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PubMed2005

A 768-lane microfabricated system for high-throughput DNA sequencing.

A 768-lane DNA sequencing system based on microfluidic plates has been designed as a near-term successor to 96-lane capillary arrays. Electrophoretic separations are implemented for the first time in large-format (25 cm x 50 cm) microdevices, with the objective of proving realistic read length, parallelism, and the scaled sample requirements for long-read de novo sequencing. Two 384-lane plates are alternatively cycled between electrophoresis and regeneration via a robotic pipettor. A total of greater than 172000 bases, 99% accuracy (corresponding to quality score 20) is achieved for each iteration of a 384 lane plate. At current operating conditions, this implies a system throughput exceeding 4 megabases of raw sequence (Phred 20) per day on the new platform. Standard operation is at "1/32x" Sanger chemistry, equal to typical genome center operation on mature capillary array machines, and a 16-fold improvement in scaling relative to previous microfabricated devices. Experiments provide evidence that sample concentration can be further reduced to 1/256x Sanger chemistry in the microdevice. Life-testing indicates a usable life of >150 hours (more than 50 runs) for the 384 lane plates. The combined advances, particularly those in read length and sample requirement, directly address the cost model requirements for adaptation of the new technology as the next step beyond capillary array instruments.

DNA↗

PubMed1987

Origin of noncoding DNA sequences: molecular fossils of genome evolution.

The total amount of noncoding sequences on chromosomes of contemporary organisms varies significantly from species to species. We propose a hypothesis for the origin of these noncoding sequences that assumes that (i) an approximately equal to 0.55-kilobase (kb)-long reading frame composed the primordial gene and (ii) a 20-kb-long single-stranded polynucleotide is the longest molecule (as a genome) that was polymerized at random and without a specific template in the primordial soup/cell. The statistical distribution of stop codons allows examination of the probability of generating reading frames of approximately equal to 0.55 kb in this primordial polynucleotide. This analysis reveals that with three stop codons, a run of at least 0.55-kb equivalent length of nonstop codons would occur in 4.6% of 20-kb-long polynucleotide molecules. We attempt to estimate the total amount of noncoding sequences that would be present on the chromosomes of contemporary species assuming that present-day chromosomes retain the prototype primordial genome structure. Theoretical estimates thus obtained for most eukaryotes do not differ significantly from those reported for these specific organisms, with only a few exceptions. Furthermore, analysis of possible stop-codon distributions suggests that life on earth would not exist, at least in its present form, had two or four stop codons been selected early in evolution.

Animals↗

PubMed2026

Megamimivirus double-stranded DNA linear genomes flanked by highly diverse terminal inverted repeats.

UNLABELLED: Giant viruses have fundamentally expanded our understanding of virology by challenging the conventional boundaries of both virion size and genome complexity. However, the scarcity of isolates has left many of their unique biological features unexplored. Here, we report the isolation and characterization of four new giant virus species belonging to the subfamily Megamimivirinae, sampled from distinct environments across China. Among these, Megavirus daqingense is the first giant virus isolated from an oil reservoir; it exhibits virion stability under high salinity, chloroform exposure, and elevated temperatures, suggesting fitness adaptations to subsurface conditions. Using a hybrid sequencing approach that integrates short- and long-read technologies, we assembled complete linear genomes for all four isolates, each flanked by long terminal inverted repeats (TIRs). Comparative genomic and synteny analyses identified 29 distinct TIRs from 46 megamimivirus genomes. Gene content within these TIRs was highly diverse, with no orthologous proteins conserved across all repeats. Furthermore, TIR genes experienced weaker purifying selection than those in non-TIR regions (i.e., the genomic regions excluding the TIRs), consistent with their role as drivers of genome plasticity. Notably, we discovered for the first time that identical tRNA genes are shared between TIRs and non-TIR regions of eukaryotic viruses. Collectively, our work provides insights into the structural and evolutionary complexity of megamimiviruses, revealing TIRs as reservoirs of genetic diversity and hotspots for gene transfer, thereby playing a pivotal role in shaping the dynamic architecture of giant virus genomes. IMPORTANCE: Terminal inverted repeats (TIRs) are critical structural elements at the termini of linear genomes essential for fundamental processes such as recombination, replication, and integration across diverse organisms. However, the inherent limitations of short-read sequencing technologies have left the complete structure, diversity, and evolutionary significance of long TIRs in giant viruses unexplored. In this study, we leverage hybrid sequencing and comparative genomic analyses to unveil the complexity of TIRs across the subfamily Megamimivirinae. We demonstrate that TIRs are dynamic genomic hotspots characterized by remarkable gene diversity and unexpected conservation of specific tRNA genes. These findings establish TIRs as key drivers of genome plasticity, serving as hotspots for horizontal gene transfer and genetic innovation. By resolving the long-hidden terminal structures of megamimivirus genomes, this work provides a foundational framework for understanding how TIRs shape the evolution of giant viruses and, more broadly, advances our understanding of genome architecture in large DNA viruses.

