Human immunodeficiency virus type 2 (HIV-2) Gag is trafficked in an AP-3 and AP-5 dependent manner

Although human immunodeficiency virus (HIV) types 1 and 2 are closely related lentiviruses with similar replication cycles, HIV-2 infection is associated with slower progression to AIDS, a higher proportion of long term non-progressors, and lower rates of transmission than HIV-1, likely as a consequence of a lower viral load during HIV-2 infection. A mechanistic explanation for the differential viral load remains unclear but knowledge of differences in particle production between HIV-1 and HIV-2 may help to shed light on this issue. In contrast to HIV-1, little is known about the assembly of HIV-2 particles, and the trafficking of HIV-2 Gag, the structural component of the virus, within cells. We have established that HIV-2 Gag accumulates in intracellular CD63 positive compartments, from which it may be delivered or recycled to the cell surface, or degraded. HIV-2 particle release was dependent on the adaptor protein complex AP-3 and the newly identified AP-5 complex, but much less so on AP-1. In contrast, HIV-1 particle release required AP-1 and AP-3, but not AP-5. AP-2, an essential component of clathrin-mediated endocytosis, which was previously shown to be inhibitory to HIV-1 particle release, had no effect on HIV-2. The differential requirement for adaptor protein complexes confirmed that HIV-1 and HIV-2 Gag have distinct cellular trafficking pathways, and that HIV-2 particles may be more susceptible to degradation prior to release

An HI absorption distance to the black hole candidate X-ray binary MAXI J1535-571

With the Australian Square Kilometre Array Pathfinder (ASKAP) we monitored the black hole candidate X-ray binary MAXI J1535--571 over seven epochs from 21 September to 2 October 2017. Using ASKAP observations, we studied the HI absorption spectrum from gas clouds along the line-of-sight and thereby constrained the distance to the source. The maximum negative radial velocities measured from the HI absorption spectra for MAXI J1535--571 and an extragalactic source in the same field of view are $-69\pm4$ km s$^{-1}$ and $-89\pm4$ km s$^{-1}$, respectively. This rules out the far kinematic distance ($9.3^{+0.5}_{-0.6}$ kpc), giving a most likely distance of $4.1^{+0.6}_{-0.5}$ kpc, with a strong upper limit of the tangent point at $6.7^{+0.1}_{-0.2}$ kpc. At our preferred distance, the peak unabsorbed luminosity of MAXI J1535--571 was $>78$ per cent of the Eddington luminosity, and shows that the soft-to-hard spectral state transition occurred at the very low luminosity of 1.2 -- 3.4 $\times$ 10$^{-5}$ times the Eddington luminosity. Finally, this study highlights the capabilities of new wide-field radio telescopes to probe Galactic transient outbursts, by allowing us to observe both a target source and a background comparison source in a single telescope pointing.Comment: Revised after favorable referee report from MNRAS Letter

Single Crystal X-Ray Diffraction Study of Pressure and Temperature Induced Spin Trapping in a Bistable FeII Hofmann Framework

This is the peer reviewed version of the following article: Turner, G. F., Campbell, F., Moggach, S. A., Parsons, S., Goeta, A. E., Muñoz, M. C., & Real, J. A. (2020). Single-Crystal X-Ray Diffraction Study of Pressure and Temperature¿Induced Spin Trapping in a Bistable Iron (II) Hofmann Framework. Angewandte Chemie International Edition, 59(8), 3106-3111, which has been published in final form at https://doi.org/10.1002/anie.201914360. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] High-pressure single-crystal X-ray diffraction has been used to trap both the low-spin (LS) and high-spin (HS) states of the iron(II) Hofmann spin crossover framework, [FeII (pdm)(H2 O)[Ag(CN)2 ]2·H2 O, under identical experimental conditions, allowing the structural changes arising from the spin-transition to be deconvoluted from previously reported thermal effects.This work was supported by the Spanish Ministerio de Economia y Competitividad (MINECO), FEDER (CTQ2016-78341-P), Unidad de Excelencia Mar&a de Maeztu (MDM 2015-0538), the Generalitat Valenciana through PROMETEO/2016/147, and the EPSRC through EP/D503744 and GR/M81830. The authors acknowledge the facilities, and the scientific and technical assistance of the Australian Microscopy & Microanalysis Research Facility at the Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, a facility funded by the University, State and Commonwealth Governments. G.F.T. acknowledges the Australian Government for the provision of an Australian Government Research Training Program (RTP) scholarship.Turner, GF.; Campbell, F.; Moggach, SA.; Parsons, S.; Goeta, AE.; Muñoz Roca, MDC.; Real, JA. (2020). Single-Crystal X-Ray Diffraction Study of Pressure and Temperature-Induced Spin Trapping in a Bistable Iron(II) Hofmann Framework. Angewandte Chemie International Edition. 59(8):3106-3111. https://doi.org/10.1002/anie.2019143603106311159

