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Peters, L.

Publications and source records attributed to Peters, L..

At least 19 recordsLinked to original sources

BayesCNet: Bayesian inference for cell type-specific regulatory networks leveraging cell type hierarchy in single-cell data

Understanding gene regulatory networks (GRNs) is essential for deciphering biological processes and disease mechanisms. Single-cell multiome technologies now enable joint profiling of chromatin accessibility and gene expression, offering an powerful means to infer cell type-specific GRNs. However, existing methods analyze each cell type independently or aggregate data into pseudo-bulk profiles, limiting their ability to resolve rare populations and capture cellular heterogeneity. We introduce BayesCNet, a Bayesian hierarchical model that jointly infers enhancer-gene linkages across all cell types while leveraging their hierarchical relationships for information sharing. Through extensive simulations, BayesCNet consistently outperforms state-of-the-art methods, with the largest improvements in rare cell types. When applied to real datasets, BayesCNet identifies enhancer-gene linkages with higher accuracy validated by promoter-capture Hi-C data, and reconstructs cell type-specific GRNs that highlight key regulators, demonstrating its power to resolve gene regulatory programs across diverse cell types.

bioinformatics↗

Neural dynamics encoding risky choices during deliberation reveal separate choice subspaces

Human decision-making involves the coordinated activity of multiple brain areas, acting in concert, to enable humans to make choices. Most decisions are carried out under conditions of uncertainty, where the desired outcome may not be achieved if the wrong decision is made. In these cases, humans deliberate before making a choice. The neural dynamics underlying deliberation are unknown and intracranial recordings in clinical settings present a unique opportunity to record high temporal resolution electrophysiological data from many (hundreds) brain locations during behavior. Combined with dynamic systems modeling, these allow identification of latent brain states that describe the neural dynamics during decision-making, providing insight into these neural dynamics and computations. Results show that the neural dynamics underlying risky decision, but not decisions without risk, converge to separate subspaces depending on the subjects preferred choice and that the degree of overlap between these subspaces declines as choice approaches, suggesting a network level representation of evidence accumulation. These results bridge the gap between regression analyses and data driven models of latent states and suggest that during risky decisions, deliberation and evidence accumulation toward a final decision are represented by the same neural dynamics, providing novel insights into the neural computations underlying human choice. HighlightsO_LIHighly accurate decoding can be accomplished with dynamical systems modeling that revealed distinct attractor-like subspaces, one for each of the two options (gamble or safe bet). C_LIO_LIEarly during deliberation, single trial neural trajectories show rapid transitioning between these subspaces, but as the time of choice selection approached, the single trial trajectories converged towards one of the subspaces, whose identity was consistent with the subjects choice. C_LIO_LIThese dynamics are specific to risky decisions as we found classification accuracy dropped to chance for trials where the gamble option was guaranteed to be successful (100% win probability) or unsuccessful (0% win probability). C_LIO_LIThese results suggest that deliberation and evidence accumulation toward a final decision in the presence of any risk can be represented by the same neural dynamics, providing novel insights into the neural computations underlying human choice. C_LI

neuroscience↗

TGF-β induces an atypical EMT to evade immune mechanosurveillance in lung adenocarcinoma dormant metastasis

The heterogeneity of epithelial-to-mesenchymal transition (EMT) programs is manifest in the diverse EMT-like phenotypes occurring during tumor progression. However, little is known about the mechanistic basis and functional role of specific forms of EMT in cancer. Here we address this question in lung adenocarcinoma (LUAD) cells that enter a dormancy period in response to TGF-{beta} upon disseminating to distant sites. LUAD cells with the capacity to enter dormancy are characterized by expression of SOX2 and NKX2-1 primitive progenitor markers. In these cells, TGF-{beta} induces growth inhibition accompanied by a full EMT response that subsequently transitions into an atypical mesenchymal state of round morphology and lacking actin stress fibers. TGF-{beta} induces this transition by driving the expression of the actin-depolymerizing factor gelsolin, which changes a migratory, stress fiber-rich mesenchymal phenotype into a cortical actin-rich, spheroidal state. This transition lowers the biomechanical stiffness of metastatic progenitors, protecting them from killing by mechanosensitive cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Inhibiting this actin depolymerization process clears tissues of dormant metastatic cells. Thus, LUAD primitive progenitors undergo an atypical EMT as part of a strategy to evade immune-mediated elimination during dormancy. Our results provide a mechanistic basis and functional role of this atypical EMT response of LUAD metastatic progenitors and further illuminate the role of TGF-{beta} as a crucial driver of immune evasive metastatic dormancy.