Megavirus↗

PubMed2026

High-Quality Genome Assembly, Metabolome, Pangenome, and Metabolic Models of Megasphaera hexanoica KCCM 43214T.

Megasphaera hexanoica KCCM 43214T, isolated from cow rumen, is capable of producing medium-chain carboxylic acids such as hexanoate and octanoate. In this study, we present a high-quality genome assembly, along with intracellular metabolomic profiling and pangenomic analysis. Illumina sequencing generated 2.3 Gbp from 15,293,634 reads with a GC content of 49.5%, while PacBio HiFi sequencing produced 331.5 Mbp across 45,266 reads, with an average read length of 7,323 bp and a HiFi read N50 of 8,214 bp. Hybrid assembly of short and long reads resulted in a single 2.88 Mbp contig, containing 2,835 protein-coding genes. Genome-scale metabolic models were constructed to evaluate its metabolic capabilities under specific growth conditions. Intracellular metabolomic analysis of cells grown in medium containing fructose and lactate revealed key metabolic activities associated with chain elongation. Pangenomic analysis across nine annotated genomes identified 6,721 orthologous genes using OrthoMCL, emphasizing the genetic and functional diversity within the Megasphaera genus. This dataset offers valuable insights into the metabolism and biotechnological potential of M. hexanoica KCCM 43214T.

Metabolome↗

PubMed2025

Molecular landscape of methicillin-resistant Staphylococcus aureus strains in clinical infections from hospitals in Lagos, Nigeria.

BACKGROUND AND OBJECTIVES: Multidrug-resistant Staphylococcus aureus (MRSA) accounts for a significant proportion of antimicrobial resistance (AMR)-associated infections worldwide. This study investigated the molecular profile of MRSA in Nigeria, providing valuable genomic data to fill existing knowledge gaps and highlighting its importance in the context of the global AMR crisis. METHODS: A total of 107 isolates were obtained from patient samples, including wound swabs/pus (65 isolates, 60.7%), blood cultures (16 isolates, 15%), urine/urinary catheter (8 isolates, 7.5%) and other sources. Species identification was performed using MALDI-TOF, and antimicrobial susceptibility testing was performed using the VITEK®2 system. Genomic DNA was extracted and subjected to whole-genome sequencing using short-read Illumina technology. In addition, a subset of isolates underwent long-read sequencing using Oxford Nanopore technology. RESULTS: Among the 107 isolates, 63 (59%) were identified as MRSA, with 58 (92%) carrying the mecA gene. The MRSA isolates exhibited high resistance to non-β-lactam antibiotics, particularly trimethoprim/sulfamethoxazole (95.3%), erythromycin (76.6%), gentamicin (71.4%) and quinolones (69.8%). The most prevalent MRSA belonged to the Bengal Bay clone [t657/ST772/Staphylococcal Cassette Chromosome mec (SCCmec) V(5C2)/Panton-Valentine leukocidin (PVL) + methicillin-susceptible Staphylococcus aureus (MRSA)], followed by t4690/ST152/SCCmec Vc(5C2&5)/PVL + MRSA and ST8 (t008, n = 1; t064, n = 4)/SCCmec Vc(5C2&5). Phylogenetic analysis suggests both community/associated transmission and possible importation of strains. CONCLUSIONS: This study highlights the significant burden of MRSA in Nigeria, with the high-risk Bengal Bay MRSA clone as the most common strain. The widespread resistance to non-β-lactam antibiotics underscores the urgent need for enhanced surveillance, infection control and antibiotic stewardship to mitigate its spread.

