Decoding RNA Metabolism by RNA-linked CRISPR Screening in Human Cells.

RNAs undergo a complex choreography of metabolic processes in human cells that are regulated by thousands of RNA-associated proteins. While the effects of individual RNA-associated proteins on RNA metabolism have been extensively characterized, the full complement of regulators for most RNA metabolic events remain unknown. Here we present a massively parallel RNA-linked CRISPR (ReLiC) screening approach to measure the responses of diverse RNA metabolic events to knockout of 2,092 human genes encoding all known RNA-associated proteins.

The complex circumstellar environment of supernova 2023ixf.

The early evolution of a supernova (SN) can reveal information about the environment and the progenitor star. When a star explodes in vacuum, the first photons to escape from its surface appear as a brief, hours-long shock-breakout flare, followed by a cooling phase of emission. However, for stars exploding within a distribution of dense, optically thick circumstellar material (CSM), the first photons escape from the material beyond the stellar edge and the duration of the initial flare can extend to several days, during which the escaping emission indicates photospheric heating.

Coordinated missplicing of TMEM14C and ABCB7 causes ring sideroblast formation in SF3B1-mutant myelodysplastic syndrome.

SF3B1 splicing factor mutations are near-universally found in myelodysplastic syndromes (MDS) with ring sideroblasts (RS), a clonal hematopoietic disorder characterized by abnormal erythroid cells with iron-loaded mitochondria. Despite this remarkably strong genotype-to-phenotype correlation, the mechanism by which mutant SF3B1 dysregulates iron metabolism to cause RS remains unclear due to an absence of physiological models of RS formation. Here, we report an induced pluripotent stem cell model of SF3B1-mutant MDS that for the first time recapitulates robust RS formation during in vitro erythroid differentiation.

Why have so many African leaders died of COVID-19?

This paper provides evidence that the COVID-19-related mortality rate of national government ministers and heads of state has been substantially higher than that of people with a similar sex and age profile in the general population, a trend that is driven by African cases (17 out of 24 reported deaths worldwide, as of 6 February 2021). Ministers' work frequently puts them in close contact with diverse groups, and therefore at higher risk of contracting SARS-CoV-2, but this is not specific to Africa. This paper discusses five non-mutually exclusive hypotheses for the Africa-specific trend, involving comorbidity, poorly resourced healthcare and possible restrictions in accessing out-of-country health facilities, the underreporting of cases, and, later, the disproportionate impact of the so-called 'South African' variant (501Y.

SIFTING FOR SAPPHIRES: SYSTEMATIC SELECTION OF TIDAL DISRUPTION EVENTS IN iPTF.

We present results from a systematic selection of tidal disruption events (TDEs) in a wide-area (4800 deg), + band, Intermediate Palomar Transient Factory (iPTF) experiment. Our selection targets typical optically-selected TDEs: bright (>60% flux increase) and blue transients residing in the center of red galaxies. Using photometric selection criteria to down-select from a total of 493 nuclear transients to a sample of 26 sources, we then use follow-up UV imaging with the Neil Gehrels Swift Telescope, ground-based optical spectroscopy, and light curve fitting to classify them as 14 Type Ia supernovae (SNe Ia), 9 highly variable active galactic nuclei (AGNs), 2 confirmed TDEs, and 1 potential core-collapse supernova.

Inhibiting the Evolution of Antibiotic Resistance.

Efforts to battle antimicrobial resistance (AMR) are generally focused on developing novel antibiotics. However, history shows that resistance arises regardless of the nature or potency of new drugs. Here, we propose and provide evidence for an alternate strategy to resolve this problem: inhibiting evolution.

A hot and fast ultra-stripped supernova that likely formed a compact neutron star binary.

Compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. The final stages in the formation of these systems have not been directly observed. We report the discovery of iPTF 14gqr (SN 2014ft), a type Ic supernova with a fast-evolving light curve indicating an extremely low ejecta mass (≈0.

Reflective all-sky thermal infrared cloud imager.

A reflective all-sky imaging system has been built using a long-wave infrared microbolometer camera and a reflective metal sphere. This compact system was developed for measuring spatial and temporal patterns of clouds and their optical depth in support of applications including Earth-space optical communications. The camera is mounted to the side of the reflective sphere to leave the zenith sky unobstructed.

Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star.

Every supernova so far observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. In addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining.

Illuminating gravitational waves: A concordant picture of photons from a neutron star merger.

Merging neutron stars offer an excellent laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of an electromagnetic counterpart (EM170817) with gravitational waves (GW170817) detected from merging neutron stars. By synthesizing a panchromatic data set, we demonstrate that merging neutron stars are a long-sought production site forging heavy elements by r-process nucleosynthesis.

iPTF16geu: A multiply imaged, gravitationally lensed type Ia supernova.

We report the discovery of a multiply imaged, gravitationally lensed type Ia supernova, iPTF16geu (SN 2016geu), at redshift = 0.409. This phenomenon was identified because the light from the stellar explosion was magnified more than 50 times by the curvature of space around matter in an intervening galaxy.

Energetic costs of mange in wolves estimated from infrared thermography.

