DNA Sequence Research Articles

Hetero-Oligomeric Protein Pores for Single-Molecule Sensing.

Protein nanopores are emerging as versatile single-molecule sensors with broad applications in DNA and protein sequencing. However, their narrow size restricts the range of detectable analytes, necessitating the development of advanced nanopores to broaden their applications in biotechnology. This review highlights a natural hetero-oligomeric porin, Nocardia farcinica porin AB (NfpAB), based on the Gram-positive mycolata, Nocardia farcinica. The pore comprises two subunits, NfpA and NfpB, that combine to form a stable structure with a unique pore geometry, asymmetrical shape, and charge distribution. Single-channel electrical recordings demonstrate that NfpAB forms stable, high-conductance channels suitable for sensing charged molecules, particularly cationic polypeptides and cyclic sugars. This pore offers advantages such as enhanced control over molecular interactions due to densely crowded charged residues, thus allowing the quantification of voltage-dependent translocation kinetics. Notably, NfpAB contains intrinsic cysteines in the pore lumen, providing an accessible site for thiol-based reactions and attachment of molecular adapters. We propose that such hetero-oligomeric pores will be effective for several applications in nanopore technology for biomolecular detection and sequencing.

Stratified Medicine Paediatrics: Cell free DNA and serial tumour sequencing identifies subtype specific cancer evolution and epigenetic states.

We profiled a large heterogenous cohort of matched diagnostic-relapse tumour tissue and paired plasma-derived cell free DNA (cfDNA) from patients with relapsed and progressive solid tumours of childhood. Tissue and cfDNA sequencing results were concordant, with a wider spectrum of mutant alleles and higher degree of intra-tumour heterogeneity captured by the latter, if sufficient circulating tumour-derived DNA (ctDNA) was present. Serial tumour sequencing identified putative drivers of relapse, with alterations in epigenetic drivers being a common feature. In keeping with epigenetic alterations being a common driver of many childhood cancers, fragmentomics analysis of cfDNA identified tumour-specific epigenetic states and transcription factor binding sites accessible in chromatin. This study leverages a large and well-annotated genomic dataset of aggressive childhood malignancies, identifies genomic and epigenetic drivers of childhood cancer relapse, and highlights the power and practicality of cfDNA analysis to capture both intra-tumoural heterogeneity and the epigenetic state of cancer cells.

Discarded sequencing reads uncover natural variation in pest resistance in Thlaspi arvense.

Understanding the genomic basis of natural variation in plant pest resistance is an important goal in plant science, but it usually requires large and labor-intensive phenotyping experiments. Here, we explored the possibility that non-target reads from plant DNA sequencing can serve as phenotyping proxies for addressing such questions. We used data from a whole-genome and -epigenome sequencing study of 207 natural lines of field pennycress (Thlaspi arvense) that were grown in a common environment and spontaneously colonized by aphids, mildew, and other microbes. We found that the numbers of non-target reads assigned to the pest species differed between populations, had significant SNP-based heritability, and were associated with climate of origin and baseline glucosinolate contents. Specifically, pennycress lines from cold and thermally fluctuating habitats, presumably less favorable to aphids, showed higher aphid DNA load, i.e., decreased aphid resistance. Genome-wide association analyses identified genetic variants at known defense genes but also novel genomic regions associated with variation in aphid and mildew DNA load. Moreover, we found several differentially methylated regions associated with pathogen loads, in particular differential methylation at transposons and hypomethylation in the promoter of a gene involved in stomatal closure, likely induced by pathogens. Our study provides first insights into the defense mechanisms of Thlaspi arvense, a rising crop and model species, and demonstrates that non-target whole-genome sequencing reads, usually discarded, can be leveraged to estimate intensities of plant biotic interactions. With rapidly increasing numbers of large sequencing datasets worldwide, this approach should have broad application in fundamental and applied research.

Structures, mechanisms, and kinetic advantages of the SgrAI filament forming mechanism.

