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Results for “amplicon sequencing”

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PubMed2026

VisPan: real-time visualisation of multiplex amplicon-based sequencing panels for rapid syndromic surveillance and pathogen detection.

MOTIVATION: Infectious diseases persist as a major global public health challenge. Diverse factors, including climate change, globalization, deforestation, human-animal interactions, lifestyle choices, and various biological factors, can contribute to their emergence and reemergence. Rapid detection and characterization of (re)emerging pathogens are therefore critical for effective outbreak management and for enhancing our understanding of epidemics by monitoring the transmission, spread, evolution, and genomics of pathogens. In this context, next-generation sequencing technologies (NGS), particularly long-read platforms such as Oxford Nanopore Technologies (ONT), have opened new avenues for real-time pathogen monitoring. However, the bioinformatics bottleneck remains a challenge, emphasizing the need for efficient, accessible, and user-friendly analysis tools. RESULTS: Here, we present a tool adapted from the RAMPART software that enables real-time data visualisation of multiplex PCR syndromic panels combined with Oxford Nanopore sequencing. This real-time analysis enables rapid pathogen detection, from raw data acquisition to taxonomic assignment, within minutes. The interface offers dynamic visual tracking of the sequencing run and amplicon coverage, facilitating immediate insights during diagnostic workflows. Validation experiments confirmed the system's reliability, accurately identifying all pathogens present in complex clinical or environmental samples. This tool provides an integrated, user-friendly solution for genomic pathogen surveillance in field or clinical settings.

Software↗

PubMed2007

A sequence based synteny map between soybean and Arabidopsis thaliana.

BACKGROUND: Soybean (Glycine max, L. Merr.) is one of the world's most important crops, however, its complete genomic sequence has yet to be determined. Nonetheless, a large body of sequence information exists, particularly in the form of expressed sequence tags (ESTs). Herein, we report the use of the model organism Arabidopsis thaliana (thale cress) for which the entire genomic sequence is available as a framework to align thousands of short soybean sequences. RESULTS: A series of JAVA-based programs were created that processed and compared 341,619 soybean DNA sequences against A. thaliana chromosomal DNA. A. thaliana DNA was probed for short, exact matches (15 bp) to each soybean sequence, and then checked for the number of additional 7 bp matches in the adjacent 400 bp region. The position of these matches was used to order soybean sequences in relation to the A. thaliana genome. CONCLUSION: Reported associations between soybean sequences and A. thaliana were within a 95% confidence interval of e(-30)-e(-100). In addition, the clustering of soybean expressed sequence tags (ESTs) based on A. thaliana sequence was accurate enough to identify potential single nucleotide polymorphisms (SNPs) within the soybean sequence clusters. An EST, bacterial artificial chromosome (BAC) end sequence and marker amplicon sequence synteny map of soybean and A. thaliana is presented. In addition, all JAVA programs used to create this map are available upon request and on the WEB.

Arabidopsis↗

PubMed2005

Identification of new papillomavirus types.

The identification of papillomavirus DNA sequences in tissue samples using polymerase chain reaction (PCR) amplification, has led to the association of these infections to a multiplicity of clinical manifestations. The cloning and sequencing of PCR-amplified products has, to date, resulted in the identification of more than 300 putative "new" papillomavirus types. The methods used to identify these unknown papillomavirus sequences are described here. The CP, FAP, and GP primers are used for PCR amplification, followed by cloning and sequencing of the amplicons. Sequence comparisons and the interpretation of DNA sequence identities are discussed. Details of defining a new papillomavirus type and of the recently approved taxonomic classification system for the Papillomaviridae are given.

Base Sequence↗

PubMed2000

Comparison of classic and molecular approaches for the identification of untypeable enteroviruses.

