The RAG1 Ubiquitin Ligase Domain Enhances Assembly and Selection of T Cell Receptor Genes to Restrain the Autoimmune Hazard of Generating T Cell Receptor Diversity RAG1/RAG2 (RAG) endonuclease-mediated assembly of diverse lymphocyte antigen receptor genes by V(D)J recombination is critical for the development and immune function of T and B cells. However, this process creates highly self-reactive cells that must be properly selected to suppress autoimmunity. The RAG1 protein contains a ubiquitin ligase domain that stabilizes RAG1 and stimulates RAG endonuclease activity in vitro. We report that mice with a mutation that inactivates the RAG1 ubiquitin ligase in vitro exhibit modestly reduced thymic cellularity, decreased assembly and altered repertoires of T cell receptor (TCR) {beta} and  genes in thymocytes, and impaired thymocyte developmental transitions that require the assembly of TCR{beta} or  genes and signaling by their proteins. These RAG1 mutant mice also exhibit less efficient positive selection and superantigen-mediated negative selection of conventional {beta} T cells, 2) impaired differentiation of iNKT lineage {beta} T cells, and 3) CD4+ {beta} T cells with elevated autoimmune potential. Our findings demonstrate that the RAG1 ubiquitin ligase domain functions in vivo to stimulate the assembly and selection of TCR{beta} and TCR genes, thereby establishing replete diversity of {beta} TCRs and {beta} T cell lineages while restraining the inherent autoimmune hazard of generating diverse antigen specificities.
Ensovibep, a novel trispecific DARPin candidate that protects against SARS-CoV-2 variants SARS-CoV-2 has infected millions of people globally and continues to undergo evolution. Emerging variants can be partially resistant to vaccine induced immunity and therapeutic antibodies, emphasizing the urgent need for accessible, broad-spectrum therapeutics. Here, we report a comprehensive study of ensovibep, the first trispecific clinical DARPin candidate, that can simultaneously engage all three units of the spike protein trimer to potently inhibit ACE2 interaction, as revealed by structural analyses. The cooperative binding of the individual modules enables ensovibep to retain inhibitory potency against all frequent SARS-CoV-2 variants, including Omicron BA.1 and BA.2, as of February 2022. Moreover, viral passaging experiments show that ensovibep, when used as a single agent, can prevent development of escape mutations comparably to a cocktail of monoclonal antibodies (mAb). Finally, we demonstrate that the very high in vitro antiviral potency also translates into significant therapeutic protection and reduction of pathogenesis in Roborovski dwarf hamsters infected with either the SARS-CoV-2 wild-type or the Alpha variant. In this model, ensovibep prevents fatality and provides substantial protection equivalent to the standard of care mAb cocktail. These results support further clinical evaluation and indicate that ensovibep could be a valuable alternative to mAb cocktails and other treatments for COVID-19.
Sex determination gene transformer regulates the male-female difference in Drosophila fat storage via the adipokinetic hormone pathway Sex differences in whole-body fat storage exist in many species. For example, Drosophila females store more fat than males. Yet, the mechanisms underlying this sex difference in fat storage remain incompletely understood. Here, we identify a key role for sex determination gene transformer (tra) in regulating the male-female difference in fat storage. Normally, a functional Tra protein is present only in females, where it promotes female sexual development. We show that loss of Tra in females reduced whole-body fat storage, whereas gain of Tra in males augmented fat storage. Tras role in promoting fat storage was largely due to its function in neurons, specifically the Adipokinetic hormone (Akh)-producing cells (APCs). Our analysis of Akh pathway regulation revealed a male bias in APC activity and Akh pathway function, where this sex-biased regulation influenced the sex difference in fat storage by limiting triglyceride accumulation in males. Importantly, Tra loss in females increased Akh pathway activity, and genetically manipulating the Akh pathway rescued Tra-dependent effects on fat storage. This identifies sex-specific regulation of Akh as one mechanism underlying the male-female difference in whole-body triglyceride levels, and provides important insight into the conserved mechanisms underlying sexual dimorphism in whole-body fat storage. Herbivore life histories are altered by drought stress in their hosts plants Drought associated with climate change can stress plants, altering their interactions with phytophagous arthropods. Dryness not only impacts cultivated plants but also their parasites, which in some cases are favoured by drought. Herbivorous arthropods feeding on drought-stressed plants typically produce bigger offspring and develop faster. However, how much responses to abiotic factors differ among populations of a species remains poorly documented. Here, we evaluate variability among populations of a major agricultural pest, the two spotted spider mite, Tetranychus urticae, in response to drought-stress. We compare key life-history parameters of twelve populations that originate from climates ranging from wet and cool Atlantic locations to medium to dry hot Mediterranean locations. We evaluated how plant drought stress affects four life history traits: development