This review documents investigations leading to the unprecedented discovery of filamentation as a mode of enzyme regulation in the type II restriction endonuclease SgrAI. Filamentation is defined here as linear or helical polymerization of a single enzyme as occurs for SgrAI, and has now been shown to occur in many other enzyme systems, including conserved metabolic enzymes. In the case of SgrAI, filamentation activates the DNA cleavage rate by up to 1000-fold and also alters the enzyme's DNA sequence specificity. The investigations began with the observation that SgrAI cleaves two types of recognition sequences, primary and secondary, but cleaves the secondary sequences only when present on the same DNA as at least one primary. DNA cleavage rate measurements showed how the primary sequence is both a substrate and an allosteric effector of SgrAI. Biophysical measurements indicated that the activated form of SgrAI, stimulated by binding to the primary sequence, consisted of varied numbers of the SgrAI bound to DNA. Structural studies revealed the activated state of SgrAI as a left-handed helical filament which stabilizes an altered enzyme conformation, which binds a second divalent cation in the active site. Efforts to determine the mechanism of DNA sequence specificity alteration are ongoing and current models are discussed. Finally, global kinetic modeling of the filament mediated DNA cleavage reaction and simulations of in vivo activity suggest that the filament mechanism evolved to rapidly cleave invading DNA while protecting the Streptomyces host genome.

CGRclust: Chaos Game Representation for twin contrastive clustering of unlabelled DNA sequences

BackgroundTraditional supervised learning methods applied to DNA sequence taxonomic classification rely on the labor-intensive and time-consuming step of labelling the primary DNA sequences. Additionally, standard DNA classification/clustering methods involve time-intensive multiple sequence alignments, which impacts their applicability to large genomic datasets or distantly related organisms. These limitations indicate a need for robust, efficient, and scalable unsupervised DNA sequence clustering methods that do not depend on sequence labels or alignment.ResultsThis study proposes CGRclust, a novel combination of unsupervised twin contrastive clustering of Chaos Game Representations (CGR) of DNA sequences, with convolutional neural networks (CNNs). To the best of our knowledge, CGRclust is the first method to use unsupervised learning for image classification (herein applied to two-dimensional CGR images) for clustering datasets of DNA sequences. CGRclust overcomes the limitations of traditional sequence classification methods by leveraging unsupervised twin contrastive learning to detect distinctive sequence patterns, without requiring DNA sequence alignment or biological/taxonomic labels. CGRclust accurately clustered twenty-five diverse datasets, with sequence lengths ranging from 664 bp to 100 kbp, including mitochondrial genomes of fish, fungi, and protists, as well as viral whole genome assemblies and synthetic DNA sequences. Compared with three recent clustering methods for DNA sequences (DeLUCS, iDeLUCS, and MeShClust v3.0.), CGRclust is the only method that surpasses 81.70% accuracy across all four taxonomic levels tested for mitochondrial DNA genomes of fish. Moreover, CGRclust also consistently demonstrates superior performance across all the viral genomic datasets. The high clustering accuracy of CGRclust on these twenty-five datasets, which vary significantly in terms of sequence length, number of genomes, number of clusters, and level of taxonomy, demonstrates its robustness, scalability, and versatility.ConclusionCGRclust is a novel, scalable, alignment-free DNA sequence clustering method that uses CGR images of DNA sequences and CNNs for twin contrastive clustering of unlabelled primary DNA sequences, achieving superior or comparable accuracy and performance over current approaches. CGRclust demonstrated enhanced reliability, by consistently achieving over 80% accuracy in more than 90% of the datasets analyzed. In particular, CGRclust performed especially well in clustering viral DNA datasets, where it consistently outperformed all competing methods.