Journal Article↗

PubMed2025

A transposable element insertion in AUX/IAA16 disrupts splicing and causes auxin resistance in Bassia scoparia.

A dicamba-resistant population of kochia (Bassia scoparia) identified in Colorado, USA in 2012 was used to generate a synthetic mapping population that segregated for dicamba resistance. Linkage mapping associating dicamba injury with genotype derived from restriction-site-associated DNA sequencing identified a single locus in the kochia genome associated with resistance on chromosome 4. A mutant version of Auxin/Indole-3-Acetic Acid 16 (AUX/IAA16; a gene previously implicated in dicamba resistance in kochia) was found near the middle of this locus in resistant plants. Long-read sequencing of dicamba-resistant plants identified a recently inserted long-terminal repeat (LTR) retrotransposon TRIM element near the beginning of the second exon of AUX/IAA16, leading to disruption of normal splicing and a mutated degron domain. Stable transgenic lines of Arabidopsis thaliana ectopically expressing the mutant and wild-type alleles of AUX/IAA16 were developed. Arabidopsis thaliana plants expressing the mutant AUX/IAA16 allele grew shorter roots on control media. However, transgenic root growth was less inhibited on media containing either dicamba (5 μM) or IAA (0.5 μM) when compared with non-transgenic plants or those expressing the wild-type allele of AUX/IAA16. In vitro assays indicate reduced binding affinity and more rapid dissociation of the mutant AUX/IAA16 with TIR1 in the presence of several auxins, and protein modeling suggests the substitution of the glycine residue in the degron domain of AUX/IAA16 is especially important for resistance. A fitness cost associated with the mutant allele of AUX/IAA16 has implications for resistance evolution and management of kochia populations with this resistance mechanism.

Indoleacetic Acids↗

PubMed1988

Organization and nucleotide sequence of the broad bean chloroplast genes trnL-UAG, ndhF and two unidentified open reading frames.

We have determined the nucleotide sequence of a 6.9 kbp BamHI-XbaI fragment of broad bean chloroplasts. Part of this fragment (subfragment BglII-ClaI) is known to contain three tRNA genes (trnL-CAA, trnL-UAA and trnF). We have now further identified a gene coding for the third tRNA(Leu) isoacceptor (trnL-UAG) which is located close to trnF. The BamHI-XbaI fragment also contains the gene for subunit 5 of NADH dehydrogenase (ndhF) and two unidentified open reading frames (ORFx and ORF48). ORFx shares a high sequence homology with the long reading frames of tobacco (ORF1708), spinach (ORF2131), and liverwort (ORF2136), while ORF48 shares sequence homology with ORF69 of liverwort and ORF55 of tobacco.

Amino Acid Sequence↗

PubMed2005

Expression of an anti apoptotic recombinant short peptide in mammalian cells.

Understanding the mechanisms of the apoptotic and anti apoptotic processes may lead to a better way to control these cascades. Here we demonstrated for the first time the feasibility to express a short functional peptide in mammalian cells that abrogates the apoptosis cascade through interference with the proteolytic activity of the initiator caspase 9 and the executing caspase 3 enzymes. The expression of a short peptide that includes the pseudo-substrate motif of the apoptosis inhibitor protein P35 (Asp-Gln-Met-Asp) leads to the abrogation of cell death induced through either the mitochondrial or the death receptors pathways. Short open reading frames have been detected in several mammalian mRNAs, primarily upstream of the main long reading frame (uORFs), however, direct evidence for de-novo peptides translation has not been provided. Utilizing biochemical and imaging techniques we demonstrate here that the functional recombinant peptide was localized to the cytpoplasmic fraction of the cell. In conclusion, this work demonstrates that ribosomes recognize short ORFs to translate stable short recombinant peptides in mammalian cells. Expression of these intracellular peptides results in the knock down of apoptotic processes to generate apoptosis resistant stable cells.

Animals↗

PubMed2025

Comprehensive benchmarking of somatic structural variant detection at ultra-low allele fractions.