cancer biology↗

SMARTER-database: a tool to explore genomic diversity in small ruminants

Underutilized sheep and goat breeds have the ability to adapt to challenging environments due to their genetic composition. Integrating publicly available genomic datasets with new data will facilitate genetic diversity analyses; however, this process is complicated by important data discrepancies, such as outdated assembly versions or different data formats. Here we present the SMARTER-database, a collection of tools and scripts to standardize genomic data and metadata mainly from SNP chips arrays on global small ruminant populations with a focus on reproducibility. SMARTER-database harmonizes genotypes for about 12,000 sheep and 6,000 goats to a uniform coding and assembly version. Users can access the genotype data via FTP and interact with the metadata through a web interface or programmatically using their custom scripts, enabling efficient filtering and selection of samples. These tools will empower researchers to focus on the crucial aspects of adaptation and contribute to livestock sustainability, leveraging the rich dataset provided by the SMARTER-database. Availability & ImplementationThe code is available as open source software under the MIT license at https://github.com/cnr-ibba/SMARTER-database.

bioinformatics↗

Inhibition of CD226 Co-Stimulation Suppresses Diabetes Development in the NOD Mouse by Augmenting Tregs and Diminishing Effector T Cell Function

Aims/hypothesisImmunotherapeutics targeting T cells are crucial for inhibiting autoimmune disease progression proximal to disease onset in type 1 diabetes. A growing number of T cell-directed therapeutics have demonstrated partial therapeutic efficacy, with anti-CD3 (-CD3) representing the only regulatory agency-approved drug capable of slowing disease progression through a mechanism involving the induction of partial T cell exhaustion. There is an outstanding need to augment the durability and effectiveness of T cell targeting by directly restraining proinflammatory T helper type 1 (Th1) and type 1 cytotoxic CD8+ T cell (Tc1) subsets, while simultaneously augmenting regulatory T cell (Treg) activity. Here, we present a novel strategy for reducing diabetes incidence in the NOD mouse model using a blocking monoclonal antibody targeting the type 1 diabetes-risk associated T cell co-stimulatory receptor, CD226. MethodsFemale NOD mice were treated with anti-CD226 between 7-8 weeks of age and then monitored for diabetes incidence and therapeutic mechanism of action. ResultsCompared to isotype-treated controls, anti-CD226 treated NOD mice showed reduced insulitis severity at 12 weeks and decreased disease incidence at 30 weeks. Flow cytometric analysis performed five weeks post-treatment demonstrated reduced proliferation of CD4+ and CD8+ effector memory T cells in spleens of anti-CD226 treated mice. Phenotyping of pancreatic Tregs revealed increased CD25 expression and STAT5 phosphorylation following anti-CD226, with splenic Tregs displaying augmented suppression of CD4+ T cell responders in vitro. Anti-CD226 treated mice exhibited reduced frequencies of islet-specific glucose-6-phosphatase catalytic subunit related protein (IGRP)-reactive CD8+ T cells in the pancreas, using both ex vivo tetramer staining and single-cell T cell receptor sequencing (scTCR-seq) approaches. 51Cr-release assays demonstrated reduced cell-mediated lysis of beta-cells by anti-CD226-treated autoreactive cytotoxic T lymphocytes. Conclusions/interpretationCD226 blockade reduces T cell cytotoxicity and improves Treg function, representing a targeted and rational approach for restoring immune regulation in type 1 diabetes. Research in ContextO_ST_ABSWhat is already known about this subject?C_ST_ABSO_LIThe co-stimulatory receptor CD226 is upregulated upon activation and is highly expressed on NK cell subsets, myeloid cells, and effector T cells. C_LIO_LIA single nucleotide polymorphism in CD226 (rs763361; C>T) results in a Gly307Ser missense mutation linked to genetic susceptibility for type 1 diabetes. C_LIO_LIGlobal knockout of Cd226 and conditional Cd226 knockout in FoxP3+ Tregs reduced insulitis severity and diabetes incidence in NOD mice, indicating a crucial role for CD226 in disease pathogenesis. C_LI What is the key question?O_LICan CD226 blockade reduce T cell cytotoxicity and improve Treg function to diminish diabetes incidence in NOD mice? C_LI What are the new findings?O_LIAnti-CD226 treatment reduced insulitis, decreased disease incidence, and inhibited splenic CD4+ and CD8+ effector memory T cell proliferation. C_LIO_LIPancreatic Tregs from anti-CD226 treated mice exhibited increased CD25 expression; splenic Tregs displayed augmented STAT5 phosphorylation and suppressive capacity in vitro. C_LIO_LIAnti-CD226 treatment reduced IGRP-specific pancreatic CD8+ T cell frequencies, and reduced autoreactive CD8+ T cell-mediated lysis of beta-cells in vitro. C_LI How might this impact on clinical practice in the foreseeable future?O_LICD226 blockade could reduce autoreactive T cell cytotoxicity, enhance Treg function, and slow disease progression in high-risk or recent-onset type 1 diabetes cases. C_LI

