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PubMed2001

Pathogenicity islands: the tip of the iceberg.

Pathogenicity islands represent distinct genetic elements encoding virulence factors of pathogenic bacteria. Pathogenicity islands belong to the class of genomic islands, which are common genetic elements sharing a set of unifying features. Genomic islands have been acquired by horizontal gene transfer. In recent years many different genomic islands have been discovered in a variety of pathogenic as well as non-pathogenic bacteria. Because they promote genetic variability, genomic islands play an important role in microbial evolution.

Animals↗

PubMed2001

Benign solitary fibrous pleural tumour. Evidence of primitive features and complex genomic imbalances, including loss of 20q.

AIMS: Cytogenetic data on solitary fibrous tumours (SFT) are very limited. We studied a benign pleural SFT for its ultrastructural and immunohistochemical details, and made cytogenetic analyses for comparison with other genetic and ultrastructural studies of SFT. RESULTS: Immunohistochemistry showed strong positivities for CD34 and vimentin, but no reactions with anti-cytokeratins and epithelial membrane antigens. Electron microscopy revealed primitive desmosomes in our SFT. The results thus evinced fibroblast-like cells with intermediate epithelial-mesenchymal character. Comparative genomic hybridization of the tumour revealed losses of 1p33-->pter, 17pter q21, entire copies of chromosomes 19 and 22, and gains of 1p21-p22, 2q23-q32.3, 3pl2-q13.2, 4p14-q28, 6p12-q21, 9p21-->pter and 13q21-q31. Furthermore, there was loss of 20q, as was previously reported elsewhere in a case of benign and a case of malignant SFT. CONCLUSIONS: The results furnish further evidence of the involvement of -20q in SFT. In addition, they show that SFT may have complex genomic imbalances and primitive features, despite having a benign appearance.

Chromosome Deletion↗

PubMed2005

Genome plasticity and ori-ter rebalancing in Salmonella typhi.

Genome plasticity resulting from frequent rearrangement of the bacterial genome is a fascinating but poorly understood phenomenon. First reported in Salmonella typhi, it has been observed only in a small number of Salmonella serovars, although the over 2,500 known Salmonella serovars are all very closely related. To gain insights into this phenomenon and elucidate its roles in bacterial evolution, especially those involved in the formation of particular pathogens, we systematically analyzed the genomes of 127 wild-type S. typhi strains isolated from many places of the world and compared them with the two sequenced strains, Ty2 and CT18, attempting to find possible associations between genome rearrangement and other significant genomic features. Like other host-adapted Salmonella serovars, S. typhi contained large genome insertions, including the 134 kb Salmonella pathogenicity island, SPI7. Our analyses showed that SPI7 disrupted the physical balance of the bacterial genome between the replication origin (ori) and terminus (ter) when this DNA segment was inserted into the genome, and rearrangement in individual strains further changed the genome balance status, with a general tendency toward a better balanced genome structure. In a given S. typhi strain, genome diversification occurred and resulted in different structures among cells in the culture. Under a stressed condition, bacterial cells with better balanced genome structures were selected to greatly increase in proportion; in such cases, bacteria with better balanced genomes formed larger colonies and grew with shorter generation times. Our results support the hypothesis that genome plasticity as a result of frequent rearrangement provides the opportunity for the bacterial genome to adopt a better balanced structure and thus eventually stabilizes the genome during evolution.

Evolution, Molecular↗

PubMed2026

Molecular epidemiology and genomic characteristics of clinical Acinetobacter baumannii isolates from patients with hospital-acquired pneumonia in China, 2019-2020: a multicentre retrospective study.

