Correction for Grünig et al., Evolution after whole-genome duplication (WGD) drives phenotypic and transcriptomic divergence more than WGD in an autopolyploid herb.
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Efficacy and safety of mitapivat in adults with transfusion-dependent α-thalassaemia or β-thalassaemia (ENERGIZE-T): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial.
BACKGROUND: The absence of disease-modifying therapies for patients with α-thalassaemia and oral disease-modifying therapies for patients with β-thalassaemia has been a substantial unmet need in these patients. We assessed the efficacy and safety of mitapivat, an oral allosteric activator of pyruvate kinase, in adults with transfusion-dependent thalassaemia. METHODS: ENERGIZE-T is a global, double-blind, randomised, placebo-controlled, phase 3 trial, conducted across 19 countries in North America, Europe, Asia-Pacific, South America, and the Middle East. Patients aged 18 years or older with transfusion-dependent α-thalassaemia or β-thalassaemia were randomly allocated (2:1) with a central interactive response technology system, stratified by geographical region and thalassaemia genotype, to receive 100 mg mitapivat or placebo orally twice a day for 48 weeks. The primary endpoint was transfusion reduction response (TRR), defined as a reduction of at least 50% in transfused red blood cell units with a reduction of at least two units in any consecutive 12-week period until week 48 compared with baseline. Efficacy was analysed in the full analysis set, comprising all randomly allocated patients. Type, severity, and relationship of adverse events and serious adverse events were assessed in patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov (NCT04770779) and is active but not recruiting. FINDINGS: Between Nov 30, 2021 and May 2, 2023, 305 patients were screened, of whom 258 were randomly allocated (median age 33·5 years [IQR 27·0-44·0]; 136 [53%] female and 122 [47%] male participants). Of 258 patients allocated, 238 (92%) completed the double-blind treatment period. All patients were required to have a safety follow-up approximately 4 weeks after the final dose of study drug, regardless of completion of the double-blind period or continuation into the open-label extension period. In the full analysis set, TRRs occurred in 52 (30%) of 171 patients in the mitapivat group and 11 (13%) of 87 in the placebo group (adjusted difference 18 percentage points [95% CI 8-27]; two-sided p=0·0003). The safety analysis set comprised 172 patients in the mitapivat group (including one patient allocated to the placebo group who received one dose of mitapivat in error) and 85 in the placebo group. Adverse events were reported in 155 (90%) patients treated with mitapivat and 71 (84%) treated with placebo; the most common events with mitapivat were headache, upper respiratory tract infection, initial insomnia, diarrhoea, and fatigue. Serious adverse events were reported in 19 (11%) patients treated with mitapivat and 13 (15%) treated with placebo. Ten (6%) patients who received mitapivat and one (1%) who received placebo discontinued study treatment due to adverse events. No deaths were reported. INTERPRETATION: Mitapivat significantly reduced the transfusion burden and was generally well tolerated, showing a favourable benefit-risk profile. These findings support mitapivat as the first oral disease-modifying therapy for adults with transfusion-dependent α-thalassaemia or β-thalassaemia, providing a new treatment option to reduce transfusion burden in this patient population. FUNDING: Agios Pharmaceuticals, Inc.
Adult↗
Vancomycin Effectiveness in Reducing Surgical Site Infection in Posterior Spinal Fusion Surgery: A Retrospective Data Analysis of the STRIVE Trial.