immunology↗

Monocytes Mobilized by Gut Neurons Remodel the Enteric Nervous System

The proper organization of the enteric nervous system (ENS) is critical for normal gastrointestinal (GI) physiology. Inflammatory bowel disease (IBD) dysregulates GI physiology, including bowel movements (motility), but in many IBD patients, GI motility disorders persist in remission through a poorly understood pathological process. Here we uncover that post-inflammatory GI dysmotility (PI-GID) stems from structural ENS remodeling driven by a combination of neuronal loss and neurogenesis. Enteric neurons respond to mucosal inflammation by upregulating CCL2 expression and facilitating the recruitment of CCR2+ monocytes into the neural myenteric plexus within the intestinal muscle. This is followed by the expansion of monocyte-derived macrophages and their migration into the myenteric ganglia and phagocytosis of neurons. However, excessive recruitment of monocytes results in disproportionate ENS remodeling and PI-GID. The expansion of inflammatory cells is known to promote tissue hypoxia. We find that enteric neurons become hypoxic upon colitis, but hypoxia-induced signaling via HIF1 initiates an adaptation program in enteric neurons to attenuate CCL2 expression and limit monocyte recruitment. We demonstrate that reinforcing HIF1 signaling in enteric neurons prevents PI-GID by reducing colitis-associated monocyte recruitment in the myenteric plexus and protecting against ENS remodeling. In summary, our findings unveil PI-GID pathogenesis and identify a regulatory axis for its prevention. One Sentence SummaryIntestinal mucosal inflammation engages enteric neurons in the inflammatory response leading to neurogenic recruitment of monocytes into the extra-mucosal myenteric plexus followed by pathological structural remodeling of the enteric nervous system by monocyte-derived macrophages.

immunology↗

Pneumonia induced rise in glucagon promotes endothelial damage and vascular thrombogenicity