BACKGROUND: Carbapenem-resistant Acinetobacter baumannii (CRAB) is a leading cause of hospital-acquired pneumonia (HAP) with high mortality. However, large-scale nationwide data of HAP-causing CRAB in China remain limited. METHODS: Here, we performed a nationwide multicentre retrospective study to characterise the molecular epidemiology and genomic features of 802 A. baumannii isolates from patients with HAP across 33 tertiary hospitals in China during 2019-2020. Antimicrobial susceptibility testing (AST), whole-genome sequencing (WGS), phylogenetic and comparative genomic analysis were used to investigate molecular epidemiology of HAP-causing CRAB strain. Clinical comparative analyses were carried out on data from 500 patients with HAP stratified by distinct antimicrobial susceptibility and genomic profiles, and a Galleria mellonella infection model was utilised for in vivo virulence assessment. FINDINGS: The overall carbapenem resistance rate of A. baumannii was 82.0% (658/802), with marked regional variations. CRAB exhibited high resistance to conventional agents but remained largely susceptible to polymyxin, tigecycline, cefiderocol and sulbactam-durlobactam. Among enrolled patients, CRAB infection was linked to substantially higher mortality (39.0% vs. 17.5%), and multivariate analysis confirmed ICU admission and advanced age as independent risk factors for patients with CRAB infection. Molecular typing revealed STPas2 (96.2%) as the absolutely predominant type; STOxf208, STOxf195, STOxf540, and STOxf369 were the most prevalent Oxford sequence types with obvious geographic stratification and divergent comorbidity profiles among corresponding patients. A total of 654 CRAB isolates harboured carbapenemase genes, with blaOXA-23 dominating at 98.8%. Genomic analysis revealed lineage-specific features: STOxf208 carried more virulence genes, while STOxf540 harboured a broader antimicrobial resistance genes (ARGs). The STOxf208 clone mainly belonged to KL2 (62.1%) and KL7 (36.8%) serotypes, with KL2 strains possessing richer ARGs and virulence factors, and in vivo virulence assays further validated that KL2 strains possessed higher pathogenicity than KL7 strains. INTERPRETATION: This study demonstrates the extremely high prevalence and clonal dominance of CRAB in Chinese patients with HAP, providing critical evidence for clinical treatment, antimicrobial stewardship, and targeted infection control. FUNDING: National Key Research and Development Program of China (2024YFE0106200), National Natural Science Foundation of China (U22A20338, 82502763, W2621007), Zhejiang Provincial Natural Science Foundation of China (LQN25H190006), Zhejiang Provincial Postdoctoral Science Foundation (ZJ2025058).

Acinetobacter baumannii↗

PubMed2026

AEGIS: an annotation extraction and genomic integration resource.

MOTIVATION: Genome annotation files (GFF3/GTF) are the standard for storing genomic feature data, yet their flexibility often results in formatting inconsistencies that create bottlenecks for downstream bioinformatics analyses. A robust, unified framework is required to parse, standardise, and validate these files to ensure interoperability and facilitate complex comparative genomic tasks. RESULTS: We present AEGIS (Annotation Extraction and Genomic Integration Suite), a comprehensive toolkit designed to parse, correct, and standardise genome annotations. Beyond quality control, AEGIS provides advanced modules for flexible feature extraction (e.g., coding sequences, promoters) and comparative genomic analysis. Uniquely, it integrates multiple lines of evidence, including sequence homology, synteny, and coordinate-based lift-overs, to assess gene model correspondence and infer orthology. We demonstrate the utility of AEGIS by quantifying complex structural changes between Arabidopsis annotation versions and identifying high-confidence orthologues across diverse plant genomes. AVAILABILITY: AEGIS is implemented in Python. Source code and documentation are freely available under the GPL-3 license at https://github.com/Tomsbiolab/aegis and as a Docker container at https://hub.docker.com/r/tomsbiolab/aegis. The package is also available on PyPI (pip install aegis-bio).

Software↗

PubMed2025

Unraveling the ecological success of Iodidimonas in a bioreactor treating oil and gas produced water.

