accounting for multiple bleach frames improves the result. Further, the software developed in this work is freely available online. 相似文献
992.
Paolo Becciu Myles H. M. Menz Annika Aurbach Sergio A. Cabrera‐Cruz Charlotte E. Wainwright Martina Scacco Micha Ciach Lars B. Pettersson Ivan Maggini Gonzalo M. Arroyo Jeffrey J. Buler Don R. Reynolds Nir Sapir 《Ecography》2019,42(5):942-955
Migratory animals are affected by various factors during their journeys, and the study of animal movement by radars has been instrumental in revealing key influences of the environment on flying migrants. Radars enable the simultaneous tracking of many individuals of almost all sizes within the radar range during day and night, and under low visibility conditions. We review how atmospheric conditions, geographic features and human development affect the behavior of migrating insects and birds as recorded by radars. We focus on flight initiation and termination, as well as in‐flight behavior that includes changes in animal flight direction, speed and altitude. We have identified several similarities and differences in the behavioral responses of aerial migrants including an overlooked similarity in the use of thermal updrafts by very small (e.g. aphids) and very large (e.g. vultures) migrants. We propose that many aerial migrants modulate their migratory flights in relation to the interaction between atmospheric conditions and geographic features. For example, aerial migrants that encounter crosswind may terminate their flight or continue their migration and may also drift or compensate for lateral displacement depending on their position (over land, near the coast or over sea). We propose several promising directions for future research, including the development and application of algorithms for tracking insects, bats and large aggregations of animals using weather radars. Additionally, an important contribution will be the spatial expansion of aeroecological radar studies to Africa, most of Asia and South America where no such studies have been undertaken. Quantifying the role of migrants in ecosystems and specifically estimating the number of departing birds from stopover sites using low‐elevation radar scans is important for quantifying migrant–habitat relationships. This information, together with estimates of population demographics and migrant abundance, can help resolve the long‐term dynamics of migrant populations facing large‐scale environmental changes. 相似文献
993.
994.
Anthropogenic nitrogen deposition enhances carbon sequestration in boreal soils 总被引:2,自引:0,他引:2
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Nadia I. Maaroufi Annika Nordin Niles J. Hasselquist Lisbet H. Bach Kristin Palmqvist Michael J. Gundale 《Global Change Biology》2015,21(8):3169-3180
It is proposed that carbon (C) sequestration in response to reactive nitrogen (Nr) deposition in boreal forests accounts for a large portion of the terrestrial sink for anthropogenic CO2 emissions. While studies have helped clarify the magnitude by which Nr deposition enhances C sequestration by forest vegetation, there remains a paucity of long‐term experimental studies evaluating how soil C pools respond. We conducted a long‐term experiment, maintained since 1996, consisting of three N addition levels (0, 12.5, and 50 kg N ha?1 yr?1) in the boreal zone of northern Sweden to understand how atmospheric Nr deposition affects soil C accumulation, soil microbial communities, and soil respiration. We hypothesized that soil C sequestration will increase, and soil microbial biomass and soil respiration will decrease, with disproportionately large changes expected compared to low levels of N addition. Our data showed that the low N addition treatment caused a non‐significant increase in the organic horizon C pool of ~15% and a significant increase of ~30% in response to the high N treatment relative to the control. The relationship between C sequestration and N addition in the organic horizon was linear, with a slope of 10 kg C kg?1 N. We also found a concomitant decrease in total microbial and fungal biomasses and a ~11% reduction in soil respiration in response to the high N treatment. Our data complement previous data from the same study system describing aboveground C sequestration, indicating a total ecosystem sequestration rate of 26 kg C kg?1 N. These estimates are far lower than suggested by some previous modeling studies, and thus will help improve and validate current modeling efforts aimed at separating the effect of multiple global change factors on the C balance of the boreal region. 相似文献
995.
