mtDNA Database Research Articles

Exploring mtDNA Databases to Evaluate the Population Structure and Genetic Diversity of Tursiops truncatus in the Atlantic Ocean: Implications for the Conservation of a Small, Offshore Population

Inshore and offshore bottlenose dolphin, Tursiops truncatus, ecotypes were distinguished through genetics, distribution, diet, morphology, diversity, and social behaviors. Although T. truncatus is a widely studied species, few studies have focused on offshore populations. Offshore biodiversity is frequently neglected due to the difficulty of data collection, and therefore, it is challenging to assess how threatened these populations are. A small, offshore population of dolphins residing around the Saint Peter Saint Paul Archipelago (SPSPA) in the middle of the Atlantic Ocean has been monitored for several years, and a decrease in the number of dolphin sightings has recently been noticed. We analyzed a comprehensive mtDNA control-region sequence dataset for this species to infer the conservation status and better understand the relationships between the SPSPA population and other offshore populations. We assessed the genetic diversity and population structure of the bottlenose dolphin from inshore and offshore populations of the Atlantic Ocean. Offshore populations are more genetically diverse and have less variation between populations than inshore populations. The offshore populations share haplotypes, indicating potential gene flow. However, the SPSPA population presented the lowest levels of genetic diversity between populations. The conservation status of the SPSPA population is concerning, and it is necessary to apply effective management strategies to guarantee its protection.

Whole mitochondrial genome analysis of the Daur ethnic minority from Hulunbuir in the Inner Mongolia Autonomous Region of China

BackgroundMitochondrial DNA (mtDNA) variations are often associated with bioenergetics, disease, and speciation and can be used to track the history of women. Although advances in massively parallel sequencing (MPS) technology have greatly promoted our understanding of the population’s history (especially genome-wide data and whole Y chromosome sequencing), the whole mtDNA sequence of many important groups has not been fully studied. In this study, we employed whole mitogenomes of 209 healthy and unrelated individuals from the Daur group, a Mongolic-speaking representative population of the indigenous groups in the Heilongjiang River basin (also known as the Amur River basin).ResultsThe dataset presented 127 distinct mtDNA haplotypes, resulting in a haplotype diversity of 0.9933. Most of haplotypes were assigned to eastern Eurasian-specific lineages, such as D4 (19.62%), B4 (9.09%), D5 (7.66%) and M7 (4.78%). Population comparisons showed that the Daurians do have certain connections with the ancient populations in the Heilongjiang River basin but the matrilineal genetic composition of the Daur group was also greatly influenced by other non-Mongolic groups from neighboring areas.ConclusionsCollectively, the whole mtDNA data generated in the present study will augment the existing mtDNA database. Our study provides genetic links between the Daur population and the aborigine peoples from Siberia and the Amur-Ussuri Region. But on the whole, compared with other Mongolic-speaking groups, the modern Daur population is closer to the East Asian ancestry group.

Echinococcus spp. and genotypes infecting humans in Tibet Autonomous Region of China: a molecular investigation with near-complete/complete mitochondrial sequences

BackgroundMolecular markers are essential to identify Echinococcus species and genotypes in areas with multiple Echinococcus species to understand their epidemiology and pathology. Tibet Autonomous Region (TAR) is one of the areas worst hit by echinococcosis. However, molecular epidemiology is still missing among echinococcosis patients in TAR. This research explored the Echinococcus species and genotypes infecting humans in TAR and the population diversity and the possible origin of G1 in TAR.MethodsCyst samples were collected in one echinococcosis-designated hospital in TAR. Echinococcus species and genotypes were identified through a maximum-likelihood approach with near-complete/complete mtDNA using IQ-TREE. Phylogenetic networks were built with PopART, and the phylogeographical diffusion pattern was identified using a Bayesian discrete phylogeographic method.ResultsUsing phylogenetic trees made with near-complete/complete mtDNA obtained from 92 cysts from TAR patients, the Echinococcus species and genotypes infecting humans in TAR were identified as Echinococcus granulosus (s.s.) G1 (81, 88.04%), accounting for the majority, followed by G6 of the E. canadensis cluster (6, 6.52%), E. granulosus (s.s.) G3 (3, 3.26%), and E. multilocularis (2, 2.17%). An expansion trend and a possible recent bottleneck event were confirmed among the G1 samples in TAR. Adding the other near-complete mtDNA of G1 samples globally from the literature, we identified the possible phylogeographic origin of the G1 samples in TAR as Turkey.ConclusionsUsing near-complete/complete mtDNA sequences of Echinococcus spp. obtained from echinococcosis patients, a variety of Echinococcus species and genotypes infecting humans throughout TAR were identified. As far as we know, this is the first comprehensive molecular investigation of Echinococcus species and genotypes infecting humans throughout TAR. We identified, for the first time to our knowledge, the possible origin of the G1 in TAR. We also enriched the long mtDNA database of Echinococcus spp. and added two complete E. multilocularis mtDNA sequences from human patients. These findings will improve our knowledge of echinococcosis, help to refine the targeted echinococcosis control measures, and serve as a valuable baseline for monitoring the Echinococcus species and genotypes mutations and trends of the Echinococcus spp. population in TAR.Graphical

