Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Genome assembly”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources

Genomes of the ex-type strains of Elsinoë mangiferae and E. perseae, the causal agents of scab on mango and avocado.

Elsinoë species are slow-growing, hemibiotrophic to necrotrophic fungi that cause scab diseases on economically important fruit crops. Genome resources for many host-specific species remain limited. We report high-quality draft genome assemblies for the ex-type strains of Elsinoë mangiferae (CBS 226.50) and E. perseae (CBS 406.34), causal agents of mango and avocado scab, respectively. Among 5 approaches tested, a Nanopore-only NextDenovo assembly produced the most contiguous genomes, yielding 24.5 Mb (E. mangiferae) and 25.1 Mb (E. perseae) assemblies with 13 and 18 contigs, respectively, BUSCO completeness scores of ∼94%, and multiple putative telomere-to-telomere chromosomes. Gene prediction identified 9,134 and 9,243 genes, respectively. Functional annotation revealed enrichment of metabolic and regulatory pathways, including those involved in posttranslational modification, protein transport, and secondary metabolism. Carbohydrate-active enzyme repertoires were small but conserved, consistent with stealth pathogenicity strategies and low plant cell wall degradation. Both genomes encoded large secretomes (>850 proteins), diverse protease repertoires (>300 proteins), Ecp2-like effector proteins, and multiple biosynthetic gene clusters, including clusters with similarity to those associated with elsinochrome and ACT-toxin II biosynthesis, some of which may contribute to host-pathogen interactions and disease development. A large fraction of genes lacked functional characterization, suggesting incomplete databases and/or the presence of lineage-specific genes potentially involved in virulence or host adaptation. These genome resources fill critical gaps for underrepresented Elsinoë species and provide taxonomically anchored references essential for diagnostics, comparative genomics, and research into the molecular basis of host specificity and pathogenicity in scab-causing fungi.

Persea↗

A chromosome-level genome of the Nicobar pigeon, Caloenas nicobarica.

The Nicobar pigeon (Caloenas nicobarica), the closest living relative of the extinct Dodo (Raphus cucullatus), is endemic to Southeast Asia with a fragmented distribution across numerous small islands. It suffers from habitat loss, hunting, and predation from invasive species, resulting in its classification as Near Threatened by the International Union for the Conservation of Nature. We have generated a haplotype-resolved and chromosome-level genome assembly of the Nicobar pigeon using a combination of PacBio HiFi long-read sequencing and Arima Hi-C chromatin interaction mapping. This assembly includes two haplotypes, each spanning approximately 1.2 Gb. Haplotype 1 has a contig N50 of 25.2 Mb and a scaffold N50 of 79.7 Mb, whereas haplotype 2 has a contig N50 of 24.7 Mb and a scaffold N50 of 107.9 Mb. As the first high-quality genome assembly of any bird in the Columbidae Indo-Pacific clade, this resource provides valuable insights for phylogenetic studies. Furthermore, the phylogenetic proximity of the Nicobar pigeon to the Dodo (R. cucullatus) and the Rodrigues Solitaire (Pezophaps solitaria) offers a unique opportunity to study these extinct species, making this assembly a critical resource for evolutionary studies. It also offers a unique model for studying genetic diversity, adaptation, and speciation in island environments. This genomic resource will not only enhance our understanding of the evolutionary history of the Nicobar pigeon but also serve as a valuable tool for future conservation efforts aimed at preserving this unique species and its fragile island ecosystem.

Animals↗

Reference genomes of Japanese raccoon dog (Nyctereutes viverrinus) and a Japanese red fox (Vulpes vulpes japonica).

We established primary fibroblast cultures from a Japanese raccoon dog (Nyctereutes viverrinus) and a Japanese red fox (Vulpes vulpes japonica) and generated highly contiguous reference genome assemblies using Oxford Nanopore Technologies PromethION long-read sequencing. The Japanese raccoon dog assembly spanned 2.69 Gb in 813 scaffolds, with a scaffold N50 of 52 Mb and a Benchmarking Universal Single-Copy Orthologs (BUSCO) completeness score of 98.2%. The Japanese red fox assembly spanned 2.47 Gb in 903 scaffolds, with a scaffold N50 of 139 Mb and a BUSCO completeness score of 97.5%. Phylogenomic analysis placed the Japanese raccoon dog in a lineage distinct from the continental raccoon dog, supporting its evolutionary differentiation within Nyctereutes. The Japanese red fox formed a distinct lineage within the red fox clade, consistent with its recognized regional differentiation. These genome assemblies and associated fibroblast cultures provide resources for studies of canid systematics, population history, local adaptation, comparative genome evolution, and conservation genetics.