STUDY DESIGN: Retrospective analysis of prospectively collected data. OBJECTIVE: To re-evaluate vancomycin as a preventive measure for surgical site infection (SSI). SUMMARY OF BACKGROUND DATA: Intrawound vancomycin powder is used to prevent SSIs in spinal surgery. Prior studies, often limited to single institutions or small samples, have shown mixed efficacy and potential increases in non- S. aureus and Gram-negative infections. We hypothesized that SSIs rates would be similar with and without intrawound vancomycin in posterior spinal fusion (PSF) surgery. METHODS: Prospectively collected data from the 3595 patients in the STaphylococcus aureus suRgical Inpatient Vaccine Efficacy (STRIVE) trial were stratified by intrawound antibiotic usage. Multivariate logistic regression assessed the effect of vancomycin use on SSI, adjusting for patient demographics and SSI-associated risk factors. Secondary outcomes included critical care stay, reoperation, sepsis, and hospital readmission. RESULTS: Of 3311 patients who underwent surgery, 847 (26%) received only intrawound vancomycin and 1534 (46%) received no intrawound antibiotics. Sixty (8%) patients developed postoperative SSI, of whom 20 (33%) had received intrawound vancomycin. Receiving intrawound vancomycin was not associated with SSI incidence versus no intrawound antibiotics [odds ratio (OR): 0.77; 95% CI: 0.42-1.42], critical care stay (OR: 0.94; 95% CI: 0.78-1.12), or sepsis (OR: 2.04; 95% CI: 0.62-6.73). However, intrawound vancomycin was associated with increased odds of hospital readmission (OR: 1.82; 95% CI: 1.28-2.6; P < 0.001) and reoperation (OR: 1.75; 95% CI: 1.18-2.6; P = 0.005). Factors significantly associated with intrawound vancomycin use included intraoperative antibiotic readministration (OR: 2.97; 95% CI: 1.36-6.5; P =0.006) and hospital location, lower odds in Europe (OR: 0.13; 95% CI: 0.06-0.29; P < 0.001) or Asia (OR: 0.02; 95% CI: 0-0.08; P < 0.001) versus North America. CONCLUSIONS: Intraoperative vancomycin use was not associated with reduced SSI incidence compared with no intrawound antibiotics after PSF surgery. LEVEL OF EVIDENCE: Level II.
Humans↗
New World screwworm: a re-emerging parasitic threat.
PURPOSE OF REVIEW: New World screwworm (NWS) is an emerging parasitic threat in Central America and Mexico, which is spreading northward into the southern United States. Here we highlight the changing epidemiology, lifecycle of the NWS fly, clinical presentation, identification, treatment, and potential complications of NWS myiasis. RECENT FINDINGS: Despite decades of successfully containing NWS flies south of the Darien Gap in southern Panama, NWS flies reemerged in the Central America region in 2023 and have continued to spread northward ever since. On 3 June 2026, United States Department of Agriculture (USDA) confirmed the identification of an NWS infestation in a young calf in southern Texas. In addition to describing the current epidemiology of the NWS outbreak, we present information about clinical presentation and management of NWS myiasis in patients and include representative cases of patients who experienced NWS myiasis. SUMMARY: This review provides important epidemiologic and clinical updates to an emerging parasitic threat so clinicians can understand the risks and clinical management for patients with suspected NWS myiasis.
Animals↗
Spironolactone, early acute eGFR changes, and clinical outcomes in patients with heart failure with preserved ejection fraction: insights from TOPCAT Americas.
AIMS: Early acute changes in estimated glomerular filtration rate (eGFR) have been well described with renin-angiotensin system inhibitors and sodium-glucose cotransporter-2 inhibitors, but less is known about the frequency, prognostic relevance, and implications of these changes after mineralocorticoid receptor antagonist (MRA) initiation in patients with heart failure with preserved ejection fraction (HFpEF). METHODS: We performed a post-hoc analysis of 1648 patients enrolled in the TOPCAT trial (Americas regional subgroup), defining an early eGFR dip as a ≥15% decrease in eGFR between baseline and week 4. Landmark analyses assessed the association of eGFR changes, treatment, and the primary composite endpoint (cardiovascular death, HF hospitalization, or aborted cardiac arrest). RESULTS: Within 4 weeks of treatment initiation, 431 (26%) patients experienced acute eGFR decrease with a higher proportion of patients assigned to spironolactone [269 (33%)] compared with placebo [162 (20%)] (odds ratio 1.97; 95% confidence interval 1.58-2.47). An acute eGFR decrease was independently associated with higher risk of subsequent cardiovascular outcomes, irrespective of treatment arm. However, treatment with spironolactone appeared beneficial in reducing the primary cardiovascular outcome irrespective of the presence [hazard ratio 0.75 (0.53-1.08)] or absence [0.80 (0.64-1.00)] of early eGFR decrease (Pinteraction = .81). At any given magnitude of eGFR decline, risk of the primary endpoint was consistently lower with spironolactone compared with placebo (Pinteraction = .64). CONCLUSIONS: Early acute eGFR changes were common and adversely prognostic in patients with HFpEF. Spironolactone treatment was beneficial in improving cardiovascular outcomes, despite a modest increase in the likelihood of acute eGFR decrease. An acute eGFR decrease early after MRA initiation should not automatically prompt treatment discontinuation. TRIAL REGISTRATION: ClinicalTrials.gov NCT00094302.