EMSA-SELEX-seq method for analysis of binding site sequences in DNA-protein complexes

The BOB1 protein (OBF1, OCA-B) is a transcriptional coactivator of two POU domain proteins — OCT1, expressed in all cells, and lymphoid-specific OCT2. The interaction of BOB1 with OCT1/2 plays an important role in the regulation of immune responses in both physiological and pathological contexts. BOB1 is known to form a ternary complex with OCT1/2 bound to DNA in monomeric and certain dimeric configurations, changing the sequence specificity of the binding. To analyze DNA sequences from these complexes, in this work we proposed the EMSA-SELEX-seq method, based on the separation of OCT/BOB1 complexes of various compositions in a non-denaturing polyacrylamide gel (EMSA) followed by the isolation and amplification of the oligonucleotides that they contain (SELEX). Based on several rounds of the enrichment followed by the NGS sequencing and bioinformatics analysis, the DNA sequences were determined and the relevance of this approach was confirmed. Thus, the proposed EMSA-SELEX-seq method allows the analysis of DNA sequences in DNA-protein complexes with varying dimensions of its protein components.

Dryopteris × subdiffracta (Dryopteridaceae), a new natural hybrid fern from Guangxi, China

A new natural hybrid fern, Dryopteris × subdiffracta (Dryopteridaceae), is reported from Guangxi, China. Molecular phylogenetic analysis based on DNA sequences from the low-copy nuclear marker Ak1 and plastid genome revealed respectively that D. polita and D. diffracta are parents of the new hybrid, with D. polita as the maternal parent. Cytometric analysis of the nuclear DNA content indicated that D. × subdiffracta might be a diploid hybrid. Morphologically, D. × subdiffracta shares a high degree of similarity with D. × subreflexipinna from Taiwan, especially in zigzag-shaped rachis and deflexed pinna stalks. However, D. × subdiffracta is distinguishable in the degree of lamina division and shapes of lamina and pinnulets. A comprehensive taxonomic description accompanied by line drawings are provided.

Exploring the influence of age and diet on gut microbiota development in children during the first 5 years: a study from Yaoundé, Cameroon

IntroductionThe development of the human gut microbiota is shaped by factors like delivery mode, infant feeding practices, maternal diet, and environmental conditions. Diet plays a pivotal role in determining the diversity and composition of the gut microbiome, which in turn impacts immune development and overall health during this critical period. The early years, which are vital for microbial shaping, highlight a gap in understanding how the shift from milk-based diets to solid foods influences gut microbiota development in infants and young children, particularly in Yaoundé, Cameroon.MethodsThis study involved an analysis of the gut microbiota composition in 70 children aged ≤5 years through 16S rDNA gene metagenomic sequencing of fecal metagenomic DNA. The participants were grouped into four age categories: 0–6 months, 7–12 months, 13–24 months, and 25–60 months.ResultsWe observed a reduction in microbial diversity in the younger age groups, which increased progressively with age. At the taxonomic level, our analysis identified Firmicutes as the predominant phylum, with its abundance rising in older age groups, suggesting a maturation of the microbiota characterized by distinct genera associations. In the 0–6 month age group, we noted an enrichment of Lactobacilli and Bifidobacteria, which may play a crucial role in modulating and supporting immune system development during infancy. After 6 months, we found a higher prevalence of Clostridium, Bacillus, Roseburia, and Faecalibacterium, which are associated with fiber fermentation and the production of short-chain fatty acids (SCFAs).ConclusionThese findings underscore the influence of milk products and complementary diets on gut microbiota across various age groups, promoting increased diversity essential for healthy gut development. More such studies in the LMICs would augment and strengthen understanding towards functional microbiome.

Application of Environmental DNA Metabarcoding to Differentiate Algal Communities by Littoral Zonation and Detect Unreported Algal Species

Coastal areas are the most biologically productive and undoubtedly among the most complex ecosystems. Algae are responsible for most of the gross primary production in these coastal regions. However, despite the critical importance of algae for the global ecosystem, the biodiversity of many algal groups is understudied, partially due to the high complexity of morphologically identifying algal species. The current study aimed to take advantage of the recently developed technology for biotic community assessment through the high-throughput sequencing (HTS) of environmental DNA (eDNA), known as the “eDNA metabarcoding”, to characterize littoral algal communities in the Northern Gulf of Mexico (NGoM). This study demonstrated that eDNA metabarcoding, based on the universal plastid amplicon (UPA) and part of the large nuclear ribosomal subunit (LSU) molecular markers, could successfully differentiate coastal biotic communities among littoral zones and geographical locations along the shoreline of the NGoM. The statistical significance of separation between biotic communities was partially dependent on the dissimilarity calculation metric; thus, the differentiation of algal community structure according to littoral zones was more distinct when phylogenetic distances were incorporated into the diversity analysis. Current work demonstrated that the relative abundance of algal species obtained with eDNA metabarcoding matches previously established zonation patterns for these species. In addition, the present study detected molecular signals of 44 algal species without previous reports for the Gulf of Mexico, thus providing an important, molecular-validated baseline of species richness for this region.

