RESUMO
Finding, characterizing and monitoring reservoirs for antimicrobial resistance (AMR) is vital to protecting public health. Hybridization capture baits are an accurate, sensitive and cost-effective technique used to enrich and characterize DNA sequences of interest, including antimicrobial resistance genes (ARGs), in complex environmental samples. We demonstrate the continued utility of a set of 19 933 hybridization capture baits designed from the Comprehensive Antibiotic Resistance Database (CARD)v1.1.2 and Pathogenicity Island Database (PAIDB)v2.0, targeting 3565 unique nucleotide sequences that confer resistance. We demonstrate the efficiency of our bait set on a custom-made resistance mock community and complex environmental samples to increase the proportion of on-target reads as much as >200-fold. However, keeping pace with newly discovered ARGs poses a challenge when studying AMR, because novel ARGs are continually being identified and would not be included in bait sets designed prior to discovery. We provide imperative information on how our bait set performs against CARDv3.3.1, as well as a generalizable approach for deciding when and how to update hybridization capture bait sets. This research encapsulates the full life cycle of baits for hybridization capture of the resistome from design and validation (both in silico and in vitro) to utilization and forecasting updates and retirement.
Assuntos
Antibacterianos , Farmacorresistência Bacteriana , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genéticaRESUMO
Mylodon darwinii is the extinct giant ground sloth named after Charles Darwin, who first collected its remains in South America. We have successfully obtained a high-quality mitochondrial genome at 99-fold coverage using an Illumina shotgun sequencing of a 12 880-year-old bone fragment from Mylodon Cave in Chile. Low level of DNA damage showed that this sample was exceptionally well preserved for an ancient subfossil, probably the result of the dry and cold conditions prevailing within the cave. Accordingly, taxonomic assessment of our shotgun metagenomic data showed a very high percentage of endogenous DNA with 22% of the assembled metagenomic contigs assigned to Xenarthra. Additionally, we enriched over 15 kb of sequence data from seven nuclear exons, using target sequence capture designed against a wide xenarthran dataset. Phylogenetic and dating analyses of the mitogenomic dataset including all extant species of xenarthrans and the assembled nuclear supermatrix unambiguously place Mylodon darwinii as the sister-group of modern two-fingered sloths, from which it diverged around 22 million years ago. These congruent results from both the mitochondrial and nuclear data support the diphyly of the two modern sloth lineages, implying the convergent evolution of their unique suspensory behaviour as an adaption to arboreality. Our results offer promising perspectives for whole-genome sequencing of this emblematic extinct taxon.
Assuntos
DNA Antigo/análise , Genoma Mitocondrial , Xenarthra/classificação , Animais , Chile , DNA Mitocondrial/análise , Éxons/genética , Fósseis , Filogenia , Bichos-Preguiça/classificação , Bichos-Preguiça/genética , Xenarthra/genéticaRESUMO
Xenarthra (armadillos, sloths, and anteaters) constitutes one of the four major clades of placental mammals. Despite their phylogenetic distinctiveness in mammals, a reference phylogeny is still lacking for the 31 described species. Here we used Illumina shotgun sequencing to assemble 33 new complete mitochondrial genomes, establishing Xenarthra as the first major placental clade to be fully sequenced at the species level for mitogenomes. The resulting data set allowed the reconstruction of a robust phylogenetic framework and timescale that are consistent with previous studies conducted at the genus level using nuclear genes. Incorporating the full species diversity of extant xenarthrans points to a number of inconsistencies in xenarthran systematics and species definition. We propose to split armadillos into two distinct families Dasypodidae (dasypodines) and Chlamyphoridae (euphractines, chlamyphorines, and tolypeutines) to better reflect their ancient divergence, estimated around 42 Ma. Species delimitation within long-nosed armadillos (genus Dasypus) appeared more complex than anticipated, with the discovery of a divergent lineage in French Guiana. Diversification analyses showed Xenarthra to be an ancient clade with a constant diversification rate through time with a species turnover driven by high but constant extinction. We also detected a significant negative correlation between speciation rate and past temperature fluctuations with an increase in speciation rate corresponding to the general cooling observed during the last 15 My. Biogeographic reconstructions identified the tropical rainforest biome of Amazonia and the Guiana Shield as the cradle of xenarthran evolutionary history with subsequent dispersions into more open and dry habitats.
