PLOS Biology

Traditional peer review is often slowed by delays in identifying willing reviewers and waiting for completed review reports. In a 2024 pilot on the journal Biology Open, we showed that Fast & Fair peer review, which uses pre-contracted paid reviewers and a structured editorial timeline, could deliver rapid, high-quality peer. Here, we report the expanded implementation of Fast & Fair at Biology Open in 2025. From 1 April 2025 onward, all direct submissions to the journal were considered for Fast & Fair peer review unless appropriate pre-contracted reviewer expertise was unavailable. Reviewers were paid {pound}220 per manuscript only if they completed the review on time, and the review met editorial quality expectations. Among peer-reviewed manuscripts submitted in 2025, Fast & Fair reduced time to first decision with reviews from a mean of 37.7 working days under conventional peer review to 5.5 working days. Reviewer commitment also improved. Fast & Fair invitations were accepted more often than conventional invitations (67% versus 23%), had lower nonresponse (13% versus 39%), and had higher completion among accepted invitations (98% versus 87%). Faster review was not associated with reduced review quality. Handling editors scored each review for usefulness in editorial decision-making. Fast & Fair produced fewer low-scoring reports than conventional peer review. Editorial behavior was also unchanged, with similar first-decision profiles and final acceptance rates (59% versus 61%). While financial sustainability remains to be tested at scale, the Fast & Fair model addresses a major bottleneck in traditional peer review by replacing ad hoc reviewer recruitment with conditional compensation, predefined quality standards and a strict editorial timeline.

Mechanosensing and mechanotransduction are essential for all living cells. In mammals, Piezo1 and Piezo2 are two mechanically activated cation channels that serve as mechanosensors for a variety of physiological and pathological processes, ranging from touch sensing to sickle cell disease. These two channels are well evolutionarily conserved, and orthologous genes can be traced back to the origin of vertebrates, which underwent whole-genome duplications (WGDs). The number of paralogous genes originating from the vertebrate WGD varies across gene families. Thus, whether there are more PIEZO paralogous genes in vertebrates remains understudied. Here, we identified piezo3, a new paralog of the piezo gene family, and analyzed its evolutionary history using phylogenetic and synteny analyses. The piezo3 gene is present in most vertebrate lineages but absent in birds and most mammals, likely due to nonfunctionalization after WGDs. In addition, we demonstrated that this channel could mediate calcium flux in response to mechanical stimuli in HEK293T cells, suggesting that Piezo3 exhibits PIEZO1/2-like activation and conduction channel functions. Our CRISPR mutation analysis revealed that the zebrafish piezo3 gene is not developmentally essential, possibly because its expression overlaps with other PIEZO channels. Mutant zebrafish showed elevated sensitivity to mechanical force and increased locomotor activity under (photopic) light illumination. Our results suggest that this new mechanical-sensing Piezo channel is widespread in vertebrates and may be critical for vertebrate adaptation by modulating mechanical sensing and light responses during evolution. SIGNIFICANCEAll living cells must sense mechanical forces, whether endogenous or exogenous, and respond to them by transforming these forces into biological signals, which is essential to a wide range of cellular processes, including cell division, growth, and differentiation. PIEZO channels are well-characterized, critical, versatile mechanotransducers for touch and pain physiology and for human diseases. Currently, PIEZO1 and PIEZO2 are the only two known PIEZO channels in most vertebrates. In zebrafish, there are two Piezo2 channels (Piezo2a and Piezo2b) due to extra genome duplication in the ray-finned fishes. Here, we report Piezo3 channel, a long-missing paralog of Piezo1 and Piezo2, in most vertebrates. This channel is present in the majority of vertebrate lineages, except for most birds and mammals. The zebrafish piezo3 gene is expressed during early embryogenesis, and mutation of this gene leads to zebrafish larvae responding to tapping mechanical force and light with active movement. The widespread distribution of this Piezo3 channel across most vertebrate species, but its absence in birds and most mammals, suggests it may play important roles in vertebrate physiology and evolution.

