RESUMEN
Ticks are obligate blood-sucking arachnid ectoparasites from the order Acarina, and many are notorious as vectors of a wide variety of zoonotic pathogens. However, the systematics of ticks in several genera is still controversial. The mitochondrial genome (mt-genome) has been widely used in arthropod phylogeny, molecular evolution and population genetics. With the development of sequencing technologies, an increasing number of tick mt-genomes have been sequenced and annotated. To date, 63 complete tick mt-genomes are available in the NCBI database, and these genomes have become an increasingly important genetic resource and source of molecular markers in phylogenetic studies of ticks in recent years. The present review summarizes all available complete mt-genomes of ticks in the NCBI database and analyses their characteristics, including structure, base composition and gene arrangement. Furthermore, a phylogenetic tree was constructed using mitochondrial protein-coding genes (PCGs) and ribosomal RNA (rRNA) genes from ticks. The results will provide important clues for deciphering new tick mt-genomes and establish a foundation for subsequent taxonomic research.
Asunto(s)
Genoma Mitocondrial , Mitocondrias/genética , Garrapatas/genética , Animales , Composición de Base , Orden Génico , FilogeniaRESUMEN
Sanger-type sequencing (STS) of mitochondrial DNA (mtDNA), specifically the control region (CR), is routinely employed in forensics in human identification and missing persons scenarios. Yet next-generation sequencing (NGS) has the potential to overcome some of the major limitations of STS processing, permitting reasonable paths forward for full mitochondrial genome (mtGenome) sequencing, while also offering higher-throughput and higher sensitivity capabilities. To establish the accuracy and reproducibility of NGS for the development of mtDNA data, 90 DNA extracts that were previously used to generate forensic quality full mtGenomes using STS were sequenced using Nextera XT library preparation and the Illumina MiSeq. Using the same amplicon product, replicate library sets were generated and sequenced at different laboratories, and analysis was performed in replicate using the CLC Genomics Workbench. Both sequencing sets resulted in 99.998% of positions with greater than 10X coverage when 96 samples (including controls) were multiplexed. Overall, 99.9996% concordance was observed between the NGS data and the STS data for the full mtGenome. The only "discordant" calls involved low level point heteroplasmies, with the differences resulting from stochastic variation and/or the increased sensitivity of NGS. Higher sensitivity also allowed for the detection of a mixed sample previously not detected with STS. Additionally, variant calls were reproducible between sequencing sets and between software analysis versions with the variant frequency only differing by 0.23% and 0.01%, respectively. Further validation studies and specialized software functionality tailored to forensic practice should facilitate the incorporation of NGS processing into standard casework applications. The data herein comprise the largest, and likely most thoroughly examined, complete mtGenome STS-NGS concordance dataset available.
Asunto(s)
ADN Mitocondrial/genética , Genoma Mitocondrial , Secuenciación de Nucleótidos de Alto Rendimiento/instrumentación , Análisis de Secuencia de ADN , Humanos , Reacción en Cadena de la Polimerasa , Reproducibilidad de los ResultadosRESUMEN
Next generation sequencing (NGS) is a time saving and cost-efficient method to detect the complete mitochondrial genome (mtGenome) compared to Sanger sequencing. In this study we focused on developing strategies for mtGenome sequencing on the Ion Torrent PGM™ platform and NGS data analysis. With our experience, 4, 15 and 30 samples could be loaded onto Ion 314™, Ion 316™ and Ion 318™ chips respectively at a pooling concentration of 26pM, achieving to sufficient average coverage of ≥1500 × and well strand balance of 1.05. Data processing software is essential to NGS mega data analysis. The in-house Perl scripts were developed for primary data analysis to screen out uncertain positions and samples from variant call format (VCF) reports and for pedigree study to perform pairwise comparisons. The Integrative Genomic Viewer (IGV) and the NextGENe software were introduced to secondary data analysis. The mthap and EMMA were employed for haplogroup assignment. The dataset was reviewed and approved by the EMPOP as the final version, which showed 2.66% error rate generated from the Torrent Variant Caller (TVC). Across the mtGenome, 4022 variants were found at 725 nucleotide positions, where ratio of transitions to transversions was estimated at 20.89:1 and 22.18% of variants was concentrated at hypervariable segments I and II (HVS-I and HVS-II). Totally, 107 complete mtGenome haplotypes were observed from 107 Northern Chinese Han and assigned to 88 haplogroups. The random match probability (RMP) of complete mtGenome was calculated as 0.009345794, decreasing 26.19% by comparison to that of HVS-I only, and the haplotype diversity (HD) was evaluated as 1, increasing 0.33% by comparison to that of HVS-I only. Principal component analysis (PCA) showed that our population was clustered to East and Southeast Asians. The strategies in this study are suitable for complete mtGenome sequencing on Ion Torrent PGM™ platform and Northern Chinese Han (EMP00670) is the first complete mtGenome dataset contributed to the EMPOP from East Asian.