time, fecundity, sex-ratio and emigration rate in an experiment comparing well-watered and drought-stressed bean plants. Mites feeding on drought-stressed plants developed faster and attempted to leave leaves less often, and young females were more fecund. The mites from wet temperate climates exhibited greater plasticity between the two water regimes than mites originating from dryer and hot climates. Thus, climate in the area of origin influences mite response to drought. PIN-FORMED1 polarity in the shoot is insensitive to the polarity of neighbouring cells In plants, epidermal cells are planar-polarized along an axis marked by the asymmetric localization patterns of several proteins including PIN-FORMED1 (PIN1), which facilitates the directional efflux of the plant hormone auxin to pattern phyllotaxis (Heisler et al., 2010; Mansfield et al., 2018; Reinhardt et al., 2003). While PIN1 polarity is known to be regulated non-cell autonomously via the MONOPTEROS (MP) transcription factor, how this occurs has not been determined (Bhatia et al., 2016). Here we use mosaic expression of the serine threonine kinase PINOID (PID) to test whether PIN1 polarizes according to the polarity of neighbouring cells. Our findings reveal that PIN1 is insensitive to the polarity of PIN1 in neighbouring cells arguing against auxin flux or extracellular auxin concentrations acting as a polarity cue, in contrast to previous model proposals (Abley et al., 2016; Stoma et al., 2008). Onset and kinetics of B cell polarization depend on substrate mechanics and antigen concentration The immune synapse is the tight contact zone between a lymphocyte and a cell presenting its cognate antigen. This structure serves as a signaling platform and entails a polarization of intra-cellular components, necessary to the immunological function of the cell. While the surface properties of the presenting cell are known to control the formation of the synapse, their impact on polarization has not yet been studied.

Using functional lipid droplets as tunable artificial presenting cells combined with a microfluidic pairing device, we simultaneously observe synchronized synapses and dynamically quantify polarization patterns of individual B cells. By assessing how the ligand concentration, the surface fluidity and the substrate rigidity impact this polarization, we show that its onset depends on the antigen concentration at the synapse, and that the substrate rigidity controls both its onset and its kinetics. Our experimental system enables a fine phenotyping of monoclonal cell populations based on their synaptic readout.

Significance statementTo fulfill their immune function, B cells acquire antigens presented on the surface of antigen-presenting cells and organize their cytoskeleton and lysosomal traffic towards the contact. The polarization mechanism is evolutionary conserved, making the system interesting both from the immunology and the cell biology point of view. We developed and finely characterized antigen-coated droplets as surrogate presenting cells with a physiological-flow microfluidic cell-pairing chip to explore the B cell lysosome polarization in response to changes in droplet mechanics and antigen concentration. We observed that polarization is sensitive to mechanical properties (responding more strongly but less fast on stiffer substrates) and to the local antigen concentration at the contact. Hence, surprisingly, a late cell response is sensitive to the mechanics of the contact. Synthetic periphyton as a model system to understand species dynamics in complex microbial freshwater communities Phototrophic biofilms, also known as periphyton, are microbial freshwater communities that drive crucial ecological processes in streams and lakes. Gaining a deep mechanistic understanding of the biological processes occurring in natural periphyton remains challenging due to the high complexity and variability of such communities. To address this challenge, we rationally developed a workflow to construct a synthetic community by co-culturing 26 phototrophic species (i.e., diatoms, green algae and cyanobacteria) that were inoculated in a successional sequence to create a periphytic biofilm on glass slides. We show that this community is diverse, stable and highly reproducible in terms of microbial composition, function and 3D spatial structure of the biofilm. We also demonstrate the ability to monitor microbial dynamics at the single species level during periphyton development and how their abundances are impacted by stressors such as increased temperature and a herbicide, singly and in combination. Overall, such a synthetic periphyton, grown under controlled conditions, can be used as a model system for theory testing through targeted manipulation. Glucose inhibits haemostasis and accelerates diet-induced hyperlipidaemia in zebrafish larvae Hyperglycaemia damages the microvasculature in part through the reduced recruitment of immune cells and interference with platelet signalling, leading to poor wound healing and accelerated lipid deposition in mammals. We investigated the utility of zebrafish larvae to model the effect of glucose on neutrophil and macrophage recruitment to a tail wound, wound-induced haemostasis, and chicken egg yolk feed challenge-induced hyperlipidaemia by supplementing larvae with exogenous glucose by immersion or injection. Neither method of glucose supplementation affected the recruitment of neutrophils and macrophages following tail transection. Glucose