The interleukin-17 (IL-17) family of cytokines comprises structurally distinct ligands and receptors which mediate immune responses at mucosal surfaces. The growing understanding of its regulatory functions beyond immunity, together with extensive genetic variation in protein-coding genes, raises the possibility that IL-17 cytokines participate in an even wider network of biologic processes. Despite successes of experimental approaches to chart IL-17 functions, inherent signaling complexities and crosstalk with multiple physiologic pathways obscure a full appreciation of the biological potential of IL-17. Here, we integrated comparative genomics, evolutionary rate covariation (ERC), and signatures of natural selection to resolve phylogenetic relationships between IL-17 ligands and receptors and discovered evidence for hidden signaling interactions. ERC analysis revealed putative ligand-receptor interactions for IL-17D and IL-17RC and suggested uncharacterized potential signaling mediator for the receptor IL-17REL, such as IL-17B. Signals of covariation extended beyond the IL-17 family to other genes encoding neurodevelopmental effectors and growth factors, emphasizing recurrent co-evolutionary patterns that delineate the immune and neuromodulatory roles of IL-17. These connections are underlined by signatures of positive selection in the disordered N-terminal domain of IL-17E and its cognate receptor, IL-17RB, key modulators of both type 2 immune response and neuronal function, suggesting functional consequences of this understudied domain. Together, our findings suggest that IL-17 biology is repeatedly impacted by lineage-specific selective pressures that dictate both immune and non-immune functions. By anchoring the expanding IL-17 field in an evolutionary framework, we propose a model for understanding the diversification and functional expansion of this and other cytokine families.

Host-pathogen interactions evolve rapidly within species, providing natural genetic resources for the identification of specific ecological interaction factors. We previously identified RNA viruses that infect the nematodes C. elegans and C. briggsae in a species-specific manner. Wild strains of both host species demonstrate ample variation in viral sensitivity. Specifically, the wild C. elegans strain MY10, despite carrying a deletion in a key immunity factor, was among the most resistant strains. Here we use recombinant inbred lines and pool-sequencing approaches to genetically map the major MY10 resistance locus, narrowing down its position by CRISPR/Cas9 mediated recombination and testing candidates by genome editing. A rare non-synonymous polymorphism in the gtnt-1 gene, encoding a putative glycosyltransferase of the GT92 family, causes resistance to viral infection in MY10. We find that viral resistance through gtnt-1 mutation occurred repeatedly in C. elegans, with diverse resistance alleles each remaining at low frequency (<1%). Furthermore, leveraging closely related C. briggsae strains differing in viral susceptibility, we demonstrate that repeated reduction-of-function alleles of the Cbr-gtnt-1 ortholog similarly impair viral infection and enhance host fitness upon infection. In conclusion, we found recurrent evolution in two host species of reduction-of-function alleles of the gtnt-1 orthologs, which repeatedly lead to viral resistance yet remain at low frequency. These repeated events provide a case of transient ecological adaptation to a pathogen through recurrent mutation of the same gene in two species. The low population frequencies of the resistant alleles point to a changing eco-evolutionary context that prevents their spread in populations, resulting in high allelic heterogeneity.

Notch-mediated lateral inhibition is a conserved patterning process that controls alternative cell fate decisions and produces regular cell fate patterns. Prevailing models posit that lateral inhibition singles-out cells from fields of initially equipotent cells by amplifying stochastic fluctuations of Notch or pre-existing fate biases. Here, we revisited the role of Notch in early Drosophila neurogenesis, studying the dynamics of Neuroblast specification by live imaging the transcription of two proneural genes, scute and lethal of scute. We found that proneural gene expression is biased spatially along the dorsal-ventral axis prior to germ band extension and that early proneural expression predicts Neuroblast fate acquisition. This indicated that Neuroblast specification is pre-patterned by positional cues. Additionally, positional cues appeared to instruct individual cells to delaminate in a correct stereotyped pattern in proneural mutant embryos. Finally, contrary to current models, Notch signaling, measured by E(spl)m8 expression, was not detectable within proneural clusters until after Neuroblasts had initiated delamination. This indicated that Notch functions to stabilize rather than initiate fate decisions. We therefore propose that positional cues, not Notch, single-out Neuroblasts during early Drosophila neurogenesis, challenging long-held assumptions about the role of Notch in Neuroblast selection.