Postzygotic mosaicism gives rise to somatic structural variants (SVs) at ultra-low variant allele fractions (VAFs), which pose challenges for detection due to the high-coverage sequencing required and noise introduced by sequencing artifacts. Although somatic SV detection has been extensively studied in cancer, these studies are not directly applicable to the study of tissue mosaicism, as they rely on matched normals, target higher VAF ranges, and are enriched for different types of SVs. We present comprehensive benchmark data and best practices for non-cancer somatic SV detection. We created a synthetic mosaic sample by combining six HapMap individuals at varying proportions, generating allele fractions as low as 0.25%. This sample was sequenced to ~2,300x total coverage using Illumina, PacBio, and Nanopore technologies across multiple sequencing centers. A high-confidence benchmark SV set containing over 21,000 pseudo-somatic insertions and deletions ≥50bp was derived from haplotype-resolved assemblies. We evaluated 12 SV discovery pipelines and identified caller-specific strengths and sequencing platform-specific shortcomings. We find that short read-based approaches show reduced recall for insertions and repeat-associated SVs, whereas long-read sequencing achieves high accuracy throughout the genome, increasing linearly with coverage. The best algorithm's sensitivity exceeded 80% for VAFs ≥4% and 15% for VAFs of 0.5-1% with 60x coverage. The publicly available benchmarking data and comparative analysis of current methods provide a foundation for robust discovery of SV mosaicism in non-cancer tissues..

Journal Article↗

PubMed2026

Coexistence of carbapenemase and hypervirulence-associated genes among Klebsiella pneumoniae high-risk clones in Hungary.

INTRODUCTION: Strains of Klebsiella pneumoniae carrying hypervirulence and carbapenemase genes represent a rapidly emerging global public health threat. Our study aimed to comprehensively characterise the genomics of hypervirulence-associated and carbapenemase genes carrying K. pneumoniae (hv(a)CpKp) isolates in Hungary. MATERIALS AND METHODS: Between January 2022 and April 2024, 89 aerobactin (iucA-D/iutA)-positive non-duplicate carbapenemase-producing K. pneumoniae isolates from 15 Hungarian healthcare institutes underwent short-read (Illumina, MiSeq, NextSeq) whole-genome sequencing, followed by detailed plasmid analysis using long-read sequencing (Nanopore, MinION) in a representative subset of 32 strains. RESULTS: Most isolates (79/89) belonged to the high-risk clone ST147. Hypervirulence-associated (hva) genes-including rmpA/rmpA2, peg344, shiF, iucA-D, and iutA-were universally present, and 59 isolates possessed chromosomally integrated yersiniabactin loci. Most isolates (87/89) carried the bla NDM-1 carbapenemase gene. Hypervirulence-associated genes were most frequently (29/32) associated with IncHI1B/IncFIB(Mar) plasmids. Notably, we identified plasmids carrying both hva and carbapenemase genes-designated as hybrid plasmids-in 13 of 32 strains. The bla NDM-1 was linked to the IS26 transposase and was present in conserved, identical cassettes on all bla NDM-1-carrying plasmids. DISCUSSION/CONCLUSION: Our study identified hv(a)CpKp strains, particularly the ST147 clone, circulating in Hungary. Our findings highlight the need for routine virulence gene monitoring and continuous genomic and plasmid-based surveillance to mitigate the clinical and epidemiological impact of emerging hv(a)CpKp lineages.

Klebsiella pneumoniae↗

PubMed1994

Open reading frames in the antisense strands of genes coding for glycolytic enzymes in Saccharomyces cerevisiae.