Optimising Exome Captures in Species With Large Genomes Using Species-Specific Repetitive DNA Blocker.

Large and highly repetitive genomes are common. However, research interests usually lie within the non-repetitive parts of the genome, as they are more likely functional, and can be used to answer questions related to adaptation, selection and evolutionary history. Exome capture is a cost-effective method for providing sequencing data from protein-coding parts of the genes. C0t-1 DNA blockers consist of repetitive DNA and are used in exome captures to prevent the hybridisation of repetitive DNA sequences to capture baits or bait-bound genomic DNA. Universal blockers target repetitive regions shared by many species, while species-specific c0t-1 DNA is prepared from the DNA of the studied species, thus perfectly matching the repetitive DNA contents of the species. So far, the use of species-specific c0t-1 DNA has been limited to a few model species. Here, we evaluated the performance of blocker treatments in exome captures of Pinus sylvestris, a widely distributed conifer species with a large (> 20 Gbp) and highly repetitive genome. We compared treatment with a commercial universal blocker to treatments with species-specific c0t-1 (30,000 and 60,000 ng). Species-specific c0t-1 captured more unique exons than the initial set of targets leading to increased SNP discovery and reduced sequencing of tandem repeats compared to the universal blocker. Based on our results, we recommend optimising exome captures using at least 60,000 ng of species-specific c0t-1 DNA. It is relatively easy and fast to prepare and can also be used with existing bait set designs.

Effects of Trophic State on the Composition and Distribution of Bacteria in the Surface Sediments of Lake Taihu

ABSTRACT1. The trophic state of water significantly affects the structure of bacterial communities in sediments. The direct and indirect impacts of trophic state, along with trophic‐induced changes in the properties of organic matter, on the composition and distribution of bacteria in sediments, remain largely unknown.2. We collected surface sediments from 21 sites across five areas of Lake Taihu, the third largest freshwater lake in China. These sites represented a range of trophic states from mesotrophic to moderately eutrophic. We investigated how trophic state influences bacterial composition and distribution in the surface sediments of Lake Taihu.3. Proteobacteria, Firmicutes and Bacteroidetes were the most abundant phyla identified in the DNA sequences of surface sediments from the sampling sites in Lake Taihu, regardless of the water trophic state. The relative abundance of Proteobacteria and Firmicutes in the surface sediments increased with trophic level index (TLI) of the water column. In contrast, the relative abundance of Bacteroidetes, Acidobacteria and Fibrinobacteria decreased with increasing TLI. The α‐biodiversity of the sediment bacterial community in Lake Taihu did not vary significantly among different water trophic states. However, surface sediments from sites with varied trophic states exhibited different groups of bacteria that were either specifically present or in higher relative abundance.4. Several factors influenced the sediment bacterial communities in Lake Taihu, including sediment total nitrogen, sediment total phosphorus, sediment organic carbon, δ13C and trophic state. However, the primary influencing factors varied between sites and trophic states. For mesotrophic states, sediment organic carbon was the most important factor, while for moderately eutrophic states, trophic state was the most significant factor.5. Our findings provide evidence for both the direct and indirect influences of water trophic state on the composition and distribution of bacteria in sediments.

Is Silver a Precious Metal for G-Quadruplex Stabilization Mediated by Porphyrins?