Withdrawal statementThe authors have withdrawn this manuscript due to a duplicate posting of manuscript number BIORXIV/2025/668902. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author. The correct preprint can be found at doi: 10.1101/2025.08.06.668902

BackgroundDuring development, the specification of individual cell types requires orchestrated shifts in the activity of thousands of genes, each following precise and coordinated trajectories. The ability of this process to succeed with remarkable reliability, despite its immense complexity, suggests that at least some underlying principles of development are fundamentally simple. Building on recent findings from epigenetic aging research, we hypothesize that linear trajectories in developing cells are influenced by concurrent oscillatory dynamics, which may help ensure synchrony and robustness. ResultsSupporting this model, we demonstrate an association between oscillatory and linear dynamics in cytosine modifications in mouse intestinal organoids, as well as in the transcriptomes of C. elegans. Furthermore, we show that transcriptomes of single cells exhibited developmental chrono-heterogeneity, enabling reconstruction of oscillatory cycles which also correlate with linear changes. ConclusionsOscillation-mediated linear dynamics may represent an evolutionary invention for encoding molecular time and orchestrating developmental processes.

Elucidating the mechanisms that control the formation of the mammalian neocortex is crucial for understanding brain functions. Synaptic activity of thalamocortical axons (TCAs), mediated by glutamate, exerts a major extrinsic influence on the maturation of their target layer 4 neurons in postnatal primary sensory cortex. However, TCAs reach the sensory cortex during mid-embryonic stages in mice, when neurons of future superficial layers, including layer 4, are still being generated from radial glia (RGs) or intermediate progenitor cells (IPCs), well before the formation of direct synapses. We previously showed that TCAs are required for the production and specification of the proper number of layer 4 neurons in sensory areas, and that part of these area-specific roles is played by the thalamus-derived molecule VGF. However, the role of TCA-derived glutamate prior to synapse formation has remained unclear. In this study, we used mutant mice lacking vGluT2, a vesicular glutamate transporter expressed in the embryonic thalamus, and found that vesicular release of thalamus-derived glutamate is required for the proper production and specification of layer 4 neurons in the sensory cortex by the neonatal stage, through mechanism distinct from those involving VGF. Our findings reveal that multiple molecular cues produced by incoming TCAs play distinct roles in the production and specification of layer 4 neurons in the sensory cortex.

Adult neurogenesis in the olfactory bulb (OB) contributes to structural and functional plasticity, influencing olfactory perception, learning, and memory. Adult-born granule cells (abGCs) exhibit unique morphological, electrophysiological, and synaptic properties compared to their neonatally born counterparts, suggesting a specialized role in olfactory processing. In the OB, such processing relies both on sensory inputs from the olfactory epithelium as well as top-down cortical feedback, which encompass both glutamatergic and GABAergic projections from the olfactory cortex back to the OB. While abGCs are known to integrate both bottom-up sensory inputs and top-down cortical projections, the specific connectivity and functional influence of cortical GABAergic inputs on abGCs remain largely unexplored. In this study, we investigated whether activity of cortical GABAergic projections is modulated by olfactory learning, how they impact olfactory behavior and whether these connections selectively influence mature abGCs. Using in vivo fiber photometry following odor-reward associative conditioning, we found odor- and reward-dependent activity of cortical GABAergic projections during learning session. Furthermore, their functional role was revealed using optogenetic activation which impaired both the acquisition and the reversal of an odor-reward association. Ex vivo patch-clamp recordings demonstrated that olfactory learning potentiates cortical GABAergic inputs specifically onto abGCs, and morphological analysis confirmed that learning increases the number of cortical GABAergic synapses. These findings highlight a novel mechanism by which top-down inhibitory control from the olfactory cortex selectively targets abGC activity during olfactory learning. Our results provide new insights into the functional specialization of abGCs and their role in adaptive olfactory behaviors.