UNLABELLED: Iodidimonas sp., a bacterium found in bioreactors treating oil and gas produced water as well as iodide-rich brines, has garnered attention for its unique ability to oxidize iodine. However, little is known about the metabolic capabilities that enable Iodidimonas sp. to thrive in certain unique ecological niches. In this study, we isolated, characterized, and sequenced three strains belonging to the Iodidimonas genus from the sludge of a membrane bioreactor used for produced water treatment. We investigated the genomic features of these isolates and compared them with the four publicly available isolate genomes from this genus, as well as a metagenome-assembled genome from the source bioreactor. Our Iodidimonas isolates had several genes associated with mitigating salinity, heavy metal, and organic compound stress, which likely help these bacteria to survive in produced water. Phenotyping tests revealed that while the isolates could utilize a wide variety of simple carbon substrates, they failed to degrade aliphatic or aromatic hydrocarbons, consistent with the lack of genes associated with common hydrocarbon degradation pathways in their genomes. We hypothesize that these microbes may lead a scavenging lifestyle in the bioreactor and similar iodide-rich brines. IMPORTANCE: Occupying a niche habitat and having few representative isolates, the genus Iodidimonas is a relatively understudied alphaproteobacterial group. Its ability to corrode pipes in iodine production facilities has economic implications, and its ability to generate potentially carcinogenic iodinated organic compounds during treatment of oil and gas produced water may cause environmental and health concerns with the recycling of treated water. Therefore, detailed characterization of the metabolic potential of the Iodidimonas isolates in this study both sheds light on their adaptation to the environmental conditions they inhabit and has environmental and economic significance.

Bioreactors↗

PubMed2026

Matching genomic evidence to claims about Mycobacterium avium subsp. paratuberculosis: Host association, host adaptation, mechanism, and virulence.

Whole-genome sequencing (WGS) permits high-resolution comparison of Mycobacterium avium subsp. paratuberculosis (MAP) isolates and pangenome analysis. Combined with animal-movement data, WGS can support transmission inference, but resolution alone does not establish the biological meaning of genomic variation. This focused narrative review applies a two-dimensional framework to purposively selected MAP studies, separating claim targets from support profiles. Claim targets include lineage identity, host-source or lineage characterization, host association, transmission, candidate genomic features, measured bacterial or host-cell phenotypes, natural-host infection fitness, disease or damage, shedding, and control outcomes. Depending on the claim, evidence operations may include characterization, context-aware comparative inference, direct endpoint ascertainment, and controlled feature perturbation; these are non-ordinal and may co-occur. On-target attribution, independent replication, and transportability are reported separately. The claim, not the study, is the unit of assessment. Typing markers support isolate or lineage discrimination, whereas phylogenomics supports evolutionary inference; neither alone establishes host adaptation. Pangenome comparisons and microbial genome-wide association studies nominate candidate features rather than establish adaptation. Cell-envelope and iron-associated studies support specified biochemical, transcriptional, or physiological phenotypes under defined conditions, while macrophage and calf models support only the endpoints measured. Annotated sequence variation alone nominates pathogenicity hypotheses. Across the illustrative studies selected here, MAP genomics most directly supported lineage classification, candidate discovery, measured bacterial phenotypes, bounded transmission inference, and natural-host infection-fitness claims. Claims about adaptation, mechanism, virulence, or control require endpoints and comparisons matched to the stated claim and model; feature-specific causal claims additionally require evidence linking the bacterial feature to the measured endpoint.

Claim boundaries↗

PubMed2005

Statistical Viewer: a tool to upload and integrate linkage and association data as plots displayed within the Ensembl genome browser.