Canidae↗

Nodules-associated Klebsiella oxytoca complex: genomic insights into plant growth promotion and health risk assessment.

The swift emergence of antibiotic resistance genes (ARGs) across interconnected One Health compartments poses a significant global threat. Although plant growth-promoting (PGP) bacteria possess numerous attributes beneficial to host plants, many of these bacteria also harbor ARGs, necessitating a focused assessment of their negative implications. In this context, here we performed whole genome sequencing of 14 PGP endophytic strains isolated from root nodules of faba beans, belonging to three Klebsiella oxytoca species complex (KoSC): K. grimontii (n = 5), K. michiganensis (n = 5), and K. pasteurii (n = 4). We performed comparative genomics, molecular typing, and pangenome analyses on these strains. We identified significant diversity within the KoSC population, classifying the strains into five sequence types (STs), three of which are novel to this study (ST-542, ST-569, and ST-629). Phylogenomic analysis revealed that the bacterial strains clustered more closely by ST than by their source of isolation. Annotation of gene clusters indicated that all assembled genomes are enriched with genes involved in PGP activities, alongside a robust array of genes conferring tolerance to abiotic stresses. Importantly, our findings disclosed that the 14 assembled genomes harbored multiple ARGs, conferring resistance to various antibiotic classes, with 71% of the population classified as multidrug-resistant based on the in vitro antibiotic susceptibility assay. Furthermore, all genomes contained an array of virulence factors critical for survival, pathogenesis, biofilm formation, and root colonization. In conclusion, this study substantiates the hypothesis that certain PGP bacteria may serve as potential reservoirs of multidrug resistance, posing significant public health risks. Thus, the future advancement of bacteria-based biofertilizers should integrate environmental considerations and monitor their impact on antibiotic resistance dissemination in soil ecosystems.

Klebsiella oxytoca↗

An allelic resolution gene atlas for tetraploid potato provides insights into tuberization and stress resilience.

Tubers are modified underground stems that enable asexual, clonal reproduction and serve as a mechanism for overwintering and avoidance of herbivory. Potato (Solanum tuberosum L.) is cultivated for its tubers, which serve as a major crop. Genes responsible for tuber initiation and disease resistance have been characterized in potato including StSP6A, a homolog of flowering time, that functions as a tuberigen, the equivalent of a florigen. To elucidate additional molecular and genetic mechanisms underlying potato biology including tuber initiation, tuber development, and stress responses, we generated a developmental and abiotic/biotic-stress gene expression atlas from 34 tissues and treatments of the tetraploid potato cultivar, Atlantic. Using the haplotype-phased tetraploid Atlantic genome assembly and expression abundances of 129 218 genes, we constructed gene coexpression modules that represent networks associated with distinct developmental stages as well as stress responses. Functional annotations were given to modules and used to identify genes involved in tuberization and stress resilience. Structural variation from a pan-genomic analysis across four cultivated potato genome assemblies as well as domestication and wild introgression data allowed for deeper insights into the modules to identify key genes involved in tuberization and stress responses. This study underscores the importance of transcriptional regulation in tuberization and provides a comprehensive framework for future research on potato development and improvement.

Solanum tuberosum↗

Non-LTR retrotransposons in the African malaria mosquito, Anopheles gambiae: unprecedented diversity and evidence of recent activity.