Humans↗
Impact of Commercial Artificial Intelligence on Radiologist Reading Time for Pulmonary Nodule Evaluation at Chest CT.
Background Chest CT is a primary method for identifying pulmonary nodules, yet interpreting scans remains time-intensive and demanding. Currently, artificial intelligence (AI) is expected to reduce reading times, but the effect of AI on reporting times in this setting is unknown. Purpose To evaluate the impact of a commercial AI software on radiologists' reading time for pulmonary nodule assessment on chest CT scans within a real-world clinical setting. Materials and Methods This retrospective study included patients who underwent chest CT examinations at a tertiary medical center between September 2021 and May 2024. The study period was divided into pre- and post-AI phases. The primary outcome was radiology reporting time. The association between AI implementation and reporting time was evaluated using a multivariable parametric Weibull shared frailty survival model adjusted for reader function, examination type, patient location, and requesting specialty, with clustering at the radiologist level. Interaction analyses assessed heterogeneity across prespecified subgroups. An exploratory extrapolation estimated projected workforce and financial impact. Results This study included 19 433 patients (mean age, 62 years ± 14.2 [SD]; 21 814 men; 39 323 chest CT examinations, 19 190 pre-AI, and 20 133 post-AI). AI implementation was associated with faster report completion (adjusted hazard ratio, 1.17; 95% CI: 1.14, 1.21; P < .001). The adjusted median reporting time decreased from 21.3 minutes pre-AI to 18.2 minutes post-AI (14.6% reduction; P < .001). Heterogeneity was observed across reader function (P < .001), examination type (P = .048), and requesting specialty (P = .03). The largest relative reductions were observed for CT thorax electrocardiogram-gated examinations (-41.1%; P < .001) and thoracic radiologists (-25.0%; P < .001), whereas emergency department examinations showed increased median reporting time (7.1%; P < .001). At institutional scan volumes (approximately 20 000-22 000 chest CT examinations annually), exploratory modeling suggested an approximate reduction of 0.5 full-time equivalent radiologist workload. Conclusion Implementation of commercial AI-assisted pulmonary nodule assessment on chest CT scans reduced radiologist reporting time in a real-world clinical setting. © The Author(s) 2026. Published by the Radiological Society of North America under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Iwasawa in this issue.
Humans↗
Integrated exome and mitochondrial genome sequencing reveals the genetic landscape of primary mitochondrial diseases: findings from a large Tunisian cohort.
Primary mitochondrial diseases are a heterogeneous group of neurometabolic disorders recognized as the most common metabolic genetic diseases. They manifest at any age, affecting any tissue or organ, especially those with high energy demands, and are caused by pathogenic variants in both mitochondrial and nuclear genomes. Here, we aimed to describe the genetic spectrum of a Tunisian pediatric cohort with suspected mitochondrial diseases. We recruited 47 unrelated families who underwent exome sequencing as a first-tier test followed by whole mitochondrial genome sequencing for unsolved cases. Dedicated bioinformatic pipelines and prediction tools were used to determine the potential disease-causing variants. Sanger sequencing confirmed the presence and segregation within parents. For the newly identified variants, structural modeling was conducted to study the impact of these variants on protein structure and motions. Dual genome sequencing yielded a molecular diagnosis in 33/47 families (70%) and 18/47 (38%) showed disease-causing variants in genes encoding mitochondrial proteins. Among them, four families disclosed novel variants in FASTKD2, SERAC1 and GATB, which were supported by in-depth in silico and structural analyses demonstrating their deleterious effect. The remaining families (32%, 15/47) disclosed other metabolic and neurological disorders. An exome-first strategy delivers a high diagnostic yield in Tunisia, where consanguinity remains high and simultaneously captures mitochondrial and non-mitochondrial etiologies. Mitochondrial sequencing remains indispensable in the case of an inconclusive exome. Thus, our data expand the clinical and genetic spectrum of primary mitochondrial diseases in Tunisia, an underrepresented and admixed population.
