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PubMed2026

Convergence and conflict among telomere-specialized transposons across 60 million years of Drosophilid evolution.

The Drosophila telomere is one of the best-studied examples of active transposable elements (TEs) benefiting, rather than harming, the host genome. All Drosophila species lack telomerase, and most species instead have telomeres composed of head-to-tail arrays of specialized retrotransposons. These TEs ostensibly act as mutualists by elongating chromosome ends, but evidence from species closely related to Drosophila melanogaster suggests that telomeric transposons may also antagonize their host genome. Importantly, the limited number of Drosophila species characterized thus far has precluded our ability to delineate idiosyncrasies from universal evolutionary forces and genetic mechanisms that shape the history of these TEs. Here, we have surveyed long-read genome assemblies of more than 100 species of Drosophila, identifying a total of 396 telomeric TE families. Our findings show that these telomere-specialized elements evolve dynamically and also undergo striking convergent evolution: The complete loss of telomeric TEs has occurred repeatedly across the genus, whereas individual telomeric TE lineages have repeatedly lost one of their two protein-coding genes. These elements have also repeatedly undergone horizontal transfer between distantly related Drosophila lineages and have repeatedly captured host gene fragments that promote their selfish suppression of host TE-silencing systems. Furthermore, telomere specialization itself appears to have evolved convergently, as some nontelomeric families have gained the ability to target their insertions to telomeres. These results provide unprecedented resolution into the evolution of these unusual TEs and highlight several novel mechanisms by which they evolve in conflict both with each other and their host genome despite the essential telomere function they provide.

Animals↗
PubMed2026

T2T genomes of Caenorhabditis nigoni and Caenorhabditis briggsae reveal divergence in satellite DNA abundance.

The two closely related nematode species, Caenorhabditis nigoni and Caenorhabditis briggsae, are commonly used to study the evolution of reproductive modes in animals, with the self-fertile C. briggsae and outcrossing C. nigoni sharing a common ancestor ∼3.5 million years ago. Earlier genomic analyses revealed that selfing Caenorhabditis species have smaller genomes and proposed that at least some gene loss in C. briggsae is adaptive. However, the incomplete C. nigoni reference genome has limited most comparative analyses to genic regions. Here, we leverage long-read sequencing to generate and annotate telomere-to-telomere (T2T) assemblies for the C. nigoni strain JU1422 and the C. briggsae strain AF16. This new 139 Mb C. nigoni genome resolves 57 gaps and 149 unassigned scaffolds from the previous genome assembly. A major driver of the size difference with the 107 Mb T2T C. briggsae genome is the abundance of satellite DNA, which accounts for 12.8 Mb (9.2%) in C. nigoni and only 3.2 Mb (3.0%) in C. briggsae Notably, the C. nigoni X Chromosome is 13.4 Mb larger than in the previous assembly, making it 60% larger than the C. briggsae X Chromosome compared with 18%-26% difference for the autosomes. We also document a surprising degree of plasticity in the ribosomal DNA, with the C. nigoni X Chromosome harboring a second 45S rDNA array that is absent in C. briggsae The hitherto undocumented divergence in the abundance of repetitive DNA elements makes the new genomes an invaluable resource for genomic analysis.

Journal Article↗
PubMed2026

Prenatal Alcohol Exposure Produces Selective Changes in Neuroimmune Gene Expression Across Brain Regions of Adult Mice.