BackgroundRecent studies have demonstrated a link between respiratory infections and increased short-term risk of cardiovascular disease (CVD). However, the molecular mechanisms underlying the increased cardiovascular risk after respiratory infections are only poorly understood. Here, we aimed to decipher pathophysiological circuits of pneumonia associated CVD in experimental models of bacterial pneumonia and vascular injury. MethodsC57BL/6J mice were exposed to intranasal inoculation with either Streptococcus pneumoniae (S. pneumoniae) serotype 4 (pneumonia group) or phosphate buffered saline (PBS) (control group). 24 hours post infectionem (p.i.) mice were treated with antibiotics until the end of the study. On day 7 p.i. carotid artery injury (CI) was induced by electric stimulation and vascular repair was analyzed 3 days after injury. Plasma proteomic analyses were performed by Olink Bioscience. Primary human aortic endothelial cells (HAECs) were used to study alterations of the endothelial functional properties, bioenergetic state and thrombogenic potential in vitro. Intravital fluorescence microscopy equipped with video recording was applied to measure thrombus formation in real-time. ResultsBacterial pneumonia impaired repair capacity of the endothelium after vascular injury. Proteomic analyses revealed significantly higher plasma levels of glucagon in mice after recovery from pneumonia relative to controls, which was further confirmed by ELISA detecting glucagon. Mechanistically, we found that glucagon impaired mitochondrial bioenergetics and migratory potential in HAECs and induced an inflammatory response. Moreover, glucagon fostered vascular thrombogenicity as demonstrated by increased thrombocyte adhesion to HAECs and accelerated carotid artery thrombus formation in vivo. Acute application of the glucagon-like peptide-1 receptor (GLP1-R) agonist liraglutide to lower blood glucagon levels, restored vascular repair potential and attenuated vascular thrombogenicity in mice with pneumonia. ConclusionsOur findings reveal a novel mechanism that associates elevated circulatory glucagon levels to dysfunctional endothelium and increased vascular thrombogenicity, suggesting glucagon signaling as a potential therapeutic target to prevent pneumonia-induced cardiovascular events. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=138 SRC="FIGDIR/small/592488v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1dab59eorg.highwire.dtl.DTLVardef@1c9a033org.highwire.dtl.DTLVardef@34a566org.highwire.dtl.DTLVardef@56e33d_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

MicroRNA-26b protects against MASH development and can be efficiently targeted with lipid nanoparticles.

Background & AimsThe prevalence of metabolic dysfunction-associated steatohepatitis (MASH) is increasing, urging more research into the underlying mechanisms. MicroRNA-26b (miR-26b) might play a role in several MASH-related pathways. Therefore, we aimed to determine the role of miR-26b in MASH and its therapeutic potential using miR-26b mimic-loaded lipid nanoparticles (LNPs). MethodsApoe-/-Mir26b-/-, Apoe-/-LysMcreMir26bfl/fl mice, and respective controls were fed a western-type diet to induce MASH. Plasma and liver samples were characterized regarding lipid metabolism, hepatic inflammation, and fibrosis. Additionally, miR-26b mimic-loaded LNPs were injected in Apoe-/-Mir26b-/- mice to rescue the phenotype and key results were validated in human precision-cut liver slices. Finally, kinase profiling was used to elucidate underlying mechanisms. ResultsApoe-/-Mir26b-/- mice showed increased hepatic lipid levels, coinciding with increased expression of scavenger receptor a and platelet glycoprotein 4. Similar effects were found in mice lacking myeloid-specific miR-26b. Additionally, hepatic TNF and IL-6 levels and amount of infiltrated macrophages were increased in Apoe-/- Mir26b-/- mice. Moreover, Tgfb expression was increased by the miR-26b deficiency, leading to more hepatic fibrosis. A murine treatment model with miR-26b mimic-loaded LNPs reduced hepatic lipids, rescuing the observed phenotype. Kinase profiling identified increased inflammatory signaling upon miR-26b deficiency, which was rescued by LNP treatment. Finally, miR-26b mimic-loaded LNPs also reduced inflammation in human precision-cut liver slices. ConclusionsOverall, our study demonstrates that the detrimental effects of miR-26b deficiency in MASH can be rescued by LNP treatment. This novel discovery leads to more insight into MASH development, opening doors to potential new treatment options using LNP technology. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/580792v2_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@b8b5b8org.highwire.dtl.DTLVardef@a26333org.highwire.dtl.DTLVardef@11ed2a0org.highwire.dtl.DTLVardef@963208_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