Humans↗
Orofacial Cleft Disparities in American Indian and Alaska Native Populations: A Systematic Review and Meta-Analysis.
ObjectiveTo evaluate the prevalence, access to care, and health outcomes of orofacial clefts (OFCs) among American Indian and Alaska Native (AI/AN) populations through a systematic review and meta-analysis.DesignSystematic review and meta-analysis performed in accordance with PRISMA 2020 guidelines and registered with PROSPERO (CRD420251035364).SettingUS-based population registries, hospital databases, and institutional or community-level retrospective studies involving AI/AN populations.Patients and ParticipantsAI/AN individuals with OFCs compared with non-Hispanic White patients.InterventionsPrimary cleft lip and palate repair, secondary cleft-related procedures, and multidisciplinary cleft care.Main Outcome Measure(s)Prevalence of OFCs, timing of cleft surgery, discharge disposition, access to specialists, and qualitative determinants of disparities.ResultsEighteen studies including more than 1985 AI/AN patients were identified. Meta-analysis of 5 studies estimated a pooled OFC prevalence of 15 per 10 000 live births (95% confidence interval: 5-49), with substantial heterogeneity (I2 = 99.8%). Individual studies reported significantly higher OFC prevalence in AI/AN populations compared to non-Hispanic Whites (odds ratio range: 1.44-2.68). Geographic maldistribution of craniofacial-trained surgeons, increased odds of nonhome discharge, and delayed cleft palate repair were consistently observed barriers. Qualitative analyses highlighted structural inequities, perceived racism, and lack of culturally responsive care as major contributors to disparities.ConclusionsAI/AN populations face a disproportionately high burden of OFCs alongside structural barriers to timely, culturally competent care. Addressing these disparities requires community-engaged, multidisciplinary interventions that improve geographic access and integrate culturally responsive approaches to care.
Humans↗
Efficacy and safety of microwave ablation for the treatment of pulmonary osteosarcoma oligometastases.
PURPOSE: Evaluate efficacy and safety of microwave ablation (MWA) for pulmonary osteosarcoma oligometastases. METHODS: Twenty-two patients (median age, 16 years [range, 9-41 years]; 15 male) with pulmonary osteosarcoma oligometastases who underwent MWA from January 2018 to December 2023 were included, with 27 MWA sessions for 36 lung metastases. Technical success and complications were evaluated in all 22 patients, while efficacy and survival were evaluated in 19 patients with 24 MWA sessions in treatment of 32 tumors. Technical success was assessed for each tumor. Local tumor control, progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan-Meier method. Complications were classified using Common Terminology Criteria for Adverse Events version 5.0. RESULTS: Technical success was achieved in all 36 tumors (100.0%). Local tumor progression occurred in five of 32 tumors (15.6%). The estimated local tumor control rates at 12, 24 and 36 months were 96.9%, 86.1% and 81.5%, respectively. No significant difference in local control was found between tumors ≤ 10 mm and > 10 mm (p = .470). Twelve of 19 patients (63.2%) developed new lung metastases outside the ablation area, including one with concurrent newly developed bone metastases and one with recurrence of primary osteosarcoma. The median PFS was 21.5 months. The estimated OS rates at 12, 24 and 60 months were 100.0%, 94.4% and 94.4%, respectively. Major complications occurred in five of 27 sessions (18.5%). CONCLUSIONS: MWA preliminarily demonstrates a high technical success rate, notable local tumor control, promising overall survival and acceptable safety for pulmonary osteosarcoma oligometastases.
Adolescent↗
Alternative genetic codes in bacteria and archaea identified with a fast k-mer-based algorithm.
The genetic code is conserved across all domains of life and is often described as universal. Nevertheless, many exceptions to the "universal" code have now been documented, most of these through manual or semiautomated inspection of highly conserved genes. Modern bioinformatics tools improved our ability to find alternative genetic codes but remain computationally expensive, preventing widespread use on thousands of new species identified by sequencing environmental samples. Here, I report a >100-fold accelerated method for inferring the genetic code directly from assembled genomes and apply it to thousands of previously uncharacterized assemblies from archaea and bacteria. I describe three candidate genetic code variations, one of which, an alternative genetic code used by a family of Asgard archaea, is a unique example of sense codon reassignments for this domain. Identifying genetic code variations is important for understanding evolution of the standard code and improving accuracy of protein databases and open reading frame identification.