BACKGROUND: An overwhelming body of evidence suggests neuroimmune dysfunction as a key underlying mechanism of fetal alcohol spectrum disorder (FASD)-associated adverse central nervous system (CNS) outcomes. While few studies have highlighted the lingering effects of prenatal alcohol exposure (PAE) on producing specific immune factors, others suggest a primed neuroimmune state in adulthood, in which a proinflammatory bias is unmasked following subsequent immune activation in later life. However, the PAE-induced neuroimmune landscape in adulthood remains poorly defined. We hypothesized that PAE induces long-term changes in gene expression linked to neuroimmune function that may be brain region-specific. METHODS: Using long-read next-generation RNA sequencing of brain tissues from a previously established model of a moderate PAE in mice, we compared across six regions: medial prefrontal cortex (mPFC), anterior cingulate cortex (ACC), hypothalamus, hippocampus, midbrain, and medulla. A comprehensive bioinformatics analysis investigated PAE-induced changes, dysregulated gene pathways, and transcriptional regulators with a focus on neuroimmune function. RESULTS: Our data identified at least 60 differentially expressed genes per brain region, many of which were associated with neuroimmune function. Upregulation of multiple pro-inflammatory factors and pathways was observed, suggesting ongoing baseline neuroimmune activation, potentially involving PXR, TNF, TLR4, the complement pathway, and various cytokine and chemokine signaling. A comparative analysis identified multiple upstream transcriptional regulators across multiple brain regions, including MECP2, TCF7L2, and IL-4. Importantly, this unbiased analysis revealed heterogeneity across brain regions in the activation of canonical immune pathways and highlighted previously unprecedented roles of pathways such as PXR, matrix metalloproteases, and cytokine signaling (e.g., IL-15, IL-27, IL-17) in PAE. CONCLUSIONS: PAE creates a unique inflammatory signature in the adult brain, even in the absence of secondary injury, with novel patterns of region-specific changes in genes implicated in glial-immune function. These data identify potential immune targets to elucidate the mechanisms underlying behavioral dysfunction and provide a framework for future therapeutic interventions.

Animals↗
PubMed2026

Elucidating the Role of SET as a Key Contributor to Neurodevelopmental Disability Within the 9q34.11 Deletion Syndrome Interval.

The 9q34.11 chromosomal region contains multiple neurodevelopmental genes involved in synaptic transmission, axonal structure and neuronal maturation. Pathogenic microdeletions, duplications and single nucleotide variants in numerous genes were previously linked with neurodevelopmental disorders (NDDs). Amongst them, SET has recently been implicated in a rare NDD with speech delay and facial dysmorphism. This study reports a female with a heterozygous de novo deletion impacting SET but not other NDD-associated genes at 9q34.11. The proband was initially diagnosed with atypical Rett syndrome with overlapping clinical features of SET haploinsufficiency. The deletion was confirmed using microarray and long-read sequencing. Subsequent quantitative proteomic evaluation identified a significant decrease of SET protein in patient-derived fibroblasts compared to control lines. This study provides insights into the proband's clinical course over their 28 year diagnostic odyssey, and emphasises the benefits of early speech therapy interventions. The proband had no functional speech, but regained the capacity to meaningfully communicate and articulate a limited vocabulary in adulthood, concordant with other reported non-paediatric cases of SET-NDD. This study expands current knowledge on the genotypic and phenotypic spectra of SET-NDD, and pinpoints a smaller 9q34.11 critical region excluding upstream NDD-associated genes, STXBP1 and SPTAN1, implicating SET as a significant NDD-associated gene.

Humans↗
PubMed1994

Cloning, sequencing and restriction fragment length polymorphism analysis of a porcine cDNA for OCT2.

A full-length pig cDNA for the POU-domain protein OCT2 has been isolated and sequenced. The 478 amino acid-long reading frame in pig OCT2 is 97% identical to human OCT2A, indicating strong conservation of function for this immunoglobulin regulatory protein. To investigate the potential use of this cDNA for mapping and identifying linkage of OCT2 to economic traits, restriction fragment length polymorphism (RFLP) analysis was used to identify a TaqI polymorphism. A population of 60 unrelated animals, as well as multigenerational families, were typed for this RFLP and showed variability in several American and Chinese breeds. The TaqI polymorphism was also detected by a non-POU-domain OCT2 probe, demonstrating that this RFLP is located in the OCT2 gene. This result suggests that OCT2 is likely to be a single-copy gene in swine as seen in other mammals.

Animals↗
PubMed1997

Sequencing-based typing of HLA-A locus using mRNA and a single locus-specific PCR followed by cycle-sequencing with AmpliTaq DNA polymerase, FS.