De novo gene emergence from non-coding sequences is increasingly recognized as an important evolutionary mechanism, yet the functional potential of random sequences remains debated. Previous experiments suggested that expression of random sequence clones in Escherichia coli can enhance growth of the cells bearing them, i.e. they provide a fitness advantage. However, these findings have been questioned, regarding potential confounding effects of the clone mixtures and a possibly negatively acting peptide expressed from the cloning vector. Here we performed controlled competitive growth assays using a defined subset of 64 random sequence clones representing a spectrum of fitness effects. Experiments across multiple conditions, including two different growth cycle durations, induction states, and replicate sets, showed high technical reproducibility and consistent clone-specific growth trajectories for the majority of the clones, but for some also influences of genomic background and experimental conditions. While vector-derived constructs that inhibit the vector-coded peptide expression showed the same fitness improvements relative to the parental vector that were previously shown, several random sequence clones exhibited higher positive selection coefficients under conditions of exponential growth. These effects persisted even when negative clones were excluded, indicating that they are not driven by competition dynamics with negative clones. Our results demonstrate that positive growth effects of random sequence clones cannot be explained by clone mixture and vector artifacts alone. Instead, a subset of random sequences confers genuine fitness advantages comparable to beneficial mutations observed in experimental evolution studies. These findings provide strong experimental support for the capacity of random sequences to generate adaptive functions and underscore their role in de novo gene evolution. Significance statementThis study provides robust experimental evidence that a subset of random DNA sequences can confer genuine fitness advantages in Escherichia coli, independent of previously proposed artifacts such as vector effects or clone competition. Based on controlled competitive assays across multiple conditions, the results show that these adaptive effects are reproducible and comparable to beneficial mutations observed in experimental evolution. These findings strengthen the case that random sequences can serve as a meaningful source of functional innovation, supporting their role in de novo gene evolution.

Quorum sensing is a communication process bacteria use to orchestrate collective behaviors. Some temperate phages monitor bacterial quorum-sensing cues to track the abundance of vicinal host cells. Quorum-sensing-responsive phages can preferentially undertake lytic replication at high cell density, presumably maximizing transmission. If nearby host cells are lysogens, infections initiated by released virions could be nonproductive due to homoimmunity or superinfection exclusion, posing a conundrum for temperate phages. We define host and phage components influencing transmission of the quorum-sensing-responsive phage VP882 in Vibrio parahaemolyticus populations. Phage VP882 uses the K-antigen of serotype O3:K6 as its receptor. Host cells prevent phage attachment via quorum-sensing-controlled export of polysaccharides that shield the K-antigen from the phage at high cell density. Phage VP882 can superinfect and superlysogenize V. parahaemolyticus, overcoming the challenge of detecting whether or not potential hosts are lysogens. Following superlysogenization, recombination of phage genomes can occur possibly promoting genome diversification. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=144 SRC="FIGDIR/small/712183v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@19c151dorg.highwire.dtl.DTLVardef@2e3a4forg.highwire.dtl.DTLVardef@f64ae4org.highwire.dtl.DTLVardef@1aee428_HPS_FORMAT_FIGEXP M_FIG C_FIG