injection reduced thrombocyte retention and fibrin plug formation while only thrombocyte retention was reduced by glucose immersion following tail transection. We observed accelerated lipid accumulation in glucose-injected larvae challenged with high fat chicken egg yolk feeding. Our study identifies conserved and divergent effects of high glucose on inflammation, haemostasis, and hyperlipidaemia in zebrafish larvae compared to mammals. The Digital Brain Bank, an open access platform for post-mortem datasets Post-mortem MRI provides the opportunity to acquire high-resolution datasets to investigate neuroanatomy, and validate the origins of image contrast through microscopy comparisons. We introduce the Digital Brain Bank (open.win.ox.ac.uk/DigitalBrainBank), a data release platform providing open access to curated, multimodal post-mortem neuroimaging datasets. Datasets span three themes - Digital Neuroanatomist: datasets for detailed neuroanatomical investigations; Digital Brain Zoo: datasets for comparative neuroanatomy; Digital Pathologist: datasets for neuropathology investigations. The first Digital Brain Bank release includes twenty one distinctive whole-brain diffusion MRI datasets for structural connectivity investigations, alongside microscopy and complementary MRI modalities. This includes one of the highest-resolution whole-brain human diffusion MRI datasets ever acquired, whole-brain diffusion MRI in fourteen non-human primate species, and one of the largest post-mortem whole-brain cohort imaging studies in neurodegeneration. The Digital Brain Bank is the culmination of our labs investment into post-mortem MRI methodology and MRI-microscopy analysis techniques. This manuscript provides a detailed overview of our work with post-mortem imaging to date, including the development of diffusion MRI methods to image large post-mortem samples, including whole, human brains. Taken together, the Digital Brain Bank provides crossscale, cross-species datasets facilitating the incorporation of post-mortem data into neuroimaging studies. The BAF A12T mutation associated with premature aging impedes lamin A/C recruitment to sites of nuclear rupture, contributing to nuclear envelope fragility. The premature aging disorder Nestor Guillermo Progeria Syndrome (NGPS) is caused by a homozygous Alanine to Threonine mutation at position 12 (A12T) in Barrier-to- Autointegration Factor (BAF). BAF is a small essential protein that binds to DNA and nuclear envelope proteins. It contributes to important cellular processes including transcription regulation and nuclear envelope reformation after mitosis. More recently, BAF was identified as an important factor for nuclear envelope repair upon rupture in interphase. However, the mechanism by which the BAF A12T mutation causes NGPS has remained unclear. To investigate the effects of this mutation on nuclear envelope integrity, we used NGPS-derived patient cells and engineered an isogenic cell line by reversing the BAF A12T homozygous mutation using CRISPR/Cas9. Using a combination of cellular models, structural data and in vitro assays, we identified that the A12T mutation reduces the affinity of BAF for lamin A/C by tenfold. As a result, BAF A12T is unable to recruit lamin A/C to sites of nuclear envelope rupture. This leads to persistent lamin A/C gaps at sites of ruptures, and contributes to nuclear fragility in NGPS patient cells, which show increased frequency of nuclear envelope re- rupturing. Overexpression of wild-type BAF in a NGPS context rescues lamin A/C recruitment to sites of nuclear rupture, which could explain why the heterozygous A12T mutation does not cause premature aging. Feedforward regulatory logic underlies robustness of the specification-to-differentiation transition and fidelity of terminal cell fate during C. elegans endoderm development Development is driven by gene regulatory networks (GRNs) that progressively dictate specification and differentiation of cell fates. The architecture of GRNs directly determines the specificity and accuracy of developmental outcomes. We report here that the core regulatory circuitry for endoderm development in C. elegans is comprised of a recursive series of interlocked feedforward modules linking a cascade of six sequentially expressed GATA-type transcription factors. This structure results in a reiterated sequential redundancy, in which removal of a single factor or alternate factors in the cascade results in no, or a mild, effect on endoderm development and gut differentiation, while elimination of any two factors that are sequentially deployed in the cascade invariably results in a strong phenotype. The strength of the observed phenotypes is successfully predicted by a computational model based on the timing and levels of transcriptional states. The feedforward regulatory logic in the GRN appears to ensure timely onset of terminal differentiation genes and allows rapid and robust lockdown of cell fate during early embryogenesis. We further found that specification-to-differentiation transition is linked through a common regulator, the END-1 GATA factor that straddles the two processes. Finally, we revealed roles for key GATA factors in establishing spatial regulatory state domains by acting as transcriptional repressors that appear to define the boundaries of the digestive tract. Our findings support a comprehensive model of the core gene network that describes how robust endoderm development is achieved during C. elegans embryogenesis.