The large number (59) of alleles now known at the HLA-A locus is a serious challenge to the existing methods for HLA typing, including many of the DNA based methods. Here, we describe a sequencing-based typing (SBT) protocol for typing of HLA-A alleles using a single A-locus-specific PCR. This reaction amplifies an 824 base pair product from cDNA, prepared from mRNA, covering exons 1-3 and most of exon 4. This product allows identification of all possible combinations of two alleles from this locus. The sequencing strategy used for allele assignment contains several improvements compared to those previously published. The enzyme AmpliTaq DNA Polymerase, FS, used, combines high-quality sequencing, i.e. long reads, low background, and uniform peak heights making the identification of heterozygous positions very reliable in a fast and easy protocol developed by determining the optima for a number of variables. Thus, this strategy meets most of the requirements for the use of sequencing in HLA typing. Furthermore, this method is very flexible. The use of a PCR primer-pair tailed with the recognition sites for two different sequencing primers allows the application of the same sets of fluorescent-labelled sequencing primers regardless of the amplified locus. Thus, the protocol can very easily be extended to cover the B- and C-locus too, simply by adding PCR reactions specific for these loci to the protocol. Using this protocol, we investigated a total of 65 cell lines and clinical samples, many of the latter chosen from samples difficult to type by serology. Our method gave in all cases unambiguous results and proved functional for work requiring the highest resolution.

Alleles↗
PubMed2026

Serotypic and Genomic Diversity of Vibrio anguillarum in Rainbow Trout Farms in Turkey: Implications for Vibriosis Control and Vaccine Candidate Selection.

Outbreaks of vibriosis caused by Vibrio anguillarum are a persistent constraint on rainbow trout (Oncorhynchus mykiss) aquaculture. However, information on the population structure of field strains in Turkey has been lacking. Here, we report the first systematic serotypic, proteomic, and genomic characterization of 23 V. anguillarum isolates collected over 10&#x2009;years from rainbow trout farms located in six major aquaculture regions of Turkey. Serological analyses based on microagglutination, supported by ELISA characterization of hyperimmune sera, identified a clear predominance of serotype O1, whereas isolate V12 exhibited a non-agglutinating, atypical O-antigen profile. Protein profiling (SDS-PAGE) and immunoblotting showed largely conserved whole-cell protein patterns among the isolates, but distinct immunogenic bands at 14, 18, and 40&#x2009;kDa were detected in isolates V18 and V21. Long-read whole-genome sequencing revealed that most Turkish isolates grouped within the global O1 clade, while V12, V25, and V28 isolates occupied more distant branches. Comparative genomics demonstrated a conserved core virulence gene set (RTX toxins, siderophore and iron-uptake systems, motility and adhesion factors, Type VI secretion system), with strain-dependent variation in accessory loci such as anguibactin and T6SS-I. Experimental infections of rainbow trout demonstrated significant differences in virulence among isolates (p&#x2009;<&#x2009;0.05), with the V18 isolate showing high, the V15 intermediate, and the V12 low-mortality rates. By elucidating the relationship among the serotype, immunogenic protein profiles, virulence gene repertoires, and in&#xa0;vivo pathogenicity, this study provides a comprehensive overview of the antigenic and genomic diversity of Vibrio anguillarum isolates from Turkey. Notably, the identification of V18 and V21 as promising candidate strains for further vaccine evaluation, characterized by high virulence and unique immunogenic features, provides a scientific foundation for the development of serotype-specific vaccination strategies to mitigate vibriosis-associated losses in aquaculture.

Animals↗
PubMed2025

Genetic Adaptation to Brackish Water and Spawning Season in European Cisco.