Over a hundred families of non-long terminal repeat retrotransposons (non-LTRs) were found in the newly released Anopheles gambiae genome assembly during a reiterative and comprehensive search using the conserved reverse transcriptase (RT) domains of known non-LTRs as the starting queries. These families, which are defined by at least 20% amino acid sequence divergence in their RT domains, range from a few to approximately 2,000 copies and occupy at least 3% of the genome. In addition to having an unprecedented number of diverse families, A. gambiae non-LTRs represent 8 of the 15 previously defined clades plus two novel clades, Loner and Outcast, more than what has been reported for any genome. Five families were found belonging to the L1 clade, which had no invertebrate representatives to date. One unique family named Sponge contains only a complete open reading frame (ORF) for the Gag-like protein and appears to have been mobilized by a family of the CR1 clade. Although most families appear to be inactive as expected, all clades except R4 have families with characteristics suggesting recent activity. At least 21 families have multiple full-length copies with over 99% nucleotide identity and some or all of the following characteristics: target site duplications (TSDs), intact ORFs, and corresponding expressed sequence tags (ESTs). The incredible diversity and the maintenance of multiple recently active lineages within different clades indicate a complex evolutionary scenario. A. gambiae non-LTRs have the potential to be developed as tools for population genetic studies and genetic manipulations of this primary vector of the devastating disease malaria. The semi-automated reiterative search approach described here may be used with any genome assembly to systematically survey and characterize non-LTRs as well as other transposable elements that encode a conserved protein.

Animals↗

mettannotator: a comprehensive and scalable Nextflow annotation pipeline for prokaryotic assemblies.

SUMMARY: In recent years, there has been a surge in prokaryotic genome assemblies, coming from both isolated organisms and environmental samples. These assemblies often include novel species that are poorly represented in reference databases creating a need for a tool that can annotate both well-described and novel taxa, and can run at scale. Here, we present mettannotator-a comprehensive, scalable Nextflow pipeline for prokaryotic genome annotation that identifies coding and noncoding regions, predicts protein functions, including antimicrobial resistance, and delineates gene clusters. The pipeline summarizes these results in a GFF (General Feature Format) file that can be easily utilized in downstream analysis or visualized using common genome browsers. Here, we show how it works on 200 genomes from 29 prokaryotic phyla, including isolate genomes and known and novel metagenome-assembled genomes, and present metrics on its performance in comparison to other tools. AVAILABILITY AND IMPLEMENTATION: The pipeline is written in Nextflow and Python and published under an open source Apache 2.0 licence. Instructions and source code can be accessed at https://github.com/EBI-Metagenomics/mettannotator. The pipeline is also available on WorkflowHub: https://workflowhub.eu/workflows/1069.

Software↗

GenoMiner: a tool for genome-wide search of coding and non-coding conserved sequence tags.

GenoMiner is a software tool that searches for regions of similarity between user-submitted genome or transcript sequences and user-specified whole genome assemblies. The program then identifies conserved sequence tags (CSTs) in these homologous regions and provides a prediction of their coding or non-coding nature. The analysis is carried out through three steps: (1) definition of sequence regions homologous to the query sequence in the selected target genomes by a fast BLAT alignment; (2) identification of CSTs by a more sensitive BLAST-like alignment between the query and the homologous regions in the target genomes and (3) assessment of the coding or non-coding nature of detected CSTs through the computation of a suitable coding potential score. GenoMiner allows the user to search the query sequence against a number of vertebrate genome assemblies in a single run providing a user-friendly graphical output.

Algorithms↗

Integrative Genotyping and Analysis of Canine Structural Variation Using Long-read and Short-read Data.

Structural variation makes an important contribution to canine evolution and phenotypic differences. Although recent advances in long-read sequencing have enabled the generation of multiple canine genome assemblies, most prior analyses of structural variation have relied on short-read sequencing. To offer a more complete assessment of structural variation in canines, we performed an integrative analysis of structural variants present in 12 canine samples with available long-read and short-read sequencing data along with genome assemblies. Use of long-reads permits the discovery of heterozygous variation that is absent in existing haploid assembly representations while offering a marked increase in the ability to identify insertion variants relative to short-read approaches. Examination of the size spectrum of structural variants shows that dimorphic LINE-1 and SINE variants account for over 45% of all deletions and identified 1,410 LINE-1s with intact open reading frames that show presence-absence dimorphism. Using a graph-based approach, we genotype newly discovered structural variants in an existing collection of 1,879 resequenced dogs and wolves, generating a variant catalog containing a 56.5% increase in the number of deletions and 705% increase in the number of insertions previously found in the analyzed samples. Examination of allele frequencies across admixture components present across breed clades identified 283 structural variants evolving with a signature of selection.