Graphic abstract

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=65 SRC="FIGDIR/small/457588v2_ufig1.gif" ALT="Figure 1">
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org.highwire.dtl.DTLVardef@8515d6org.highwire.dtl.DTLVardef@15ca234org.highwire.dtl.DTLVardef@9d0fe7org.highwire.dtl.DTLVardef@17f28db_HPS_FORMAT_FIGEXP  M_FIG C_FIG The ribose methylation enzyme FTSJ1 has a conserved role in neuron morphology and learning performance FTSJ1 is a conserved human 2-O-methyltransferase (Nm-MTase) that modifies several transfer RNAs (tRNAs) at position 32 and the wobble position 34 in the AntiCodon Loop (ACL). Its loss of function has been linked to Non-Syndromic X-Linked Intellectual Disability (NSXLID), and more recently to cancers. However, the molecular mechanisms underlying these pathologies are currently unclear. Here we report a novel FTSJ1 pathogenic variant from a NSXLID patient. Using blood cells derived from this patient and other affected individuals carrying FTSJ1 mutations, we performed an unbiased and comprehensive RiboMethSeq analysis to map the ribose methylation (Nm) on all tRNAs and identify novel targets. In addition, we performed a transcriptome analysis in these cells and found that several genes previously associated with intellectual disability and cancers were deregulated. We also found changes in the miRNA population that suggest potential cross-regulation of some miRNAs with these key mRNA targets. Finally, we show that differentiation of FTSJ1-depleted human neuronal progenitor cells (NPC) into neurons displays long and thin spine neurites compared to control cells. These defects are also observed in Drosophila and are associated with long term memory deficit in this organism. Altogether, our study adds insight into FTSJ1 pathologies in human by the identification of novel FTSJ1 targets and the defect in neuron morphology. TCF11 Has a Potent Tumor-Repressing Effect than Its Prototypic Nrf1α by Definition of both Similar yet Different Regulatory Profiles, with a Striking Disparity from Nrf2 Nrf1 and Nrf2, as two principal CNC-bZIP transcription factors, regulate similar but different targets involved in a variety of biological functions for maintaining cell homeostasis and organ integrity. Of note, the unique topobiological behavior of Nrf1 makes its functions more complicated than Nrf2, because it is allowed for alternatively transcribing and selectively splicing to yield multiple isoforms (e.g., TCF11, Nrf1). In order to gain a better understanding of their similarities and differences in distinct regulatory profiles, all four distinct cell models for stably expressing TCF11, TCF11{Delta}N, Nrf1 or Nrf2 have been herein established by an Flp-In T-REx-293 system and then identified by transcriptomic sequencing. Further analysis revealed that Nrf1 and TCF11 have similar yet different regulatory profiles, although both contribute basically to positive regulation of their co-targets, which are disparate from those regulated by Nrf2. Such disparity in those gene regulation by Nrf1 and Nrf2 was further corroborated by scrutinizing comprehensive functional annotation of their specific and/or common target genes. Conversely, the mutant TCF11{Delta}N, resulting from a deletion of the N-terminal amino acids 2-156 from TCF11, resembles Nrf2 with the largely consistent structure and function. Interestingly, our further experimental evidence demonstrates that TCF11 acts as a potent tumor-repressor relative to Nrf1, albeit both isoforms possess a congruous capability to prevent malignant growth of tumor and upregulate those genes critical for improving the survival of patients with hepatocellular carcinoma. A unified mechanism for innate and learned visual landmark guidance in the insect central complex Insects can navigate efficiently in both novel and familiar environments, and this requires flexiblity in how they are guided by sensory cues. A prominent landmark, for example, can ellicit strong innate behaviours (attraction or menotaxis) but can also be used, after learning, as a specific directional cue as part of a navigation memory. However, the mechanisms that allow both pathways to co-exist, interact or override each other are largely unknown. Here we propose a model for the behavioural integration of innate and learned guidance based on the neuroanatomy of the central complex (CX), adapted to control landmark guided behaviours. We consider a reward signal provided either by an innate attraction to landmarks or a long-term visual memory in the mushroom bodies (MB) that modulates the formation of a local vector memory in the CX. Using an operant strategy for a simulated agent exploring a simple world containing a single visual cue, we show how the generated short-term memory can support both innate and learned steering behaviour. In addition, we show how this architecture is consistent with the observed effects of unilateral MB lesions in ants that cause a reversion to innate behaviour. We suggest the formation of a directional memory in the CX can be interpreted as transforming rewarding (positive or negative) sensory signals into a mapping of the environment that describes the geometrical attractiveness (or repulsion). We discuss how this scheme might represent an ideal way to combine multisensory information gathered during the exploration of an environment and support optimized cue integration.