Assuntos
Evolução Molecular , Genoma Mitocondrial , Genômica , Filogenia , Xenarthra/classificação , Xenarthra/genética , Animais , Teorema de Bayes , Evolução Biológica , Biologia Computacional , Sequenciamento de Nucleotídeos em Larga EscalaRESUMO
In the 19th century, there were several major cholera pandemics in the Indian subcontinent, Europe, and North America. The causes of these outbreaks and the genomic strain identities remain a mystery. We used targeted high-throughput sequencing to reconstruct the Vibrio cholerae genome from the preserved intestine of a victim of the 1849 cholera outbreak in Philadelphia, part of the second cholera pandemic. This O1 biotype strain has 95 to 97% similarity with the classical O395 genome, differing by 203 single-nucleotide polymorphisms (SNPs), lacking three genomic islands, and probably having one or more tandem cholera toxin prophage (CTX) arrays, which potentially affected its virulence. This result highlights archived medical remains as a potential resource for investigations into the genomic origins of past pandemics.
Assuntos
Cólera/história , Pandemias/história , Vibrio cholerae/genética , Técnicas de Tipagem Bacteriana , Cólera/epidemiologia , Cólera/microbiologia , DNA Bacteriano/isolamento & purificação , DNA Mitocondrial/análise , Evolução Molecular , Genoma Bacteriano , Ilhas Genômicas , História do Século XIX , Humanos , Intestinos/microbiologia , Intestinos/patologia , Masculino , Philadelphia/epidemiologia , Filogenia , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA , Vibrio cholerae/classificação , Vibrio cholerae/patogenicidade , Virulência , Fatores de Virulência/análiseRESUMO
We report metrics from complete genome capture of nuclear DNA from extinct mammoths using biotinylated RNAs transcribed from an Asian elephant DNA extract. Enrichment of the nuclear genome ranged from 1.06- to 18.65-fold, to an apparent maximum threshold of â¼80% on-target. This projects an order of magnitude less costly complete genome sequencing from long-dead organisms, even when a reference genome is unavailable for bait design.
Assuntos
Genoma , Genômica/métodos , Mamutes/genética , Análise de Sequência de DNA/métodos , Animais , DNA/genética , DNA/isolamento & purificação , Elefantes/genética , Fósseis , História Antiga , Alinhamento de Sequência/métodosRESUMO
High-throughput sequencing (HTS) has radically altered approaches to human evolutionary research. Recent contributions highlight that HTS is able to reach depths of the human lineage previously thought to be impossible. In this paper, we outline the methodological advances afforded by recent developments in DNA recovery, data output, scalability, speed, and resolution of the current sequencing technology. We review and critically evaluate the 'DNA pipeline' for ancient samples: from DNA extraction, to constructing immortalized sequence libraries, to enrichment strategies (e.g., polymerase chain reaction [PCR] and hybridization capture), and finally, to bioinformatic analyses of sequence data. We argue that continued evaluations and improvements to this process are essential to ensure sequence data validity. Also, we highlight the role of contamination and authentication in ancient DNA-HTS, which is particularly relevant to ancient human genomics, since sequencing the genomes of hominins such as Homo erectus and Homo heidelbergensis may soon be within the realm of possibility.
Assuntos
Evolução Biológica , Fósseis , Genômica , Sequenciamento de Nucleotídeos em Larga Escala , Hominidae/genética , Animais , Antropologia Física , DNA/análise , DNA/genética , HumanosRESUMO
The present erratum is in regards to our article entitled 'Ancient DNA and the tropics: a rodent's tale'. We were made aware of problems with some of the ancient sequences submitted to GenBank and conducted a systematic review of all the files used in our study. We discovered that, unfortunately, an incorrect file was sent to GenBank and was also used in some of our downstream analyses. We immediately contacted GenBank, explained the situation and corrected the file. We have redone some analyses with the correct file and describe these changes below.
