Micron-Scale Plasma Membrane Curvature is Recognized by the Septin Cytoskeleton

Cells change shape in response to diverse environmental and developmental conditions, creating topologies with micron-scale features. Although individual proteins can sense nanometer-scale membrane curvature, it is unclear if a cell could also use nanometer-scale components to sense micron-scale contours, such as the cytokinetic furrow and base of neuronal branches. Septins are filament-forming proteins that serve as signaling platforms and are frequently associated with areas of the plasma membrane where there is micron-scale curvature, including the cytokinetic furrow and the base of cell protrusions. We report here that fungal and human septins are able to distinguish between different degrees of micron-scale curvature in cells. By preparing supported lipid bilayers on beads of different curvature, we reconstitute and measure the intrinsic septin curvature preference. We conclude that micron-scale curvature recognition is a fundamental property of the septin cytoskeleton that provides the cell with a mechanism to know its local shape

Septin assemblies form by diffusion-driven annealing on membranes

Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 111 (2014): 2146-2151, doi:10.1073/pnas.1314138111.Septins assemble into filaments and higher-order structures that act as scaffolds for diverse cell functions including cytokinesis, cell polarity, and membrane remodeling. Despite their conserved role in cell organization, little is known about how septin filaments elongate and are knit together into higher-order assemblies. Using fluorescence correlation spectroscopy (FCS), we determined that cytosolic septins are in small complexes suggesting that septin filaments are not formed in the cytosol. When the plasma membrane of live cells is monitored by total internal reflection fluorescence (TIRF) microscopy, we see that septin complexes of variable size diffuse in two dimensions. Diffusing septin complexes collide and make end-on associations to form elongated filaments and higher-order structures, an assembly process we call annealing. Septin assembly by annealing can be reconstituted in vitro on supported lipid bilayers with purified septin complexes. Using the reconstitution assay, we show that septin filaments are highly flexible, grow only from free filament ends and do not exchange subunits in the middle of filaments. This work shows for the first time that annealing is an intrinsic property of septins in the presence of membranes and demonstrates that cells exploit this mechanism to build large septin assemblies.This project was supported with funding from by NSF (MCB-507511, ASG) and NIH (GM100160, TT and ASG), and Colwin, Lemann and Spiegel summer fellowships and The Nikon Award for summer investigation at MBL in Woods Hole, MA (ASG) and instrument support from Micro Video Instruments (MVI).2014-07-2

Landscape-Scale Land-Cover Change and Long-Term Abundance of Scaled Quail and Northern Bobwhite in Texas

Between 1978 and 1998, scaled quail (Callipepla squamata) abundance in the Rolling Plains ecological region declined (r1 = -0.85, P \u3c 0.001), while no trend (P = 0.74) was exhibited in the South Texas Plains. Northern bobwhites (Colinus virginianus) exhibited no trend (P \u3e 0.10) in either ecological region. Changes in land-cover between 1976 and 1998 indicated a loss of Savannah and Shrubland and an increase in Parkland cover types in the Rolling Plains. In the South Texas Plains, Woodland and Brush/Shrubland decreased between 1976 and 1998, whereas Brush/Shrub Parkland and Parkland increased. We examined land-cover change as a possible component in the scaled quail decline in the Rolling Plains. Loss of the Shrubland cover type may explain the decline of scaled quail in the Rolling Plains. Our results further suggest intraspecific spatial usability boundaries. These boundaries differed by species, with scaled quail associated with dense structure near the ground, whereas northern bobwhite were less abundant in areas dominated by scattered shrubs and trees, and large expanses of short, close-canopy cover types. A method is proposed for quickly obtaining data on land-cover changes on time