Cancer is a leading cause of death, so continuous efforts into cancer therapy are imperative. In tumor cells, telomerase and oncogene activity are key points for uncontrolled cell growth. Targeting these processes with ligands that inhibit telomerase and/or reduce oncogene expression has been identified as a promising cancer therapy. This study evaluated the selectivity and affinity of the silverII complex of 5,10,15,20-tetrakis(N-methyl-4-pyridinium)porphyrin (AgTMPyP) to stabilize DNA sequences capable of forming G4 structures mimicking the telomeric and oncogene regions, using spectroscopic, biochemical methods and in vitro assays. The tetracationic silver complex was compared with the free base, H2TMPyP, and the zincII complex, ZnTMPyP. The results obtained from UV-Vis and fluorescence methods pointed to a great affinity and good selectivity of AgTMPyP to G4 structures, especially for the oncogene MYC. In general, an increase in the ability of the studied ligands for 1O2 generation when interacting with oncogenic and telomeric G4 sequences was found. The results of the PCR stop assays proved that AgTMPyP has the ability to inhibit Taq polymerase. Additionally, in vitro assays demonstrated that the silverII complex exhibits low cytotoxicity against HaCaT— an immortalized, non-tumorigenic, skin keratinocytes cell line—and, although nonexclusive, AgTMPyP shows nuclear co-localization.

The landscape in telomere related gene prognostic signature for survival and medication treatment effectiveness prediction in hepatocellular carcinoma

ObjectiveTelomeres, made of repetitive DNA sequences and shelterin complexes, which were found at the ends of chromosomes and had been extensively studied in cancer research. However, in hepatocellular carcinoma (HCC) was still relatively scarce. In this study, we investigated the correlation between telomerase-related genes (TRGs) and the prognosis and immunotherapy of HCC patients to enhance clinical outcomes.MethodsIn this work, TRGs were gathered using TelNet, while clinical information and gene expression data for HCC patients were retrieved from the Cancer Genome Atlas (TCGA) database. A risk prediction model based on TRGs was created using COX and Lasso regression analyses, with ROC curves used to assess prognostic efficacy. Univariate and multifactorial COX regression analyses were used to determine if the risk model had an independent impact on prognosis. Nomograms were created to enhance clinical usability, and calibration curves were used to assess predictive ability at various time points. The Tumor Immune Dysfunction and Exclusion (TIDE) score was used to analyze differences in immune infiltrating cells between risk groups. The study analyzed the relationship between risk ratings and drug treatment effectiveness using data from the CellMiner database. The hub gene was identified and its relationship to prognostic markers of HCC patients was examined. The expression of hub genes in immune cell subpopulations was also investigated by single-cell data.Results2093 TRGs were identified, with 949 showing significant differences in expression between HCC and paracancerous tissues. Seven risk genes were overexpressed in tumor tissues, leading to lower survival rates in high-risk patients. Risk model could independently predict the prognosis of HCC patients. Analysis of tumor immune infiltrating cells revealed significant differences in cell abundance between risk groups, with notable variations in immune subset enrichment between subgroups. Higher risk scores correlated with increased sensitivity to sorafenib, mitoxantrone, oxaliplatin, gemcitabine, and entinostat, while sensitivity decreased for vincristine, etc. CDCA8 was identified as a key gene in the Protein Interaction Network, while high expression associated with poorer overall survival, tumor proliferation and metastasis. The results of single-cell data analysis suggest that CDCA8 may promote the development of HCC by affecting T lymphocytes.ConclusionThe TRG-based risk model could predict HCC patient prognosis and closely linked to tumor immune environment, which could offer new possibilities for clinical treatment.