Members of the family Picornaviridae are the most common viruses infecting humans, and species in several genera also infect a wide variety of other mammals. Picornaviruses have traditionally been classified by antigenic type, based on a serum neutralization assay. However, this method is time-consuming and labor-intensive, is sensitive to virus aggregation and antigenic variation, and requires a large number of antisera to identify all serotypes, even when antiserum pools are used. We developed generic reverse transcription (RT)-PCR primers that will amplify all human enterovirus serotypes, as well as many rhinoviruses and other picornaviruses, and used RT-PCR amplification of the VP1 gene and amplicon sequencing to identify enteroviruses that were refractory to typing by neutralization with pooled antisera. Enterovirus serotypes determined by sequencing were confirmed by neutralization with monospecific antisera. Of 55 isolates tested, 49 were of known enterovirus serotypes, two were rhinoviruses, and four were clearly picornaviruses but did not match any known picornavirus sequence. All four untyped picornaviruses were closely related to one another in sequence, suggesting that they are of the same serotype. RT-PCR, coupled with amplicon sequencing, is a simple and rapid method for the typing and classification of picornaviruses and may lead to the identification of many new picornavirus serotypes.

Animals↗

PubMed2026

Mulberry-derived endophytic Bacillus velezensis suppresses gray mold and promotes mulberry growth via reshaping the root metabolism and microbiome.

INTRODUCTION: Gray mold is an important fungal disease caused by Botrytis cinerea which threatens global agriculture. As chemical control faces limitations, biological control using Bacillus has gained attention for its environmental friendliness and growth promotion. However, their ecological basis and application potential in mulberry gray mold control remain insufficiently understood. OBJECTIVE: This study aimed to evaluate the biocontrol efficacy of the mulberry derived endophytic strain Bacillus velezensis ZJU_268 and to investigate its associated effects on plant growth, root-associated microbiomes, and metabolic profiles. METHODS: Greenhouse assays were combined with genomic and comparative genomic analyses, amplicon sequencing, non-targeted metabolomics, and functional validation of isolated microbes and metabolites to assess the effects of ZJU_268 and its cell free supernatant (CFS) on mulberry seedlings. RESULTS: This study isolated a mulberry derived endophytic bacterium, B. velezensis ZJU_268, which exhibits strong antifungal activity and reduces the incidence of gray mold in mulberry seedlings. Whole-genome sequencing and comparative genomic analyses revealed strain-specific regions and genes associated with root colonization, stress adaptation, and antimicrobial biosynthesis. Both live cells and CFS significantly promoted seed germination, seedling growth, and biomass accumulation in a dose dependent manner. Amplicon sequencing showed that ZJU_268 and its supernatant reshaped the mulberry root microbiome, enriching beneficial bacterial and fungal taxa while reducing potentially pathogenic members. Cultivable members of the enriched microbiota displayed strong antifungal activity against B. cinerea and promoted mulberry growth. Metabolomic profiling further showed that ZJU_268 and its supernatant were associated with marked metabolic shifts in mulberry roots, accompanied by the accumulation of selected metabolites that supported the growth of representative enriched isolates. CONCLUSIONS: This study demonstrates that ZJU_268 suppresses gray mold and promotes mulberry growth in association with direct antagonistic activity, microbiome restructuring, and holobiont-level metabolic shifts, providing a promising biological strategy for sustainable mulberry disease management.

Bacillusvelezensis↗

PubMed1987

DNA sequence responsible for the amplification of adjacent genes.

