Biology subjects

Xiao, J.

Publications and source records attributed to Xiao, J..

At least 37 records · Page 2Linked to original sources

bioRxiv2026

Near telomere-to-telomere Linum genomes reveal a lineage-specific DNA transposon associated with chromosome architecture remodeling

Chromosome number variation and structural reorganization are key drivers of plant evolution, yet their genomic basis remains unclear due to incomplete representation of repetitive regions in existing assemblies. The Linum genus exhibits exceptional karyotypic diversity (n = 7-43), providing a powerful system to investigate chromosome evolution. Here, we generated near telomere-to-telomere (T2T) genome assemblies for four species, including cultivated flax (L. usitatissimum cv. CDC Bethune; n = 15), its wild progenitor (L. bienne; n = 15), and two related species (L. decumbens and L. grandiflorum; n = 8). Together with published genomes of L. lewisii (n = 9) and L. tenue (n = 10), these enabled reconstruction of chromosome evolution across six lineages. Phylogenomic analyses revealed a shared ancestral whole-genome duplication (WGD) associated with the n = 9 karyotype, followed by lineage-specific WGDs and divergent diploidization. The transition from n = 8 to the derived n = 15 flax lineage not only occurred without chromosome length expansion, but also with genome size reduction, indicating extensive internal restructuring. Comparative analyses showed that this restructuring was associated with lineage-specific expansion of a single DNA transposon family (TE_00003234; hAT), which is highly enriched in expansive pericentromeric regions that are characterized by low gene density and nucleotide diversity, suppressed recombination, segregation distortion, and extensive synteny disruption, unlike the LTR retrotransposon-rich pericentromeres typical of most plant genomes. These findings support a model in which lineage-specific DNA transposon expansion is associated with remodeling of pericentromeric architecture and large-scale chromosome restructuring following polyploidization.

genomics↗

bioRxiv2026

STAT: A multi-agent framework for integrated and interactive spatial transcriptomics analysis

Spatial transcriptomics analysis often involves a myriad of computational methods across diverse platforms, leading analysts to spend excessive time on data assembly rather than deriving biological insights. Current AI solutions tend to either oversimplify spatial data into generic single-cell tables or operate autonomously without opportunities for intermediate review, thus hindering the visual and iterative analyses essential for spatial biology. In response to these challenges, we introduce STAT, a multi-agent framework designed to make spatial analysis more conversational and user-friendly while maintaining transparency and control. STAT integrates a persistent session, a shared interactive tissue viewer, and a staged skill-aware pipeline, enabling a more intuitive analytical experience. In a comprehensive benchmark evaluation encompassing eleven analytical task categories across three spatial platforms and both cell- and spot-resolution data, STAT demonstrates superior performance compared to a vanilla large language model and existing autonomous spatial analysis agents, excelling in task completion, analytical quality, and token efficiency. Notably, STAT enables multi-task spatial analysis of a mixed-resolution breast cancer cohort and successfully reproduces key findings from a published Visium HD colorectal cancer study using natural language prompts alone. STAT thus facilitates trustworthy and scientifically rigorous spatial transcriptomics analysis, allowing researchers to focus more on biological interpretation.

bioinformatics↗

bioRxiv2026

EnzCast: Prediction of Patient-Specific Enzymatic Kinetics through Multi-Modal Deep Learning and Isoform-Resolved Bayesian Inference based on Single-Cell Transcriptomics

Enzyme kinetic parameters underpin mechanistic biology but remain sparse in physiological context. We present EnzCast, a multi-modal framework jointly predicting Km, kcat, kcat/Km, and Ki from protein sequence, 3D structure, substrate chemistry, and experimental conditions, paired with IsoKin, an isoform-resolved Bayesian framework converting EnzCast priors into patient-specific in vivo kinetics. Trained on KinBench, the largest curated kinetics database, task-adaptive EnzCast achieved R2 = 0.413, 0.455, 0.227, and 0.105 for Km, Ki, kcat, and kcat/Km, surpassing all baselines on catalytic tasks. Systematic condition scans recovered compartment-specific pH direction inversion and pathway-level temperature responses. In a 20-patient colorectal cancer single-cell cohort, IsoKin reduced posterior uncertainty by 73.3% and 77.3%, revealing cell-type-specific rewiring. Orthogonal validation--scFEA flux, DepMap essentiality (permutation P = 0.0008) and TCGA survival-- provided mixed but directionally consistent support. Together, EnzCast and IsoKin bridge in vitro prediction, condition-aware biochemical interrogation and patient-resolved in vivo inference.