Polyketide synthase-derived sphingolipids determine microbiota-mediated protection against pathogens in C. elegans

Protection against pathogens is a major function of the gut microbiota. Although bacterial natural products have emerged as crucial components of host-microbiota interactions, their exact role in microbiota-mediated protection is largely unexplored. We addressed this knowledge gap with the nematode Caenorhabditis elegans and its microbiota isolate Pseudomonas fluorescens MYb115 that is known to protect against Bacillus thuringiensis (Bt) infection. We find that MYb115-mediated protection depends on sphingolipids that are derived from an iterative type I polyketide synthase (PKS), thereby describing a noncanonical pathway of bacterial sphingolipid production. We provide evidence that MYb115-derived sphingolipids affect C. elegans tolerance to Bt infection by altering host sphingolipid metabolism. This work establishes sphingolipids as structural outputs of bacterial PKS and highlights the role of microbiota-derived sphingolipids in host protection against pathogens.

molecular biology↗

Regulators of health and lifespan extension in genetically diverse mice on dietary restriction

Caloric restriction (CR) delays aging and extends healthy lifespan in multiple species. Alternative forms of dietary restriction (DR) such as intermittent fasting (IF) have drawn significant interest as a more sustainable regimen, but the landscape of longevity-promoting dietary interventions remains largely unexplored. Identifying the most robust, efficacious, and experimentally tractable modes of DR is key to better understanding and implementing effective longevity interventions for human healthspan. To that end, we have performed an extensive assessment of DR interventions, investigating the effects of graded levels of CR (20% and 40%) and IF (1 day and 2 days of fasting per week) on the health and survival of 960 genetically diverse female mice. All interventions extended lifespan, although only CR significantly reduced the mortality doubling time. Notably, IF did not extend lifespan in mice with high pre-intervention bodyweight. We carried out extensive phenotyping to determine the health effects of long-term DR and to better understand the mechanisms driving within-diet heterogeneity in lifespan. The top within-diet predictor of lifespan was the ability of mice to maintain bodyweight through periods of handling, an indicator of stress resilience. Additional predictors of long lifespan include specific changes in immune cells, red blood cell distribution width (RDW), and retention of adiposity in late life. We found that lifespan is heritable (h2 = 0.24), and that genetic background has a larger influence on lifespan than dietary interventions. We identified a significant association for lifespan and RDW on chromosome 18 that explained 4.3% of the diet-adjusted variation in lifespan. Diet-induced changes on metabolic traits, although beneficial, were relatively poor predictors of lifespan, arguing against the long-standing notion that DR works by counteracting the negative effects of obesity. These findings indicate that improving health and extending lifespan are not synonymous and that metabolic parameters may be inappropriate endpoints for evaluating aging interventions in preclinical models and clinical trials.