Fine-Tuning Phylogenetic Alignment and Haplogrouping of mtDNA Sequences.

In this paper, we present a new algorithm for alignment and haplogroup estimation of mitochondrial DNA (mtDNA) sequences. Based on 26,011 vetted full mitogenome sequences, we refined the 5435 original haplogroup motifs of Phylotree Build 17 without changing the haplogroup nomenclature. We adapted 430 motifs (about 8%) and added 966 motifs for yet undetermined subclades. In summary, this led to an 18% increase of haplogroup defining motifs for full mitogenomes and a 30% increase for the mtDNA control region that is of interest for a variety of scientific disciplines, such as medical, population and forensic genetics. The new algorithm is implemented in the EMPOP mtDNA database and is freely accessible.

Forensic Application of ATP6 Gene Haplogroups in a Cohort of Obese Saudis

Blood samples from 108 obese individuals (73 males and 35 females) and 106 healthy ones (79 males and27 females) were collected from a cohort of Saudis inhabiting Riyadh province. ATP6 mitochondrial genewas amplified and sequenced to identify obesity-related SNPs and the mitochondrial DNA haplogroups forforensic purposes. A novel site (A8660G) was found while C8655T and T9103C were obesity- related sites.The haplogroups H2a and H1a were common as they were found in 70.4% and 66% of obese and non-obeseindividuals, respectively. L2 was recorded in the obese samples only and H21 was recorded in the obesemales only. The J2a haplohroup was more common in obese individuals. Constructing mtDNA database forpeople inhabiting different regions of Saudi Arabia for forensic purpose and to affirm the utility of H21 andL2 in identifiying obesity is necessary.

Whole Mitochondrial Genome Analysis in Serbian Cases of Leber’s Hereditary Optic Neuropathy

Leber’s hereditary optic neuropathy (LHON) is a maternally inherited disorder that affects central vision in young adults and is typically associated with mitochondrial DNA (mtDNA) mutations. This study is based on a mutational screening of entire mtDNA in eight Serbian probands clinically and genetically diagnosed with LHON and four of their family members, who are asymptomatic mutation carriers. All obtained sequence variants were compared to human mtDNA databases, and their potential pathogenic characteristics were assessed by bioinformatics tools. Mitochondrial haplogroup analysis was performed by MITOMASTER. Our study revealed two well-known primary LHON mutations, m.11778G>A and m.3460G>A, and one rare LHON mutation, m.8836A>G. Various secondary mutations were detected in association with the primary mutations. MITOMASTER analysis showed that the two well-known primary mutations belong to the R haplogroup, while the rare LHON m.8836A>G was detected within the N1b haplogroup. Our results support the need for further studies of genetic background and its role in the penetrance and severity of LHON.

Mitochondrial DNA variation in Sub-Saharan Africa: Forensic data from a mixed West African sample, Côte d’Ivoire (Ivory Coast), and Rwanda

This study provides 398 novel complete mitochondrial control region sequences that augment the still underrepresented data from Africa by three datasets: a mixed West African sample set deriving from 12 countries (n = 145) and datasets from Côte d’Ivoire (Ivory Coast) (n = 100) as well as Rwanda (n = 153). The analysis of mtDNA variation and genetic comparisons with published data revealed low random match probabilities in all three datasets and typical West African and East African diversity, respectively. Genetic parameters indicate that the presented mixed West African dataset may serve as first forensic mtDNA control region database for West Africa in general. In addition, a strategy for responsible forensic application of precious mtDNA population samples potentially containing close maternal relatives is outlined. The datasets will be uploaded to the forensic mtDNA database EMPOP (https://empop.online) upon publication.