BACKGROUND: To facilitate efficient selection and the prioritization of candidate complex disease susceptibility genes for association analysis, increasingly comprehensive annotation tools are essential to integrate, visualize and analyze vast quantities of disparate data generated by genomic screens, public human genome sequence annotation and ancillary biological databases. We have developed a plug-in package for Ensembl called "Statistical Viewer" that facilitates the analysis of genomic features and annotation in the regions of interest defined by linkage analysis. RESULTS: Statistical Viewer is an add-on package to the open-source Ensembl Genome Browser and Annotation System that displays disease study-specific linkage and/or association data as 2 dimensional plots in new panels in the context of Ensembl's Contig View and Cyto View pages. An enhanced upload server facilitates the upload of statistical data, as well as additional feature annotation to be displayed in DAS tracts, in the form of Excel Files. The Statistical View panel, drawn directly under the ideogram, illustrates lod score values for markers from a study of interest that are plotted against their position in base pairs. A module called "Get Map" easily converts the genetic locations of markers to genomic coordinates. The graph is placed under the corresponding ideogram features a synchronized vertical sliding selection box that is seamlessly integrated into Ensembl's Contig- and Cyto- View pages to choose the region to be displayed in Ensembl's "Overview" and "Detailed View" panels. To resolve Association and Fine mapping data plots, a "Detailed Statistic View" plot corresponding to the "Detailed View" may be displayed underneath. CONCLUSION: Features mapping to regions of linkage are accentuated when Statistic View is used in conjunction with the Distributed Annotation System (DAS) to display supplemental laboratory information such as differentially expressed disease genes in private data tracks. Statistic View is a novel and powerful visual feature that enhances Ensembl's utility as valuable resource for integrative genomic-based approaches to the identification of candidate disease susceptibility genes. At present there are no other tools that provide for the visualization of 2-dimensional plots of quantitative data scores against genomic coordinates in the context of a primary public genome annotation browser.

Chromosome Mapping↗

PubMed2026

Hybrid genome assembly of Penicillium oxalicum UV4 delineates cryptic secondary metabolite pathways and robust lignocellulolytic potential.

Penicillium oxalicum is a saprophytic fungus well-known for its hydrolytic potential; however, little is known about its metabolic flexibility and secondary metabolite biosynthesis, especially in isolates from underrepresented areas. In this study, we sequenced the genomic DNA of Penicillium oxalicum UV4 using Illumina and Oxford Nanopore platforms, generating a high-quality hybrid genome assembly of 30.28 Mb. The genome features 7,944 predicted genes (7,747 protein-coding sequences and 197 tRNAs) and demonstrates high completeness (99.0% BUSCO). Genomic analysis revealed 40 Biosynthetic Gene Clusters (BGCs), including distant orthologs of the Alternaria phytotoxin ACT-toxin II and the mycotoxin alternariol, as well as a putative clavaric acid-like biosynthetic cluster. Further investigation revealed an expanded CAZyme repertoire comprising 150 secreted proteins, featuring an AA16 lytic polysaccharide monooxygenase and putative multi-domain architectures, such as a pectin methylesterase-polygalacturonase fusion. This comprehensive genomic profiling highlights the dynamic metabolic capacity of P. oxalicum UV4, establishing it as a highly promising candidate for bio-refining studies and the discovery of cryptic bioactive metabolites.

Penicillium↗

PubMed2000

Reclassification of the Caliciviridae into distinct genera and exclusion of hepatitis E virus from the family on the basis of comparative phylogenetic analysis.

Caliciviridae and Picornaviridae belong to the same subphylum and genera within Picornaviridae are well characterized. Until 1998, Caliciviridae included one genus Calicivirus, containing strains with distinct structural and genomic features. Phylogenetic analyses of capsid genes revealed five clusters within Caliciviridae corresponding to differences in genome organization. In order to determine to what taxonomic level these clusters correspond, genomic sequences of caliciviruses, picornavirus prototypes, and two togavirus strains were analyzed. Distance and maximum likelihood methods were used to estimate the phylogenetic relationships among strains. Analysis of the capsid gene revealed separation of five main clusters (Norwalk-like, and Sapporo-like human caliciviruses, hepatitis E virus, vesicular exanthem of swine-like, and lapine caliciviruses) and distances corresponding to those observed among picornavirus genera. Utilizing more conserved (presumed helicase and polymerase) regions for the analyses, only major groups of caliciviruses were separated with confidence, with distances also comparable to those separating picornavirus genera. Analysis in these regions that included togavirus sequences moved HEV strains out of the calicivirus cluster. Our findings support the reclassification of caliciviruses into four genera. The phylogenetic position of hepatitis E virus, by analysis of non-structural genes, is outside of the caliciviruses, in an uncertain taxonomic position.