genetics↗

The C. elegans proteome response to two protective Pseudomonas symbionts

The C. elegans natural microbiota isolates Pseudomonas lurida MYb11 and Pseudomonas fluorescens MYb115 protect the host against pathogens through distinct mechanisms. While P. lurida produces an antimicrobial compound and directly inhibits pathogen growth, P. fluorescens MYb115 protects the host without affecting pathogen growth. It is unknown how these two protective microbes affect host biological processes. We used a proteomics approach to elucidate the C. elegans response to MYb11 and MYb115. We found that both Pseudomonas isolates increase vitellogenin protein production in young adults, which confirms previous findings on the effect of microbiota on C. elegans reproductive timing. Moreover, the C. elegans responses to MYb11 and MYb115 exhibit common signatures with the response to other vitamin B12-producing bacteria, emphasizing the importance of vitamin B12 in C. elegans-microbe metabolic interactions. We further analyzed signatures in the C. elegans response specific to MYb11 or MYb115. We provide evidence for distinct modification in lipid metabolism by both mutualistic microbes. We could identify activation of host pathogen defense responses as MYb11-specific proteome signature and provide evidence that the intermediate filament protein IFB-2 is required for MYb115-mediated protection. These results indicate that MYb11 not only produces an antimicrobial compound, but also activates host antimicrobial defenses, which together might increase resistance to infection. In contrast, MYb115 affects host processes such as lipid metabolism and cytoskeleton dynamics, which might increase host tolerance to infection. Overall, this study pinpoints proteins of interest that form the basis for additional exploration into the mechanisms underlying C. elegans microbiota-mediated protection from pathogen infection and other microbiota-mediated traits.

molecular biology↗

Human immune phenotyping reveals accelerated aging in type 1 diabetes

The composition of immune cells in peripheral blood is dramatically remodeled throughout the human lifespan, as environmental exposures shape the proportion and phenotype of cellular subsets. These dynamic shifts complicate efforts to identify disease-associated immune signatures in type 1 diabetes (T1D), which is variable in age of onset and rate of {beta}-cell decline. Herein, we conducted standardized flow cytometric immune profiling on peripheral blood from a cross-sectional cohort of T1D participants (n=240), their first-degree relatives (REL, n=310), those at increased risk with two or more islet autoantibodies (RSK, n=24), and autoantibody negative healthy controls (CTR, n=252). We constructed an immune-age predictive model in healthy subjects and developed an interactive data visualization portal (ImmScape; https://ufdiabetes.shinyapps.io/ImmScape/). When applied to the T1D cohort, this model revealed accelerated immune aging (p<0.001) as well as phenotypic signatures of disease after age correction. Of 192 investigated flow cytometry and complete blood count readouts, 46 were significantly associated with age only, 25 with T1D only, and 23 with both age and T1D. Phenotypes associated with T1D after age-correction were predictive of T1D status (AUROC=82.3%). Phenotypes associated with accelerated aging in T1D included increased CXCR3+ and PD-1+ frequencies in naive and memory T cell subsets, despite reduced PD-1 expression levels (mean fluorescence intensity) on memory T cells. Additionally, quantitative trait locus analysis linked an increase in HLA-DR expression on monocytes with the T1D-associated HLA-DR4/DQ8 genotype, regardless of clinical group. Our findings demonstrate advanced immune aging in T1D and highlight disease-associated phenotypes for biomarker monitoring and therapeutic interventions. One Sentence SummaryPeripheral blood characterization reveals accelerated immune-age and age-adjusted proinflammatory immune phenotypes in type 1 diabetes.

immunology↗

Sex-differences in the genetic architecture of individual recombination rates in wild house sparrows (Passer domesticus).

Meiotic recombination through chromosomal crossing-over is a fundamental feature of sex and an important driver of genomic diversity. It ensures proper disjunction, allows increased selection responses, and prevents mutation accumulation; however, it is also mutagenic and can break up favourable haplotypes. This cost/benefit dynamic is likely to vary depending on mechanistic and evolutionary contexts, and indeed, recombination rates show huge variation in nature. Identifying the genetic architecture of this variation is key to understanding its causes and consequences. Here, we investigate individual recombination rate variation in wild house sparrows (Passer domesticus). We integrate genomic and pedigree data to identify autosomal crossover counts (ACC) and intra-chromosomal allelic shuffling ([r]intra) in 13,056 gametes. Females had 1.37 times higher ACC, and 1.55 times higher[r] intra than males. ACC and[r] intra were heritable in females and males (ACC h2 = 0.23 and 0.11;[r] intra h2 = 0.12 and 0.14), but cross-sex additive genetic correlations were low (rA = 0.29 and 0.32 for ACC and[r] intra). Conditional bivariate analyses showed that all measures remained heritable after accounting for genetic values in the opposite sex, indicating that sex-specific ACC and[r] intra can evolve somewhat independently. Genome-wide models showed that ACC and[r] intra are polygenic and driven by many small-effect loci, many of which are likely to act in trans as global recombination modifiers. Our findings show that recombination rates of females and males can have different evolutionary potential in wild birds, providing a compelling mechanism for the evolution of sexual dimorphism in recombination.