Berkeleyomyces rouxiae—A Pathogen Causing the Black Root Rot of Tobacco

Black root rot is a dangerous disease affecting many crops. It is caused by pathogens formerly known as Thielaviopsis basicola and then reclassified as two cryptic species, Berkeleyomyces basicola and B. rouxiae. The aim of this study was to perform species identification, morphological characterization, and pathogenicity tests for fungal isolates obtained from tobacco roots with black root rot symptoms in Poland. DNA sequences of the three regions (ITS, ACT, MCM7) were highly similar to the sequences of B. rouxiae deposited in the NCBI database. Phylogenetic analysis confirmed the assignment of the obtained isolates to this species. The cultures of four representative isolates (namely OT2, OT3, WPT7, WPT8) showed a similar structure and gray/brown color of the mycelium, although their growth rate varied from 3.8 to 5.1 mm/day depending on the isolate. The sizes of the endoconidia and chlamydospores showed a considerable variation, although they fit within ranges previously described for B. rouxiae. Pathogenicity tests performed on young tobacco plants grown in the inoculated peat substrate revealed differences among the four isolates. WPT7 demonstrated the lowest level of aggressiveness for tobacco. In contrast, the remaining three isolates caused severe disease symptoms and significantly reduced shoot and root dry weights of the susceptible cultivar Virginia Joyner. A parallel pathogenicity test performed on cultivar VRG 10TL confirmed the effectiveness of black root rot resistance derived from Nicotiana debneyi.

Advanced Ligase Chain Reaction Strategy to Generate a Circular DNA Walker for Electrochemiluminescent Detection of Single Nucleotide Polymorphism.

Single nucleotide polymorphism (SNP) primarily refers to DNA sequence polymorphism caused by variations in a single nucleotide, which is closely associated with many diseases such as genetic disorders and tumors. However, trace DNA mutants typically exist in a large pool of wild-type DNA, making it challenging to establish accurate and sensitive approaches for SNP detection. Herein, we developed an advanced ligase chain reaction (LCR) strategy to output the circular DNA walker for signal amplification, which realized accuracy and sensitive SNP detection based on the electrochemiluminescent (ECL) platform. Unlike the general LCR system that utilizes two sets of short single-stranded DNA (ssDNA) primers to generate double-stranded DNA amplification products, we ingeniously designed a long single-stranded DNA primer to replace one set of short ssDNA primers, allowing for the generation of circular DNA products upon complementing the target. Noticeably, the circular DNA serves as a DNA walker that can be easily purified by nucleases to eliminate unreacted primers and byproducts, significantly improving accuracy and sensitivity. Then, the circular DNA walker moved along a linearly ordered DNA quenching probe track modified on the ECL sensing interface, restoring the ECL signals by cleaving the quenching probes labeled on the DNA track with the help of apurinic/apyrimidinic endonuclease 1. Employing the p53 gene as a model, we realized the sensitive detection of mutant p53 in the range from 10 aM to 10 pM, with a detection limit of 6 aM, providing a promising platform for SNP detection.

QTL mapping provides new insights into emamectin benzoate resistance in salmon lice, Lepeophtheirus salmonis

BackgroundThe salmon louse (Lepeophtheirus salmonis) is a parasite of wild and farmed salmonid fish, causing huge economic damage to the commercial farming of Atlantic salmon (Salmo salar) in the northern hemisphere. The avermectin emamectin benzoate (EMB) is widely used for salmon delousing. While resistance to EMB is widespread in Atlantic populations of L. salmonis, the molecular mechanisms of resistance remain to be elucidated. The aim of the present work was to obtain insights into potential EMB resistance mechanisms by identifying genetic and transcriptomic markers associated with EMB resistance.ResultsCrosses were performed between EMB-susceptible and -resistant L. salmonis, sourced from two parental strains isolated in Scotland, producing fully pedigreed families. The EMB susceptibility of individual parasites was characterised using time-to-response bioassays. Parasites of two families were subjected to double digest restriction site-associated DNA sequencing (ddRAD-seq) for simultaneous discovery of single nucleotide polymorphisms (SNPs) and genotyping. Data analysis revealed that EMB resistance is associated with one quantitative trait locus (QTL) region on L. salmonis chromosome 5. Marker-trait association was confirmed by genotyping assays for 7 SNPs in two additional families. Furthermore, the transcriptome of male parasites of the EMB-susceptible and -resistant L. salmonis parental strains was assessed. Among eighteen sequences showing higher transcript expression in EMB-resistant as compared to drug-susceptible lice, the most strongly up-regulated gene is located in the above QTL region and shows high homology to β spectrin, a cytoskeleton protein that has roles in neuron architecture and function. Further genes differentially regulated in EMB-resistant lice include a glutathione S-transferase (GST), and genes coding for proteins with predicted roles in mitochondrial function, intracellular signalling or transcription.ConclusionsMajor determinants of EMB resistance in L. salmonis are located on Chromosome 5. Resistance can be predicted using a limited number of genetic markers. Genes transcriptionally up-regulated in EMB resistant parasites include a β spectrin, a cytoskeletal protein with still incompletely understood roles in neuron structure and function, as well as glutathione S-transferase, an enzyme with potential roles in the biochemical defence against toxicants.