A 10.3-kb DNA fragment in the 5'-flanking region of the rat prolactin (rPRL) gene was isolated from F1BGH(1)2C1, a strain of rat pituitary tumor cells (GH cells) that produces prolactin in response to 5-bromodeoxyuridine (BrdU). Following transfection and integration into genomic DNA of recipient mouse L cells, this DNA induced amplification of the adjacent thymidine kinase gene from Herpes simplex virus type 1 (HSV1TK). We confirmed the ability of this "Amplicon" sequence to induce amplification of other linked or unlinked genes in DNA-mediated gene transfer studies. When transferred into the mouse L cells with the 10.3-5'rPRL gene sequence of BrdU-responsive cells, both the human growth hormone and the HSV1TK genes are amplified in response to 5-bromodeoxyuridine. This observation is substantiated by BrdU-induced amplification of the cotransferred bacterial Neo gene. Cotransfection studies reveal that the BrdU-induced amplification capability is associated with a 4-kb DNA sequence in the 5'-flanking region of the rPRL gene of BrdU-responsive cells. These results demonstrate that genes of heterologous origin, linked or unlinked, and selected or unselected, can be coamplified when located within the amplification boundary of the Amplicon sequence.

Animals↗

PubMed2026

An Amplicon Panel for High-Throughput and Low-Cost Genotyping of Yesso Scallop Mizuhopecten yessoensis.

The Yesso scallop Mizuhopecten yessoensis was imported from Japan to western Canada in the late 1980s to establish an economically viable scallop aquaculture industry. Since this time, the industry in Canada has operated with existing genetic diversity within the broodstock, which is considerably limited relative to wild populations. The sector has not been able to realise its full potential in part due to idiopathic hatchery failures and farm stock collapses due to disease outbreaks associated with the intracellular bacterial pathogen Francisella halioticida. To support Yesso scallop production and breeding, here we generate a low-density, genotyping-by-sequencing amplicon panel using single nucleotide polymorphism (SNP) markers that are evenly spaced across the M. yessoensis genome and that show high heterozygosity in Canada and Japan. The panel can also exploit the high genetic polymorphism of the M. yessoensis genome, with de novo SNP calling identifying over 2,500 high quality SNPs within the 579 sequenced amplicons. We demonstrate the utility and versatility of this new genotyping tool for breeding applications including parentage assignment, low density family-based genome-wide association study, trait heritability evaluation to determine potential for genomic selection, and species differentiation (against the weathervane scallop Patinopecten caurinus). We did not find any genomic regions significantly associated with F. halioticida resistance but did identify potential for genomic selection. We could separate the two species based on genotypes, and did not see evidence of a past M. yessoensis x P. caurinus hybridization event within the M. yessoensis breeding population at Vancouver Island University. This low-cost genotyping panel is expected to accelerate selective breeding improvements for M. yessoensis in Canada and elsewhere.

Animals↗

PubMed2026

Diversity analysis of indoor and outdoor fungal bioaerosols in UK households: a prospective, observational, longitudinal study.

BACKGROUND: Long-term exposure to indoor fungal bioaerosols is a recognised risk factor for respiratory illness, particularly in damp and poorly ventilated housing. However, the diversity and seasonal variability of these fungal communities are poorly understood. As part of the West London Healthy Home and Environment Study (WellHome), this study aimed to characterise the composition, diversity, and temporal dynamics of indoor fungal bioaerosols in urban UK homes, as compared with outdoor air, to inform future exposure baselines and policy development. METHODS: In this prospective, community-based observational study, 118 households were recruited across West London, UK, via community networks and partner organisations, prioritising families with children aged 5-17 years with asthma or allergies, from diverse socioeconomic backgrounds. Sampling occurred between Oct 3, 2022, and June 14, 2024. Participant data were collected via questionnaires completed by household members, capturing demographics, building characteristics, and respiratory health. Passive-air samplers were used in living rooms for 28 days during two seasonal campaigns, with concurrent outdoor sampling at four fixed community sites. Fungal bioaerosols were identified by ITS2 amplicon sequencing and quantified using broad-range quantitative PCR targeting the 18S rRNA gene. Diversity indexes and temporal dynamics were analysed using ecological statistics and generalised additive models. FINDINGS: 118 households were enrolled, comprising 504 residents (263 women, 237 men, and four not reported). Among 504 participants who self-identified, the largest groups comprised individuals identifying as Black African (n=47), Somali (n=46), White British (n=42), and African (n=38), with additional representation from mixed race ethnic backgrounds (n=29), Black British (n=27), White (n=22), and Black Caribbean (n=18), alongside several other ethnicities each represented at lower frequencies. Of 118 households, 104 completed both seasonal campaigns and 14 completed one, yielding 262 air samples (222 indoor and 40 outdoor). DNA was successfully recovered from all samples, identifying 2027 fungal genera. Indoor environments showed significantly higher richness (mean 646 vs 495 amplicon sequence variants; p<0·0001) and Shannon diversity (4·21 vs 3·53; p<0·0001) than outdoors. Community composition differed markedly (permutational multivariate ANOVA p<0·0001), with Penicillium, Aspergillus, and Wallemia enriched indoors. Indoor fungal communities presented stronger seasonal cycling (R2=0·203) than outdoor communities (R2=0·012). Fungal burden across all homes had a median 11 043 genomic equivalence (GE); IQR 4598-20 579 GE. The highest levels were observed in homes with visible mould; one household showed elevated Aspergillus exposure linked to repeated asthma hospitalisations in a sensitised resident. INTERPRETATION: Indoor fungal bioaerosols are more diverse and dynamic than outdoor communities in urban UK homes. These findings establish foundational exposure data and highlight the need for incorporating fungal bioaerosol monitoring into public health policy to mitigate mould-related health risks. FUNDING: UK Research and Innovation (UKRI) Strategic Priorities Fund (SPF) Clean Air Programme.