Genetic Code↗
In vivo genome-wide CRISPR screens identify FOXR1 as a suppressor of CD8+ T cell antitumor immunity.
T cell dysfunction critically limits the efficacy of T cell-based immunotherapies in solid tumors, yet the intrinsic regulators of T cell dysfunction remain incompletely understood. Through an in vivo genome-wide CRISPR screen in tumor-infiltrating CD8+ T cells, we identified Forkhead Box R1 (FOXR1) as a potent transcriptional suppressor of CD8+ T cell effector functions. Genetic ablation of FOXR1 significantly enhanced cytokine production and cytotoxic capacity in both murine and human CD8+ T cells, whereas its overexpression impaired T cell activation and effector molecule expression. Mechanistically, multiomics integration of RNA-seq, CUT&Tag-seq, and ATAC-seq revealed that FOXR1 binds directly to promoter regions of key effector genes, including IL2, GZMB, and PRF1, and represses their expression. Importantly, FOXR1 deletion in human anti-CD19 CAR T cells improved their efficacy against solid tumors, demonstrating that FOXR1 is a checkpoint of T cell effector function and targeting FOXR1 is a promising strategy to enhance CAR T cell efficacy against solid tumors.
Animals↗
Early mobilization within 24 to 48 h improves postoperative clinical outcomes in older adults with hip fracture: A systematic review and meta-analysis.
BACKGROUND: Hip fracture is a major public health concern among older adults, often resulting in prolonged disability, institutionalization, and increased healthcare burden. Early mobilization has been widely recommended to enhance postoperative recovery; however, there is a lack of consolidated evidence quantifying its impact on clinical and functional outcomes. This study aimed to synthesize and evaluate the impact of early mobilization following hip fracture surgery in older adults and to explore potential sources of heterogeneity to better inform clinical and nursing practice. METHODS: A comprehensive literature search was conducted across seven databases (PubMed, Embase, Scopus, Web of Science, Cumulative Index to Nursing and Allied Health Literature, Cochrane Library, and Emcare) from inception to June 15, 2025. Eligible studies included randomized controlled trials and observational cohort studies comparing early mobilization (defined as ambulation within 24 to 48 h postoperatively) to delayed or usual mobilization in patients undergoing hip fracture surgery. Primary outcomes included mortality, discharge destination, and length of hospital stay. Secondary outcomes included postoperative complications, functional recovery, and readmission. Risk of bias was assessed using funnel plots and Egger's test. RESULTS: Twenty-six studies involving 297,435 patients were included. Compared with delayed mobilization, early mobilization significantly reduced 30-day mortality (relative risk = 0.40, 95% confidence interval: 0.25-0.64) and 1-year mortality (relative risk = 0.57, 95% confidence interval: 0.40-0.80) (both p < 0.05). In regional analyses of pooled mortality, similar reductions were observed across Asia-Pacific, North America, and Europe. Patients receiving early mobilization were more likely to be discharged home and had shorter hospital stays. Early mobilization also resulted in a reduced risk of postoperative complications (relative risk = 0.79, 95% confidence interval: 0.74-0.84, p < 0.05), with specific improvements in pneumonia and thromboembolism rates. Functional independence was significantly improved, as shown by higher Barthel Index scores and increased odds of achieving Functional Independence Measure ≥5 at discharge. No significant difference was observed in readmission rates. CONCLUSIONS: lization within 24 to 48 h following hip fracture surgery was associated with favorable outcomes, including reduced mortality, improved functional independence, higher rates of discharge to home, shorter hospital length of stay, and fewer postoperative complications. Although heterogeneity across studies and the predominance of observational evidence warrant cautious interpretation, these findings support current recommendations for early mobilization and highight the potential value of structured and standardized mobilization protocols in routine postoperative hip fracture care.
Humans↗
Cryo-EM structure of TGFBIp fibrils driven by a corneal dystrophy-linked mutation enables design of peptide inhibitors of aggregation.