Animals↗

An allelic resolution gene atlas for tetraploid potato provides insights into tuberization and stress resilience.

Tubers are modified underground stems that enable asexual, clonal reproduction and serve as a mechanism for overwintering and avoidance of herbivory. Tubers are wide-spread across angiosperms with some species such as Solanum tuberosum L. (potato) serving as a vital crop for human consumption. Genes responsible for tuber initiation and disease resistance have been characterized in potato including StSP6A, a homolog of Flowering Time, that functions as tuberigen, the equivalent of florigen. To elucidate additional molecular and genetic mechanisms underlying potato biology including tuber initiation, tuber development, and stress responses, we generated a developmental and abiotic/biotic-stress gene expression atlas from 34 tissues and treatments of Atlantic, a tetraploid cultivar. Using the haplotype-phased tetraploid Atlantic genome assembly and expression abundances of 129,218 genes, we constructed gene coexpression modules that represent networks associated with distinct developmental stages as well as stress responses. Functional annotations were given to modules and used to identify genes involved in tuberization and stress resilience. Structural variation from a pan-genomic analysis across four cultivated potato genome assemblies as well as domestication and wild introgression data allowed for deeper insights into the modules to identify key genes involved in tuberization and stress responses. This study underscores the importance of transcriptional regulation in tuberization and provides a comprehensive framework for future research on potato development and improvement.

Journal Article↗

A genome-wide survey of Major Histocompatibility Complex (MHC) genes and their paralogues in zebrafish.

BACKGROUND: The genomic organisation of the Major Histocompatibility Complex (MHC) varies greatly between different vertebrates. In mammals, the classical MHC consists of a large number of linked genes (e.g. greater than 200 in humans) with predominantly immune function. In some birds, it consists of only a small number of linked MHC core genes (e.g. smaller than 20 in chickens) forming a minimal essential MHC and, in fish, the MHC consists of a so far unknown number of genes including non-linked MHC core genes. Here we report a survey of MHC genes and their paralogues in the zebrafish genome. RESULTS: Using sequence similarity searches against the zebrafish draft genome assembly (Zv4, September 2004), 149 putative MHC gene loci and their paralogues have been identified. Of these, 41 map to chromosome 19 while the remaining loci are spread across essentially all chromosomes. Despite the fragmentation, a set of MHC core genes involved in peptide transport, loading and presentation are still found in a single linkage group. CONCLUSION: The results extend the linkage information of MHC core genes on zebrafish chromosome 19 and show the distribution of the remaining MHC genes and their paralogues to be genome-wide. Although based on a draft genome assembly, this survey demonstrates an essentially fragmented MHC in zebrafish.

Animals↗

Highly Contiguous Is Not Chromosomally Accurate: Integrated Cytogenetic and Genomic Mapping in Two Turtle Genome.

High-quality genome assemblies are essential for robust research across biological and medical fields. Assembly errors can have far-reaching consequences for downstream analyses, including gene annotation and the inference of synteny. In contrast to the rapid growth of genomic data volume, there is a notable lag in the integration of chromosome-level assemblies with cytogenetic data. We conducted the first direct genome-to-genome comparison, integrating comparative chromosome painting, the alignment of chromosome-specific probes to available genome assemblies, and synteny-based comparison of independent chromosome-level assemblies of the loggerhead sea turtle (Caretta caretta, 2n = 56) and the red-eared slider (Trachemys scripta elegans, 2n = 50). Using two independent sets of flow-sorted chromosome-specific probes in cross-species hybridizations, together with the sequencing and mapping of chromosome-derived DNA libraries, we assigned assembled scaffolds to all physical chromosomes of both species. In C. caretta, chromosomal assignments and genome-wide synteny were fully consistent with the published assembly, except for the reduced sizes of two microchromosome scaffolds, which we attribute to under-representation of repetitive DNA. In contrast, in T. s. elegans, cytogenetic validation of the assemblies revealed a false rearrangement compared to a missed one. Our results show that even highly contiguous vertebrate genome assemblies can misrepresent chromosome structure. When cytogenetic analyses reveal such inaccuracies, updated reference genomes should be generated for widely studied species to enable accurate inference of karyotype evolution and downstream comparative genomic analyses.