Humans↗

PubMed2026

XXYLT1 and Mendelian Retinal Dystrophy.

IMPORTANCE: Substantial unexplained heritability remains for pathogenic inherited retinal disease (IRD) variants. Application of genome-wide association studies (GWAS) could help identify causal genes in rare diseases. OBJECTIVE: To leverage a GWAS for the discovery of IRD-associated genes. DESIGN, SETTING, AND PARTICIPANTS: This GWAS analysis was combined with replication of findings in 2 independent IRD cohorts. The study was conducted from January 2024 to December 2025 in a multicenter setting through FinnGen, 100 000 Genomes Project, and the National Health Service Genomic Medicine Service combined with clinical cohort from the Oulu University Hospital. Using IRD criteria from the International Classification of Diseases, 9th and 10th Revisions, 540 individuals with IRD and 473 945 control individuals were identified in the FinnGen study. For validation of FinnGen results, 49 patients were recruited from Oulu University Hospital. Results were further validated in 2 individuals identified from the UK cohort. MAIN OUTCOMES AND MEASURES: The GWAS and proteomics analysis were performed in the FinnGen cohort. Sanger and whole-genome sequencing and RNA approaches were used in a clinical IRD cohort to validate pathogenicity of the identified XXYLT1 variant. RESULTS: This GWAS identified 13 recessive loci reaching genome-wide significance (defined as P < 5 × 10-8). Of these, 4 (near or within XXYLT1, ANKRD10, DYM, and CBLN4) had not been associated with IRD, including the XXYLT1 c.505-1G>C founder variant. This variant was further genotyped in the clinical replication cohort, leading to identification of 5 more homozygous individuals from 4 families. The phenotype was consistent with a cone-rod or macular dystrophy, with visual deterioration, cystoid macular edema and/or schisislike macular abnormalities. The effect of the XXYLT1 c.505-1G>C variant was further investigated using RNA sequencing and complementary DNA amplicon sequencing, demonstrating exon 2 skipping and a loss-of-function effect. These findings were replicated in an independent population identifying 2 patients from the UK harboring a homozygous XXYLT1 c.766G>A, p.(Glu256Lys) missense variant. CONCLUSIONS AND RELEVANCE: This GWAS identified an association between XXYLT1 and IRD. These results affirm that GWAS in a founder population can be used as a potential tool for the discovery of rare mendelian disease genes and that XXYLT1 should be considered in clinical IRD gene panels.