Using negative-latency gravitational wave alerts to detect prompt radio bursts from binary neutron star mergers with the Murchison Widefield Array

We examine how fast radio burst (FRB)-like signals predicted to be generated during the merger of a binary neutron star (BNS) may be detected in low-frequency radio observations triggered by the aLIGO/Virgo gravitational wave detectors. The rapidity, directional accuracy, and sensitivity of follow-up observations with the Murchison Widefield Array (MWA) are considered. We show that with current methodology, the rapidity criteria fails for triggered MWA observations above 136 MHz for BNS mergers within the aLIGO/Virgo horizon, for which little dispersive delay is expected. A calculation of the expected reduction in response time by triggering on `negative latency' alerts from aLIGO/Virgo observations of gravitational waves generated by the BNS inspiral is presented. This allows for observations up to 300 MHz where the radio signal is expected to be stronger. To compensate for the poor positional accuracy expected from these alerts, we propose a new MWA observational mode that is capable of viewing one quarter of the sky. We show the sensitivity of this mode is sufficient to detect an FRB-like burst from an event similar to GW170817 if it occurred during the ongoing aLIGO/Virgo third science run (O3).Comment: Published in MNRAS Letters. 8 pages (5 main + 3 supplemental), 4 figures. Link to article: https://academic.oup.com/mnrasl/advance-article-abstract/doi/10.1093/mnrasl/slz129/555266

Amphotericin forms an extramembranous and fungicidal sterol sponge.

For over 50 years, amphotericin has remained the powerful but highly toxic last line of defense in treating life-threatening fungal infections in humans with minimal development of microbial resistance. Understanding how this small molecule kills yeast is thus critical for guiding development of derivatives with an improved therapeutic index and other resistance-refractory antimicrobial agents. In the widely accepted ion channel model for its mechanism of cytocidal action, amphotericin forms aggregates inside lipid bilayers that permeabilize and kill cells. In contrast, we report that amphotericin exists primarily in the form of large, extramembranous aggregates that kill yeast by extracting ergosterol from lipid bilayers. These findings reveal that extraction of a polyfunctional lipid underlies the resistance-refractory antimicrobial action of amphotericin and suggests a roadmap for separating its cytocidal and membrane-permeabilizing activities. This new mechanistic understanding is also guiding development of what are to our knowledge the first derivatives of amphotericin that kill yeast but not human cells

On the Use of Carbon Cables from Plastic Solvent Combinations of Polystyrene and Toluene in Carbon Nanotube Synthesis