The emergence in 2025/26 of the influenza A/H3N2 K substrain (H3N2/K) was the cause of significant public health concern. This genetically divergent virus was assessed to have a strongly decreased reactivity to contemporary vaccine strains. Respectively prolonged and early influenza seasons in the Southern and Northern Hemispheres contributed to concerns about vaccine efficacy. Here we retrospectively assessed the genetic and antigenic properties of this virus, combining epidemiological surveillance data, computational antigenic analysis, and serological data using samples from a well-stratified UK cohort. In contrast to initial indications, we found that despite the genetic distinctiveness of H3N2/K the virus had undergone limited antigenic change, suggesting that its emergence was instead the result of selection for non-antigenic properties. We confirmed previous results showing that contemporary vaccines produced an enhanced neutralising response to H3N2/K but, in a stratified serological analysis, showed that responses to the J and K substrains were age-dependent, largely driven by patterns of vaccination. Our results have implications for antigenic surveillance and for public communication strategies in future influenza seasons.

Serological testing is important for assessing past exposure and immunity, but interpretation can be complicated by antibody cross-reactivity between closely related viruses. We assess this challenge for Usutu virus (USUV) and West Nile virus (WNV), flaviviruses that recently emerged in Europe. We analysed samples from wild blackbirds collected in the Netherlands between 2016-2022. Samples (N=1742) were screened using an NS1-based protein micro-array, with positives confirmed by Focus Reduction Neutralization Tests (FRNT). We jointly estimated seroprevalence and antibody responses by fitting a Bayesian latent-variable model to FRNT values. Estimates of homologous and cross-reactive antibody responses were used to improve interpretation of observed titres for serosurveillance. Estimated seroprevalence varied across time and regions between 4.9% (95%CrI 3.5-6.7) to 18.5% (95%CrI 14.9-22.7) for USUV and between 2.4% (95%CrI 1.3-3.8) to 6.4% (95%CrI 3.9-9.6) for WNV. These were 1.5 (USUV) to 2.4 times (WNV) higher than estimates based on the current threshold-based algorithm. USUV induced a higher antibody response and was more likely to induce a cross-reactive response than WNV. Our classification algorithm informed by these estimates showed high sensitivity (WNV: 0.88, USUV: 0.97) and specificity (both: >0.99). Our results illustrate how quantitative frameworks can improve serological interpretation in settings with co-circulating pathogens.

Interferons (IFNs) are essential mediators of antiviral defense in vertebrates, having gradually replaced the RNA interference (RNAi) antiviral mechanism that predominates in invertebrates and plants. To date, IFNs have been identified exclusively in jawed vertebrates, leaving the origin of IFN-based antiviral mechanisms largely mysterious. In this study, by conducting a genome-wide screening of IFN homologs accross various species, we successfully identified seveal IFN homologs from agnatha and lancelet, but not other invertebrates. Notably, both agnatha and lancelet IFN homologs have ability to induce a set of interferon-stimulated genes (ISGs)-like genes, thus tracing the origin of IFN to basal chordate. Using VSV infected peripheral blood mononuclear cells (PBMCs) of Japanese lampreys, we found that lamprey IFNs have antiviral functionality by inducing the expression of hundreds of ISGs through interacting with a heterodimeric complex composed of CRFB7 and CRFB14. In addition to robustly mediating antiviral responses in monocytes, lamprey IFNs exert their effects on variable lymphocyte receptor B (VLRB)+ cells by remodeling the cytokine/chemokine networks to orchestrate antiviral innate and adaptive immunity. Furthermore, cross-species functional comparison of Dicer revealed that changes in residues essential for dsRNA processing occurred concurrently with the evolution of the IFN system. Collectively, these findings uncover the evolutionary origin of IFN and underscore its ancient roles in antiviral response and immune regulation, especially in the takeover of the RNAi antiviral mechanism during the early evolution of vertebrates. Significance StatementInterferons (IFNs) represent a hallmark of vertebrate antiviral immunity, yet their origin has remained elusive. Here, we reported bona fide IFN ligands and cognate receptors in both lamprey and lancelet, two key species placed at the transition from invertebrates to vertebrates. Using the VSV infection model, we further demonstrated the roles of lamprey IFN in antiviral defense and immune regulation. We also found that substitutions in residues essential for Dicer mediated dsRNA processing coincided with the emergence of the IFN system. Collectively, our findings provide key insights into the evolutionary origin of IFN-based immunity and its gradual replacement of RNAi as the dominant antiviral strategy in vertebrates.