FISH↗

Large-scale benchmarking of prokaryotic annotation tools across thousands of species.

BACKGROUND: Genome annotation is an important step in deriving functional meaning from prokaryotic sequencing data, yet systematic evaluations guiding tool selection are lacking. We present the first large-scale investigation of four prominent open-source annotation tools (Prokka, Bakta, EggNOG-mapper, and PGAP) across 156,033 diverse genomes. This includes Escherichia coli strains for baseline performance, thousands of archaea and bacteria genomes, as well as frameshifted and metagenome-assembled genomes. RESULTS: Bakta excels in annotating high-quality bacterial genomes, while PGAP was better for archaeal genomes and challenging bacterial assemblies, including metagenome-assembled, fragmented, or contaminated samples. For Gene Ontology annotation, PGAP consistently provides broader term coverage, whereas EggNOG-mapper offers more terms per feature. CONCLUSIONS: Our findings highlight tool-specific strengths crucial for selecting optimal solutions based on genome quality, taxonomy, and origin (e.g. MAGs). This study provides an evidence-based guide for users and informs future tool development.

Molecular Sequence Annotation↗

Haplotype-specific expression of a terpene synthase underlies linalool variation in the grapevine cultivar Riesling.

Grapevine cultivars vary widely in monoterpenoid content, yet the genetic and regulatory mechanisms underlying this variation remain poorly characterized beyond highly aromatic Muscat types. We profiled free volatiles and monoterpenoid glycosides in a Riesling × Cabernet Sauvignon F1 mapping population, revealing extensive variation and transgressive segregation consistent with multigenic control. QTL mapping identified 70 significant loci associated with 48 volatile compounds and monoterpene glycosides, including two major QTLs explaining 33.6% and 33.4% of phenotypic variance in (3S)-linalool accumulation. Integration of haplotype-resolved transcriptomics with metabolite data, enabled by a chromosome-scale diploid Riesling genome assembly, resolved a (3S)-linalool/nerolidol synthase cluster on chromosome 10 and identified VviTPS54 as the strongest candidate underlying linalool variation. VviTPS54 exhibited haplotype-specific expression strongly correlated with (3S)-linalool accumulation across genotypes, while no QTL was detected at the 1-deoxy-D-xylulose-5-phosphate synthase 1 (VviDXS1) locus previously identified in Muscat cultivars. In addition, VviDXS1 expression was not correlated with terpene levels, indicating that regulatory variation within terpene synthase clusters, rather than methylerythritol phosphate (MEP) pathway flux, drives monoterpenoid composition in this population. These results establish regulatory variation of terpene synthases as a key mechanism underlying monoterpenoid diversity in grapevine and demonstrate that resolving such variation requires haplotype-phased genome assemblies coupled with haplotype-resolved transcriptomics to detect allele-specific expression differences at complex, heterozygous loci.

Grapevine↗

Protocol for telomere-to-telomere assembly of Borrelia genomes using a hybrid method.

Borrelia has a linear chromosome and linear plasmids capped by hairpin telomeres that short-read sequencing cannot resolve. Here, we present a protocol for telomere-to-telomere assembly of Borrelia genomes. We describe steps for spanning B. burgdorferi culture, DNA extraction, and sequencing through hybrid genome assembly to generate complete Borrelia genomes. The pipeline integrates Oxford Nanopore long reads and Illumina short reads to assemble hairpin telomeres, resolve paralogous linear and circular plasmids, and annotate and validate the assembled complete Borrelia genome. For complete details on the use and execution of this protocol, please refer to Amin et al.1.

Bioinformatics↗

Exploring the hypothetical role of Bacteroides species in depression progression: insights from metagenomic analysis.