1 Author summaryIn this paper, we modeled the neural pathway allowing insects to perform landmark guided behaviours using their internal compass. First, we observed the intrinsic property of the connectome, extracted from drosophila online database, between the internal compass neurons and the steering neurons to support an oriented behaviour towards a single landmark. Then, we proposed and evaluated an adaptation of the bees path integration neural circuit, to sustain flexible landmark guidance behaviours such as attraction or menotaxis. We showed the model ability to form a memory during the exploration of the local environment to support both innate or learned navigation behaviour using a single landmark in the environment. In addtion, we demonstrated the transformation of a simple goodness/badness signal, from innate or long-term memory pathways, into an oriented steering signal that could be applied to other sensory pathways. Furthermore, by reproducing lesion experiments in the mushroom bodies of wood ants we highlight the consistency of the model with biological observation. We then discuss the different emergent properties and the potential outcome that this local, and operant, memory supports. An Evolutionary Process Without Variation and Selection Natural selection successfully explains how organisms accumulate adaptive change despite that traits acquired over a lifetime are eliminated at the end of each generation. However, in some domains that exhibit cumulative, adaptive change--e.g., cultural evolution, and earliest life--acquired traits are retained; these domains do not face the problem that Darwins theory was designed to solve. Lack of transmission of acquired traits occurs when germ cells are protected from environmental change, due to a self-assembly code used in two distinct ways: (i) actively interpreted during development to generate a soma, and (ii) passively copied without interpretation during reproduction to generate germ cells. Early life and cultural evolution appear not to involve a self-assembly code used in these two ways. We suggest that cumulative, adaptive change in these domains is due to a lower-fidelity evolutionary process, and model it using Reflexively Autocatalytic and Foodset-generated networks. We refer to this more primitive evolutionary process as Self-Other Reorganisation (SOR) because it involves internal self-organising and self-maintaining processes within entities, as well as interaction between entities. SOR encompasses learning but in general operates across groups. We discuss the relationship between SOR and Lamarckism, and illustrate a special case of SOR without variation. From adverse to beneficial - contrasting dietary effects of freshwater mixotrophs on zooplankton O_LIThe importance of mixotrophic algae as key bacterivores in microbial food webs is increasingly acknowledged, but their effects on the next trophic level remain poorly understood. Their high stoichiometric food quality is contrasted by anti-grazing strategies.
C_LIO_LIWe tested the quality of freshwater mixotrophs as prey for zooplankton, using four non-colonial chrysophyte species and a cryptophyte as a high quality reference food. We (1) analyzed the stoichiometric and biochemical (fatty acid) composition of the mixotrophs, and (2) quantified their dietary effects on Daphnia longispina survival.
C_LIO_LISurvival of D. longispina significantly depended on the identity of species provided as food, ranging from higher to lower as compared to starvation. This was not reflected in differences in cellular stoichiometry or fatty acid profiles of the mixotrophs. We suggest that toxicity may be the driver for the observed differences.
C_LIO_LIGeneralization of the dietary effects of mixotrophic chrysophytes does not appear straightforward. Besides fundamental species-specific differences, potential toxic effects may vary depending on environmental cues or physiological strategies. Notably in our study, Ochromonas tuberculata, a species previously reported to be deleterious turned out to be a beneficial food source, in terms of enabling high survival of D. longispina.
C_LIO_LIWe challenge the generality of the assumption that chrysophytes are of low value as food for zooplankton. We recommend that future studies test how environmental conditions and physiological strategies shape the quality of mixotrophs as food for consumers at higher trophic levels, specifically focusing on effects of dietary toxicity.