bioinformatics↗

bioRxiv2026

Targeting Gi/o-coupled GPCRs to inhibit nociceptors: insights from the serotonin receptor Htr1b and triptans

Pain perception is initiated upon activation of nociceptors of the dorsal root ganglia (DRG) and trigeminal ganglia. We identified G protein-coupled receptors (GPCRs) expressed in CGRP+ mouse and human DRG neurons and found that agonists of several identified Gi/o-coupled and orphan GPCRs attenuated neuronal excitability. Experiments focusing on the Gi/o-coupled serotonin receptor Htr1b, which is expressed in mouse and human CGRP+ DRG neurons, revealed that Htr1b/1d agonists, the triptans sumatriptan and zolmitriptan, attenuated CGRP+ neuron excitability in vitro and exhibited analgesia across several pain models, including neuropathic pain. Conditional genetic deletion experiments showed that triptan-induced analgesia is mediated by Htr1b expressed in A-fiber mechanonociceptors. Also, triptan-associated adverse effects are partially mediated by Htr1b-independent targets. Further testing identified the GPCR Gpr19 as an additional promising target for treating pain. These findings establish a preclinical screening platform for identifying novel analgesics and reveal nociceptor GPCRs that may be targeted to treat pain.

neuroscience↗

bioRxiv2026

MTB-KB: A Curated Knowledgebase of Mycobacterium tuberculosis Related Studies

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), has regained its position as the worlds leading killer among infectious diseases. Despite extensive research progress across epidemiology, diagnosis, drug development, treatment regimens, vaccines, drug resistance, virulence factors, and immune mechanisms, MTB-related knowledge remains fragmented across thousands of publications, limiting its effective use. To address this gap, we present MTB-KB, a literature-curated knowledgebase that systematically integrates high-impact findings from eight major sections of TB research. The current release contains 75,170 associations from 1,246 publications, covering 18,439 entities standardized using authoritative databases and WHO-endorsed classifications. A central feature is the interactive knowledge graph, which links cross-section associations to reveal and infer MTB-host interactions, treatment strategies, and vaccine development opportunities. MTB-KB also provides a user-friendly interface with browsing, advanced search, and statistical visualization. Overall, by consolidating dispersed MTB knowledge into a structured and accessible platform, MTB-KB provides a valuable resource for researchers, clinicians, and policymakers, supporting both basic and clinical TB research, enabling evidence-based TB prevention, diagnosis, and treatment, and contributing to global elimination efforts. MTB-KB is accessible at https://ngdc.cncb.ac.cn/mtbkb/.

bioinformatics↗

bioRxiv2026

Blockade of Tim-3 pathway in a mouse model of Toxoplasmosis: impact on brain leukocyte infiltration, parasite burden, and neuroinflammation

Cell-mediated immune responses are crucial for protecting the host against Toxoplasma gondii infection. However, impaired immunity, such as T-cell exhaustion, is a common phenomenon during chronic infection. This may represent a strategy employed by T. gondii to evade host defenses. T-cell immunoglobulin and mucin-domain containing 3 (Tim-3) is an important regulatory molecule involved in cell-mediated immunity. This study examined the expression of Tim-3 and the effects of its blockade in a mouse model of toxoplasmosis. In mice with chronic T. gondii infection, we found that Tim-3 is highly expressed in both cyst-bearing and non-cyst-bearing tissues, and its expression correlates with the parasite burden. Blocking the Tim-3 pathway with an anti-Tim-3 antibody enhances the immune response, resulting in elevated levels of cytokines (IFN-{gamma}, IL-12p70, IL-2, IL-9) and the chemokine CXCL1 in the serum, increased leukocyte infiltration (CD3+, CD14+ cells) in the brain, and downregulation of Tim-3 expression in microglial cells. As a result, the anti-Tim-3 treatment resulted in a 62% reduction in the number of tissue cysts and a trend towards an increase in the homeostatic signature, P2RY12, in microglia. Our study provides proof of concept for an anti-Tim-3 approach in treating chronic T. gondii infection and potentially other brain-residing pathogens.

microbiology↗

bioRxiv2026

Differential Regulation of Hepatic Akt/mTOR Signaling During Acute and Chronic Toxoplasma gondii Infection in a Murine Model