Spectroscopy of Globular Clusters in M81

We present moderate-resolution spectroscopy of globular clusters (GCs) around the Sa/Sb spiral galaxy M81 (NGC 3031). Sixteen candidate clusters were observed with the Low Resolution Imaging Spectrograph on the Keck I telescope. All are confirmed as bona fide GCs, although one of the clusters appears to have been undergoing a transient event during our observations. In general, the M81 globular cluster system (GCS) is found to be very similar to the Milky Way (MW) and M31 systems, both chemically and kinematically. A kinematic analysis of the velocities of 44 M81 GCS, (the 16 presented here and 28 from previous work) strongly suggests that the red, metal-rich clusters are rotating in the same sense as the gas in the disk of M81. The blue, metal-poor clusters have halo-like kinematics, showing no evidence for rotation. The kinematics of clusters whose projected galactocentric radii lie between 4 and 8 kpc suggest that they are rotating much more than those which lie outside these bounds. We suggest that these rotating, intermediate-distance clusters are analogous to the kinematic sub-population in the metal-rich, disk GCs observed in the MW and we present evidence for the existence of a similar sub-population in the metal-rich clusters of M31. With one exception, all of the M81 clusters in our sample have ages that are consistent with MW and M31 GCs. One cluster may be as young as a few Gyrs. The correlations between absorption-line indices established for MW and M31 GCs also hold in the M81 cluster system, at least at the upper end of the metallicity distribution (which our sample probes). On the whole, the mean metallicity of the M81 GCS is similar to the metallicity of the MW and M31 GCSs. The projected mass of M81 is similar to the masses of the MW and M31. Its mass profile indicates the presence of a dark matter halo.Comment: 35 pages, including 11 figures and 9 tables. Accepted for publication in the Astronomical Journa

Micron-scale plasma membrane curvature is recognized by the septin cytoskeleton

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Cell Biology 213 (2016): 23-32, doi: 10.1083/jcb.201512029.Cells change shape in response to diverse environmental and developmental conditions, creating topologies with micron-scale features. Although individual proteins can sense nanometer-scale membrane curvature, it is unclear if a cell could also use nanometer-scale components to sense micron-scale contours, such as the cytokinetic furrow and base of neuronal branches. Septins are filament-forming proteins that serve as signaling platforms and are frequently associated with areas of the plasma membrane where there is micron-scale curvature, including the cytokinetic furrow and the base of cell protrusions. We report here that fungal and human septins are able to distinguish between different degrees of micron-scale curvature in cells. By preparing supported lipid bilayers on beads of different curvature, we reconstitute and measure the intrinsic septin curvature preference. We conclude that micron-scale curvature recognition is a fundamental property of the septin cytoskeleton that provides the cell with a mechanism to know its local shape.This work was supported by grants from the National Science Foundation (MCB-507511 to A.S. Gladfelter) and the National Institutes of Health (NIGMS-T32GM008704 to A.A. Bridges)

Using Hyperfine Electron Paramagnetic Resonance Spectroscopy to Define the Proton-Coupled Electron Transfer Reaction at Fe-S Cluster N2 in Respiratory Complex I.

Energy-transducing respiratory complex I (NADH:ubiquinone oxidoreductase) is one of the largest and most complicated enzymes in mammalian cells. Here, we used hyperfine electron paramagnetic resonance (EPR) spectroscopic methods, combined with site-directed mutagenesis, to determine the mechanism of a single proton-coupled electron transfer reaction at one of eight iron-sulfur clusters in complex I, [4Fe-4S] cluster N2. N2 is the terminal cluster of the enzyme's intramolecular electron-transfer chain and the electron donor to ubiquinone. Because of its position and pH-dependent reduction potential, N2 has long been considered a candidate for the elusive "energy-coupling" site in complex I at which energy generated by the redox reaction is used to initiate proton translocation. Here, we used hyperfine sublevel correlation (HYSCORE) spectroscopy, including relaxation-filtered hyperfine and single-matched resonance transfer (SMART) HYSCORE, to detect two weakly coupled exchangeable protons near N2. We assign the larger coupling with A(1H) = [-3.0, -3.0, 8.7] MHz to the exchangeable proton of a conserved histidine and conclude that the histidine is hydrogen-bonded to N2, tuning its reduction potential. The histidine protonation state responds to the cluster oxidation state, but the two are not coupled sufficiently strongly to catalyze a stoichiometric and efficient energy transduction reaction. We thus exclude cluster N2, despite its proton-coupled electron transfer chemistry, as the energy-coupling site in complex I. Our work demonstrates the capability of pulse EPR methods for providing detailed information on the properties of individual protons in even the most challenging of energy-converting enzymes