Parasites, by definition, extract energy from their hosts and thus affect trophic and food web dynamics even when the parasite may have limited effects on host population size. We studied the energetic costs of mange (Sarcoptes scabiei) in wolves (Canis lupus) using thermal cameras to estimate heat losses associated with compromised insulation during the winter. We combined the field data of known, naturally infected wolves with a data set on captive wolves with shaved patches of fur as a positive control to simulate mange-induced hair loss.

Evaluation of efficacy of prion reduction filters using blood from an endogenously infected 263K scrapie hamster model.

Background: The P-Capt prion reduction filter (MacoPharma) removes prion infectivity in model systems. This independent evaluation assesses prion removal from endogenously infected animal blood, using CE-marked P-Capt filters, and replicates the proposed use of the filter within the UK Blood Services.

Study Design And Methods: Two units of blood, generated from 263K scrapie-infected hamsters, were processed using leukoreduction filters (LXT-quadruple, MacoPharma).

A strong ultraviolet pulse from a newborn type Ia supernova.

Type Ia supernovae are destructive explosions of carbon-oxygen white dwarfs. Although they are used empirically to measure cosmological distances, the nature of their progenitors remains mysterious. One of the leading progenitor models, called the single degenerate channel, hypothesizes that a white dwarf accretes matter from a companion star and the resulting increase in its central pressure and temperature ignites thermonuclear explosion.

Visible and invisible mirages: comparing inferior mirages in the visible and thermal infrared.

Visible (VIS)-light and thermal infrared (IR) inferior mirages in the 8-14 μm waveband have been observed simultaneously for the takeoff and landing of various airplanes at distances of several kilometers. Similarities as well as differences between the VIS and IR mirages are discussed.

Infrared Moon imaging for remote sensing of atmospheric smoke layers.

Simultaneous visible and long-wave infrared (IR) images of the Moon were used with a simple energy-balance model to study the spatial pattern of lunar surface temperatures. The thermal images were obtained with a radiometrically calibrated, compact, low-cost, commercial IR camera mounted on a small telescope. Differences between the predicted and measured maximum Moon temperatures were used to determine the infrared optical depth (OD), which represents the path-integrated extinction of an elevated layer of wildfire smoke in the atmosphere.

Colors of thermal pools at Yellowstone National Park.

The brilliant visible colors of various hot springs and pools in Yellowstone National Park are explained with a combination of scattering from the water and from microbial mats that coat the bottoms of these thermal features. A simple 1D radiative transfer model was used to simulate the colors recorded in visible photographs and the spectrum of light making up these colors. The model includes attenuation in water by absorption and molecular scattering as well as reflection characteristics of the microbial mats and surface reflection of the water.

An underlying mechanism for the increased mutagenesis of lagging-strand genes in Bacillus subtilis.

We previously reported that lagging-strand genes accumulate mutations faster than those encoded on the leading strand in Bacillus subtilis. Although we proposed that orientation-specific encounters between replication and transcription underlie this phenomenon, the mechanism leading to the increased mutagenesis of lagging-strand genes remained unknown. Here, we report that the transcription-dependent and orientation-specific differences in mutation rates of genes require the B.

Intracellular calcium regulates nonsense-mediated mRNA decay.

The nonsense-mediated mRNA decay (NMD) pathway selectively eliminates aberrant transcripts containing premature translation termination codons and regulates the levels of a number of physiological mRNAs. NMD modulates the clinical outcome of a variety of human diseases, including cancer and many genetic disorders, and may represent a target for therapeutic intervention. Here, we have developed a new multicolored bioluminescence-based reporter system that can specifically and effectively assay NMD in live human cells.

Crystalline and quasicrystalline allotropes of Pb formed on the fivefold surface of icosahedral Ag-In-Yb.

Crystalline and quasicrystalline allotropes of Pb are formed by evaporation on the fivefold surface of the icosahedral (i) Ag-In-Yb quasicrystal under ultra-high vacuum. Lead grows in three dimensional quasicrystalline order and subsequently forms fivefold-twinned islands with the fcc(111) surface orientation atop of the quasicrystalline Pb. The islands exhibit specific heights (magic heights), possibly due to the confinement of electrons in the islands.

Hemodynamic correlates of drug-induced vascular injury in the rat using high-frequency ultrasound imaging.

Several classes of drugs have been shown to cause drug-induced vascular injury (DIVI) in preclinical toxicity studies. Measurement of blood flow and vessel diameter in numerous vessels and across various tissues by ultrasound imaging has the potential to be a noninvasive translatable biomarker of DIVI. Our objective was to demonstrate the utility of high-frequency ultrasound imaging for measuring changes in vascular function by evaluating blood flow and vessel diameter in the superior mesenteric arteries (SMA) of rats treated with compounds that are known to cause DIVI and are known vasodilators in rat: fenoldopam, CI-1044, and SK&F 95654.

Recombinant antigens based on toxins A and B of Clostridium difficile that evoke a potent toxin-neutralising immune response.

Infection with the bacterium Clostridium difficile causes symptoms ranging from mild to severe diarrhoea with life-threatening complications and remains a significant burden to healthcare systems throughout the developed world. Two potent cytotoxins, TcdA and TcdB are the prime mediators of the syndrome and rapid neutralisation of these would afford significant benefits in disease management. In the present study, a broad range of non-toxic, recombinant fragments derived from TcdA and TcdB were designed for soluble expression in E.