Open reading frames longer than 300 bases were observed in the antisense strands of the genes coding for the glycolytic enzymes phosphoglucose isomerase, phosphoglycerate mutase, pyruvate kinase and alcohol dehydrogenase I. The open reading frames on both strands are in codon register. It has been suggested that proteins coded in codon register by complementary DNA strands can bind to each other. Consequently, it was interesting to investigate whether the open reading frames in the antisense strands of glycolytic enzyme genes are functional. We used oligonucleotide-directed mutagenesis of the PGI1 phosphoglucose isomerase gene to introduce pairs of closely spaced base substitutions that resulted in stop codons in one strand and only silent replacements in the other. Introduction of the two stop codons into the PGI1 sense strand caused the same physiological defects as already observed for pgil deletion mutants. No detectable effects were caused by the two stop codons in the antisense strand. A deletion that removed a section from -31 bp to +109 bp of the PGI1 gene but left 83 bases of the 3' region beyond the antisense open reading frame had the same phenotype as a deletion removing both reading frames. A similar pair of deletions of the PYK1 gene and its antisense reading frame showed identical defects. Our own Northern experiments and those reported by other authors using double-stranded probes detected only one transcript for each gene. These observations indicate that the antisense reading frames are not functional. On the other hand, evidence is provided to show that the rather long reading frames in the antisense strands of these glycolytic enzyme genes could arise from the strongly selective codon usage in highly expressed yeast genes, which reduces the frequency of stop codons in the antisense strand.

Base Sequence↗

PubMed1985

Physical and genetic map of a Rhizobium meliloti nodulation gene region and nucleotide sequence of nodC.

Infection of alfalfa by the soil bacterium Rhizobium meliloti proceeds by deformation of root hairs and bacterial invasion of host tissue by way of an infection thread. We studied an 8.7-kilobase (kb) segment of the R. meliloti megaplasmid, which contains genes required for infection. Site-directed Tn5 mutagenesis was used to examine this fragment for nodulation genes. A total of 81 R. meliloti strains with mapped Tn5 insertions in the 8.7-kb fragment were evaluated for nodulation phenotype on alfalfa plants; 39 of the insertions defined a 3.5-kb segment containing nodulation functions. Of these 39 mutants, 37 were completely nodulation deficient (Nod-), and 2 at the extreme nif-distal end were leaky Nod-. Complementation analysis was performed by inoculating plants with strains carrying a genomic Tn5 at one location and a plasmid-borne Tn5 at another location in the 3.5-kb nodulation segment. Mutations near the right border of the fragment behaved as two distinct complementation groups. The segment in which these mutations are located was analyzed by DNA sequencing. Several open reading frames were found in this region, but the one most likely to function is 1,206 bases long, reading from left to right (nif distal to proximal) and spanning both mutation groups. The genetic behavior of this segment may be due either to the gene product having two functional domains or to a recombinational hot spot between the apparent complementation groups.

Amino Acid Sequence↗

PubMed2026

Complex structural variation, phylogeny, and disease associations of the mucin pangenome.

Mucins are large glycoproteins that provide hydration and barrier function to epithelial tissues. Although genetically heterogeneous, all mucins harbor a large exon composed of variable number tandem repeats (VNTRs). Short-read sequencing has limited our understanding of mucin VNTR diversity and makes disease association studies challenging. We leverage 296 long-read phased genome assemblies to characterize 14 mucin family members, achieving ≥97% accuracy across 572 haplotypes. Phylogenetic haplogroup analysis reveals extraordinary structural heterozygosity, with MUC4 harboring the greatest allelic diversity (n=240 distinct lengths) and MUC12 the greatest size range (Δ = 55,233 bp; 23,080 amino acids). Ten mucins show significant population stratification (pFDR < 0.05). At the MUC4/MUC20 locus, we characterize higher-order structural variation, including a recurrent inversion, copy number variation, and interlocus gene conversion. Optimized genotyping achieves ≥95% haplogroup concordance across 10 loci. We apply this to 4,637 deeply phenotyped cystic fibrosis patients and identify a significant association between short MUC1 VNTRs and severe disease (p=0.0056), demonstrating the pangenome's utility for complex locus genotyping and disease discovery.

Journal Article↗

PubMed2026

A Chromosome-Level Genome Assembly of the Potato Leafhopper Empoasca fabae (Hemiptera: Cicadellidae).