How species adapt to diverse environmental conditions is essential for understanding evolution and the maintenance of biodiversity. The European cisco (Coregonus albula) is a salmonid that occurs in both fresh and brackish water, and this together with the presence of sympatric spring- and autumn-spawning lacustrine populations provides an opportunity for studying the genetics of adaptation in relation to salinity and timing of reproduction. Here, we present a high-quality reference genome of the European cisco based on PacBio HiFi long read sequencing and HiC-directed scaffolding. We generated low-coverage whole-genome sequencing data from 336 individuals across 12 population samples to explore population structure and genetics of ecological adaptation. We found a major subdivision between two groups of populations most likely reflecting colonisation from different glacial refugia. Within the two major groups, we detected further genetic differentiation between spring- and autumn-spawning populations and between populations from freshwater lakes, rivers and brackish water (Bothnian Bay). A genome-wide screen for genetic differentiation among populations identified a set of outlier SNPs strongly correlated with spawning timing and salinity. Several of the genes associated with spawning time, including BHLHE40, TIMELESS and CPT1A, have previously been shown to have a role in circadian rhythm biology. As many as 17 loci were associated with genetic differentiation between populations reproducing in fresh and brackish water. This study provides insights into the genomic basis of ecological adaptation in European cisco with implications for sustainable fishery management.

Animals↗
PubMed2025

Large Haplotypes Linked to Climate and Life History Variation in Divergent Lineages of Atlantic Salmon (Salmo salar).

Advances in sequencing are revealing that linked genomic architectures, enabling the evolution of co-adapted alleles at multiple loci, often shape complex phenotypes. Several recent studies have identified such architectures (e.g., chromosomal rearrangements and supergenes) contributing to adaptation or divergence across diverse species, from plants to mammals. Specifically, within Atlantic salmon (Salmo salar ), genomic studies are revealing large haplotypes and structural variants that may underpin local adaptation in the species. Using data from >&#x2009;4000 individuals from 134 locations spanning the North Atlantic Ocean, we identify a large (~3&#x2009;Mbp) genomic region on Ssa18 showing patterns of differentiation and linkage disequilibrium (LD) indicative of a large haplotype block containing three divergent haplotypes (herein A, B and C haplotypes). In Europe, haplotypes A and B were common, whereas A and C were more common within North America, suggesting a shared 'ancestral' A haplotype, with different continent-specific alternative haplotypes. Data support independent origins of divergent haplotypes in each continent, as well as signals of trans-oceanic introgression of haplotypes. Haplotype frequency is strongly associated with latitude, climate and life history (smolt age); however, the strength and direction of these relationships vary across continents. Overall, our analyses were consistent with other studies that identify chromosomal rearrangements; however, long-read sequence data did not find evidence of a structural variant, and instead an ancestral fusion may explain the formation and maintenance of the observed haplotypes. Our study contributes to ongoing efforts to understand the evolutionary role of linked genomic architecture in Atlantic salmon and its significance in salmonid diversification.

Climate Change↗
PubMed2026

A Mobile Glycosylation Locus Modulates Cell Wall Architecture in Lactobacillus crispatus.

Lactobacillus crispatus dominance in the vaginal microbiome is associated with beneficial health outcomes, yet strain-level variation and its implications remain poorly understood. Here, we resolve the genomic context of three glycosyltransferase gene fragments (GT1-3) previously linked with dysbiotic states. Long-read resequencing revealed that GT1-3 are part of a ~18.7&#x2009;kb Wzx/Wzy-dependent cell wall polysaccharide (CWPS) locus, containing several IS256-family transposases. Serial propagation in&#xa0;vitro produced isolates with 4.1&#x2009;kb excised via a composite transposon encompassing the GT3, UDP-galactopyranose mutase, flippase, and hypothetical protein, demonstrating structural plasticity. Transmission electron microscopy showed a ~20%-25% thinner peptidoglycan layer in the derived strains, while FT-IR and monosaccharide analysis indicated no gross changes. Molecular dynamics simulations suggest that GT3 contributes to the structural stability of the glycosyltransferase complex, without compromising catalytic function. Together, these findings establish the CWPS locus as a mobile, structurally plastic element that directly influences cell wall architecture in L. crispatus.

Lactobacillus crispatus↗
PubMed2026

The cold case of state transition 7 (stt7) mutants of Chlamydomonas reinhardtii, solved by whole-genome sequencing.