C_LI Induction of exaggerated cytokine production in human peripheral blood mononuclear cells by a recombinant SARS-CoV-2 spike glycoprotein S1 and its inhibition by dexamethasone An understanding of the pathological inflammatory mechanisms involved in SARS-CoV-2 virus infection is necessary in order to discover new molecular pharmacological targets for SARS-CoV-2 cytokine storm. In this study, the effects of a recombinant SARS-CoV-2 spike glycoprotein S1 was investigated in human peripheral blood mononuclear cells (PBMCs). Stimulation of PBMCs with spike glycoprotein S1 (100 ng/mL) resulted in significant elevation in the production of TNF, IL-6, IL-1{beta} and IL-8. However, pre-treatment with dexamethasone (100 nM) caused significant reduction in the release of these cytokines. Further experiments revealed that S1 stimulation of PBMCs increased phosphorylation of NF-{kappa}B p65 and I{kappa}B, and I{kappa}B degradation. DNA binding of NF-{kappa}B p65 was also significantly increased following stimulation with spike glycoprotein S1. Treatment of PBMCs with dexamethasone (100 nM) or BAY11-7082 (1 {micro}M) resulted in inhibition of spike glycoprotein S1-induced NF-{kappa}B activation. Activation of p38 MAPK by S1 was blocked in the presence of dexamethasone and SKF 86002. CRID3, but not dexamethasone pre-treatment produced significant inhibition of S1-induced activation of NLRP3/caspase-1. Further experiments revealed that S1-induced increase in the production of TNF, IL-6, IL-1{beta} and IL-8 was reduced in the presence of BAY11-7082 and SKF 86002, while CRID3 pre-treatment resulted in the reduction of IL-1{beta} production. These results suggest that SARS-CoV-2 spike glycoprotein S1 stimulated PBMCs to release pro-inflammatory cytokines through mechanisms involving activation of NF-{kappa}B, p38 MAPK and NLRP3 inflammasome. It is proposed that the clinical benefits of dexamethasone in COVID-19 is possibly due to its anti-inflammatory activity in reducing SARS-CoV-2 cytokine storm. In-depth characterization of denitrifier communities across different soil ecosystems in the tundra BackgroundIn contrast to earlier assumptions, there is now mounting evidence for the role of tundra soils as important sources of the greenhouse gas nitrous oxide (N2O). However, the microorganisms involved in the cycling of N2O in this system remain largely uncharacterized. Since tundra soils are variable sources and sinks of N2O, we aimed at investigating differences in community structure across different soil ecosystems in the tundra.

ResultsWe analysed 1.4 Tb of metagenomic data from soils in northern Finland covering a range of ecosystems from dry upland soils to water-logged fens and obtained 796 manually binned and curated metagenome-assembled genomes (MAGs). We then searched for MAGs harbouring genes involved in denitrification, an important process driving N2O emissions. Communities of potential denitrifiers were dominated by microorganisms with truncated denitrification pathways (i.e., lacking one or more denitrification genes) and differed across soil ecosystems. Upland soils showed a strong N2O sink potential and were dominated by members of the Alphaproteobacteria such as Bradyrhizobium and Reyranella. Fens, which had in general net-zero N2O fluxes, had a high abundance of poorly characterized taxa affiliated with the Chloroflexota lineage Ellin6529 and the Acidobacteriota subdivision Gp23.

ConclusionsBy coupling an in-depth characterization of microbial communities with in situ measurements of N2O fluxes, our results suggest that the observed spatial patterns of N2O fluxes in the tundra are related to differences in the composition of denitrifier communities. Deficiency of gluconeogenic enzyme PCK1 promotes murine NASH progression and fibrosis by activation PI3K/AKT/PDGF axis Background and AimsNonalcoholic steatohepatitis (NASH) is a chronic liver disease characterized by hepatic lipid accumulation, inflammation, and progressive fibrosis. However, the pathomechanisms underlying NASH are incompletely explored. Phosphoenolpyruvate carboxykinase 1 (PCK1) catalyzes the first rate-limiting step of gluconeogenesis. This study was designed to determine the role of PCK1 in regulating NASH progression.

MethodsLiver metabolism, hepatic steatosis, and fibrosis were evaluated at 24 weeks in liver-specific Pck1-knockout mice fed with NASH diet or chow diet. Gain- or loss-of-function approaches were used to explore the underlying mechanism in vitro. AKT and RhoA inhibitors were evaluated for NASH treatment in vivo.

ResultsHepatic PCK1 was downregulated in patients with NASH and mouse models of NASH. Mice with liver Pck1 deficiency displayed hepatic lipid disorder and liver injury fed with normal diet, while showed aggravated fibrosis and inflammation when fed NASH diet. Mechanistically, PCK1 deficiency upregulated genes involved in fatty acid transport and lipid droplet formation. Moreover, metabolomics analysis showed the accumulation of glycerol 3-phosphate, the substrate of triglyceride synthesis. Furthermore, the loss of hepatic PCK1 could activate the RhoA/PI3K/AKT pathway, which leads to increased secretion of PDGF-AA and promotes the activation of hepatic stellate cells. Accordingly, treatment with RhoA and AKT inhibitors alleviated NASH progression in the presence of Pck1 deletion in vivo.