Exercise-based cardiac rehabilitation for adults with heart failure

Background Chronic heart failure (HF) is a growing global health challenge. People with HF experience substantial burden that includes low exercise tolerance, poor health-related quality of life (HRQoL), increased risk of mortality and hospital admission, and high healthcare costs. The previous (2014) Cochrane systematic review reported that exercise-based cardiac rehabilitation (CR) compared to no exercise control shows improvement in HRQoL and hospital admission among people with HF, as well as possible reduction in mortality over the longer term, and that these reductions appear to be consistent across patient and programme characteristics. Limitations noted by the authors of this previous Cochrane Review include the following: (1) most trials were undertaken in patients with HF with reduced (< 45%) ejection fraction (HFrEF), and women, older people, and those with preserved (≥ 45%) ejection fraction HF (HFpEF) were under-represented; and (2) most trials were undertaken in the hospital/centre-based setting. Objectives To determine the effects of exercise-based cardiac rehabilitation on mortality, hospital admission, and health-related quality of life of people with heart failure. Search methods We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and three other databases on 29 January 2018. We also checked the bibliographies of systematic reviews and two trial registers. Selection criteria We included randomised controlled trials that compared exercise-based CR interventions with six months’ or longer follow-up versus a no exercise control that could include usual medical care. The study population comprised adults (> 18 years) with evidence of HF - either HFrEF or HFpEF. Data collection and analysis Two review authors independently screened all identified references and rejected those that were clearly ineligible for inclusion in the review. We obtained full papers of potentially relevant trials. Two review authors independently extracted data from the included trials, assessed their risk of bias, and performed GRADE analyses. Main results We included 44 trials (5783 participants with HF) with a median of six months’ follow-up. For this latest update, we identified 11 new trials (N = 1040), in addition to the previously identified 33 trials. Although the evidence base includes predominantly patients with HFrEF with New York Heart Association classes II and III receiving centre-based exercise-based CR programmes, a growing body of studies include patients with HFpEF and are undertaken in a home-based setting. All included studies included a no formal exercise training intervention comparator. However, a wide range of comparators were seen across studies that included active intervention (i.e. education, psychological intervention) or usual medical care alone. The overall risk of bias of included trials was low or unclear, and we downgraded results using the GRADE tool for all but one outcome. Cardiac rehabilitation may make little or no difference in all-cause mortality over the short term (≤ one year of follow-up) (27 trials, 28 comparisons (2596 participants): intervention 67/1302 (5.1%) vs control 75/1294 (5.8%); risk ratio (RR) 0.89, 95% confidence interval (CI) 0.66 to 1.21; low-quality GRADE evidence) but may improve all-cause mortality in the long term (> 12 months follow up) (6 trials/comparisons (2845 participants): intervention 244/1418 (17.2%) vs control 280/1427 (19.6%) events): RR 0.88, 95% CI 0.75 to 1.02; high-quality evidence). Researchers provided no data on deaths due to HF. CR probably reduces overall hospital admissions in the short term (up to one year of follow-up) (21 trials, 21 comparisons (2182 participants): (intervention 180/1093 (16.5%) vs control 258/1089 (23.7%); RR 0.70, 95% CI 0.60 to 0.83; moderate-quality evidence, number needed to treat: 14) and may reduce HF-specific hospitalisation (14 trials, 15 comparisons (1114 participants): (intervention 40/562 (7.1%) vs control 61/552 (11.1%) RR 0.59, 95% CI 0.42 to 0.84; low-quality evidence, number needed to treat: 25). After CR, a clinically important improvement in shortterm disease-specific health-related quality of life may be evident (Minnesota Living With Heart Failure questionnaire - 17 trials, 18 comparisons (1995 participants): mean difference (MD) -7.11 points, 95% CI -10.49 to -3.73; low-quality evidence). Pooling across all studies, regardless of the HRQoL measure used, shows there may be clinically important improvement with exercise (26 trials, 29 comparisons (3833 participants); standardised mean difference (SMD) -0.60, 95% CI -0.82 to -0.39; I² = 87%; Chi² = 215.03; lowquality evidence). ExCR effects appeared to be consistent different models of ExCR delivery: centre vs. home-based, exercise dose, exercise only vs. comprehensive programmes, and aerobic training alone vs aerobic plus resistance programmes. Authors’ conclusions This updated Cochrane Review provides additional randomised evidence (11 trials) to support the conclusions of the previous version (2014) of this Cochane Review. Compared to no exercise control, CR appears to have no impact on mortality in the short term (< 12 months’ follow-up). Low- to moderate-quality evidence shows that CR probably reduces the risk of all-cause hospital admissions and may reduce HF-specific hospital admissions in the short term (up to 12 months). CR may confer a clinically important improvement in health-related quality of life, although we remain uncertain about this because the evidence is of low quality. Future ExCR trials need to continue to consider the recruitment of traditionally less represented HF patient groups including older, female, and HFpEF patients, and alternative CR delivery settings including home- and using technology-based programmes