The potato leafhopper, Empoasca fabae (Harris, 1841), is a highly polyphagous, migratory insect pest of eastern North America that feeds on more than 200 herbaceous and woody plant species, causing substantial losses to forage and field crops. Despite its agricultural and ecological importance, no genome has been available for this species. Here, we present the first chromosome-level genome assembly of E. fabae, generated from Oxford Nanopore long reads, Illumina short reads, and Omni-C proximity-ligation data. The final assembly spans 908 Mb across 132 scaffolds, with 99.8% of the assembly captured in ten chromosome-length scaffolds (nine autosomes and an X chromosome) with a scaffold N50 of 96.2 Mb. The assembly is highly complete, recovering 92.9% of conserved hemipteran single-copy orthologs from protein annotations, and is composed of 47.6% repetitive sequence, dominated by long terminal repeat retrotransposons and unclassified elements. Read-depth comparison between male and female individuals supports assignment of a single sex-linked chromosome, consistent with an XO sex determination system. BRAKER3 gene annotation predicted 31,406 protein-coding genes after retaining the longest isoform per locus. Comparative genome analysis of the two closest related Typhlocybinae species with genomes available, Matsumurasca onukii and Hebata decipiens, revealed extensive chromosome-scale collinearity while defining a shared core gene repertoire. This reference genome provides a foundation for comparative and population genomic studies and for investigating genetic traits in this economically important crop pest species.

Animals↗

PubMed2025

A comprehensive atlas of full-length Arabidopsis eccDNA populations identifies their genomic origins and epigenetic regulation.

Extrachromosomal circular DNA (eccDNA) has been described in several eukaryotic species and has been shown to impact phenomena as diverse as cancer and herbicide tolerance. EccDNA is thought to arise mainly through transposable element (TE) mobilization. Because studies based on short-read sequencing cannot efficiently identify full-length eccDNA forms generated from TEs, we employed the CIDER-Seq pipeline based on long-read sequencing, to obtain full-length eccDNAs from Arabidopsis. The generated eccDNA datasets identified centromeric/pericentromeric regions as hotspots of eccDNAs with several eccDNA molecules originating from Helitron and LTR TEs. To investigate the role of epigenetic marks on TE-derived eccDNA biogenesis, we studied Arabidopsis methylation mutants dcl3, rdr6, ros1, and ddm1. Contrasting the TE-suppression previously reported in the hypermethylated ros1 mutants, we identified activation of TEs in ros1, specifically of LTR/Gypsy TEs. An enrichment of LTR/Copia elements was identified in actively dividing calli and the shoot apical meristem (SAM). Uncharacterized "variable TEs" with high eccDNA and expression were identified in the SAM, including ATCOPIA58. Together, our study reveals the genomic origins of eccDNAs and delineates the link between epigenetic regulation, transposon mobilization, and eccDNA biogenesis.

Arabidopsis↗

PubMed1996

Reading skills in children with Turner's syndrome: an analysis of hyperplexia.

Most neuropsychological studies of cases of chromosomal abnormalities report associations with disorders or disabilities. Studies of Turner's Syndrome (TS), in which their is functional absence of the information carried on the short arm of the second X chromosome, have emphasised disorders of spatial skill and potential abnormality of the parietal lobes or right hemisphere. In contrast, language skills have received little investigation despite suggestions by Shaffer (1962) of considerable verbal skill. This paper reports on an analysis of reading skill, in girls with TS. The girls with TS attained reading levels higher than those predicted on the basis of their age and intelligence. Moreover, they attained significantly higher reading levels than controls. Unlike many previous studies of hyperlexia, reading comprehension was also better than controls. The hyperlexia of the girls with TS was characterised by strength in both lexical reading systems, as assessed by the ability to read irregular words, and strength in alphabetical or phonological reading skills, as assessed by the ability to read long unfamiliar regular words. Hyperlexia need not therefore co-occur with comprehension difficulties nor need it reflect strength in only part of the reading system. In TS it appears to represent a genuine hyperdevelopment of a skill. The strength of reading skill counterbalances the spatial difficulties of a comparable sample of girls with TS (Temple and Carney, 1995), and with other verbal skills may potentially be exploited in remedial enterprises.

Child↗

PubMed2026

A hybrid and cost-efficient barcoding strategy for full-length 16S rRNA gene nanopore sequencing of environmental samples.