RESUMO
Most genetic studies of Holocene fauna have been performed with ancient samples from dry and cold regions, in which preservation of fossils is facilitated and molecular damage is reduced. Ancient DNA work from tropical regions has been precluded owing to factors that limit DNA preservation (e.g. temperature, hydrolytic damage). We analysed ancient DNA from rodent jawbones identified as Ototylomys phyllotis, found in Holocene and Late Pleistocene stratigraphic layers from Loltún, a humid tropical cave located in the Yucatan peninsula. We extracted DNA and amplified six short overlapping fragments of the cytochrome b gene, totalling 666 bp, which represents an unprecedented success considering tropical ancient DNA samples. We performed genetic, phylogenetic and divergence time analyses, combining sequences from ancient and modern O. phyllotis, in order to assess the ancestry of the Loltún samples. Results show that all ancient samples fall into a unique clade that diverged prior to the divergence of the modern O. phyllotis, supporting it as a distinct Pleistocene form of the Ototylomys genus. Hence, this rodent's tale suggests that the sister group to modern O. phyllotis arose during the Miocene-Pliocene, diversified during the Pleistocene and went extinct in the Holocene.
Assuntos
Arvicolinae/genética , Evolução Molecular , Fósseis , Animais , Citocromos b/genética , DNA/genética , México , Filogenia , Análise de Sequência de DNA , Fatores de Tempo , Clima TropicalRESUMO
Phylogenomic data are revolutionizing the field of insect phylogenetics. One of the most tenable and cost-effective methods of generating phylogenomic data is target enrichment, which has resulted in novel phylogenetic hypotheses and revealed new insights into insect evolution. Orthoptera is the most diverse insect order within polyneoptera and includes many evolutionarily and ecologically interesting species. Still, the order as a whole has lagged behind other major insect orders in terms of transitioning to phylogenomics. In this study, we developed an Orthoptera-specific target enrichment (OR-TE) probe set from 80 transcriptomes across Orthoptera. The probe set targets 1828 loci from genes exhibiting a wide range of evolutionary rates. The utility of this new probe set was validated by generating phylogenomic data from 36 orthopteran species that had not previously been subjected to phylogenomic studies. The OR-TE probe set captured an average of 1037 loci across the tested taxa, resolving relationships across broad phylogenetic scales. Our detailed documentation of the probe design and bioinformatics process is intended to facilitate the widespread adoption of this tool.
Assuntos
Ortópteros , Filogenia , Animais , Ortópteros/genética , Ortópteros/classificação , Transcriptoma/genética , Biologia Computacional/métodos , Sondas de DNA/genética , Evolução MolecularRESUMO
As genome resources for wheat (Triticum L.) expand at a rapid pace, it is important to update targeted sequencing tools to incorporate improved sequence assemblies and regions of previously unknown significance. Here, we developed an updated regulatory region enrichment capture for wheat and other Triticeae species. The core target space includes sequences from 2-Kbp upstream of each gene predicted in the Chinese Spring wheat genome (IWGSC RefSeq Annotation v1.0) and regions of open chromatin identified with an assay for transposase-accessible chromatin using sequencing from wheat leaf and root samples. To improve specificity, we aggressively filtered candidate repetitive sequences using a combination of nucleotide basic local alignment search tool (BLASTN) searches to the Triticeae Repetitive Sequence Database (TREP), identification of regions with read over-coverage from previous target enrichment experiments, and k-mer frequency analyses. The final design comprises 216.5 Mbp of predicted hybridization space in hexaploid wheat and showed increased specificity and coverage of targeted sequences relative to previous protocols. Test captures on hexaploid and tetraploid wheat and other diploid cereals show that the assay has broad potential utility for cost-effective promoter and open chromatin resequencing and general-purpose genotyping of various Triticeae species.
Assuntos
Genoma de Planta , Triticum , Triticum/genética , Análise Custo-Benefício , Poliploidia , Regiões Promotoras Genéticas , CromatinaRESUMO
Age profiling of archaeological bone assemblages can inform on past animal management practices, but is limited by the fragmentary nature of the fossil record and the lack of universal skeletal markers for age. DNA methylation clocks offer new, albeit challenging, alternatives for estimating the age-at-death of ancient individuals. Here, we take advantage of the availability of a DNA methylation clock based on 31,836 CpG sites and dental age markers in horses to assess age predictions in 84 ancient remains. We evaluate our approach using whole-genome sequencing data and develop a capture assay providing reliable estimates for only a fraction of the cost. We also leverage DNA methylation patterns to assess castration practice in the past. Our work opens for a deeper characterization of past husbandry and ritual practices and holds the potential to reveal age mortality profiles in ancient societies, once extended to human remains.