Corneal dystrophy is a heterogeneous group of diseases which manifests clinically by progressive corneal opacity and diminishing visual acuity. A group of corneal dystrophies are linked to autosomal dominant mutations in transforming growth factor β-induced protein (TGFBIp) and characterized by extracellular amyloid-positive deposits of unknown molecular structure. Here, we determined the cryogenic-electron microscopy (cryo-EM) structure of amyloid fibrils formed by the TGFBIp FAS1-4 domain with corneal dystrophy-linked mutation V624M. The L569 to N609 fibril core, which includes the Y571-R588 segment enriched in patient corneal deposits, forms symmetrical protofilaments with internal solvent channels. Leveraging this structure, we designed peptide inhibitors intended to bind onto fibril ends to block elongation, targeting the unequal growth of symmetrical protofilaments. Our G1 and H4 inhibitors exhibit concentration-dependent reduction of TGFBIp FAS1-4 aggregation as assessed by Thioflavin T, solubility fractionation, and electron microscopy. Our work illustrates how fibril structures can guide rational inhibitor design and suggests the targeting of protein aggregates as a therapeutic approach for corneal and ocular diseases.
betaIG-H3 Protein↗
Malnutrition and adverse outcomes after spine surgery: a systematic review and meta-analysis.
BACKGROUND CONTEXT: Malnutrition is linked to adverse surgical outcomes, but its impact in spine surgery remains unclear due to inconsistent findings and heterogeneous definitions, including use of serum albumin, prealbumin, lymphocyte count, the Geriatric Nutritional Risk Index, and the Prognostic Nutritional Index. We conducted a systematic review and meta-analysis to evaluate the relationship between malnutrition and postoperative outcomes in spine surgery. PURPOSE: To systematically evaluate the association between preoperative malnutrition and postoperative outcomes in patients undergoing spine surgery. STUDY DESIGN: Systematic review and meta-analysis. PATIENT SAMPLE: Patients undergoing elective or urgent spine surgery across included observational studies comparing malnourished vs well-nourished cohorts. OUTCOME MEASURES: Primary outcomes included postoperative mortality and overall surgical complications. Secondary outcomes included infectious complications (sepsis, urinary tract infection, wound complications), delirium, reoperation, 30-day and 90-day readmission, and prolonged length of hospital stay. METHODS: A systematic search of PubMed, Embase, Cochrane Library, and Web of Science was performed on April 7, 2025, following PRISMA guidelines. Studies directly comparing postoperative outcomes in malnourished vs well-nourished spine surgery patients were included. A random-effects model generated pooled odds ratios for complications. Outcomes assessed included mortality, surgical complications, infectious outcomes, readmission, reoperation, delirium, prolonged length of stay, and wound complications. RESULTS: Of 2,851 screened articles, 37 met the inclusion criteria, encompassing 16,987 malnourished patients. Malnutrition was associated with significantly increased odds of mortality (OR: 4.05, 95% CI [2.97-5.54]), delirium (OR: 3.95, 95% CI [2.49-6.27]), sepsis (OR: 2.77, 95% CI [2.31-3.33]), surgical complications (OR: 1.79, 95% CI [1.57-2.04]), urinary tract infection (OR: 1.81, 95% CI [1.59-2.06), wound complications (OR: 2.10, 95% CI [1.80-2.45]), reoperation (OR: 1.70, 95% CI [1.46-1.97]), prolonged length of hospital stay (OR: 3.46, 95% CI [2.57-4.65]), 30-day readmission (OR: 1.59, 95% CI [1.36-1.86]), and 90-day readmission (OR: 2.13, 95% CI [1.67-2.71]). CONCLUSIONS: Malnutrition was consistently associated with adverse outcomes after spine surgery. Routine nutritional assessment and targeted preoperative optimization should be considered a standard component of perioperative spine care to help reduce postoperative complications and improve recovery.
Humans↗
Evolution of maize recombination landscape during domestication.