Humans↗

PubMed2025

Intratumoral fungus Neurospora crassa is associated with worsened prognosis in ovarian cancer via modulation of extracellular matrix.

Landmark studies on intratumoral fungi (ITF) have raised concerns due to irreproducible results and data-analysis errors. We aimed to determine whether ITF exist in ovarian cancer (OvCa) and, if so, whether they play a role in disease biology. Formalin-fixed, paraffin-embedded OvCa samples and multiple controls underwent operational decontamination, qPCR, internal transcribed spacer sequencing, and post-hoc data decontamination. We also leveraged updated fungal reads from The Cancer Genome Atlas generated by the TCMbio group, which addressed human-read contamination and artificial inflation, to validate findings and assess prognostic associations. A murine syngeneic model established using mouse ovarian cancer cell line (OVHM) with intratumoral Neurospora crassa injection was established. Transcriptomic and metabolomic analyses were performed to explore mechanisms. Tumor-containing blocks harbored significantly higher fungal loads than environmental controls but had loads comparable to paraffin controls. Applying a two-pass decontamination filter reduced raw sequence features from 9289 amplicon sequence variants (ASVs) to 659 ASVs. We focused on high-abundance features present in human tissues but absent from xenografts and paraffin controls and identified one candidate, N. crassa, associated with unfavorable prognosis in OvCa. Integrating human and murine data, we found Neurospora correlated with eosinophils, whereas N. crassa itself was not immune-related. Neurospora crassa promoted OvCa progression with downregulation of integrin-linked kinase and decreased extracellular matrix-receptor interaction. Most ITF signals are likely contaminants. We identified N. crassa as associated with unfavorable prognosis in OvCa, potentially via modulation of the extracellular matrix.

Neurospora crassa↗

PubMedDate not supplied

An investigation of the prevalence of the toxigenic types of Clostridium perfringens in horses with anterior enteritis: preliminary results.

Equine anterior enteritis is an acute syndrome with unknown aetiology, although salmonellosis and infection with Clostridium perfringens have both been suggested as potential causes. The main aim of this preliminary study was to compare the prevalence of toxigenic types of C. perfringens in clinically healthy horses and in horses with anterior enteritis. From horses admitted with colic at Phillip Leverhulme Large Animal Hospital in 1995-1996, samples of gastric reflux, small intestinal contents and faeces were taken for isolation of C. perfringens. Five of those horses were admitted as anterior enteritis cases, of which C. perfringens was isolated in pure culture in all five horses. Two of the anterior enteritis cases from which viable bacterial counts had been performed revealed 10(6) CFU/g faeces C. perfringens. Samples of gastric reflux and small intestinal contents submitted from one of these horses revealed 10(4) CFU/mL and 10(5) CFU/mL respectively. The number of C. perfringens observed in the gastric reflux was considered significant as the total volume removed was 12 L. The counts observed in faeces taken from horses admitted with anterior enteritis, were significantly higher than the <10(2) CFU/g faeces observed in faeces from healthy horses and horse presenting with colic and with other diagnoses. The major toxigenic types of C. perfringens in both healthy and diseased horses are being investigated using the polymerase chain reaction (PCR) to amplify target DNA sequences of the toxin genes. Primers have been designed from the published DNA sequences of the enterotoxin, alpha, beta, epsilon and iota toxin genes. PCR products obtained from NCTC strains of C. perfringens have been cloned and the sequenced, to verify that the amplicon sequence is correct. Initial typing suggests that C. perfringens type A is the predominant toxin type isolated from healthy horses and horses with colic with other diagnoses.C. perfringens strains isolated from horses with anterior enteritis are of type D.

Journal Article↗

PubMed2001

Two rare confounding polymorphisms proximal to the factor V Leiden mutation.