Whole mitochondrial genome analysis of highland Tibetan ethnicity using massively parallel sequencing

Mitochondrial DNA (mtDNA) is a key player in numerous multifaceted and intricate biological processes and plays a pivotal role in dissecting the peopling of different populations, due to its maternally inherited property and comparatively high mutation rate. In this study, 119 Tibetan individuals from the Muli Tibetan Autonomous County of China (average altitude above 3,000 m) were employed in mitochondrial genome (mitogenome) sequencing by massively parallel sequencing (MPS) techniques using the Precision ID mtDNA Whole Genome Panel on an Ion S5XL system. The dataset presented 88 distinct haplotypes, resulting in the haplotype diversity of 0.9909. The majority of haplotypes were assigned to East Asian lineages and the distribution of haplogroups of Muli Tibetan significantly differed from reference Tibetan populations. The maximum parsimony phylogeny reconstructed by 119 newly generated mitogenomes revealed 12 major Muli Tibetan lineages. Intriguingly, a Sherpa-specific sub-haplogroup A15c1 with the lack of mutations at 4216 and 15,924 was discerned in our dataset, which suggested that the maternal gene pool of Sherpas may derive from Tibetan populations. The shared haplogroups between Muli Tibetan and lowland Han Chinese hinted that these lineages may derive from non-Tibetans and have already differentiated before their arrival on the Tibetan Plateau. Furthermore, extensive pairwise population comparisons displayed that Muli Tibetan had a closer genetic relationship with ethnically or linguistically close Nyingtri Tibetan, Nyingtri Lhoba and Chamdo Tibetan populations. Genetic affinity was also observed between the Muli Tibetan and North Han Chinese. Collectively, the results generated in this study enriched the existing forensic mtDNA database and raised additional interest in the application of whole mitogenome sequencing in forensic investigations.

Whole mtGenome analysis in United Arab Emirates populations

Mitochondrial DNA analysis has earned its place in the field of genetics for providing a new window into understanding population ancestry. Its ability to produce results from minimal or decayed samples where nucleus DNA profiling proves are difficult is an additional benefit to forensic genetics. A total of 150 whole blood samples were collected on FTA paper, from Arabs population in United Arab Emirates, including inhabitants from rural regions. Both extraction of whole blood samples using PrepFiler® as well as direct amplification of mtDNA control region from purified 1.2 mm disc of FTA card stained with blood were attempted in this study. Quantity of the amplified control region was estimated using gel electrophoresis. Three sets of primers were used afterward to sequence purified products of amplified control region of mtDNA using Sanger sequencing method. 150 mtGenome sequences were obtained for UAE Arabs population, generated using MPS technology – Ion™ 5S. Concordance with control region sequences obtained using Sanger Sequencing approach was investigated. Resulted haplotypes were compared against worldwide mtDNA database (EMPOP) and estimated haplotypes frequency is shown in this study. As a forensic lab, non-probative challenging bone samples were tested to highlight the potentials value of using MPS technology – Ion™ 5S. This study shows the first mtGenome data generated for UAE Arabs population which helps extending the current available mtDNA control region database. As a result, this study shows great value of implementing MPS in the routine work in forensic genetics at Dubai Police.

The maternal inheritance of the Ashaninka native group from Peru

The Amazonia rainforest, in South America, harbours native populations with high ethnic diversity. The evaluation of the genetic composition of these populations represents a challenge, and only few studies are available describing its native groups. In this work, the maternal inheritance of 170 Ashaninka individuals living in the Amazonia region of Pasco department, Peru, was evaluated by mtDNA control region sequencing. As previously observed for other native groups from Amazonia, low haplotype diversity was obtained, and only Native American haplogroups were found. Strong founder effects were observed, especially for sub haplogroups A2aa, B2b+152, C1b and D1. During the European colonial period, the Ashaninka population seems to have remained relatively isolated, which can be explained by its remote location in the tropical forest. A comparison with other native South American populations from different linguistic families showed a lack of geographic or linguistic affiliations, highlighting the importance of having specific mtDNA database for the native groups in South America.