Asunto(s)
ADN Mitocondrial/genética , Ciencias Forenses/métodos , Genoma Mitocondrial , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Mitocondrias/genética , Análisis de Secuencia de ADN/métodos , Pueblo Asiatico/genética , Secuencia de Bases , ADN Mitocondrial/análisis , Ciencias Forenses/instrumentación , Haplotipos , Humanos , Mitocondrias/químicaRESUMEN
Mitochondrial DNA is a useful marker for population studies, human identification, and forensic analysis. Commonly used hypervariable regions I and II (HVI/HVII) were reported to contain as little as 25% of mitochondrial DNA variants and therefore the majority of power of discrimination of mitochondrial DNA resides in the coding region. Massively parallel sequencing technology enables entire mitochondrial genome sequencing. In this study, buccal swabs were collected from 114 unrelated Estonians and whole mitochondrial genome sequences were generated using the Illumina MiSeq system. The results are concordant with previous mtDNA control region reports of high haplogroup HV and U frequencies (47.4 and 23.7% in this study, respectively) in the Estonian population. One sample with the Northern Asian haplogroup D was detected. The genetic diversity of the Estonian population sample was estimated to be 99.67 and 95.85%, for mtGenome and HVI/HVII data, respectively. The random match probability for mtGenome data was 1.20 versus 4.99% for HVI/HVII. The nucleotide mean pairwise difference was 27 ± 11 for mtGenome and 7 ± 3 for HVI/HVII data. These data describe the genetic diversity of the Estonian population sample and emphasize the power of discrimination of the entire mitochondrial genome over the hypervariable regions.
Asunto(s)
Variación Genética , Genética de Población , Genoma Mitocondrial/genética , ADN Mitocondrial/genética , Estonia , Haplotipos , Humanos , Análisis de SecuenciaRESUMEN
Monozygotic (MZ) twins, considered to be genetically identical, cannot be distinguished from one another by standard forensic DNA testing. A recent study employed whole genome sequencing to identify extremely rare mutations and reported that mutation analysis could be used to differentiate between MZ twins. Compared with nuclear DNA, mitochondrial DNA (mtDNA) has higher mutation rates; therefore, minor differences theoretically exist in MZ twins' mitochondrial genome (mtGenome). However, conventional Sanger-type sequencing (STS) is neither amenable to, nor feasible for, the detection of low-level sequence variants. The recent introduction of massively parallel sequencing (MPS) has the capability to sequence many targeted regions of multiple samples simultaneously with desirable depth of coverage. Thus, the aim of this study was to assess whether full mtGenome sequencing analysis can be used to differentiate between MZ twins. Ten sets of MZ twins provided blood samples that underwent extraction, quantification, mtDNA enrichment, library preparation, and ultra-deep sequencing. Point heteroplasmies were observed in eight sets of MZ twins, and a single nucleotide variant (nt15301) was detected in five sets of MZ twins. Thus, this study demonstrates that ultra-deep mtGenome sequencing could be used to differentiate between MZ twins.
Asunto(s)
ADN Mitocondrial/química , Genética Forense/métodos , Genoma Mitocondrial , Mutación Puntual , Polimorfismo de Nucleótido Simple , Gemelos Monocigóticos , Adulto , China , ADN Mitocondrial/sangre , Biblioteca Genómica , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Persona de Mediana Edad , Tasa de Mutación , Análisis de Secuencia de ADNRESUMEN
The mitochondrial genome (mtGenome) contains genetic information amenable to numerous applications such as medical research, population and evolutionary studies, and human identity testing. However, inconsistent nomenclature assignment makes haplotype comparison difficult and can lead to false exclusion of potentially useful profiles. Massively Parallel Sequencing (MPS) is a platform for sequencing large datasets and potentially whole populations with relative ease. However, the data generated are not easily parsed and interpreted. With this in mind, mitoSAVE has been developed to enable fast conversion of Variant Call Format (VCF) files. mitoSAVE is an Excel-based workbook that converts data within the VCF into mtDNA haplotypes using phylogenetically-established nomenclature as well as rule-based alignments consistent with current forensic standards. mitoSAVE is formatted for human mitochondrial genome; however, it can easily be adapted to support other reasonably small genomes.
Asunto(s)
Genoma Mitocondrial , Programas Informáticos , Haplotipos , HumanosRESUMEN
Mitochondrial DNA typing in forensic genetics has been performed traditionally using Sanger-type sequencing. Consequently sequencing of a relatively-large target such as the mitochondrial genome (mtGenome) is laborious and time consuming. Thus, sequencing typically focuses on the control region due to its high concentration of variation. Massively parallel sequencing (MPS) has become more accessible in recent years allowing for high-throughput processing of large target areas. In this study, Nextera(®) XT DNA Sample Preparation Kit and the Illumina MiSeq™ were utilized to generate quality whole genome mitochondrial haplotypes from 283 individuals in a both cost-effective and rapid manner. Results showed that haplotypes can be generated at a high depth of coverage with limited strand bias. The distribution of variants across the mitochondrial genome was described and demonstrated greater variation within the coding region than the non-coding region. Haplotype and haplogroup diversity were described with respect to whole mtGenome and HVI/HVII. An overall increase in haplotype or genetic diversity and random match probability, as well as better haplogroup assignment demonstrates that MPS of the mtGenome using the Illumina MiSeq system is a viable and reliable methodology.