BACKGROUND: Comprehensive assessment of thrombophilia risk includes characterization of the R506Q (Leiden) mutation in factor V in many patients. Although activated protein C resistance is often assessed by means of a coagulation test, molecular interrogation of the G1691A mutation provides confirmation and interpretive utility in patients undergoing anticoagulation. Many molecular methods are available to provide genotyping at this locus. Among these, PCR-restriction fragment length polymorphism (RFLP) is widely used. Unfortunately, because this common mutation is 11 bp from the 3' end of exon 10, one PCR primer often anneals within intron 10. As a consequence, polymorphism can confound test results. METHOD AND RESULTS: In the course of a clinical diagnostic test of 15,301 patients, two samples repeatedly showed two different unusual electrophoretic mobilities after PCR and restriction enzyme digestion. After stripping patient identifiers and entering a research protocol, the amplicons from these DNAs were sequenced in parallel with normal and heterozygous G1691A control genomic DNA samples. This sequencing showed two novel polymorphisms, each mapping to intron 10. CONCLUSION: PCR-RFLP-based methods rely on sequence conservation in the interrogated region. Amplification of mutated loci adjacent to introns present a special risk for confounding restriction patterns. Sequencing amplicons with reproducibly unusual restriction patterns resolved the paradoxical restriction pattern in this case.

Activated Protein C Resistance↗

PubMed2025

Integrated 16 S rRNA and transcriptome analysis reveal molecular and microbial mechanisms of cold-tolerant germination in hulless barley.

BACKGROUND: Elucidating the mechanisms underlying cold-tolerant germination is crucial for enhancing crop resilience to low temperatures. Hulless barley (Hordeum vulgare var. coeleste L.), with remarkable natural cold adaptation, serves as an ideal model to study cold stress tolerance mechanisms in gramineous crops. In this study, cold-tolerant variety 37 and cold-sensitive variety 44 were screened and used to investigate the molecular mechanisms of cold-tolerant germination, via seed germination assays, combined with phytohormone determination, transcriptome sequencing and 16 S rRNA amplicon sequencing. RESULTS: Low temperature significantly inhibited hulless barley seed germination: the germination rate of cold-sensitive variety 44 decreased by 69%, while that of cold-tolerant variety 37 only decreased by 2%. Transcriptome analysis identified 2,647 and 2,392 differentially expressed genes (DEGs) in variety 37 and 44, respectively. Weighted gene co-expression network analysis (WGCNA) revealed a green module significantly positively correlated with gibberellic acid (GA) content, containing 10 core genes such as late embryogenesis abundant protein (LEA) and Homeobox genes. 16 S rRNA sequencing showed that the cold-tolerant variety 37 had enriched abundances of dominant endophytes including Sphingomonas and Pelomonas, with correlation coefficients of 0.70 and 0.87 with GA content, respectively. Additionally, exogenous GA treatment significantly increased germination rates under cold stress by 176.67% in cold-sensitive variety 44. CONCLUSIONS: This study confirms that the enhanced cold tolerance of hulless barley during seed germination originates from the synergistic interaction between beneficial endophytes (Sphingomonas, Pelomonas), GA, and core genes (e.g., LEA, Homeobox). Exogenous GA application can significantly restore the germination ability of cold-sensitive varieties. These findings provide a critical theoretical basis for improving cold tolerance in hulless barley germplasm.

Hordeum↗

PubMed2026

Metagenomic Insights Into Microbial Diversity of Tea Rhizosphere of the Kangra Valley.