A view of the maternal inheritance of Espírito Santo populations: The contrast between the admixed and Pomeranian descent groups

In addition to its valuable utility in forensic investigations, mitochondrial DNA (mtDNA) analysis is a reliable tool to uncover the origins of admixed populations, such as Brazilians. The state of Espírito Santo (ES), similar to other coastal Brazilian states, has a population shaped by 3 main ancestral roots: Amerindian, African and European. Among the latter, the Pomeranian descendants stand out due to the preservation of the traditional aspects of their culture, especially the Pomeranian language. Despite the genetic data already available, there is no mtDNA database that adequately reflects the diversity, the geographic distribution, and the origins of the maternal lineages from ES. To increase the knowledge of maternal ancestry and to investigate the population’s genetic stratification, a total of 291 samples were collected in the 4 macroregions (Metropolitan, South, Central and North) of ES and in the Pomeranian communities. Complete control region data were produced for the general (N=214) and Pomeranian (N=77) groups. Regarding the general population, the high values of haplotype diversity (H=99.9%) and pairwise differences (MNPD=16.9) found are in agreement with those reported for other populations in the southeast region of the country. Regarding maternal inheritance, the ES populations stood out due to the predominance of European haplogroups (49.5%), although the North macroregion had a higher African ancestry (47.1%). Among the Pomeranians, the lowest MNPD value (11.2) and the high percentage of shared haplotypes (15%) were indicative of founder events. The FST analysis showed that the Pomeranians (98.7% of European lineages) are genetically isolated from the other admixed populations in Brazil. This study demonstrated that the ES state contains singularities regarding the intrapopulational and interpopulational diversity of mtDNA. Even after 5 centuries of interethnic admixture, the present-day population of Espírito Santo harbors genetic marks that trace back to the historical aspects of its formation.

Combining ultraconserved elements and mtDNA data to uncover lineage diversity in a Mexican highland frog (Sarcohyla; Hylidae).

Molecular studies have uncovered significant diversity in the Mexican Highlands, leading to the description of many new endemic species. DNA approaches to this kind of species discovery have included both mitochondrial DNA (mtDNA) sequencing and multilocus genomic methods. While these marker types have often been pitted against one another, there are benefits to deploying them together, as linked mtDNA data can provide the bridge between uncovering lineages through rigorous multilocus genomic analysis and identifying lineages through comparison to existing mtDNA databases. Here, we apply one class of multilocus genomic marker, ultraconserved elements (UCEs), and linked mtDNA data to a species complex of frogs (Sarcohyla bistincta, Hylidae) found in the Mexican Highlands. We generated data from 1,891 UCEs, which contained 1,742 informative SNPs for S. bistincta and closely related species and captured mitochondrial genomes for most samples. Genetic analyses based on both whole loci and SNPs agree there are six to seven distinct lineages within what is currently described as S. bistincta. Phylogenies from UCEs and mtDNA mostly agreed in their topologies, and the few differences suggested a more complex evolutionary history of the mtDNA marker. Our study demonstrates that the Mexican Highlands still hold substantial undescribed diversity, making their conservation a particularly urgent goal. The Trans-Mexican Volcanic Range stands out as a significant geographic feature in Sarcohyla and may have acted as a dispersal corridor for S. bistincta to spread to the north. Combining multilocus genomic data with linked mtDNA data is a useful approach for identifying potential new species and associating them with already described taxa, which will be especially important in groups with undescribed subadult phenotypes and cryptic species.

Next generation database search algorithm for forensic mitogenome analyses

Mitochondrial DNA (mtDNA) variation is being reported relative to the corrected version of the first sequenced human mitochondrial genome. A review of the existing literature across disciplines that employ mtDNA demonstrates that insertions and deletions are not reported in a standardized way. This may lead to false exclusions of identical sequences, unidentified matches in missing persons mtDNA databases, biased mtDNA database frequency estimates and overestimation of the genetic evidence. Seven years ago we introduced alignment-free database search software (SAM) and implemented it into the mtDNA database EMPOP (https://empop.online) to produce reliable and conservative frequency estimates that are required in the forensic context. However, ambiguity remained in how laboratories have been reporting mitotypes, as often more than one single alignment of a given mtDNA sequence was feasible. In order to overcome this limitation we here describe a concept and provide software for producing stable, harmonized phylogenetic alignment of mtDNA sequences for database searches. The new software SAM 2 will be made available via EMPOP and provide the user with the already established conservative frequency estimates. In addition, SAM 2 offers the rCRS-coded haplotype of a given mtDNA sequence following the established and widely accepted phylogenetic alignment. This provides the user with feedback on how mitotypes are stored in EMPOP and how they should be reported in order to harmonize nomenclature. Finally, this approach does not only permit reliable mtDNA nomenclature in forensics but invites related disciplines to take advantage of a standardized way of reporting mtDNA variation, thus closing the ranks between different genetic fields and supporting dialogue and collaboration between mtDNA scholars from various disciplines.