Toxoplasma gondii is an obligate intracellular parasite that infects virtually all warm-blooded animals, progressing through acute and chronic stages. The Akt/mTOR signaling axis plays critical roles in cell survival, proliferation, and metabolism, making it a key target for intracellular pathogens. This study investigated how T. gondii infection modulates this pathway during both infections. Outbred CD-1 mice were infected intraperitoneally with the virulent GT1 strain of T. gondii. Mice for acute studies were sacrificed five days post-infection, while those for chronic studies were treated with sulfadiazine and sacrificed five months post-infection. Phosphoprotein expression of eight Akt/mTOR pathway components was measured in liver tissues using a multiplexed bead-based immunoassay. Acute T. gondii infection caused broad suppression of Akt/mTOR signaling, with 6 of 8 markers significantly downregulated, including pS6RPSer235/236, pAKTS473, pBADSer136, pIRS1S636/639, pPTENSer380, and pGSK-3/{beta}Ser21/9. In contrast, chronic infection selectively activates specific nodes of the pathway in a cyst burden-dependent manner, including pBADSer136, pmTORSer2448, and pGSK-3/{beta}Ser21/9. There are strong correlations in signaling changes between inter-components, which reflect coherent and coordinated pathway-level reprogramming rather than random perturbation. These findings show that acute and chronic T. gondii infections have opposing effects on host Akt/mTOR signaling for their own benefit, which may present new therapeutic targets. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=157 SRC="FIGDIR/small/716682v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@8c5021org.highwire.dtl.DTLVardef@1e0cdcaorg.highwire.dtl.DTLVardef@1e690eaorg.highwire.dtl.DTLVardef@342c0b_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIAcute T. gondii infection broadly suppresses hepatic Akt/mTOR signaling C_LIO_LIChronic infection exerts cyst burden-dependent activation of specific Akt/mTOR nodes C_LIO_LIT. gondii has distinct strategies to manipulate host survival based on its life stages. C_LIO_LIThe Akt/mTOR pathway may serve as a therapeutic target for the treatment of T. gondii. C_LI

microbiology↗

bioRxiv2026

Wnt/β-catenin signaling restrains developmental beiging and imprints long-term energy expenditure

Beige adipocytes that emerge during the peri-weaning period support sympathetic nervous system (SNS)-independent thermogenesis, yet the mechanisms governing this spontaneous beiging remain unclear. Here, by integrating transcriptomic profiling with adipocyte-targeted Ctnnb1 deletion in mice, we identify the canonical Wnt signaling as an endogenous brake on developmental beige thermogenesis. Peri-weaning inguinal fat from adipocyte Ctnnb1 knockout mice exhibits enhanced beige adipocyte biogenesis, with increased thermogenesis-related gene expression and mitochondrial oxidative capacity, which programs durable activation of adaptive thermogenesis and augmented whole-body energy expenditure into adulthood. Mechanistically, suppression of Wnt/{beta}-catenin signaling induces a non-canonical Wnt5a-Ca2-AMPK axis that promotes triglyceride lipolysis and subsequent PPAR-driven fatty acid oxidation, thereby fueling mitochondrial respiration. Genetic or pharmacological disruption of this axis blunts thermogenic responses induced by {beta}-catenin inhibition in both murine and human subcutaneous adipocytes, indicating that Wnt5a-Ca2-AMPK axis is required for the cell-autonomous activation of beige fat. These results reveal Wnt/{beta}-catenin signaling as a developmental constraint on beige adipocyte formation and suggest an SNS-independent route to sustainably raise energy expenditure and improve metabolic health.

physiology↗

bioRxiv2026

Repetitive extragenic palindrome (REP) elements are local, context-dependent, dual 3'UTR regulators in Escherichia coli

Repetitive extragenic palindromes (REPs) are the most abundant repetitive noncoding elements in the E. coli genome. Despite their abundance, the primary function of REPs has remained unclear. At different times, REPs have been proposed to contribute to chromosome organization, mRNA decay regulation, and transcription termination, among other functions. Here, we show that the model REP, REP325, does not measurably compact the chromosome but instead acts as a 3UTR-associated transcription regulator within the yjdMN operon, functioning both as a partially Rho-dependent terminator that limits transcription into the downstream yjdN gene and as an mRNA stabilizer that protects the upstream yjdM transcript from degradation. This dual role in controlling both transcriptional readthrough and susceptibility to decay provides a framework that reconciles several previously conflicting observations about REP function. Our genome-wide RNA-seq analysis further reveals that REPs with more canonical sequence and hairpin structures are more often associated with upstream-biased expression in tandem gene pairs, and that REPs positioned between convergent genes correlate with elevated expression of both genes. The large variance in expression patterns in both gene pair configurations is consistent with context-dependent termination and degradation blocking. Similarly, REPs do not uniformly affect mRNA half-lives. Because REP locations vary between E. coli strains, REPs likely contribute to regulatory diversity by tuning gene expression without altering protein-coding sequences or promoter regions, opening new avenues for modulating gene expression through REP-mediated transcription regulation.