The process of State Transitions (ST) corresponds to an STT7 kinase-driven redistribution of the transmembrane LHCII antenna proteins between Photosystem II (PSII) and Photosystem I (PSI), which results from changes in their phosphorylation state. For the past two decades, two LHCII-kinase mutants, stt7-1 and stt7-9, have been instrumental in the study of STs in Chlamydomonas reinhardtii, the former being a null mutant for the kinase but quasi-sterile in crosses, while the latter, although fertile, has a leaky phenotype. Using long-read sequencing, this study further characterized the genetic lesions of the stt7 mutant strains through whole-genome reconstruction and de novo chromosome assembly. In addition, two new stt7 null mutants were generated, one derived by crosses from the original stt7-1 and one obtained by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-associated protein 9 (Cas9) technology. This work provides a comprehensive genomic characterization of the original stt7-1 null mutant, revealing extensive chromosomal rearrangements and high levels of aneuploidy, associated with increased cell size and meiotic dysfunction. Reassessment of their physiology and genetic backgrounds highlights the need for caution in interpreting genetic information. We thus produced more reliable null mutants for the LHCII-kinase, amenable to genetic crosses for the study of STs in a variety of genetic backgrounds.

Chlamydomonas reinhardtii↗
PubMed2025

Turbo-charging crop improvement: harnessing multiplex editing for polygenic trait engineering and beyond.

Multiplex CRISPR editing has emerged as a transformative platform for plant genome engineering, enabling the simultaneous targeting of multiple genes, regulatory elements, or chromosomal regions. This approach is effective for dissecting gene family functions, addressing genetic redundancy, engineering polygenic traits, and accelerating trait stacking and de novo domestication. Its applications now extend beyond standard gene knockouts to include epigenetic and transcriptional regulation, chromosomal engineering, and transgene-free editing. These capabilities are advancing crop improvement not only in annual species but also in more complex systems such as polyploids, undomesticated wild relatives, and species with long generation times. At the same time, multiplex editing presents technical challenges, including complex construct design and the need for robust, scalable mutation detection. We discuss current toolkits and recent innovations in vector architecture, such as promoter and scaffold engineering, that streamline workflows and enhance editing efficiency. High-throughput sequencing technologies, including long-read platforms, are improving the resolution of complex editing outcomes such as structural rearrangements-often missed by standard genotyping-when targeting repetitive or tandemly spaced loci. To fully realize the potential of multiplex genome engineering, there is growing demand for user-friendly, synthetic biology-compatible, and scalable computational workflows for gRNA design, construct assembly, and mutation analysis. Experimentally validated inducible or tissue-specific promoters are also highly desirable for achieving spatiotemporal control. As these tools continue to evolve, multiplex CRISPR editing is poised to become a foundational technology of next-generation crop improvement to address challenges in agriculture, sustainability, and climate resilience.

Gene Editing↗
PubMed2026

Transposable elements as modulators of homoeologous gene&#xa0;expression in bread wheat: lessons from the pan-transcriptome era.

Bread wheat (Triticum aestivum L.) is an allohexaploid (AABBDD) whose three ancestral subgenomes generate complex patterns of gene regulation. Most genes exist as homoeologous triads, and the relative expression balance among copies, homoeolog expression bias, is central to polyploid evolution and adaptation. Recent high-quality assemblies, long-read transcriptomics, and pan-transcriptome resources have uncovered extensive cultivar-specific transcriptional diversity. Because transposable elements (TEs) compose over 80% of the wheat genome, they are prime candidates for shaping subgenome asymmetry. We synthesize recent pan-genomic and transcriptomic evidence, including genome-wide associations between TE insertions and genome-specific expression, and propose a unifying framework in which TEs modulate homoeolog expression by donating cis-regulatory sequences, altering chromatin states, producing small RNAs, and driving structural variation. We discuss experimental and computational challenges for establishing causality, and outline future functional and translational strategies to leverage TE-associated regulatory diversity in wheat breeding.

Triticum↗
PubMed2000

Thogoto virus matrix protein is encoded by a spliced mRNA.

