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Point-scanning imaging systems are among the most widely used tools for high-resolution cellular and tissue imaging, benefiting from arbitrarily defined pixel sizes. The resolution, speed, sample preservation and signal-to-noise ratio (SNR) of point-scanning systems are difficult to optimize simultaneously. We show these limitations can be mitigated via the use of deep learning-based supersampling of undersampled images acquired on a point-scanning system, which we term point-scanning super-resolution (PSSR) imaging. We designed a ‘crappifier’ that computationally degrades high SNR, high-pixel resolution ground truth images to simulate low SNR, low-resolution counterparts for training PSSR models that can restore real-world undersampled images. For high spatiotemporal resolution fluorescence time-lapse data, we developed a ‘multi-frame’ PSSR approach that uses information in adjacent frames to improve model predictions. PSSR facilitates point-scanning image acquisition with otherwise unattainable resolution, speed and sensitivity. All the training data, models and code for PSSR are publicly available at 3DEM.org.Point-scanning super-resolution imaging uses deep learning to supersample undersampled images and enable time-lapse imaging of subcellular events. An accompanying ‘crappifier’ rapidly generates quality training data for robust performance.

Pathological obesity can result from genetic predisposition, obesogenic diet, and circadian rhythm disruption. Obesity compromises function of muscle, which accounts for a majority of body mass. Behavioral intervention that can counteract obesity arising from genetic, diet or circadian disruption and can improve muscle function holds untapped potential to combat the obesity epidemic. Here we show that Drosophila melanogaster (fruit fly) subject to obesogenic challenges exhibits metabolic disease phenotypes in skeletal muscle; sarcomere disorganization, mitochondrial deformation, upregulation of Phospho-AKT level, aberrant intramuscular lipid infiltration, and insulin resistance. Imposing time-restricted feeding (TRF) paradigm in which flies were fed for 12 h during the day counteracts obesity-induced dysmetabolism and improves muscle performance by suppressing intramuscular fat deposits, Phospho-AKT level, mitochondrial aberrations, and markers of insulin resistance. Importantly, TRF was effective even in an irregular lighting schedule mimicking shiftwork. Hence, TRF is an effective dietary intervention for combating metabolic dysfunction arising from multiple causes. Time-restricted feeding (TRF) has beneficial metabolic effects. Here the authors examine how TRF impacts muscle physiology using fly models of metabolically adverse conditions, including diet and genetic models of obesity as well as circadian rhythm disruption, and find that TRF ameliorates skeletal muscle dysfunction.

This historical opinion article draws parallels between mid-20th-century psychiatric deinstitutionalization and today's rapid expansion of home-based medical care. While psychiatric conditions differ fundamentally from acute medical illnesses, lessons from deinstitutionalization can inform current and future telemedicine models. Deinstitutionalization resulted from social, legal, and pharmaceutical advances but also produced unforeseen consequences, including increased incarceration, homelessness, medication misuse, and significant family burden. Similarly, shifting acute care to the home may expose patients and caregivers to new stresses: elevated risk of medical complications, uneven access to technology, cost-shifting, and the potential neglect of those most vulnerable or socially disadvantaged. Historical patterns show that successful community-based care demands strong infrastructure, equitable resource allocation, and thorough patient selection. This manuscript urges stakeholders to heed these lessons and build robust, multidisciplinary, and family-centered systems to support patients transitioning to home care. With proper planning, the current dehospitalization process can achieve its promise of high-quality, cost-effective care without repeating the pitfalls of past reforms.