Root-knot nematodes are obligate plant parasites that cause substantial agricultural losses worldwide. They induce highly specialized, metabolically hyperactive feeding sites within host roots, which serve as their sole source of nutrients throughout their life cycle. The formation and maintenance of these feeding sites depend on the manipulation of host developmental pathways by nematode-derived secretions. Phytosulfokines (PSKs) are small plant peptide hormones that regulate cell division, tissue expansion, and growth responses, processes essential for feeding site development. Here, we identify root-knot nematode genes predicted to encode peptides with a conserved PSK functional motif. These genes are predominantly expressed during the early stages of infection and localize to secretory glands, suggesting a role in early parasitism. Moreover, silencing PSK-like gene expression reduces root gall formation and nematode reproduction. Together, these findings reveal that root-knot nematodes deploy PSK-like peptides as virulence factors to promote successful parasitism, providing the first report of PSK peptide mimicry in any plant pathogen.

Cell type specification in the embryonic brain and spinal cord is thought to begin within molecularly defined progenitor domains that do not intermix. Our data provide an alternative model that is spatially and temporally dynamic within a basal ganglia anlage, the medial ganglionic eminence (MGE). MGE progenitor cells are progressively displaced ventrally and caudally from a rostral growth zone (the MGE/LGE sulcus). Progenitors that leave the MGE/LGE sulcus early occupy caudoventral MGE regions, while ones that leave later reside in rostrodorsal MGE regions. As they change position, their transcriptional states and cell type output change. Transcriptional analyses showed an upregulation of the Nfi TFs during the period of progenitor movement. Nfia and Nfib double mutants alter the repertoire of cortical interneuron subtypes. Overall, we present a mechanism that synchronizes regional patterning with tissue growth and links spatial and temporal specification in producing diverse neuronal subtypes.

Inhibition of return (IOR) refers to the slowing of response times (RTs) for stimuli presented at previously inspected locations relative to novel locations. However, the exact processing stage(s) at which IOR occurs, and its nature across different response modalities, remain debated. By reanalyzing RT data from a target-target IOR paradigm with a single noisy accumulator model, we tested whether IOR could occur at sensory or attentional stages of processing, or at later stages of decision and action selection. We considered IOR under two conditions: manual and saccadic responses. The within-trial Gaussian noise parameter best explained both manual and saccadic IOR, suggesting that in both modalities, IOR may result from a more fluctuating accumulation of evidence for repeated locations. These results support the hypothesis that target-target IOR may primarily involve attentional-level mechanisms. Significance statementWe respond more slowly to a stimulus that is presented within a short interval in the same location ("inhibition of return"), a bias thought to promote efficient visual exploration. Using evidence-accumulation modeling of manual and eye-movement reaction times from two previous studies, we found that the key change linked to inhibition of return is greater within-trial variability (noise) in evidence accumulation, not a higher decision threshold. Understanding which processing stage is affected can help connect behavioral effects to the brain networks that support attention and orienting.