Depression, a psychiatric disorder with significant morbidity and mortality, has a complex etiology. Recent advances in microbiome research have highlighted the potential role of fecal microbiota in depression pathogenesis. This study utilized shotgun metagenomic sequencing to compare the fecal microbiota of 28 depression patients and 26 healthy individuals. Significant differences in fecal microbiota composition were observed between the two groups. We generated 350 non-redundant high-quality metagenome-assembled genomes (MAGs) by binning and conducted comparisons between the depression and control groups. Notably, we found that the MAGs enriched in people with depression mostly belonged to Bacteroides, indicating a close link between Bacteroides abundance and the development of depression, suggesting that Bacteroides might be a potential culprit for depression. In the depression group, we found that the module of nitric oxide synthesis was remarkably enriched, and all Bacteroides MAGs contained genes annotated as nitric oxide synthase, suggesting that increased levels of Bacteroides may contribute to elevated nitric oxide synthesis. A distinct microbial signature consisting of Arthrobacter sp._U41, Bacillus cereus, Campylobacter rectus, and Pasteurella dagmatis accurately discriminates between depressed individuals and healthy controls, achieving an average area under the receiver operating characteristic curve of 0.950. This research sheds light on the potential role of fecal microbiota in depression and highlights specific metabolic pathways and microbial markers for further investigation.IMPORTANCEThis research highlighted significant differences in the composition and function of fecal microbiota between individuals with depression and healthy individuals, particularly the enrichment of Bacteroides metagenome-assembled genomes (MAGs) in depression patients. The upregulation of the nitric oxide synthesis pathway associated with these MAGs belonging to Bacteroides in the gut of depression patients had also been observed. The selected bacterial biomarkers reliably differentiate depression cases from healthy controls with high diagnostic accuracy (mean area under the receiver operating characteristic curve = 0.950). Our results suggest the importance of exploring microbial markers as potential diagnostic and therapeutic targets in managing depression.

Humans↗

The genome sequence of Hypericum androsaemum L., 1753 (Malpighiales: Hypericaceae).

We present a genome assembly of Hypericum androsaemum (Tutsan; Streptophyta; Magnoliopsida; Malpighiales; Hypericaceae). The genome sequence has a total length of 384.54 megabases. Most of the assembly (99.96%) is scaffolded into 20 chromosomal pseudomolecules. The mitochondrial sequences have lengths of 138.63, 75.57, 98.15 and 103.38 kilobases and the plastid genome assembly has a length of 165.0 kilobases. This assembly was generated as part of the Darwin Tree of Life project, which produces reference genomes for eukaryotic species found in Britain and Ireland.

Hypericum androsaemum↗

Rhodococcus dendrobeaniae sp. nov., an actinomycete isolated from an Arctic marine invertebrate exhibiting cytotoxic activity, and an emended description of Rhodococcus sovatensis.

A polyphasic study was conducted to establish the taxonomic status of strain T060T, an orange, aerobic, coccoid and non-motile actinomycete, isolated from a marine bryozoan (Dendrobeania sp.) collected in the Barents Sea. Phylogenetic analysis of the 16S rRNA gene sequences revealed Rhodococcus sovatensis DSM 102881T as the closest related species to strain T060T with a similarity of 99.54%. Phylogenomic analysis confirmed a close relationship between T060T and R. sovatensis DSM 102881T, while supporting their distinction. Digital DNA-DNA hybridization and average nucleotide identity values between strain T060T and R. sovatensis DSM 102881T were 26.4 and 84.3%, respectively, supporting the delineation of the isolate as a new species. Genomic characterization of the assembled genomes of T060T and R. sovatensis DSM 102881T showed genome sizes of 5.3 and 4.2 Mbp, with a G + C content of 64.38 and 65.01%, respectively. Genome analysis of strain T060T identified 15 biosynthetic gene clusters (BGCs) with low sequence similarity to known BGCs, indicating its capacity to produce unknown, potentially bioactive secondary metabolites. Furthermore, growth of T060T in eight different media revealed condition-dependent cytotoxic activity. The strongest cytotoxicity was observed for fractionated extracts from T060T grown in half-strength ISP 2 with filtered seawater against the human malignant cell lines MCF7 and A2058, and to a lesser extent against the non-malignant MRC5 cell line, highlighting its biotechnological potential. Based on the data from polyphasic taxonomy studies, it is proposed that strain T060T be classified in the genus Rhodococcus as Rhodococcus dendrobeaniae sp. nov. Additionally, the acquired data of R. sovatensis were used to amend its original description.

Rhodococcus↗