genetics↗

Selection, recombination and population history effects on runs of homozygosity (ROH) in wild red deer (Cervus elaphus)

The distribution of runs of homozygosity (ROH) may be shaped by a number of interacting processes such as selection, recombination and population history, but little is known about the importance of these mechanisms in shaping ROH in wild populations. We combined an empirical dataset of >3,000 red deer genotyped at >35,000 genome-wide autosomal SNPs and evolutionary simulations to investigate the influence of each of these factors on ROH. We assessed ROH number and location in two populations of red deer (a focal and comparison) to investigate the effect of population history. We investigated the role of recombination using both a physical map and a genetic linkage map to search for ROH. We found differences in ROH distribution between both populations and both map types indicating that population history and local recombination rate have a substantial effect on ROH. Finally, we ran forward genetic simulations with varying population histories, recombination rates and levels of selection, allowing us to further interpret our empirical data. These simulations showed that population history has a greater effect on ROH distribution than either recombination or selection. We further show that selection can cause genomic regions where ROH are common, so called ROH hotspots, only when the effective population size (Ne) is large or selection is particularly strong. In populations having undergone a population bottleneck, genetic drift can outweigh the effect of selection. We show that most ROH hotspots in the Rum population are in line with expectations from neutral simulations, however two ROH hotspots show possible signatures of selection. Overall, we conclude that in this population, genetic drift resulting from a historical population bottleneck is most likely to have resulted in the observed ROH distribution, with selection possibly playing a minor role.

genetics↗

A metabolomic view on local climate adaptation: Latitudinal divergence of heat and drought responses in a coastal plant

Studying natural variation in multi-stress resistance is central for predicting and managing the population dynamics of wild plant species under rapid global change. Yet, it remains a challenging goal in this field to integrate knowledge on the complex biochemical underpinnings for the targeted non-model species. Here, we studied latitudinal divergence in combined drought and heat stress resistance in European populations of the dune plant Cakile maritima, by combining comprehensive plant phenotyping with metabolic profiling via FT-ICR-MS and UPLC-TQ-MS/MS. We observed pronounced constitutive divergence in growth phenology, leaf functional traits and defence chemistry (glucosinolates, alkaloids) among population origins. Most importantly, the magnitude of growth reduction under stress was partly weaker in southern plants and associated with divergence in plastic growth responses (root expansion, leaf abscission) and the stress-induced modulation of primary and specialized metabolites with known central functions not only in plant abiotic but also biotic stress resistance. Our study supports that divergent selection has shaped the constitutive and stress-induced expression of numerous morphological and biochemical functional traits to mediate higher abiotic stress resistance in southern Cakile populations, and highlights that metabolomics is a powerful tool to explore the mechanistic underpinnings of local stress adaptation in non-model species. HighlightPlant defence chemistry and its modulation by abiotic stress exhibits latitudinal clines across natural populations of a coastal plant.

ecology↗

Sex matters: effects of sex and mating in the presence and absence of a protective microbe

In most animals, female investment in offspring production is greater than for males. Lifetime reproductive success (LRS) is predicted to be optimised in females through extended lifespans to maximise reproductive events. Extended lifespan can be achieved through increased investment in immunity. Males, however, maximise lifetime reproductive success by obtaining as many matings as possible. Microbe-mediated protection (MMP) is known to affect both immunity and reproduction, but whether the two sexes respond differently to the provision of MMP remains to be explored. Here, we investigated the sex-specific differences in host life history traits between female and male Caenorhabditis elegans following pathogenic infection with Staphylococcus aureus with or without MMP by Enterococcus faecalis. Overall, female survival decreased with increased mating. With MMP, females increased investment into offspring production, while males displayed higher behavioural activity. These results highlight the different strategies employed by the two sexes under pathogen infection with and without MMP.

microbiology↗

Genomic analysis reveals a polygenic architecture of antler morphology in wild red deer (Cervus elaphus).