This study provides the first metagenomic assessment of microbial diversity from the tea rhizosphere of the Kangra valley. Tea rhizosphere soil samples were collected from 4 locations (Dharamshala, Baijnath, Palampur, and Joginder Nagar) of the Kangra valley. DNA extracts of rhizosphere samples were analysed for bacterial and Archaeal diversity using amplicon sequencing (V3-V4) region of the 16S rRNA gene and Fungal diversity using ITS1 and ITS2 regions. Baijnath and Palampur samples showed the highest bacterial richness, while Dharamshala and Palampur had the highest fungal richness. Proteobacteria was a dominant phylum in all the rhizosphere samples, followed by Firmicutes, Actinobacteria, Acidobacteria, and Bacteroidetes. A total of 11 fungal phyla were identified among all the locations, with abundance of Ascomycota and Basidiomycota. For the Archaea domain, uncultured archaeon and Aeropyrum camini were the most common found among all the locations. A small fraction (< 0.5%) of Bacillus and Pseudomonas species were observed among all the locations. Alpha and beta diversity indices displayed notable differences within and between microbial diversities. Soil factors were variably associated with microbial diversity, with nitrogen positively aligned with fungal diversity, while EC and K were associated with Archaeal diversity. Soil pH and OM% showed moderate associations with bacterial diversity. These findings provided valuable and comprehensive insights into tea rhizosphere microbial ecology and could be used to better understand microbial functions and their role in plant health.

Rhizosphere↗

PubMed2004

Expression analysis of the Arabidopsis peroxidase multigenic family.

Class III peroxidases form a numerous multigenic family in higher plants, whose expression is particularly sensitive to internal or external events. Arabidopsis thaliana genome harbours 73 genes encoding peroxidases. Since they exhibit homologies ranging from 28% to 93% at the nucleotide level, the risk of cross-hybridisation may be important when measuring the level of transcripts by blotting techniques, using whole cDNA sequences. We developed a procedure to assess the expression of all peroxidase genes on one membrane, with a high specificity. The method was based on the determination for each gene of a short specific sequence (amplicon) exhibiting at the most 70% homology with any other sequences of the Arabidopsis genome. Amplicons specific for each of the 73 peroxidase genes and two pseudogenes were blotted on a nylon membrane that was hybridised with radiolabelled cDNA libraries prepared from mRNAs of Arabidopsis roots, stems, leaves and flowers. Many genes were expressed at a low level, often in all organs, while sixteen genes were rather strongly expressed, in two to four organs. Some genes with no ESTs reported in databases were found to be expressed and this was confirmed by RT-PCR. Isoelectric focusing analysis revealed that the isoperoxidase pattern was similar in leaves, stems and flowers, but was quite different in roots. To our knowledge, only one similar study has been performed on the cytochrome P450 family, using microarrays, but this is the first work describing the expression profile of a whole large multigenic family using specific macroarrays.

Arabidopsis↗

PubMed2002

Allele-specific PCR amplification due to sequence identity between a PCR primer and an amplicon: is direct sequencing so reliable?

PCR-direct sequencing (DS) is thought to be a very reliable method of determining DNA sequence and genotyping. Under certain conditions, however, DS can generate inaccurate results. Here we report a case of erroneous DS, in which a single nucleotide polymorphism (SNP) in the human PAX9 gene was mistyped due to allele-dependent PCR amplification. Examination of the amplified region showed that the 5' eight bases of one of the PCR primers were identical to the eight bases of the reverse strand downstream of the SNP, and the ninth base matched one of the alleles. Altering the primer so that it matched the other allele reversed the allele-specific inhibition. Reducing the base-pairing abolished the inhibition. Thus, the SNP was responsible for the difference in annealing efficacy of the primer and was therefore critical for the allele dependency. The allele-specific inhibition presented here can occur with any PCR primer sequence that encompasses a site that is polymorphic in the gene sequence. This phenomenon needs to be considered as a possibility when interpreting results from all PCR-based experiments. Sequence similarity between PCR primers and internal amplified regions should be considered for all methods for mutation detection and genotyping using PCR.

Alleles↗

PubMed2025

Altered mitochondrial DNA methylation in blood in individuals with mild cognitive impairment.