RESUMO
Cell-free (cf)DNA signatures are quickly becoming the target of choice for non-invasive screening, diagnosis, treatment and monitoring of human tumors. DNA methylation changes occur early in tumorigenesis and are widespread, making cfDNA methylation an attractive cancer biomarker. Already a proven technology for targeted genome sequencing, hybridization probe capture is emerging as a method for high-throughput targeted methylation profiling suitable to liquid biopsy samples. However, to date there are no reports describing the performance of this approach in terms of reproducibility, scalability, and accuracy. In the current study we performed hybridization probe capture using the myBaits® Custom Methyl-seq kit on 172 plasma samples and standards to evaluate its performance on cfDNA methylation analysis. The myBaits® assay showed high target recovery (>90%), demonstrated excellent reproducibility between captures (R 2 = 0.92 on average), and was unaffected by increasing the number of targets in a capture. Finally, myBaits® accurately replicated 'gold standard' beta values from WGBS (average R 2 = 0.79). The results of this study show that custom targeted methylation sequencing with myBaits® offers a cost-effective, reliable platform to profile DNA methylation at a set of discrete custom regions, with potential applicability to liquid biopsies for cancer monitoring.
RESUMO
Disease resistance (R) genes from wild relatives could be used to engineer broad-spectrum resistance in domesticated crops. We combined association genetics with R gene enrichment sequencing (AgRenSeq) to exploit pan-genome variation in wild diploid wheat and rapidly clone four stem rust resistance genes. AgRenSeq enables R gene cloning in any crop that has a diverse germplasm panel.
Assuntos
Clonagem Molecular , Produtos Agrícolas/genética , Resistência à Doença/genética , Genes de Plantas , Doenças das Plantas/genética , Mapeamento Cromossômico , Estudos de Associação Genética , Variação Genética , Genômica , Genótipo , Modelos Genéticos , Fenótipo , Filogenia , Polimorfismo de Nucleotídeo Único , Plântula , Triticum/genéticaRESUMO
Dogs were present in the Americas before the arrival of European colonists, but the origin and fate of these precontact dogs are largely unknown. We sequenced 71 mitochondrial and 7 nuclear genomes from ancient North American and Siberian dogs from time frames spanning ~9000 years. Our analysis indicates that American dogs were not derived from North American wolves. Instead, American dogs form a monophyletic lineage that likely originated in Siberia and dispersed into the Americas alongside people. After the arrival of Europeans, native American dogs almost completely disappeared, leaving a minimal genetic legacy in modern dog populations. The closest detectable extant lineage to precontact American dogs is the canine transmissible venereal tumor, a contagious cancer clone derived from an individual dog that lived up to 8000 years ago.
Assuntos
Evolução Biológica , Doenças do Cão/transmissão , Cães , Domesticação , Neoplasias/veterinária , Infecções Sexualmente Transmissíveis/veterinária , América , Animais , Núcleo Celular/genética , Doenças do Cão/genética , Cães/classificação , Cães/genética , Genoma Mitocondrial , Migração Humana , Humanos , Filogenia , Infecções Sexualmente Transmissíveis/transmissão , Sibéria , Lobos/classificação , Lobos/genéticaRESUMO
Pregnancy complications are poorly represented in the archeological record, despite their importance in contemporary and ancient societies. While excavating a Byzantine cemetery in Troy, we discovered calcified abscesses among a woman's remains. Scanning electron microscopy of the tissue revealed 'ghost cells', resulting from dystrophic calcification, which preserved ancient maternal, fetal and bacterial DNA of a severe infection, likely chorioamnionitis. Gardnerella vaginalis and Staphylococcus saprophyticus dominated the abscesses. Phylogenomic analyses of ancient, historical, and contemporary data showed that G. vaginalis Troy fell within contemporary genetic diversity, whereas S. saprophyticus Troy belongs to a lineage that does not appear to be commonly associated with human disease today. We speculate that the ecology of S. saprophyticus infection may have differed in the ancient world as a result of close contacts between humans and domesticated animals. These results highlight the complex and dynamic interactions with our microbial milieu that underlie severe maternal infections.