ConclusionsPCK1 deficiency plays a key role in the development of hepatic steatosis and fibrosis by facilitating the RhoA/PI3K/AKT/PDGF-AA axis. These findings provide a novel insight into therapeutic approaches for the treatment of NASH. A chromosome-level assembly of the "Cascade" hop (Humulus lupulus) genome uncovers signatures of molecular evolution and improves time of divergence estimates for the Cannabaceae family O_LIWe present a chromosome-level assembly of the Cascade hop (Humulus lupulus L. var. lupulus) genome. The hop genome is large (2.8 Gb) and complex, and early attempts at assembly resulted in fragmented assemblies. Recent advances have made assembly of the hop genome more tractable, transforming the extent of investigation that can occur.
C_LIO_LIThe chromosome-level assembly of Cascade was developed by scaffolding the previously-reported Cascade assembly generated with PacBio long-read sequencing, and polishing with Illumina short-read DNA sequencing. We developed gene models and repeat annotations, and used a controlled bi-parental mapping population to identify significant sex-associated markers. We assess molecular evolution in gene sequences, gene family expansion and contraction, and time divergence using Bayesian inference.
C_LIO_LIWe identified the putative sex chromosome in the female genome based on significant sex-associated markers from the bi-parental mapping population. While the estimate of repeat content (~64%) is similar to the hemp genome, syntenic blocks in hop contain a greater percentage of LTRs. Hop is enriched for disease resistance-associated genes in syntenic gene blocks and expanded gene families.
C_LIO_LIThe Cascade chromosome-level assembly will inform cultivation strategies and serve to deepen our understanding of the hop genomic landscape, benefiting hop researchers and the Cannabaceae genomics community.
C_LI The coiled-coil domain of E. coli FtsLB is a structurally detuned element critical for modulating its activation in bacterial cell division The FtsLB complex is a key regulator of bacterial cell division, existing in either an off or on state which supports the activation of septal peptidoglycan synthesis. In Escherichia coli, residues known to be critical for this activation are located in a region near the C-terminal end of the periplasmic coiled-coil domain of FtsLB, raising questions about the precise role of this conserved domain in the activation mechanism. Here, we investigate an unusual cluster of polar amino acids found within the core of the FtsLB coiled coil. We hypothesized that these amino acids likely reduce the structural stability of the domain and thus may be important for governing conformational changes. We found that mutating these positions to hydrophobic residues increased the thermal stability of FtsLB but caused cell division defects, suggesting that the coiled-coil domain is a "detuned" structural element. In addition, we identified suppressor mutations within the polar cluster, indicating that the precise identity of the polar amino acids is important for fine-tuning the structural balance between the off and on states. We propose a revised structural model of the tetrameric FtsLB (named the "Y-model") in which the periplasmic domain splits into a pair of coiled-coil branches. In this configuration, the hydrophilic terminal moieties of the polar amino acids remain more favorably exposed to water than in the original four-helix bundle model ("I-model"). We propose that a shift in this architecture, dependent on its marginal stability, is involved in activating the FtsLB complex and triggering septal cell wall reconstruction. Biophysical characterization of the oligomeric states of recombinant Immunoglobulins type-M and their C1q binding kinetics by Biolayer Interferometry The Immunoglobulins type-M (IgMs) are one of the first antibody classes mobilized during immune responses against pathogens and tumor cells. Binding to specific target antigens enables the interaction with the C1 complex which strongly activates the classical complement pathway. This biological function is the basis for the huge therapeutic potential of IgMs but due to their high oligomeric complexity, in vitro production, biochemical and biophysical characterizations are challenging. In the present study, we present recombinant production of two IgM models (IgM617 and IgM012) in pentameric and hexameric states and the evaluation of their polymer distribution using different biophysical methods (AUC, SEC-MALLS, Mass Photometry and Transmission Electron Microscopy). Each IgM oligomer has individual specific expression pattern and yield with different protein quality likely due to intrinsic IgM properties and patterning. Nevertheless, the purified recombinant IgMs retain their ability to activate complement in a C1q dependent manner. And more importantly, a new method to evaluate their functional quality attribute by characterizing the kinetics of C1q binding to recombinant IgM has been developed using BioLayer Interferometry (BLI). We show that recombinant IgMs possess similar C1q binding properties as IgMs purified from human plasma. Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition The teeth of sharks famously form a series of transversely-organised files with conveyor-belt replacement that are borne directly on the jaw cartilages, in contrast to the dermal plate-borne dentition of bony fishes that undergoes site-specific replacement. A major obstacle in understanding how this system evolved is the poorly understood relationships of the earliest chondrichthyans and the profusion of morphologically and terminologically diverse bones, cartilages, splints and whorls that they possess. Here we use tomographic methods to investigate mandibular structures in several early branching  acanthodian-grade stem-chondrichthyans. We show that the dentigerous jaw bones of disparate genera of ischnacanthids are united by a common construction, being growing bones with non-shedding dentition. Mandibular splints, which support the ventro-lateral edge of the Meckels cartilage in some taxa, are formed from dermal bone and may be an acanthodid synapomorphy. We demonstrate that the teeth of Acanthodopsis are borne directly on the mandibular cartilage and that this taxon is deeply nested within an edentulous radiation, representing an unexpected independent origin of teeth. Many or even all of the range of unusual oral structures may be apomorphic, but they should nonetheless be considered when building hypotheses of tooth and jaw evolution, both in chondrichthyans and more broadly. Citation needed? Wikipedia and the COVID-19 pandemic BackgroundWith the COVID-19 pandemics outbreak, millions flocked to Wikipedia for updated information. Amid growing concerns regarding an "infodemic", ensuring the quality of information is a crucial vector of public health. Investigating if and how Wikipedia remained up to date and in line with science is key to formulating strategies to counter misinformation. Using citation analyses, we asked: which sources informed Wikipedias COVID-19-related articles before and during the pandemics first wave (January-May 2020).