Detection and classification of long terminal repeat sequences in plant LTR-retrotransposons and their analysis using explainable machine learning

BackgroundLong terminal repeats (LTRs) represent important parts of LTR retrotransposons and retroviruses found in high copy numbers in a majority of eukaryotic genomes. LTRs contain regulatory sequences essential for the life cycle of the retrotransposon. Previous experimental and sequence studies have provided only limited information about LTR structure and composition, mostly from model systems. To enhance our understanding of these key sequence modules, we focused on the contrasts between LTRs of various retrotransposon families and other genomic regions. Furthermore, this approach can be utilized for the classification and prediction of LTRs.ResultsWe used machine learning methods suitable for DNA sequence classification and applied them to a large dataset of plant LTR retrotransposon sequences. We trained three machine learning models using (i) traditional model ensembles (Gradient Boosting), (ii) hybrid convolutional/long and short memory network models, and (iii) a DNA pre-trained transformer-based model using k-mer sequence representation. All three approaches were successful in classifying and isolating LTRs in this data, as well as providing valuable insights into LTR sequence composition. The best classification (expressed as F1 score) achieved for LTR detection was 0.85 using the hybrid network model. The most accurate classification task was superfamily classification (F1=0.89) while the least accurate was family classification (F1=0.74). The trained models were subjected to explainability analysis. Positional analysis identified a mixture of interesting features, many of which had a preferred absolute position within the LTR and/or were biologically relevant, such as a centrally positioned TATA-box regulatory sequence, and TG..CA nucleotide patterns around both LTR edges.ConclusionsOur results show that the models used here recognized biologically relevant motifs, such as core promoter elements in the LTR detection task, and a development and stress-related subclass of transcription factor binding sites in the family classification task. Explainability analysis also highlighted the importance of 5’- and 3’- edges in LTR identity and revealed need to analyze more than just dinucleotides at these ends. Our work shows the applicability of machine learning models to regulatory sequence analysis and classification, and demonstrates the important role of the identified motifs in LTR detection.

Mitochondria-targeted oligomeric α-synuclein induces TOM40 degradation and mitochondrial dysfunction in Parkinson’s disease and parkinsonism-dementia of Guam

Mitochondrial dysfunction is a central aspect of Parkinson’s disease (PD) pathology, yet the underlying mechanisms are not fully understood. This study investigates the link between α-Synuclein (α-Syn) pathology and the loss of translocase of the outer mitochondrial membrane 40 (TOM40), unraveling its implications for mitochondrial dysfunctions in neurons. We discovered that TOM40 protein depletion occurs in the brains of patients with Guam Parkinsonism-Dementia (Guam PD) and cultured neurons expressing α-Syn proteinopathy, notably, without corresponding changes in TOM40 mRNA levels. Cultured neurons expressing α-Syn mutants, with or without a mitochondria-targeting signal (MTS) underscores the role of α-Syn’s mitochondrial localization in inducing TOM40 degradation. PDe-related etiological factors, such as 6-hydroxydopamine or ROS/metal ions stress, which promotes α-Syn oligomerization, exacerbate TOM40 depletion in PD patient-derived cells with SNCA gene triplication. Although α-Syn interacts with both TOM40 and TOM20 in the outer mitochondrial membrane, degradation is selective for TOM40, which occurs via the ubiquitin-proteasome system (UPS) pathway. Our comprehensive analyses using Seahorse technology, mitochondrial DNA sequencing, and damage assessments, demonstrate that mutant α-Syn-induced TOM40 loss results in mitochondrial dysfunction, characterized by reduced membrane potential, accumulation of mtDNA damage, deletion/insertion mutations, and altered oxygen consumption rates. Notably, ectopic supplementation of TOM40 or reducing pathological forms of α-Syn using ADP-ribosylation inhibitors ameliorate these mitochondrial defects, suggesting potential therapeutic avenues. In conclusion, our findings provide crucial mechanistic insights into how α-Syn accumulation leads to TOM40 degradation and mitochondrial dysfunction, offering insights for targeted interventions to alleviate mitochondrial defects in PD.