biophysics↗

bioRxiv2026

Integrative multi-omics and multi-trait analysis prioritizes regulatory mechanisms and genes for metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent condition that progresses from simple steatosis to advanced fibrosis, significantly affecting liver function and systemic health. Despite its widespread impact, therapeutic options are limited, highlighting the urgent need for comprehensive exploration to identify potential therapeutic targets. In this study, we created an analysis pipeline anchored on liver gene expression, integrating differential meta-analysis of transcriptomic data across three MASLD stages, transcriptome-wide Mendelian randomization (MR), and transcriptome-wide association studies (TWAS), to identify 39 candidate genes potentially involved in MASLD progression. Furthermore, we prioritized these genes using a scoring system that incorporated gene expression-clinical phenotype correlation meta-analysis, proteome-wide association studies (PWAS), and external genetic data from the GWAS Catalog and ExPheWAS. Single-nucleus RNA sequencing (snRNA-seq) analysis of liver cells from healthy to cirrhotic stages revealed stage- and cell-type-specific expression patterns of these prioritized genes. Through experimental validation in a lipid overload hepatocyte model, we confirmed the role of MLIP in lipid metabolism. These findings, available through an interactive web portal (masldportal.net), provide valuable insights into MASLD mechanisms and offer an easy-accessible resource for the research community. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/706502v2_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@184c03eorg.highwire.dtl.DTLVardef@6965ccorg.highwire.dtl.DTLVardef@19a5937org.highwire.dtl.DTLVardef@576b53_HPS_FORMAT_FIGEXP M_FIG C_FIG

systems biology↗

bioRxiv2026

Substrate binding and activation mechanism of the essential bacterial septal cell wall synthase FtsW

Septal peptidoglycan (sPG) synthesis in most bacteria is driven by the essential, highly conserved FtsWIOLB synthase complex, comprising the SEDS glycosyltransferase FtsW, the monofunctional transpeptidase FtsI, and the scaffolding subcomplex FtsOLB. Although apo structures of FtsWIOLB are known, no substrate-bound structures exist, likely due to the intrinsic flexibility of lipid II (L2) substrates. Here, we combined all-atom molecular dynamics simulations of E. coli FtsWIOLB with cysteine-based mutagenesis and cell-based assays to define donor and acceptor L2 binding sites in FtsW and to elucidate the complexs activation mechanism. We show that conserved arginine residues adjacent to membrane-accessible cavities in FtsW coordinate donor and acceptor L2 pyrophosphate groups, stabilizing substrate binding. The FtsWIOLB complex appears to adopt a self-inhibitory architecture in which gating elements and a periplasmic loop prevent the donor and acceptor from approaching FtsWs catalytic residue D297. Activation by FtsN or a superfission FtsW variant relieves these constraints, stabilizes acceptor-site binding, and reorients both substrates into a catalytically primed state. Long donor glycan chains further stabilize this activated conformation at the acceptor site, promoting processive sPG polymerization. Comparative modeling of ESKAPE pathogen homologs reveals conserved and divergent features of binding-site engagement and activation. We corroborate these computational findings with cysteine-based mutagenesis and crosslinking experiments. These results establish a mechanistic framework for FtsW substrate recognition and functional activation, highlighting tractable sites for structure and mechanism-based antibiotic discovery targeting SEDS-class cell wall synthases.

biophysics↗

bioRxiv2026

AbNovoBench: a resource and benchmarking platform for monoclonal antibody de novo sequencing

Monoclonal antibodies (mAbs) are critical in disease diagnostics and therapeutics, yet the performance of mass spectrometry (MS)-based de novo sequencing remains incompletely characterized due to limited antibody-specific datasets and the absence of a standardized benchmark framework. Here we present AbNovoBench, a comprehensive framework for evaluating data analysis strategies for mAb de novo sequencing. It features the largest high-quality dataset to date, generated in-house, comprising 1,638,248 peptide-spectrum matches from 131 mAbs across six species and 11 proteases, supplemented by eight mAbs with known full-length sequence for end-to-end reconstruction assessment. Employing a unified training dataset, we systematically benchmarked 13 deep learning-based de novo peptide sequencing algorithms and three assembly strategies across peptide sequencing metrics (accuracy, robustness, efficiency, error types) and assembly metrics (coverage depth, assembly score). AbNovoBench (https://abnovobench.com) provides an online platform enriched with curated antibody MS resources and pre-trained models, enabling customizable antibody sequencing workflows, accelerating antibody-specific algorithms development, and improving reproducibility in proteomics.