Thogoto virus (THOV) is a tick-transmitted orthomyxovirus with a segmented, negative-stranded RNA genome. In this study, we investigated the coding strategy of RNA segment 6 and found that it contains 956 nucleotides and codes for the matrix (M) protein. The full-length cDNA contains a single, long reading frame that lacks a stop codon but has coding capacity for a putative 35-kDa protein. In contrast, the M protein of THOV has an apparent molecular mass of 29 kDa as assessed by polyacrylamide gel electrophoresis. Therefore, we investigated the possibility of posttranscriptional processing of segment 6 transcripts by reverse transcription-PCR and identified a spliced mRNA that contains a stop codon and is translated into the 29-kDa M protein. Interestingly, the nontemplated UGA stop codon is generated by the splicing event itself. Thus, the unusual M coding strategy of THOV resembles that of Influenza C virus.

Amino Acid Sequence↗
PubMed2025

Molecular epidemiological surveillance for non-tuberculous mycobacterial pulmonary disease: a single-center prospective cohort study.

UNLABELLED: Bacterial species cultured from sputum change during treatment or observation for non-tuberculous mycobacterial pulmonary disease; however, strain-level changes remain unrecognized. Variable number tandem repeat typing is a standard technique for strain identification; nonetheless, its labor-intensive and time-consuming nature limits routine clinical use. Therefore, we aimed to elucidate species-subspecies and strain dynamics in non-tuberculous mycobacteria and develop a simple sequence-based strain-level determination method. We performed a single-center prospective cohort study of 112 patients with non-tuberculous mycobacterial pulmonary disease. Whole-genome sequencing was performed on two sputum samples collected at enrollment and at the end of follow-up, followed by variable number tandem repeat (VNTR) typing. We also developed a simple long-read sequencing-based digital VNTR (dVNTR) typing method and evaluated its efficacy. Our results demonstrate that core genome multi-locus sequencing typing revealed species/subspecies changes in 13 patients (11.6%); VNTR typing detected strain changes in 16 patients (14.3%) without species/subspecies changes. Overall, pathogen shifts occurred in 29 patients (shift [+] group, 25.9%), whereas 83 had no detectable pathogen shift (shift [-] group, 74.1%). Interestingly, macrolide and amikacin susceptibility changed in both groups, but resistance remained higher in shift (-) patients. dVNTR results aligned with those of conventional VNTR typing. In conclusion, since susceptibility factors remain unclear, routine species/subspecies identification and molecular typing, such as VNTR, are optimal for patient care. Core genome multi-locus sequencing typing with a dVNTR identified pathogen shifts, innovating non-tuberculous mycobacterial pulmonary disease management.Clinical TrialsThis study is registered with UMIN as UMIN 000056067. IMPORTANCE: Pulmonary non-tuberculous mycobacterial disease is a chronic infection in which the causative pathogens may change at the species, subspecies, or strain level over time. Accurate tracking of these changes is essential for optimizing treatment; however, conventional clinical practice lacks efficient methods for monitoring such dynamics. Our study revealed pathogen changes in approximately one-quarter of patients over 1.5 years, prompting the development of a novel surveillance system that integrates next-generation sequencing for both species-subspecies identification and strain-level molecular epidemiology. This innovation enables real-time monitoring of pathogen dynamics, allowing clinicians to promptly adjust treatment strategies and improve patient care through more informed decision-making.

Humans↗
PubMed2026

Complete genome of multiply antibiotic resistant ST10 Acinetobacter baumannii isolate NL6 from Vietnam and relationship to available ST10 genomes.