ResultsWe found that coronavirus-related articles referenced trusted media sources and high-quality academic research. Moreover, despite a surge in COVID-19 preprints, Wikipedia had a clear preference for open-access studies published in respected journals and made little use of preprints. Building a timeline of English COVID-19 articles from 2001-2020 revealed a nuanced trade-off between quality and timeliness. It further showed how preexisting articles on key topics related to the virus created a framework for integrating new knowledge. Supported by a rigid sourcing policy, this "scientific infrastructure" facilitated contextualization and regulated the influx of new information. Lastly, we constructed a network of DOI-Wikipedia articles, which showed the shifting landscape of pandemic-related knowledge on Wikipedia and how academic citations create a web of shared knowledge supporting topics like COVID-19 vaccine development.

ConclusionsUnderstanding how scientific research interacts with the digital knowledge-sphere during the pandemic provides insight into how Wikipedia can facilitate access to science. It also reveals how, aided by what we term its "citizen encyclopedists", it successfully fended off COVID-19 disinformation and how this unique model may be deployed in other contexts. Using Hierarchical Similarity To Examine The Genetics of Behcet's disease Behcets disease (BD) is a multisystem inflammatory disease that affects patients along the historic silk road. Thus far, the pathogenesis of the disease has proved elusive due to the complex genetic interactions and unknown environmental or viral triggering factors of the disease. In this paper, we seek to clarify the genetic factors of the disease while also uncovering other diseases of interest that present with a similar genotype as BD. To do this, we employ a convergent functional genomics approach by leveraging the hierarchical similarity tool available in Geneweaver. Through our analysis, we were able to ascertain 7 BD consensus genes and 16 autoimmune diseases with genetic overlap with BD. The results of our study will inform further research into the pathogenesis of Behcets Disease. On-pathway multivalency of a broadly neutralizing evolution drug candidate A promising approach to prevent antibiotic resistance is design of multivalent antibiotics that constrain bacterial evolvability by blocking multiple escape routes. Previously we discovered that an "evolution drug" lead designed to broadly neutralize bacterial dihydrofolate reductase (DHFR) and its trimethoprim escape variants is multivalent in E. coli cells. In this work we identified the second target of this new lead. We analysed antibiotic induced global metabolic perturbations and deployed metabolic-network analysis and structural similarity search of the putative targets and narrowed down the search to a few enzymes. Further, combining in vivo and in vitro analyses, we identified HPPK (folK), an essential protein in bacterial folate-metabolism, as the non-DHFR target of the lead. We observed that compounds with interaction specificity against WT do not develop multivalency against related proteins. This multivalent-design strategy is effective in blocking the emergence of drug-resistant phenotypes.

HighlightsO_LIAn evolution drug lead designed to block bacterial evolvability manifested behaviours suggesting an intra-cellular multivalent activity.
C_LIO_LIA multi-layered metabolomic and structure guided approach unravelled the second intra-cellular target of the evolution-drug lead, showing folate-pathway inhibitions at two metabolic points.
C_LIO_LIThe on-pathway anti-folate activity is exhibited by inhibiting two essential proteins viz. DHFR and its upstream protein HPPK.
C_LIO_LIMultivalent drug development schemes present a promising anti-evolution strategy to address the problem of "drug-resistance" by inhibiting more than one metabolic protein.
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