Anna Gillman Shaman Muradrasoli Andreas M?rdn?s Hanna S?derstr?m Ganna Fedorova Max L?wenthal Michelle Wille Annika Daggfeldt Josef D. J?rhult 《PloS one》2015,10(9)
Background
Wild waterfowl is the natural reservoir of influenza A virus (IAV); hosted viruses are very variable and provide a source for genetic segments which can reassort with poultry or mammalian adapted IAVs to generate novel species crossing viruses. Additionally, wild waterfowl act as a reservoir for highly pathogenic IAVs. Exposure of wild birds to the antiviral drug oseltamivir may occur in the environment as its active metabolite can be released from sewage treatment plants to river water. Resistance to oseltamivir, or to other neuraminidase inhibitors (NAIs), in IAVs of wild waterfowl has not been extensively studied.Aim and Methods
In a previous in vivo Mallard experiment, an influenza A(H6N2) virus developed oseltamivir resistance by the R292K substitution in the neuraminidase (NA), when the birds were exposed to oseltamivir. In this study we tested if the resistance could be maintained in Mallards without drug exposure. Three variants of resistant H6N2/R292K virus were each propagated during 17 days in five successive pairs of naïve Mallards, while oseltamivir exposure was decreased and removed. Daily fecal samples were analyzed for viral presence, genotype and phenotype.Results and Conclusion
Within three days without drug exposure no resistant viruses could be detected by NA sequencing, which was confirmed by functional NAI sensitivity testing. We conclude that this resistant N2 virus could not compete in fitness with wild type subpopulations without oseltamivir drug pressure, and thus has no potential to circulate among wild birds. The results of this study contrast to previous observations of drug induced resistance in an avian H1N1 virus, which was maintained also without drug exposure in Mallards. Experimental observations on persistence of NAI resistance in avian IAVs resemble NAI resistance seen in human IAVs, in which resistant N2 subtypes do not circulate, while N1 subtypes with permissive mutations can circulate without drug pressure. We speculate that the phylogenetic group N1 NAs may easier compensate for NAI resistance than group N2 NAs, though further studies are needed to confirm such conclusions. 相似文献996.
David J. Matson Darryl T. Hamamoto Howard Bregman Melanie Cooke Erin F. DiMauro Liyue Huang Danielle Johnson Xingwen Li Jeff McDermott Carrie Morgan Ben Wilenkin Annika B. Malmberg Stefan I. McDonough Donald A. Simone 《PloS one》2015,10(9)
While genetic evidence shows that the Nav1.7 voltage-gated sodium ion channel is a key regulator of pain, it is unclear exactly how Nav1.7 governs neuronal firing and what biophysical, physiological, and distribution properties of a pharmacological Nav1.7 inhibitor are required to produce analgesia. Here we characterize a series of aminotriazine inhibitors of Nav1.7 in vitro and in rodent models of pain and test the effects of the previously reported “compound 52” aminotriazine inhibitor on the spiking properties of nociceptors in vivo. Multiple aminotriazines, including some with low terminal brain to plasma concentration ratios, showed analgesic efficacy in the formalin model of pain. Effective concentrations were consistent with the in vitro potency as measured on partially-inactivated Nav1.7 but were far below concentrations required to inhibit non-inactivated Nav1.7. Compound 52 also reversed thermal hyperalgesia in the complete Freund’s adjuvant (CFA) model of pain. To study neuronal mechanisms, electrophysiological recordings were made in vivo from single nociceptive fibers from the rat tibial nerve one day after CFA injection. Compound 52 reduced the spontaneous firing of C-fiber nociceptors from approximately 0.7 Hz to 0.2 Hz and decreased the number of action potentials evoked by suprathreshold tactile and heat stimuli. It did not, however, appreciably alter the C-fiber thresholds for response to tactile or thermal stimuli. Surprisingly, compound 52 did not affect spontaneous activity or evoked responses of Aδ-fiber nociceptors. Results suggest that inhibition of inactivated states of TTX-S channels, mostly likely Nav1.7, in the peripheral nervous system produces analgesia by regulating the spontaneous discharge of C-fiber nociceptors. 相似文献
997.
Christian Schlenstedt Steffen Paschen Annika Kruse Jan Raethjen Burkhard Weisser Günther Deuschl 《PloS one》2015,10(10)
Background
Reduced muscle strength is an independent risk factor for falls and related to postural instability in individuals with Parkinson’s disease. The ability of resistance training to improve postural control still remains unclear.Objective
To compare resistance training with balance training to improve postural control in people with Parkinson’s disease.Methods
40 patients with idiopathic Parkinson’s disease (Hoehn&Yahr: 2.5–3.0) were randomly assigned into resistance or balance training (2x/week for 7 weeks). Assessments were performed at baseline, 8- and 12-weeks follow-up: primary outcome: Fullerton Advanced Balance (FAB) scale; secondary outcomes: center of mass analysis during surface perturbations, Timed-up-and-go-test, Unified Parkinson’s Disease Rating Scale, Clinical Global Impression, gait analysis, maximal isometric leg strength, PDQ-39, Beck Depression Inventory. Clinical tests were videotaped and analysed by a second rater, blind to group allocation and assessment time.Results
32 participants (resistance training: n = 17, balance training: n = 15; 8 drop-outs) were analyzed at 8-weeks follow-up. No significant difference was found in the FAB scale when comparing the effects of the two training types (p = 0.14; effect size (Cohen’s d) = -0.59). Participants from the resistance training group, but not from the balance training group significantly improved on the FAB scale (resistance training: +2.4 points, Cohen’s d = -0.46; balance training: +0.3 points, Cohen’s d = -0.08). Within the resistance training group, improvements of the FAB scale were significantly correlated with improvements of rate of force development and stride time variability. No significant differences were found in the secondary outcome measures when comparing the training effects of both training types.Conclusions
The difference between resistance and balance training to improve postural control in people with Parkinson’s disease was small and not significant with this sample size. There was weak evidence that freely coordinated resistance training might be more effective than balance training. Our results indicate a relationship between the enhancement of rate of force development and the improvement of postural control.Trial Registration
ClinicalTrials.gov ID: NCT02253563 相似文献998.