BACKGROUND: Previous studies reported that altered mitochondrial methylation in Alzheimer's disease (AD), however, whether epigenetic modifications in mitochondrial genomes contribute to preclinical AD remains unclear. This study aimed to investigate mitochondrial methylation changes in individuals with cognitive decline. RESEARCH DESIGN AND METHODS: We examined whole mitochondrial genome methylation in 50 individuals with mild cognitive impairment (MCI) and 50 individuals without MCI, using bisulfite amplicon sequencing, assessing methylation at 366 Cytosine-guanine oligodeoxynucleotide (CpG) sites. RESULTS: We found the overall methylation level of mitochondrial DNA (mtDNA) in each subject was relatively low, ranging from 0% to 15%. Global methylation was significantly higher in individuals with cognitive decline compared to controls (3.86% vs. 3.46%, p = 0.037), with 34 differentially methylated CpG sites identified. Methylation differences (MD) between cognitive decline individuals and controls were 22.93 ± 5.60% at chrM6465 (Q = 0.013), 12.55 ± 3.02% at chrM9612 (Q = 0.013), 11.45 ± 3.88% at chrM11762 (Q = 0.159) and 11.03 ± 3.88% at chrM11766 (Q = 0.172), respectively, while the level of MD at chrM15812 was -13.11 ± 4.31% (Q = 0.159) after Benjamini-Hochberg FDR adjusted. Furthermore, Methylation at specific sites were significantly correlated with Mini-Mental State Examination scores, distinguishing individuals with cognitive decline from controls. CONCLUSIONS: Our study provides an mtDNA methylation map and suggests a role for these sites in preclinical AD pathogenesis.

Humans↗

PubMed2026

Reduced legacy precipitation decreases microbial community growth efficiency and alters soil organic carbon in a California grassland.

BACKGROUND: Changes in global patterns can leave a lasting legacy in semiarid grasslands by reshaping microbial growth dynamics and carbon cycling during the first wet-up in the autumn-a period known for intense microbial activity and significant carbon emissions. To study the lasting impacts of decreased winter rain, we implemented two precipitation regimes (100% vs. 50% mean annual precipitation) in California Mediterranean-climate grassland field plots. After the dry season, soils were rewetted in the laboratory with H218O and sampled at 0 h, 3 h, 24 h, 48 h, 72 h, and 168 h post rewet. We quantified CO2 efflux, measured microbial growth and mortality via quantitative 18O stable isotope probing and 16S rRNA gene amplicon sequencing, and characterized the soil organic carbon chemical composition, metagenomes, and metatranscriptomes. RESULTS: We found that reduced winter precipitation imposed a strong legacy effect on microbial turnover; despite maintaining similar respiration rates, microbial growth declined by ~1 order of magnitude, yielding decreased community growth efficiency (CGE = new biomass growth/respiration), and microbial mortality declined by ~2 orders of magnitude. Soil organic carbon also shifted from lipid-like, amino-sugar-like, and protein-like compounds (indicative of microbial necromass) to more oxidized lignin-like and tannin-like compounds (indicative of decomposing plant-derived compounds). Meta-omics revealed distinct metabolic strategies linked to CGE. At high-CGE, microbes appeared to consume more energetically favorable N-rich necromass (released via high microbial turnover); this allowed for increased amino acids and peptidoglycan biosynthesis and greater aromatic compound degradation, fueling further energy production and growth efficiency. At low CGE, communities had elevated carbohydrate metabolism and lipid turnover, consistent with increased investment in plant detritus degradation and membrane repair and maintenance rather than growth. CONCLUSIONS: Together, our findings demonstrate that reduced winter rainfall decreases microbial turnover following rewetting without a concurrent reduction in CO2 emissions. This shift results in persistently lower CGE, which has the potential to increase soil carbon loss as CO2. If such conditions are maintained over multiple years, these changes could reshape soil organic carbon stocks and alter the balance of grassland ecosystems under future climate scenarios. While our data suggest that sustained reductions in CGE may drive SOC decline, the magnitude and persistence of these effects depend on long-term environmental dynamics and warrant further investigation. Video Abstract.

Soil Microbiology↗