Despite the plethora of knowledge about the benefits of meiotic recombination and numerous theoretical studies examining how recombination rates evolve, there is a general lack of empirical support and consensus across species. To fill this knowledge gap, we characterized the evolution of recombination landscape in maize during its domestication from teosinte and related the observed changes to established theoretical frameworks. Through examining recombination in experimental populations of maize and teosinte and the population genomics approach of identifying historical recombination events using ancestral recombination graph inference to generate saturated maize and teosinte recombination maps, we found that during domestication, maize experienced a 12% increase in its genome-wide recombination rate. Furthermore, maize evolved higher recombination rates on the long arms of chromosomes in regions closer to centromeres, where recombination is generally very low. The repatterning of crossover events came from changes in global crossover positioning rather than alterations in cis-acting chromatin factors. Consequently, we found evidence of selection acting on trans-acting recombination modifiers affecting crossover interference and controlling the interference-dependent class I crossover pathway. We show that CO repatterning was likely beneficial for maize fitness, as significant recombination rate increases were predominantly in gene-rich regions, which harbor domestication-related variation. This work suggests genomic and mechanistic processes leading to the evolution of meiotic recombination landscape in response to directional selection pressure and provides evidence for the evolutionary advantage of recombination.
Zea mays↗
eIF5A and polyamines restrict mRNA levels in response to ribosome stalls.
Obstacles to translation elongation stall ribosomes and allow deleterious proteins to accumulate, which threatens cellular health. Cells recognize and clear stalled ribosomes via several interrelated pathways, although the mechanisms by which cells distinguish stalled from normally elongating ribosomes and mount an appropriate response are incompletely understood. While recent work highlights how ribosome collisions help cells to recognize stalled ribosomes, how other factors contribute to detection remains unclear. Here, we report a requirement for the translational factor eIF5A in the mRNA decay response to ribosomal stalling, i.e., No-Go mRNA Decay (NGD). We identified the Caenorhabditis elegans polyamine transporter, catp-6, via a forward genetic screen as a factor required for NGD. During our mechanistic dissection of the catp-6 phenotype, we uncovered a role for cellular polyamines and the translation elongation factor eIF5A in NGD, and we show this requirement is conserved from C. elegans to Saccharomyces cerevisiae. Our analyses support the idea that cells use eIF5A to identify ribosomal stalls and execute NGD and uncover a molecular function for a core protein synthesis factor in limiting expression from stall-inducing mRNAs. Our work offers insight into how cells identify and remove problematic mRNAs from the translational pool. Our work also raises the possibility that dysregulated mRNA decay is an unrecognized pathophysiology associated with polyaminopathies and eIF5A disorders, of relevance to varied neurodegenerative and aging phenotypes and efforts to pharmacologically inhibit eIF5A.
Animals↗
A host-encoded prophage targets a Candidate Phyla Radiation bacterium and shapes episymbiotic interactions.
The Patescibacteriota, also known as the Candidate Phyla Radiation (CPR), represent a large lineage of ultrasmall bacteria with highly reduced genomes and obligate dependence on bacterial hosts. Although genomic analyses have revealed CRISPR-Cas and restriction-modification systems in many CPR genomes, no cognate bacteriophages (phages) have been isolated, leaving CPR-phage interactions unexplored. Nanosynbacter lyticus TM7x, the first cultivated CPR bacterium, grows episymbiotically on its host, Schaalia odontolytica XH001, in the human oral microbiome. Here, we identify Xhp1, an inducible prophage of XH001 that is preferentially activated during episymbiosis with TM7x. Released Xhp1 particles infect prophage-free XH001 via distinct strategies determined by host growth mode, establishing lysogeny under planktonic conditions but driving lytic infection during surface-associated growth. Xhp1 also binds efficiently to TM7x and exhibits limited infection under the conditions tested, indicating direct phage-CPR interactions. Importantly, TM7x modulates Xhp1 availability in a spatially dependent manner. In planktonic culture, free-floating TM7x reduces lysogenic conversion of XH001ΔXhp1, consistent with TM7x acting as a phage sink that lowers effective phage concentration. In contrast, during surface-associated growth, TM7x increases XH001ΔXhp1 susceptibility to lytic infection, likely by locally concentrating phage particles within a constrained niche. These results demonstrate that CPR bacteria can regulate viral encounter rates through spatial organization. In spatially structured environments such as oral biofilms, such modulation may shape infection dynamics and community structure. Together, this work characterizes the first CPR-targeting phage and reveals a an important role for phages in CPR-host bacteria interactions.
Prophages↗