Efficacy of early PET-CT directed switch to carboplatin and paclitaxel based definitive chemoradiotherapy in patients with oesophageal cancer who have a poor early response to induction cisplatin and capecitabine in the UK: a multi-centre randomised controlled phase II trial induction cisplatin and capecitabine in the UK: a multi-centre randomised controlled phase II trial

Background: The utility of early metabolic response assessment to guide selection of the systemic component of definitive chemoradiotherapy (dCRT) for oesophageal cancer is uncertain.// Methods: In this multi-centre, randomised, open-label, phase II substudy of the radiotherapy dose-escalation SCOPE2 trial we evaluated the role of 18F-Fluorodeoxyglucose positron emission tomography (PET) at day 14 of cycle 1 of three-weekly induction cis/cap (cisplatin (60 mg/m2)/capecitabine (625 mg/m2 days 1–21)) in patients with oesophageal squamous cell carcinoma (OSCC) or adenocarcinoma (OAC). Non-responders, who had a less than 35% reduction in maximum standardised uptake value (SUVmax) from pre-treatment baseline, were randomly assigned to continue cis/cap or switch to car/pac (carboplatin AUC 5/paclitaxel 175 mg/m2) for a further induction cycle, then concurrently with radiotherapy over 25 fractions. Responders continued cis/cap for the duration of treatment. All patients (including responders) were randomised to standard (50Gy) or high (60Gy) dose radiation as part of the main study. Primary endpoint for the substudy was treatment failure-free survival (TFFS) at week 24. The trial was registered with International Standard Randomized Controlled Trial Number 97125464 and ClinicalTrials.gov NCT02741856.// Findings: This substudy was closed on 1st August 2021 by the Independent Data Monitoring Committee on the grounds of futility and possible harm. To this point from 22nd November 2016, 103 patients from 16 UK centres had participated in the PET-CT substudy; 63 (61.2%; 52/83 OSCC, 11/20 OAC) of whom were non-responders. Of these, 31 were randomised to car/pac and 32 to remain on cis/cap. All patients were followed up until at least 24 weeks, at which point in OSCC both TFFS (25/27 (92.6%) vs 17/25 (68%); p = 0.028) and overall survival (42.5 vs. 20.4 months, adjusted HR 0.36; p = 0.018) favoured cis/cap over car/pac. There was a trend towards worse survival in OSCC + OAC cis/cap responders (33.6 months; 95%CI 23.1-nr) vs. non-responders (42.5 (95%CI 27.0-nr) months; HR = 1.43; 95%CI 0.67–3.08; p = 0.35).// Interpretation: In OSCC, early metabolic response assessment is not prognostic for TFFS or overall survival and should not be used to personalise systemic therapy in patients receiving dCRT

Evaluating the contribution of a wildlife health capacity building program on orangutan conservation

One Health is increasingly being used as a tool in ecosystem protection. The Orangutan Veterinary Advisory Group (OVAG) is working to address One Health concerns in Pongo spp. (orangutan) welfare and conservation. Orangutans are vital contributors to the ecosystem health of their range areas. Strengthening national capacity is crucial to make a lasting difference in the currently bleak outlook for orangutan species survival. OVAG is a capacity strengthening and expertise network that brings together all those working with orangutans, in- and ex-situ, to share knowledge, skills, and to collectively learn. Using the One Health paradigm embedded to enhance professional development, the OVAG network is successfully supporting conservation outcomes and impact. As part of our adaptive management approach, and to assess individual and organizational change attributable to the capacity strengthening work of OVAG, we evaluated technical skill test data, program satisfaction data, and asked participants to complete a self-reflective survey. This pilot study of our work demonstrates statistically significant improvements in conservation medicine (t = 5.481, p < 0.0001) and wildlife clinical skills knowledge (t = 3.923, p < 0.001) for those in the OVAG program. Most consider OVAG participation to be either critical or very useful in their conservation medicine decision-making process, with a perceived positive impact on their skills at handling multiple situations. Additionally, participant feedback shows a sense of being able to drive positive change locally and nationally (within their own countries) as a consequence of OVAG participation. The authors hope the OVAG model including its associated capacity support mechanisms and pedagogical approaches can be used as a template for other One Health efforts