For every three people on the planet, there are approximately two Tonnes (Te) of plastic waste. We show that carbon recovery from polystyrene (PS) plastic is enhanced by the coaddition of solvents to grow carbon nanotubes (CNTs) by liquid injection chemical vapour deposition. Polystyrene was loaded up to 4 wt% in toluene and heated to 780 °C in the presence of a ferrocene catalyst and a hydrogen/argon carrier gas at a 1:19 ratio. High resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Raman spectroscopy were used to identify multiwalled carbon nanotubes (MWCNTs). The PS addition in the range from 0 to 4 wt% showed improved quality and CNT homogeneity; Raman “Graphitic/Defective” (G/D) values increased from 1.9 to 2.3; mean CNT diameters increased from 43.0 to 49.2 nm; and maximum CNT yield increased from 11.37% to 14.31%. Since both the CNT diameters and the percentage yield increased following the addition of polystyrene, we conclude that carbon from PS contributes to the carbon within the MWCNTs. The electrical contact resistance of acid-washed Bucky papers produced from each loading ranged from 2.2 to 4.4 Ohm, with no direct correlation to PS loading. Due to this narrow range, materials with different loadings were mixed to create the six wires of an Ethernet cable and tested using iPerf3; the cable achieved up- and down- link speeds of ~99.5 Mbps, i.e., comparable to Cu wire with the same dimensions (~99.5 Mbps). The lifecycle assessment (LCA) of CNT wire production was compared to copper wire production for a use case in a Boeing 747-400 over the lifespan of the aircraft. Due to their lightweight nature, the CNT wires decreased the CO2 footprint by 21 kTonnes (kTe) over the aircraft’s lifespan.We would like to thank Keysight Technologies for the use of a test model of the B2900A SMU. We would like to acknowledge the assistance provided by Swansea University College of Engineering AIM Facility. We would like to thank TRIMTABS Ltd. for purchasing equipment required for making ethernet cables. Thanks to Swansea Employability Academy (SEA) for the summer placements scheme. Thanks to the Swansea University Texas Strategic Partnership. R.E.P. acknowledges his work was associated with the IMPACT operation. We acknowledge pixabay for use of imagery in the graphical abstract (https://pixabay.com/vectors/airplane-boeing-747-transport-48 11157/ (accessed on 1 December 2021))

Short Timescale Evolution of the Polarized Radio Jet during V404 Cygni's 2015 Outburst

We present a high time resolution, multi-frequency linear polarization analysis of Very Large Array (VLA) radio observations during some of the brightest radio flaring (~1 Jy) activity of the 2015 outburst of V404 Cygni. The VLA simultaneously captured the radio evolution in two bands (each with two 1 GHz base-bands), recorded at 5/7 GHz and 21/26 GHz, allowing for a broadband polarimetric analysis. Given the source's high flux densities, we were able to measure polarization on timescales of ~13 minutes, constituting one of the highest temporal resolution radio polarimetric studies of a black hole X-ray binary (BHXB) outburst to date. Across all base-bands, we detect variable, weakly linearly polarized emission (<1%) with a single, bright peak in the time-resolved polarization fraction, consistent with an origin in an evolving, dynamic jet component. We applied two independent polarimetric methods to extract the intrinsic electric vector position angles and rotation measures from the 5 and 7 GHz base-band data and detected a variable intrinsic polarization angle, indicative of a rapidly evolving local environment or a complex magnetic field geometry. Comparisons to the simultaneous, spatially-resolved observations taken with the Very Long Baseline Array at 15.6 GHz, do not show a significant connection between the jet ejections and the polarization state.Comment: 24 pages, 9 figures, accepted by MNRA

Precise Measurements of Self-absorbed Rising Reverse Shock Emission from Gamma-ray Burst 221009A

The deaths of massive stars are sometimes accompanied by the launch of highly relativistic and collimated jets. If the jet is pointed towards Earth, we observe a "prompt" gamma-ray burst due to internal shocks or magnetic reconnection events within the jet, followed by a long-lived broadband synchrotron afterglow as the jet interacts with the circum-burst material. While there is solid observational evidence that emission from multiple shocks contributes to the afterglow signature, detailed studies of the reverse shock, which travels back into the explosion ejecta, are hampered by a lack of early-time observations, particularly in the radio band. We present rapid follow-up radio observations of the exceptionally bright gamma-ray burst GRB 221009A which reveal an optically thick rising component from the reverse shock in unprecedented detail both temporally and in frequency space. From this, we are able to constrain the size, Lorentz factor, and internal energy of the outflow while providing accurate predictions for the location of the peak frequency of the reverse shock in the first few hours after the burst.Comment: 11 figures, 4 table