systems biology↗

bioRxiv2026

Understanding Coral Health from Reactor Engineering Perspective: Multiphysics Modeling of Coral - Environment Interactions

Coral, as a bioreactor, has to continuously interact with surrounding environment to maintain a healthy state. A multi-physics reaction engineering model has been developed to capture this interaction. The coral interior is modeled as interconnected reaction units respectively for photosynthesis, respiration, and calcification, whose reaction kinetics are influenced by environmental fluctuations. Coupling between coral and environment is realized by bi-directional mass transfer at the coral-seawater interface, with consideration of the unique flow fields induced by ciliary beating. By resorting to this comprehensive model, we discover that ciliary beating demonstrates distinctively different diurnal and nocturnal functions. During daytime, beating can help reduce photosynthetic oxygen accumulation to prevent hyperoxia-induced mortality, while enhancing carbon dioxide uptake efficiency to promote nutrient production. At night, however, beating promotes oxygen acquisition for adequate respiration, while expelling carbon dioxide to inhibit symbiotic destruction under acidic stress. The model further enables mechanistic analysis of the detrimental impact of climate change on coral health, where the influences from two key factors (i.e., temperature and CO2 level) can be decoupled. Its interesting to find out that the elevated temperature plays a dominant role during daytime, while at night the coral is dominantly influenced by rising CO2 level.

systems biology↗

bioRxiv2026

Single-cell transcriptomic landscapes reveal cell-type-specific regulatory mechanisms of nutrient accumulation and transport in wheat grain

To elucidate the transcriptional regulatory mechanisms underlying wheat grain development, we constructed single-cell transcriptomic atlases of wheat grains at 4 and 8 days after pollination (DAP) using single-nucleus RNA sequencing. A total of 58,546 high-quality nuclei were clustered into 16 distinct cell populations representing all major seed tissues, including the embryo, aleurone layer, transfer cells, endosperm, inner pericarp, seed coat, and embryo surrounding region. Comparative analysis revealed a dynamic transcriptional reprogramming from growth-related pathways at DAP 4 to nutrient accumulation at DAP 8, which coincided with shifts in the expression of hormone signaling and organ development genes, as well as starch and storage protein genes. Pseudotime trajectory analysis identified two major differentiation branches, highlighting distinct roles in nutrient storage and support. Notably, the transcription factor TaMADS58 was found to regulate pericarp cell number while simultaneously enhancing protein content and processing quality. Concurrently, TaJEKLL, specifically expressed in nucellar projection cells, was demonstrated to influence nucellar projection development and nutrient transport. Natural variation in TaMADS58 and TaJEKLL revealed their potential to decouple yield from quality traits, offering promising applications for crop improvement. Collectively, this study provides a high-resolution single-cell resource for wheat seed biology and demonstrates that investigating gene expression with spatiotemporal precision at the single-cell level can facilitate the discovery of key genes for precisely regulating individual traits.

plant biology↗

bioRxiv2025

Defining the role of RNase E in the mycobacterial degradosome-like network

mRNA degradation is a fundamentally important process that is regulated in response to stress in the globally important pathogen Mycobacterium tuberculosis. Several mycobacterial ribonucleases (RNases) are hypothesized to function together to coordinate mRNA degradation, but the interactions among them are mostly undefined. One of the rate-limiting enzymes, RNase E, contains intrinsically disordered regions (IDRs). Here, we have defined the interactions among major mycobacterial mRNA degradation enzymes and identified the functions of the two IDRs of RNase E in the nonpathogenic model Mycolicibacterium smegmatis. We found that the two IDRs differentially impact mRNA degradation rates in vivo but are largely functionally redundant in their impact on steady-state transcript abundance. In vitro, the IDRs are uninvolved in catalysis but play major roles in RNA binding and interactions with other mRNA degradation enzymes, namely PNPase, RNase J, and RhlE1, including stimulation of RhlE1 activity. In vivo, these enzymes localize with RNase E, but its IDRs play only a minor role, suggesting substantial redundancy in subcellular localization mechanisms. Collectively, we propose a degradosome-like network model in mycobacteria, held together by dynamic, transient interactions among RNA degradation enzymes and RNA that can be disrupted during physiologically relevant stress to allow for adaptability.