The genome of NL6, a multiply antibiotic-resistant Acinetobacter baumannii ST10:KL49:OCL2 carriage isolate from Vietnam, was sequenced using Nanopore technology, and complete chromosome and plasmid sequences were assembled from the long reads and available short reads. Resistance genes and their locations were identified, and transfer of a conjugative plasmid carrying several resistance genes into a new host was tested. The acquired resistance genes in NL6 were distributed between the chromosome and two of three plasmids present. The chromosome carries multiple copies of several insertion sequences, an incomplete copy of the ISAba1-bounded Tn6250 that includes the sul2 and strAB genes, and an integrative element carrying copper resistance genes designated IECuR. Plasmid pNL6-2 (r3-T5; 15 Kbp) is a Rep_3/OrfX plasmid that includes a tet39 dif module, and pNL6-3 (r3-T20; 66.9 Kbp) carries aacC2d, aphA6, and blaCARB-16 and a second ampC gene preceded by an ISAba1. Conjugation of pNL6-3 into derivatives of ATCC17978 was demonstrated, confirming that the ampC gene confers resistance to third-generation cephalosporins. NL6 was compared to other complete ST10 genomes. Several acquired elements in the chromosome were shared with the ST10 isolate LAC-4 (USA), indicating shared ancestry, but the plasmid content differed. The KL and plasmid content were variable in 17 further complete ST10 genomes downloaded from GenBank. Tn6250 and IECuR were only found together in the chromosome of two further KL49 isolates. Antibiotic resistance in ST10 A. baumannii was acquired mainly via plasmid acquisition, but resistance genes varied, and a variety of plasmids was involved.IMPORTANCEMembers of the CC10 clonal complex of Acinetobacter baumannii comprising ST10 plus single and double locus variants are known to be particularly virulent. However, antibiotic resistance in members of this group has rarely been examined. Here, determination of the complete genome (chromosome and plasmids) of a representative ST10 isolate from Vietnam allowed the context and location of acquired antibiotic resistance genes and of other mobile genetic elements to be determined. Mobile genetic element locations in completed chromosomes facilitate comparisons of potentially related genomes, revealing those with recent shared ancestry. Differences in plasmid content can also be examined.

Acinetobacter baumannii↗
PubMed2026

Optimizing a culture-enriched hybrid metagenomics pipeline to assess the AMR footprint of livestock manure in anaerobic digestate.

The role of environmental samples from livestock production systems, including manure and anaerobic digestate, as reservoirs of antimicrobial resistance genes (ARGs) is likely underestimated because conventional metagenomic approaches can overlook low-abundance ARGs and often lack the resolution to associate these genes with their microbial hosts and co-localized mobile genetic elements (MGEs). We evaluated whether culture-enriched metagenomics (CEMG), with and without antibiotic selection, enhances ARG detection in anaerobic digestate and improves the resolution of ARG-MGE-host associations using hybrid short- and long-read metagenomic assembly. CEMG increased ARG recovery; mean ARG abundance rose from 15.4 counts per million (CPM) in metagenomic fresh digestate (FD) to 124 CPM in CEMG without antibiotics and 160 CPM in antibiotic-selective CEMG. In FD, only 9 unique ARGs were detected, whereas CEMG recovered 112, including ARGs of clinical importance, such as glycopeptide resistance, beta-lactamase genes, and the cfr 23S rRNA methyltransferase conferring cross-resistance to multiple antibiotic classes. Antibiotic selection induced targeted, class-specific shifts in ARG profiles, with ARGs associated with tetracycline resistance consistently enriched across treatments. Hybrid metagenomic assembly resolved the genomic context of 784 ARGs, of which 59.3% were co-localized with at least one class of MGEs, predominantly plasmids and integrative conjugative elements/integrative mobilizable elements. Biocide and metal resistance genes frequently co-occurred with ARGs on the same contigs. Together, these findings demonstrate that antibiotic-selective culture enrichment enhances resistome surveillance by improving detection of low-abundance ARGs, while hybrid assembly provides critical genomic context for assessing their mobility and host associations.IMPORTANCELivestock manure and its byproducts, such as anaerobic digestate, are recognized as important environmental reservoirs of antimicrobial resistance genes (ARGs) and resistant bacteria, yet current metagenomic approaches may underestimate this risk by failing to detect low-abundance but clinically relevant ARGs. Here, we show that integrating culture enrichment with hybrid metagenomics improves ARG recovery and reveals ARG co-localization with mobile genetic elements and putative bacterial hosts. This approach captures a cultivable and condition-responsive fraction of the resistome that is not readily accessible through direct metagenomic sequencing alone, providing a more informative framework for environmental AMR surveillance.

anaerobic digestion↗