BACKGROUND: Accurate species-level identification of bacteria in complex environmental samples is essential for applications in biotechnology, ecological monitoring, and clinical diagnostics. Short-read platforms such as Illumina frequently truncate the 16S rRNA gene, limiting taxonomic resolution. In this work, we applied Oxford Nanopore Technology (ONT) long-read sequencing to full-length 16S rRNA amplicon in samples from natural soil amended with lignocellulosic biomass and a simplified microbial community derived from cultures grown on selective and differential carboxymethyl cellulose (CMC)-based substrates, with the aim to evaluate the difference in performance between a real, complex community and a less complex system. To reduce consumable costs, we substituted the standard ONT Barcoding kits with an in-house hybrid barcoding workflow. Specifically, PacBio PCR-based barcoding protocol was used for sample indexing, followed by library preparation using the ONT Ligation Sequencing Kit. This simplified approach retained compatibility with MinION and Flongle flow cells and supported accurate downstream demultiplexing while lowering barcode costs substantially. Additionally, a new bioinformatic workflow tailored to ONT data was implemented. RESULTS: Overall, the hybrid protocol significantly reduced per-sample barcoding costs while preserving high sequencing quality and throughput. The sequencing run yielded over 5 Gb of quality-filtered data (Q-score ≥ 10). Furthermore, the new bioinformatic workflow allowed taxonomic assignment at the species level for 49.38% of annotated taxa, compared to just 4.59% using Illumina NovaSeq sequencing of the V3-V4 region. ONT also recovered 2.3 times more genera and 1.3 times more families. Although 16S rRNA gene sequencing often cannot distinguish between closely related species, particularly within taxonomically complex groups, in this work, full-length reads substantially improved both taxonomic resolution and database matching. CONCLUSIONS: These results show that full-length 16S rRNA sequencing with ONT, paired with a low-cost barcoding strategy, enhanced taxonomic resolution compared to short-read workflows. This approach also offers a scalable and cost-effective option for high-resolution microbiome profiling in research and applied settings.

RNA, Ribosomal, 16S↗

PubMed2025

Chromosome scale genomes of two invasive Adelges species enable virtual screening for selective adelgicides.

Two invasive hemipteran adelgids are associated with widespread damage to several North American conifer species. Adelges tsugae, hemlock woolly adelgid, was introduced from Japan and reproduces parthenogenetically in North America, where it has rapidly decimated Tsuga canadensis and Tsuga caroliniana (the eastern and Carolina hemlocks, respectively). Adelges abietis, eastern spruce gall adelgid, introduced from Europe, forms distinctive pineapple-shaped galls on several native spruce species. While not considered a major forest pest, it weakens trees and increases susceptibility to additional stressors. Broad-spectrum insecticides that are often used to control adelgid populations can have off-target impacts on beneficial insects. Whole genome sequencing was performed on both species to aid in development of targeted solutions that may minimize ecological impact. Adelges abietis was sequenced using Illumina Linked-Read technology from 30 pooled individuals, with Hi-C scaffolding performed using data from a single individual collected from the same host plant. Adelges tsugae used Oxford Nanopore long-read sequencing from pooled nymphs. The assembled A. tsugae and A. abietis genomes, pooled from several parthenogenetic females, are 220.75 Mbp and 253.16 Mbp, respectively. Each consists of eight autosomal chromosomes, as well as two sex chromosomes (X1/X2), supporting the XX-XO sex determination system. The genomes are over 96% complete based on BUSCO assessment. Genome annotation identified 11,424 and 12,060 protein-coding genes in A. tsugae and A. abietis, respectively. Comparative analysis of proteins across 29 hemipteran species and 14 arthropod outgroups identified 31,666 putative gene families. Gene family evolution analysis with CAFE revealed lineage-specific expansions in immune-related aminopeptidases (ERAP1) and juvenile hormone binding proteins (JHBP), contractions in juvenile hormone acid methyltransferases (JHAMT), and conservation of nicotinic acetylcholine receptors (nAChR). These genes were explored as candidate families towards a long-term objective of developing adelgid-selective insecticides. Structural comparisons of proteins across seven focal species (Adelges tsugae, Adelges abietis, Adelges cooleyi, Rhopalosiphum maidis, Apis mellifera, Danaus plexippus, and Drosophila melanogaster) revealed high conservation of nAChR and ERAP1, while JHAMT exhibited species-specific structural divergence. The potential of JHAMT as a lineage-specific target for pest control was explored through virtual drug and pesticide screening.

adelgids↗