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Abstract The Nucleocapsid protein (N) of SARS-CoV-2 plays a critical role in the viral lifecycle by regulating RNA replication and by packaging the viral genome. N and RNA phase separate to form condensates that may be important for these functions. Both functions occur at membrane surfaces, but how N toggles between these two membrane-associated functional states is unclear. Here, we reveal that phosphorylation switches how N condensates interact with membranes, in part by modulating condensate material properties. Our studies also show that phosphorylation alters N’s interaction with viral membrane proteins. We gain mechanistic insight through structural analysis and molecular simulations, which suggest phosphorylation induces a conformational change in N that softens condensate material properties. Together, our findings identify membrane association as a key feature of N condensates and provide mechanistic insights into the regulatory role of phosphorylation. Understanding this mechanism suggests potential therapeutic targets for COVID infection. 

Oxidative metabolism meets the majority of vertebrate energy demands through the coupling of mitochondrial respiration to ATP production (OXPHOS). In endotherms, variations in OXPHOS coupling efficiency influence metabolic thermogenesis, locomotor economy and reactive oxygen species (ROS) generation. However, the extent of these variations and their functional implications in ectotherms are less clear. We measured mitochondrial oxygen consumption, ATP production and ROS production in permeabilized skeletal muscle fibres from salamanders, frogs and lizards representing ectotherm clades with low, medium and high standard metabolic rates (SMRs), respectively. Consistent with predicted associations with SMR, lizards had the highest capacities for muscle mitochondrial ATP production, while salamanders had the lowest. Unexpectedly, corresponding rates of oxygen consumption followed an opposite trend, reflecting 8.5-fold variations in OXPHOS coupling efficiency between salamanders (the lowest) and lizards (the highest). Intrinsic proton permeability of the inner mitochondrial membrane was the primary source of OXPHOS coupling variation across species, being highest in salamanders and lowest in lizards. Basal proton leak mediated by uncoupling proteins and the adenine nucleotide translocase was only seen in lizards, where it limits mitochondrial ROS production. We infer that diverse evolutionary selection pressures drive unexpectedly wide variations in muscle OXPHOS efficiency with different functional implications across ectotherm clades. 

Abstract Weakened magnetic braking (WMB) was originally proposed in 2016 to explain anomalously rapid rotation in old field stars observed by the Kepler mission. The proximate cause was suggested to be a transition in magnetic morphology from larger to smaller spatial scales. In a series of papers over the past 5 yr, we have collected spectropolarimetric measurements to constrain the large-scale magnetic fields for a sample of stars spanning this transition, including a range of spectral types from late F to early K. During this time, we gradually improved our methods for estimating the wind braking torque in each of our targets, and for evaluating the associated uncertainties. Here, we reanalyze the entire sample with a focus on uniformity for the relevant observational inputs. We supplement the sample with two additional active stars to provide more context for the evolution of wind braking torque with stellar Rossby number (Ro). The results demonstrate unambiguously that standard spin-down models can reproduce the evolution of wind braking torque for active stars, but WMB is required to explain the subsequent abrupt decrease in torque as Ro approaches a critical value for dynamo excitation. This transition is seen in both the large-scale magnetic field and the X-ray luminosity, indicating weakened coronal heating. We interpret these transitions as evidence of a rotational threshold for the influence of Coriolis forces on global convective patterns and the resulting inefficiency of the global stellar dynamo. 

ABSTRACT Collaboration and communication are important competencies for undergraduate life science education, as noted in theVision and Change in Undergraduate Biology Educationreport. However, initiating collaboration and communication in the classroom can be an anxiety-inducing experience for many students. In contrast to traditional-style icebreakers, we introduce a course content-focused icebreaker activity that served as a group-forming undertaking on the first day of class. We developed four sets of handouts (icebreaker tickets), each having a common course theme (e.g., microbiology, cell biology, physiological system infections/disorders, virology). Students were randomly provided with a ticket at the beginning of the course, and they worked to establish groups with their peers, based on their own interpretation of the ticket’s content and rationalization of a grouping scheme. Student feedback and engagement data collected from implementation at three independent institutions were largely positive, where students reported the activity to be an effective tool for building a course content-focused community of learners. The icebreaker tickets and instructor’s notes disseminated in this manuscript can be adapted to fit educators’ course goals and help set the tone for the first day of the class and beyond that fosters communication and collaboration among students. 

p-type Cr2MnO4 with bandgap 3.01 eV was sputter deposited onto (2¯01) and (001) n-type or semi-insulating β-Ga2O3.The heterojunction of p-type CrMnO4 on n-type Ga2O3 is found to be type II, staggered gap, i.e., the band offsets are such that both the conduction and valence band edges of Ga2O3 are lower in energy than those of the Cr2MnO4. This creates a staggered band alignment, which can facilitate the separation of photogenerated electron-hole pairs. The valence band edge of Cr2MnO4 is higher than that of Ga2O3 by 1.82–1.93 eV depending on substrate orientation and doping, which means that holes in Cr2MnO4 would have a lower energy barrier to overcome to move into Ga2O3. Conversely, the conduction band edge of Cr2MnO4 is higher than that of Ga2O3 by 0.13–0.30 eV depending on substrate doping and orientation, which would create a barrier for electrons in Ga2O3 to move into Cr2MnO4. This heterojunction looks highly promising for p-n junction formation for advanced Ga2O3-based power rectifiers.