Caliciviridae↗

PubMed1992

Large-scale methylation patterns in the nuclear genomes of plants.

Methylation was investigated in compositional fractions of nuclear DNA preparations (50-100 kb in size) from five plants (onion, maize, rye, pea and tobacco), and was found to increase from GC-poor to GC-rich fractions. This methylation gradient showed different patterns in different plants and appears, therefore, to represent a novel, characteristic genome feature which concerns the noncoding, intergenic sequences that make up the bulk of the plant genomes investigated and mainly consist of repetitive sequences. The structural and functional implications of these results are discussed.

5-Methylcytosine↗

PubMed2003

Shopping in the genome market with EnsMart.

Life scientists who work with the supermarket of genome data will find the EnsMart database and software package offers a valuable door to a wealth of genes and genome features. Not only available to lab biologists on the web, this popular multi-organism genome database can be installed and used on your own Unix computer with relative ease. It offers a flexible, fast and practical data-mining framework for computer-savvy biologists and bioinformaticians.

Animals↗

PubMed2025

Large-scale Genome Analyses Provide Insights into Hymenoptera Evolution.

The order Hymenoptera includes a large number of species with diverse lifestyles and is known for its significant contributions to natural ecosystems. To better understand the evolution of this diverse order, we performed large-scale comparative genomics on 131 species from 13 superfamilies, covering most representative groups. We used these genomes to reveal an overall pattern of genomic change in terms of gene content and evolutionary rate throughout hymenopteran history. We identified genes that possibly contributed to the evolution of several key innovations, such as parasitoidism, wasp-waist, stinger, and secondary phytophagy. We also discovered the distinct genomic trajectories between the clade containing major parasitoid wasps (Parasitoida) and stinging species (Aculeata) since their divergence, which are involved in many aspects of genomic change, such as rapidly evolving gene families, gene gain and loss, and metabolic pathway evolution. In addition, we explored the genomic features accompanying the three independent evolution of secondary phytophagy. Our work provides insights for understanding genome evolution and the genomic basis of diversification in Hymenoptera.

Animals↗

PubMed2004

Sequencing strategies for parasite genomes.

Recent advances in the field of sequencing have enabled the determination of the complete nucleotide sequence of a large number of complex genomes. The complete genome sequence of the parasite Plasmodium falciparum has been published recently, and many other parasite genome initiatives are underway. Parasite genomes vary in size, nucleotide composition, polymorphism level, content, and distribution of repetitive elements. These genomic features affect the performance of sequencing strategies. As a consequence, each of the ongoing parasite genome projects has adopted distinct sequencing approaches. The degree of completeness and accuracy desired as well as available funds should be considered carefully when choosing the most appropriate sequencing strategy.

Animals↗

PubMed2002

Numerous potentially functional but non-genic conserved sequences on human chromosome 21.

The use of comparative genomics to infer genome function relies on the understanding of how different components of the genome change over evolutionary time. The aim of such comparative analysis is to identify conserved, functionally transcribed sequences such as protein-coding genes and non-coding RNA genes, and other functional sequences such as regulatory regions, as well as other genomic features. Here, we have compared the entire human chromosome 21 with syntenic regions of the mouse genome, and have identified a large number of conserved blocks of unknown function. Although previous studies have made similar observations, it is unknown whether these conserved sequences are genes or not. Here we present an extensive experimental and computational analysis of human chromosome 21 in an effort to assign function to sequences conserved between human chromosome 21 (ref. 8) and the syntenic mouse regions. Our data support the presence of a large number of potentially functional non-genic sequences, probably regulatory and structural. The integration of the properties of the conserved components of human chromosome 21 to the rapidly accumulating functional data for this chromosome will improve considerably our understanding of the role of sequence conservation in mammalian genomes.

Animals↗

PubMed2006

The genome sequence of the obligately chemolithoautotrophic, facultatively anaerobic bacterium Thiobacillus denitrificans.