Triatominae bugs are the main vectors of Chagas disease in Latin America and rely on microbial nutritional symbiosis to complement their haematophagous diet with B-vitamins. While Rhodococcus bacteria have been identified as key symbionts, diverse metabarcoding analyses have suggested additional candidates. However, symbiont genomic data and metabolic capabilities remain largely uncharacterized. To address this gap, we generated metagenomic assemblies for 14 Triatominae and captured 15 bacterial genomes belonging to 4 genera (Rhodococcus, Wolbachia, Symbiopectobacterium and Arsenophonus) across 9 triatominae species. We identified five co-infection cases, including one involving two distinct Arsenophonus symbionts, one exhibiting hallmarks of massive genome degradation. Phylogenetic analyses revealed that Triatominae-associated symbionts form monophyletic groups within each genus, suggesting common origins followed by co-evolution with their hosts. Annotation of vitamin B metabolic genes indicates that most symbionts harbour incomplete pathways, with evidence of metabolic complementation between co-infecting symbionts. Additionally, we identified bacterial genes laterally transferred into host insect genomes, interpreted as footprints of present or past symbiotic associations. Nearly all Triatominae genomes displayed transferred genes from all four bacterial genera, including hosts with no detectable symbiont in genome assemblies. Taken together with these discoveries support the existence of a stable and limited network of four possible nutritional symbiont lineages with rare evidence of symbiont turn-overs. Significance statementTriatominae bugs, vectors of Chagas disease, are known to harbor a diverse community of nutritional bacterial symbionts whose genomic and metabolic roles have remained largely unexplored. By reconstructing 15 symbiont genomes that segregate as four bacterial genera, we provide important insight into the origins, the evolution and the metabolic structure of the nutritional symbiosis in triatominae. These findings support a stable, evolutionary conserved network of nutritional symbionts with limited turnover.

The adrenal glands are central regulators of systemic stress responses through tightly controlled glucocorticoid production. Yet, the contribution of local immune-vascular interactions to adrenal stress adaptation remains poorly understood. Here, we investigated the role of adrenal gland macrophages in coordinating stress-induced immune remodeling and vascular function. By integrating single-cell RNA sequencing datasets across four distinct stress models, including acute cold exposure, chronic social defeat, chronic inflammation, and systemic Candida albicans infection, we identified a conserved increase in monocyte recruitment to the adrenal gland, accompanied by dynamic macrophage transitions. Comparative transcriptomic and ligand-receptor analyses identified transforming growth factor-{beta} (TGF{beta}) as a dominant macrophage-derived signal targeting adrenal endothelial cells across all stress conditions. Pharmacological blockade of TGF{beta} receptor signaling reduced endothelial activation, vascular permeability, and monocyte infiltration into the adrenal gland following stress, without directly altering resident macrophage numbers. Using genetic fate-mapping and conditional knockout models, we demonstrate that macrophage-derived, but not endothelial-derived, TGF{beta} is required to promote enhanced endothelial adhesion molecule expression, vascular fenestration, permeability, and efficient monocyte recruitment. Loss of macrophage TGF{beta} production also led to exacerbated systemic stress hormone levels. Together, these findings uncover a previously unrecognized macrophage-endothelial axis in the adrenal gland, whereby macrophage-derived TGF{beta} regulates vascular properties to support immune cell recruitment and stress adaptation. This immune-vascular crosstalk provides new mechanistic insights into adrenal homeostasis and suggests potential therapeutic avenues for disorders associated with dysregulated chronic stress.

Accurate learning requires the brain to distinguish between expected and unexpected uncertainties so that new information can update memory appropriately. It is proposed that the neuromodulator acetylcholine reconfigures neuronal networks for learning and is a key factor signalling uncertainty. Here we tested this hypothesis by measuring acetylcholine release and neuronal representations in the retrosplenial cortex of mice whilst challenging them with expected and unexpected uncertainties of reward location. Acetylcholine release increased with changes in expected uncertainty but only responded to unexpected uncertainty coincident with contextual shifts that altered expected uncertainty. In tandem, as expected uncertainty increased, neuronal representations initially shifted from a position reference frame to focus on salient landmarks, such as reward location. Transitions in expected uncertainty also accelerated remapping of representations and behavioural adaptation when unexpected uncertainty was experienced. Thus, we demonstrate acetylcholine release discerns between types of uncertainty and positively correlates with learning speed in uncertain environments.