Genetic Characterization of Plasmodium falciparum Histidine-Rich Protein 2 Deletions and Their Impact on Malaria Interventions in Odisha, India.

Diagnostic escape via Plasmodium falciparum (P. falciparum) histidine-rich protein 2 (pfhrp2) gene deletions is a major potential hurdle for global malaria elimination efforts. We investigated the prevalence of pfhrp2 gene deletions in 15 malaria-endemic villages in the state of Odisha, India, and modeled their impact on an ongoing in-country malaria intervention program. We found that 61.6% of subpatent P. falciparum infections (i.e., rapid diagnostic test [RDT]-negative and positive by polymerase chain reaction [PCR]) had pfhrp2 gene deletions, which were predominantly located in the exon 2 region (96.2%) and largely identified in samples from febrile individuals (82.6%). DNA sequencing and protein diversity features were characterized in a subset of samples from individuals with subpatent infections carrying intact pfhrp2 exon 2 loci. Our analyses revealed novel amino acid repeat motifs (231-293 amino acids), and these variant repeat sequences differed from those of RDT+/PCR+ samples. We also evaluated the state-sponsored mass screening and treatment intervention in the context of pfhrp2 gene deletions. We found that mass screening and treatment conducted alongside additional interventions (e.g., long-lasting insecticidal net distribution, indoor residual spraying) reduced the relative risk of infection for both P. falciparum parasites harboring a pfhrp2 deletion (adjusted relative risk ratio [aRRR] = 0.3; 95% CI = 0.1-1.0) and P. falciparum parasites with intact pfhrp2 genes (aRRR = 0.4; 95% CI = 0.2-1.1) when compared with the use of mass screening and treatment by RDT alone. Combined, our findings highlight the need for alternative diagnostic targets and tools as India moves toward its goal of malaria elimination by 2030.

Botryobasidium bambusinum (Botryobasidiaceae, Cantharellales): a new species from Yunnan, Southwest China, based on morphology and phylogeny

ABSTRACT Botryobasidium bambusinum sp. nov. was collected in Yunnan Province, China, is described here as a new species based on its morphology and phylogeny. In this study, the taxon Botryobasidium bambusinum is characterised by its resupinate, coriaceous conidiomata with a smooth, hypochnoid, rubiginous to slightly reddish-brown hymenial surface, a slightly thick-walled basal hyphae with simple septa, subcylindrical, septate subglobose to globose, slightly thick-walled conidia measuring as 7.2–9.5 × 7–9 µm. Phylogenetic analyses of the new species were based on the internal transcribed spacer (ITS) and large subunit (nrLSU) of ribosomal DNA (rDNA) sequences. The phylogenetic tree indicated that the new species belonged to the genus Botryobasidium, and was closely related to B. gossypirubiginosum, B. rubiginosum and B. simile. Botryobasidium gossypirubiginosum differs from B. bambusinum by having a floccose to cotton conidiomata. Botryobasidium rubiginosum differentiates from B. bambusinum by having a cottony conidiomata, and ovoid to ellipsoid, larger conidia (14.5–16 × 10.5–12.5 µm vs 7.2–9.5 × 7–9 µm). Botryobasidium simile can be distinguished from B. bambusinum by having an ochraceous to fulvous conidiomata, and larger conidia (21.5–27 × 16–18 µm vs 7.2–9.5 × 7–9 µm). A detailed description, illustrations and phylogenetic analysis of the new species are provided.