The complete genome sequence of Thiobacillus denitrificans ATCC 25259 is the first to become available for an obligately chemolithoautotrophic, sulfur-compound-oxidizing, beta-proteobacterium. Analysis of the 2,909,809-bp genome will facilitate our molecular and biochemical understanding of the unusual metabolic repertoire of this bacterium, including its ability to couple denitrification to sulfur-compound oxidation, to catalyze anaerobic, nitrate-dependent oxidation of Fe(II) and U(IV), and to oxidize mineral electron donors. Notable genomic features include (i) genes encoding c-type cytochromes totaling 1 to 2 percent of the genome, which is a proportion greater than for almost all bacterial and archaeal species sequenced to date, (ii) genes encoding two [NiFe]hydrogenases, which is particularly significant because no information on hydrogenases has previously been reported for T. denitrificans and hydrogen oxidation appears to be critical for anaerobic U(IV) oxidation by this species, (iii) a diverse complement of more than 50 genes associated with sulfur-compound oxidation (including sox genes, dsr genes, and genes associated with the AMP-dependent oxidation of sulfite to sulfate), some of which occur in multiple (up to eight) copies, (iv) a relatively large number of genes associated with inorganic ion transport and heavy metal resistance, and (v) a paucity of genes encoding organic-compound transporters, commensurate with obligate chemolithoautotrophy. Ultimately, the genome sequence of T. denitrificans will enable elucidation of the mechanisms of aerobic and anaerobic sulfur-compound oxidation by beta-proteobacteria and will help reveal the molecular basis of this organism's role in major biogeochemical cycles (i.e., those involving sulfur, nitrogen, and carbon) and groundwater restoration.

Bacterial Proteins↗

PubMed2002

Discovering lactic acid bacteria by genomics.

This review summarizes a collection of lactic acid bacteria that are now undergoing genomic sequencing and analysis. Summaries are presented on twenty different species, with each overview discussing the organisms fundamental and practical significance, environmental habitat, and its role in fermentation, bioprocessing, or probiotics. For those projects where genome sequence data were available by March 2002, summaries include a listing of key statistics and interesting genomic features. These efforts will revolutionize our molecular view of Gram-positive bacteria, as up to 15 genomes from the low GC content lactic acid bacteria are expected to be available in the public domain by the end of 2003. Our collective view of the lactic acid bacteria will be fundamentally changed as we rediscover the relationships and capabilities of these organisms through genomics.

Bifidobacterium↗

PubMed2002

Identification of tandemly-repeated C/D snoRNA genes at the imprinted human 14q32 domain reminiscent of those at the Prader-Willi/Angelman syndrome region.

A human imprinted domain at 14q32 contains two co-expressed and reciprocally imprinted genes, DLK1 and GTL2, which are expressed from the paternally and maternally inherited alleles, respectively. We have previously shown that another imprinted locus, on human 15q11-q13, contains a large number of tandemly repeated C/D small nucleolar RNA genes (or C/D snoRNAs) only expressed from the paternal allele. Here we show that the region downstream from the GTL2 gene is also characterized by a transcription unit spanning many repeated intron-encoded C/D snoRNA genes, most of them arranged into two tandem arrays of 31 and 9 copies. Intriguingly, these snoRNAs depart from previously reported rRNA or snRNA methylation guides by their tissue-specific expression and by their lack of complementarity to rRNA or snRNA within their sequences. Analysis of the orthologous region in the mouse shows that the previously reported maternally expressed Rian gene, located downstream of Gtl2 on the distal 12 chromosome, encodes at least nine C/D snoRNAs. Through a systematic search in rodents, we could identify other C/D snoRNA genes in this domain. All snoRNAs identified on mouse distal 12 are brain-specific and only expressed from the maternally inherited allele. The human imprinted 14q32 domain therefore shares common genomic features with the imprinted 15q11-q13 loci. This link between tandemly repeated C/D snoRNA genes and genomic imprinting suggests a role for these snoRNAs and/or their host non-coding RNA genes in the evolution and/or mechanism of the epigenetic imprinting process.

Angelman Syndrome↗