Cell polarity is fundamental to the development of both eukaryotes and prokaryotes, yet the mechanisms behind its formation are not well understood. Here we found that, phytohormone auxin-induced, sterol-dependent nanoclustering of cell surface transmembrane receptor kinase 1 (TMK1) is critical for the formation of polarized domains at the plasma membrane (PM) during the morphogenesis of cotyledon pavement cells (PC) in Arabidopsis . Auxin-induced TMK1 nanoclustering stabilizes flotillin1-associated ordered nanodomains, which in turn promote the nanoclustering of ROP6 GTPase that acts downstream of TMK1 to regulate cortical microtubule organization. In turn, cortical microtubules further stabilize TMK1- and flotillin1-containing nanoclusters at the PM. Hence, we propose a new paradigm for polarity formation: A diffusive signal triggers cell polarization by promoting cell surface receptor-mediated nanoclustering of signaling components and cytoskeleton-mediated positive feedback that reinforces these nanodomains into polarized domains. The significance of protein nanoclustering in cell polarization is unclear. Here Pan et al. show that auxin-induced TMK1/sterol nanoclustering as well as microtubule-based positive feedback regulation of the TMK1/sterol nanoclusters is critical for cell polarity formation in Arabidopsis.

Mitochondria are crucial for cellular metabolism and signalling. Mitochondrial activity is modulated by mitochondrial fission and fusion, which are required to properly balance metabolic functions, transfer material between mitochondria, and remove defective mitochondria. Mitochondrial fission occurs at mitochondria-endoplasmic reticulum (ER) contact sites, and requires the formation of actin filaments that drive mitochondrial constriction and the recruitment of the fission protein DRP1. The role of actin in mitochondrial fusion remains entirely unexplored. Here we show that preventing actin polymerisation on either mitochondria or the ER disrupts both fission and fusion. We show that fusion but not fission is dependent on Arp2/3, whereas both fission and fusion require INF2 formin-dependent actin polymerization. We also show that mitochondria-associated actin marks fusion sites prior to the fusion protein MFN2. Together, our work introduces a method for perturbing organelle-associated actin and demonstrates a previously unknown role for actin in mitochondrial fusion. The actin cytoskeleton is crucial for cell and organelle motility. Here, the authors show that actin acts upstream of the mitochondrial fusion machinery to bridge two fusing mitochondria.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Ferroptosis is a form of cell death that results from the catastrophic accumulation of lipid reactive oxygen species (ROS). Oncogenic signaling elevates lipid ROS production in many tumor types and is counteracted by metabolites that are derived from the amino acid cysteine. In this work, we show that the import of oxidized cysteine (cystine) via system xC⁻ is a critical dependency of pancreatic ductal adenocarcinoma (PDAC), which is a leading cause of cancer mortality. PDAC cells used cysteine to synthesize glutathione and coenzyme A, which, together, down-regulated ferroptosis. Studying genetically engineered mice, we found that the deletion of a system xC⁻ subunit, Slc7a11, induced tumor-selective ferroptosis and inhibited PDAC growth. This was replicated through the administration of cyst(e)inase, a drug that depletes cysteine and cystine, demonstrating a translatable means to induce ferroptosis in PDAC.