molecular biology↗

bioRxiv2025

DYT1 mutation alters gut microbiome composition and gut-brain axis dynamics in a mouse model

Dystonia is a neurological movement disorder characterized by involuntary, sustained, or intermittent muscle contractions, that result in twisting movements, repetitive motor patterns, or abnormal postures. While genetic mutations such as Tor1a+/{Delta}GAG are known contributors, the environmental and peripheral factors influencing disease onset and progression remain poorly understood. Emerging evidence implicates the gut microbiome in shaping neurodevelopment and host behavioral function, yet its contribution to dystonia pathobiology is largely unexplored. Here, we longitudinally profiled the gut microbiome of Tor1a+/{Delta}GAG mouse model using 16S rRNA gene sequencing and uncovered early emerging, persistent disruptions in microbial diversity and community composition that track with progressive motor impairment. Mutant mice exhibited an alteration of key commensal taxa, and molecular signatures indicative of compromised gut-barrier integrity. Parallel transcriptomic profiling of colonic epithelium reveals coordinated dysregulation of pathways governing epithelial stress responses, endoplasmic reticulum homeostasis, lipid signaling, autophagy, and DNA damage and repair, pointing to a previously unrecognized epithelial stress state in Tor1a+/{Delta}GAG mouse model. Integrative microbial-host interaction correlation analyses uncovered robust associations between specific dysbiotic taxa and host signaling pathways. These peripheral perturbations coincide with longitudinal motor deficits, suggesting a mechanistic gut-brain axis linking intestinal dysfunction to central neuronal vulnerability. Together, our findings provide the first experimental framework connecting microbiome perturbations, gut-barrier disruption, and neuronal vulnerability in a genetic model of dystonia. This work positions the gut microbiome and its regulation of epithelial and neuronal homeostasis as a novel entry point for disease modification in individuals carrying deleterious dystonia-associated variants.

neuroscience↗

bioRxiv2025

A coherent feed-forward loop fine-tunes KatG to maintain redox homeostasis in mycobacteria

Bacteria survive and reproduce in fluctuating environments by balancing their basic physiological needs, such as relying on iron-containing enzymes to detoxify reactive oxygen species (ROS) while conserving scarce iron. Understanding the regulatory networks that balance these conflicting needs is key to deciphering bacterial adaptability. Here, we identify a coherent feed-forward loop in mycobacteria that integrates the transcriptional regulator FurA3, the small RNA MrsI, RNA sponge FutR, and the catalase-peroxidase KatG. This circuit fine-tunes antioxidant responses according to iron availability. Under iron limitation, the iron-containing enzyme KatG is dually repressed by FurA3 transcriptionally and by MrsI post-transcriptionally, which conserves iron at the cost of antioxidant capacity. However, when iron deprivation coincides with oxidative stress, the circuit triggers an emergency response: H2O2 inactivates FurA3, relieving transcriptional repression of katG and futR, while induced FutR sequesters MrsI to post-transcriptionally derepress katG expression, enabling rapid KatG synthesis for effective peroxide detoxification. Our findings reveal a tightly regulated network that allows mycobacteria to balance iron homeostasis and oxidative stress defense, providing mechanistic insights into bacterial physiological trade-offs.

microbiology↗

bioRxiv2025

Projection-specific Routing of Odor Information in the Olfactory Cortex

Sensory processing in the mammalian cortex relies on extensive feedforward and feedback connections, yet how information is routed along these pathways remains poorly understood. Here, we examined the functional properties of feedback and feedforward neurons in the mouse olfactory (piriform) cortex. We selectively labeled neurons projecting to the olfactory bulb (OB, feedback) or medial prefrontal cortex (mPFC, feedforward) and recorded their activity during passive odor exposure and learning of an odor discrimination task. We found that odor identity and reward associations were encoded by OB-projecting ensembles early during odor exposure, whereas mPFC-projecting neurons encoded this information later, aligned with behavioral responses. Moreover, mPFC-projecting neurons maintained a stable representation of valence across days, while OB-projecting neurons exhibited pronounced plasticity. Together, these findings reveal that odor information is selectively routed through feedforward and feedback pathways and suggest that the functional properties of piriform neurons mirror the computational demands of their downstream targets.

neuroscience↗