Assuntos
Abscesso/patologia , Fósseis , Infecções por Bactérias Gram-Positivas/patologia , Complicações Infecciosas na Gravidez/patologia , Abscesso/microbiologia , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Feminino , Gardnerella vaginalis/classificação , Gardnerella vaginalis/genética , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos , Microscopia Eletrônica de Varredura , Gravidez , Staphylococcus saprophyticus/classificação , Staphylococcus saprophyticus/genéticaRESUMO
Near the end of the Pleistocene epoch, populations of the woolly mammoth (Mammuthus primigenius) were distributed across parts of three continents, from western Europe and northern Asia through Beringia to the Atlantic seaboard of North America. Nonetheless, questions about the connectivity and temporal continuity of mammoth populations and species remain unanswered. We use a combination of targeted enrichment and high-throughput sequencing to assemble and interpret a data set of 143 mammoth mitochondrial genomes, sampled from fossils recovered from across their Holarctic range. Our dataset includes 54 previously unpublished mitochondrial genomes and significantly increases the coverage of the Eurasian range of the species. The resulting global phylogeny confirms that the Late Pleistocene mammoth population comprised three distinct mitochondrial lineages that began to diverge ~1.0-2.0 million years ago (Ma). We also find that mammoth mitochondrial lineages were strongly geographically partitioned throughout the Pleistocene. In combination, our genetic results and the pattern of morphological variation in time and space suggest that male-mediated gene flow, rather than large-scale dispersals, was important in the Pleistocene evolutionary history of mammoths.
Assuntos
Distribuição Animal , Evolução Biológica , DNA Mitocondrial/genética , Genoma Mitocondrial , Mamutes/genética , Filogenia , Animais , Ásia , Europa (Continente) , Extinção Biológica , Feminino , Fósseis , Fluxo Gênico , Masculino , Mamutes/classificação , América do Norte , Filogeografia , Análise de Sequência de DNARESUMO
The processes leading up to species extinctions are typically characterized by prolonged declines in population size and geographic distribution, followed by a phase in which populations are very small and may be subject to intrinsic threats, including loss of genetic diversity and inbreeding. However, whether such genetic factors have had an impact on species prior to their extinction is unclear; examining this would require a detailed reconstruction of a species' demographic history as well as changes in genome-wide diversity leading up to its extinction. Here, we present high-quality complete genome sequences from two woolly mammoths (Mammuthus primigenius). The first mammoth was sequenced at 17.1-fold coverage and dates to â¼4,300 years before present, representing one of the last surviving individuals on Wrangel Island. The second mammoth, sequenced at 11.2-fold coverage, was obtained from an â¼44,800-year-old specimen from the Late Pleistocene population in northeastern Siberia. The demographic trajectories inferred from the two genomes are qualitatively similar and reveal a population bottleneck during the Middle or Early Pleistocene, and a more recent severe decline in the ancestors of the Wrangel mammoth at the end of the last glaciation. A comparison of the two genomes shows that the Wrangel mammoth has a 20% reduction in heterozygosity as well as a 28-fold increase in the fraction of the genome that comprises runs of homozygosity. We conclude that the population on Wrangel Island, which was the last surviving woolly mammoth population, was subject to reduced genetic diversity shortly before it became extinct.
Assuntos
Genoma , Mamutes/genética , Animais , Extinção Biológica , Feminino , Variação Genética , Genética Populacional , Heterozigoto , Densidade Demográfica , Análise de Sequência de DNA , SibériaRESUMO
Ancient human remains of paleopathological interest typically contain highly degraded DNA in which pathogenic taxa are often minority components, making sequence-based metagenomic characterization costly. Microarrays may hold a potential solution to these challenges, offering a rapid, affordable, and highly informative snapshot of microbial diversity in complex samples without the lengthy analysis and/or high cost associated with high-throughput sequencing. Their versatility is well established for modern clinical specimens, but they have yet to be applied to ancient remains. Here we report bacterial profiles of archaeological and historical human remains using the Lawrence Livermore Microbial Detection Array (LLMDA). The array successfully identified previously-verified bacterial human pathogens, including Vibrio cholerae (cholera) in a 19th century intestinal specimen and Yersinia pestis ("Black Death" plague) in a medieval tooth, which represented only minute fractions (0.03% and 0.08% alignable high-throughput shotgun sequencing reads) of their respective DNA content. This demonstrates that the LLMDA can identify primary and/or co-infecting bacterial pathogens in ancient samples, thereby serving as a rapid and inexpensive paleopathological screening tool to study health across both space and time.