Reduction in cortical parvalbumin expression due to intermittent theta‐burst stimulation correlates with maturation of the perineuronal nets in young rats
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We recently showed that intermittent theta‐burst stimulation (iTBS) using transcranial magnetic stimulation strongly reduces the number of rat neocortical interneurons expressing glutamic acid decarboxylase 67 kDa (GAD67) and parvalbumin (PV), indicating changed activity of fast‐spiking (FS) interneurons. In advance of in vitro studies intended to characterize changes in electrical properties of FS interneurons under these conditions, we tested whether the iTBS effect is age‐dependent. Conscious Sprague‐Dawley rats aged between 28 and 90 days received three blocks of iTBS at 15 min intervals. We found that iTBS‐related reduction in PV+ cells was absent up to an age of 32 days, then gradually increased, and approached a maximum of about 40% reduction at an age of about 40 days. The relative number of cells expressing PV (PV+, 8–9%) did not change with age in sham‐controls and also the increase in cortical c‐Fos expression induced by iTBS was not principally age‐dependent. However, a prominent growth of the perineuronal nets, typically surrounding the PV+ cells, exactly paralleled the increase in the iTBS effect. Based on these findings, we conclude that the functional development of the inhibitory network of PV+ interneurons with regard to intracortical synaptic connectivity is not sufficiently matured in rats younger than 35d to enable activity‐dependent modifications during iTBS. Outgrowth of the perineuronal nets and associated maturation of excitatory cortical inputs, as is characteristic for the critical cortical period, may take place before PV+ interneurons can be sufficiently activated via repetitive transcranial magnetic stimulation, allowing plastic changes of molecular phenotype and likely also synaptic plasticity. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 75: 1–11, 2015 相似文献
999.
?rjan Ekblom Elin Ekblom-Bak Annika Rosengren Mattias Hallsten G?ran Bergstr?m Mats B?rjesson 《PloS one》2015,10(6)
Background
Previous studies on the relation between lifestyle and the metabolic syndrome lack one or several aspects of the physical activity pattern in the analyses or cardiorespiratory fitness. Likewise, both uni- and triaxial accelerometry have been used, though, the predictive validity of these two modes has not been compared.Objectives
The aims of the present study were firstly to investigate the independent relation between cardiorespiratory fitness and physical activity pattern to the metabolic syndrome (MetS) and secondly to examine the predictive validity of uni- and triaxial accelerometry, respectively.Methods
Data was extracted from the SCAPIS pilot study (n=930, mean age 57.7 yrs). Physical activity pattern was assessed by accelerometry. Cardiorespiratory fitness was estimated using cycle ergometry. MetS was defined per the Adult Treatment Panel III from the National Cholesterol Education Program definition.Results
Time spent sedentary (OR: 2.38, 95% CI: 1.54-4.24 for T3 vs T1), in light intensity (OR: 0.50, 95% CI: 0.28-0.90) and in moderate-to-vigorous activity (OR: 0.33, 95% CI: 0.18-0.61), as well as cardiorespiratory fitness (OR: 0.24, 95% CI:0.12-0.48), were all independently related to the prevalence of MetS after adjustment for potential confounders, fitness and/or the other aspects of the physical activity pattern. In addition, we found that triaxial analyses were more discriminant, with ORs farther away from the reference group and additional significant ORs.Conclusion
The finding that several aspects of the physical activity pattern reveal independent relations to the MetS makes new possible targets for behaviour change of interest, focusing on both exercise and everyday life. When assessing the risk status of a patient, it is advised that triaxial accelerometry is used. 相似文献1000.
A disintegrin and metalloproteinases (ADAMs) constitute a protein family essential for extracellular signaling and regulation of cell adhesion. Catalytic activity of ADAMs and their predicted potential for Src-homology 3 (SH3) domain binding show a strong correlation. Here we present a comprehensive characterization of SH3 binding capacity and preferences of the catalytically active ADAMs 8, 9, 10, 12, 15, 17, and 19. Our results revealed several novel interactions, and also confirmed many previously reported ones. Many of the identified SH3 interaction partners were shared by several ADAMs, whereas some were ADAM-specific. Most of the ADAM-interacting SH3 proteins were adapter proteins or kinases, typically associated with sorting and endocytosis. Novel SH3 interactions revealed in this study include TOCA1 and CIP4 as preferred partners of ADAM8, and RIMBP1 as a partner of ADAM19. Our results suggest that common as well as distinct mechanisms are involved in regulation and execution of ADAM signaling, and provide a useful framework for addressing the pathways that connect ADAMs to normal and aberrant cell behavior. 相似文献