Mitochondrial division, essential for survival in mammals, is enhanced by an inter-organellar process involving ER tubules encircling and constricting mitochondria. The force for constriction is thought to involve actin polymerization by the ER-anchored isoform of the formin protein inverted formin 2 (INF2). Unknown is the mechanism triggering INF2-mediated actin polymerization at ER-mitochondria intersections. We show that a novel isoform of the formin-binding, actin-nucleating protein Spire, Spire1C, localizes to mitochondria and directly links mitochondria to the actin cytoskeleton and the ER. Spire1C binds INF2 and promotes actin assembly on mitochondrial surfaces. Disrupting either Spire1C actin- or formin-binding activities reduces mitochondrial constriction and division. We propose Spire1C cooperates with INF2 to regulate actin assembly at ER-mitochondrial contacts. Simulations support this model's feasibility and demonstrate polymerizing actin filaments can induce mitochondrial constriction. Thus, Spire1C is optimally positioned to serve as a molecular hub that links mitochondria to actin and the ER for regulation of mitochondrial division. Mitochondria are structures within cells that provide the energy to power many biological processes that are essential for complex life. These structures are also highly dynamic and go through cycles of fission (in which a single mitochondrion splits in two) and fusion (in which two mitochondria merge into one). These processes both maintain the correct number of mitochondria in a cell and remove damaged ones, and defects in either can result in many diseases. Previous research had shown that mitochondria are in close contact with another cellular structure called the endoplasmic reticulum. The points of contact mark the sites where mitochondria undergo fission, as small tubes of the endoplasmic reticulum wrap around, and then constrict, to split a mitochondrion. Other recent work revealed that a protein called INF2 is anchored on the endoplasmic reticulum where it promotes mitochondrial constriction. This protein builds actin subunits into long filaments that provide the force for constriction. However, it was not clear how INF2 became active, and whether there are proteins on mitochondria that interact with INF2 or actin. Manor, Bartholomew et al. have now used a combination of microscopy-based methods and biochemical analysis to discover that a mitochondrial protein called Spire1C performs all of these roles. Spire1C is found on the outer membrane of mitochondria; it interacts with INF2 to drive the formation of actin filaments that constrict mitochondria. These results suggest that Spire1C bridges the endoplasmic reticulum with the network of actin filaments. Further experiments then showed that increasing Spire1C levels in cells resulted in the mitochondria becoming fragmented due to increased constriction. On the other hand, depleting Spire1C had the opposite effect and caused mitochondria to become unusually elongated. Following on from this work, the next challenge is to see if Spire1C is used differently or similarly in the different processes that involve mitochondrial fission.

We present an auxiliary learning task for the problem of neuron segmentation in electron microscopy volumes. The auxiliary task consists of the prediction of local shape descriptors (LSDs), which we combine with conventional voxel-wise direct neighbor affinities for neuron boundary detection. The shape descriptors capture local statistics about the neuron to be segmented, such as diameter, elongation, and direction. On a study comparing several existing methods across various specimen, imaging techniques, and resolutions, auxiliary learning of LSDs consistently increases segmentation accuracy of affinity-based methods over a range of metrics. Furthermore, the addition of LSDs promotes affinity-based segmentation methods to be on par with the current state of the art for neuron segmentation (flood-filling networks), while being two orders of magnitudes more efficient—a critical requirement for the processing of future petabyte-sized datasets. During segmentation of neurons in electron microscopy datasets, auxiliary learning via the prediction of local shape descriptors increases efficiency, which is important for the processing of datasets of ever-increasing size.

Background and Aims Empathy improves clinical outcomes, patient satisfaction, and adherence to treatment. Few studies have explored the real-world use of large language models in conveying empathy. We compared the empathy in emergency department (ED) discharge letters written by GPT-4 and physicians. Methods We conducted a retrospective, blinded, comparative study in a tertiary ED. All patients discharged for one 8-h shift were included. For each patient, we compared the original ED discharge letter to a GPT-4 generated letter. GPT-4 generated the letters using ED notes, excluding the original discharge letter. Seventeen evaluators (seven physicians, five nurses, five patients) compared the letters side by side. They were blinded to the source. Evaluators first chose between the AI and human letters. Then they rated each letter for empathy, overall quality, clarity of summary, and clarity of recommendations using a 5-point Likert scale. Results Evaluators preferred GPT-4 over physician letters in 83.7% of comparisons (1009 vs. 197; p < 0.001). GPT-4 letters received higher scores for empathy (median 4.0 vs. 3.0; p < 0.001), overall quality, and clarity of summary across all evaluator groups. Among patients, no significant difference was found in the clarity of recommendations (p = 0.771). Qualitative analysis showed that GPT-4's empathetic expressions, though sometimes generic, were perceived as effective. Conclusion GPT-4 shows strong potential in generating empathetic ED discharge letters. These letters are preferred by healthcare professionals and patients. GPT-4 offers a promising tool to reduce the workload of ED physicians. Further research is necessary to explore patient perceptions and best practices for integrating AI with physicians in clinical practice.