Assuntos
Arqueologia , DNA Bacteriano , Análise de Sequência com Séries de Oligonucleotídeos , Biologia Computacional , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Filogenia , Vibrio cholerae/classificação , Vibrio cholerae/genética , Yersinia pestis/classificação , Yersinia pestis/genéticaRESUMO
BACKGROUND: Yersinia pestis has caused at least three human plague pandemics. The second (Black Death, 14-17th centuries) and third (19-20th centuries) have been genetically characterised, but there is only a limited understanding of the first pandemic, the Plague of Justinian (6-8th centuries). To address this gap, we sequenced and analysed draft genomes of Y pestis obtained from two individuals who died in the first pandemic. METHODS: Teeth were removed from two individuals (known as A120 and A76) from the early medieval Aschheim-Bajuwarenring cemetery (Aschheim, Bavaria, Germany). We isolated DNA from the teeth using a modified phenol-chloroform method. We screened DNA extracts for the presence of the Y pestis-specific pla gene on the pPCP1 plasmid using primers and standards from an established assay, enriched the DNA, and then sequenced it. We reconstructed draft genomes of the infectious Y pestis strains, compared them with a database of genomes from 131 Y pestis strains from the second and third pandemics, and constructed a maximum likelihood phylogenetic tree. FINDINGS: Radiocarbon dating of both individuals (A120 to 533 AD [plus or minus 98 years]; A76 to 504 AD [plus or minus 61 years]) places them in the timeframe of the first pandemic. Our phylogeny contains a novel branch (100% bootstrap at all relevant nodes) leading to the two Justinian samples. This branch has no known contemporary representatives, and thus is either extinct or unsampled in wild rodent reservoirs. The Justinian branch is interleaved between two extant groups, 0.ANT1 and 0.ANT2, and is distant from strains associated with the second and third pandemics. INTERPRETATION: We conclude that the Y pestis lineages that caused the Plague of Justinian and the Black Death 800 years later were independent emergences from rodents into human beings. These results show that rodent species worldwide represent important reservoirs for the repeated emergence of diverse lineages of Y pestis into human populations. FUNDING: McMaster University, Northern Arizona University, Social Sciences and Humanities Research Council of Canada, Canada Research Chairs Program, US Department of Homeland Security, US National Institutes of Health, Australian National Health and Medical Research Council.
Assuntos
DNA Bacteriano/isolamento & purificação , Pandemias/história , Filogenia , Peste/história , Yersinia pestis/genética , África/epidemiologia , Animais , Ásia/epidemiologia , Reservatórios de Doenças , Europa (Continente)/epidemiologia , História Medieval , Humanos , Peste/epidemiologia , Peste/genética , Dente/microbiologia , Yersinia pestis/isolamento & purificaçãoRESUMO
Targeted DNA enrichment through hybridization capture (EHC) is rapidly replacing PCR as the method of choice for enrichment prior to genomic resequencing. This is especially true in the case of ancient DNA (aDNA) from long-dead organisms, where targets tend to be highly fragmented and outnumbered by contaminant DNA. However, the behavior of EHC using aDNA has been quite variable, making success difficult to predict and preventing efficient sample equilibration during multiplexed sequencing runs. Here, we evaluate whether quantitative PCR (qPCR) measurements of aDNA samples correlate with on-target read counts before and after EHC. Our data indicate that not only do simple target qPCRs correlate strongly with high-throughput sequencing (HTS) data but that certain sample characteristics, such as overall target abundance as well as experimental parameters (e.g., bait concentration and secondary structure propensity), consistently influenced enrichment of our diverse set of aDNA samples. Taken together, our results should help guide experimental design, screening strategies, and multiplexed sample equilibration, increasing yield and reducing the expected and actual cost of aDNA EHC high-throughput sequencing projects in the future.