Sexually-selected traits show large variation and rapid evolution across the animal kingdom, yet genetic variation often persists within populations despite apparent directional selection. A key step in solving this long-standing paradox is to determine the genetic architecture of sexually-selected traits to understand evolutionary drivers and constraints at the genomic level. Antlers are a form of sexual weaponry in male red deer. On the island of Rum, Scotland, males with larger antlers have increased breeding success, yet there has been no response to selection observed at the genetic level. To better understand the underlying mechanisms of this observation, we investigate the genetic architecture of ten antler traits and their principle components using genomic data from >38,000 SNPs. We estimate the heritabilities and genetic correlations of the antler traits using a genomic relatedness approach. We then use genome-wide association and haplotype-based regional heritability to identify regions of the genome underlying antler morphology, and an Empirical Bayes approach to estimate the underlying distributions of allele effect sizes. We show that antler morphology is heritable with a polygenic architecture, highly repeatable over an individuals lifetime, and that almost all aspects are positively genetically correlated with some loci identified as having pleiotropic effects. Our findings suggest that a large mutational target and pleiotropy with traits sharing similar complex polygenic architectures are likely to contribute to the maintenance of genetic variation in antler morphology in this population.

evolutionary biology↗

Differential Effects of RASA3 Mutations on Hematopoiesis are Profoundly Influenced by Genetic Background and Molecular Variant

Studies of the severely pancytopenic scat mouse model first demonstrated the crucial role of RASA3, a dual RAS and RAP GTPase activating protein (GAP), in hematopoiesis. RASA3 is required for survival in utero; germline deletion is lethal at E12.5-13.5 due to severe hemorrhage and decreased fetal liver erythropoiesis. Conditional deletion in hematopoietic stem and progenitor cells (HSPCs) using Vav-Cre recapitulates the null phenotype demonstrating that RASA3 is required at the stem and progenitor level to maintain blood vessel development and integrity and effective blood production. In adults, bone marrow blood cell production and spleen stress erythropoiesis are suppressed significantly upon induction of RASA3 deficiency, leading to pancytopenia and death within two weeks. Notably, RASA3 missense mutations in mouse models scat (G125V) and hlb381 (H794L) show dramatically different hematopoietic consequences specific to both genetic background and molecular variant. Global transcriptomic studies in scat suggest potential targets to ameliorate disease progression. Author SummaryHematopoiesis is the process by which blood cells are formed. The individual must have a normal complement of red blood cells to prevent anemia, platelets to control bleeding, and white blood cells to maintain immune functions. All blood cells are derived from hematopoietic stem cells that differentiate into progenitor cells that then develop into mature circulating cells. We studied several mouse strains carrying different mutations in RASA3. We show that RASA3 is required at the earliest stages of blood formation, the stem and progenitor cells, and that the complement of genes other than RASA3, or the genetic background of the mutant strain, profoundly alters the overall effect on blood formation. Further, the molecular nature of the mutation in RASA3 also has a profound and independent effect on overall blood formation. One strain, designated scat, suffers cyclic anemia characterized by severe anemic crisis episodes interspersed with remissions where the anemia significantly improves. Comparison of scat crisis and remission hematopoietic stem and progenitor cells reveals striking differences in gene expression. Analyses of these expression differences provide clues to processes that potentially drive improvement of anemia in scat and provide new avenues to pursue in future studies to identify novel therapeutics for anemia.

genetics↗