Mitochondrial DNA control region diversity in a population from Parana state-increasing the Brazilian forensic database.

The entire mitochondrial DNA (mtDNA) control region (nucleotide position 16024-576) sequences were obtained through Sanger sequencing method for 122 individuals from Parana state, South of Brazil. We observed a total of 108 different haplotypes of which 97 were unique and 11 were shared by more than one individual. The haplogroups were classified according to the updated mtDNA phylogeny, by EMMA (estimating mitochondrial haplogroups using a maximum likelihood approach). Our results revealed the predominance of Amerindian haplogroups with a frequency of 49.2% of the population sample, followed by European lineages with 38.5% and 12.3% of African lineages. Parana population sample set presented a high haplotype diversity (0.9976) and the random match probability was 0.0106. The phylogenetical findings and the diversity indices confirm the high genetic heterogeneity of this population and suggest a high informativeness of mtDNA analyses in forensic cases. The population data will contribute to increase the Brazilian mtDNA database for forensic purposes and it is available through EMPOP (European DNA Profiling Group mitochondrial DNA population database) under the accession number EMP00714.

The Highest Mutation in mtDNA Hypervariable Region and Application of Biostatistics with Nucleotide Base X t-n in Determining the Identity of the Mutation through a Transition Intensity Matrix

Human mitochondrial DNA (mtDNA) have been used intensively in the field of forensic identification of victims or suspects of crime through biological evidence. The number of mtDNA molecules in a single cell are in the tens of thousands which enable analysis of samples very little or damaged. Till now there is no standard method for identification using mtDNA in a mass disaster victims such as natural disasters, wars and accidents so that the identification process can not run fast. This study found C16.223t variants in mtDNA sequences that can be used to divide the database into two groups so as to accelerate the process of identification through a mathematical algorithm. This variant has the highest frequency (29.7%) of the 91 polymorphic human mtDNA HVS1 along the 300 nucleotide (16,024-16,324) derived from the NCBI database as much as 142 sequences. MtDNA sequences obtained from data collection Papuan human mtDNA groups that have been published in the NCBI. The next variant that can be used as a classifier in a row in the sequence is 16,311; 16,304; 16,189; and 16,270 with the identity (T→c). For a matrix Q is reversible so the matrix and could have the opposite diagonal. Thus the above equation can be solved by using the diagonal method that can be written: U³ = Uµ רUµ aµ†1 . This equation could count the number of transitions and transversion substitution mutations that occur in a nucleotide sequence of mtDNA. With this grouping, the database can be reduced so as to accelerate the process of identification of samples. Expected method of grouping by the variant with the highest frequency can be developed in the codification database for forensic interest such as the police or the mtDNA database purposes of study anthropology and evolutionary biology.

The mitochondrial landscape of African Americans: An examination of more than 2500 control region haplotypes from 22 U.S. locations

The mitochondrial DNA (mtDNA) control region (16024-576) was Sanger-sequenced for a total of 2563 self-identified African Americans, using automated processing techniques and data review standards exceeding guidelines for forensic applications. Genetic diversity ranged from 0.9952 to 0.9998 in 22 population samples from 20 different states.Haplogroups of African ancestry, found in 82.48% of individuals overall, were most concentrated in the Southeast U.S. and decreased to the north and west. West African and West Central African haplotypes were well-represented in the population samples, especially in the southern U.S. states, while East African haplogroups were observed in low-frequency clusters in a handful of locations across the country. East Asian, Native American, and West Eurasian admixture was present in 3.16%, 2.93%, and 11.43% of samples, respectively. While some geographic substructure was detected across the population samples as clines in admixture frequencies, 20 of the 22 population samples were found to be statistically indistinguishable by pairwise comparisons and AMOVA calculations. Datasets from Hawaii and Idaho, however, were clear outliers. Overall, these more than 2500 control region sequences represent the most comprehensive regional sampling of African American mtDNA diversity to date, and are suitable for use in a forensic mtDNA database. The population data are made available via EMPOP (www.empop.org) and GenBank.

Population and forensic genetic analyses of mitochondrial DNA control region variation from six major provinces in the Korean population

We generated complete mitochondrial DNA (mtDNA) control region sequences from 704 unrelated individuals residing in six major provinces in Korea. In addition to our earlier survey of the distribution of mtDNA haplogroup variation, a total of 560 different haplotypes characterized by 271 polymorphic sites were identified, of which 473 haplotypes were unique. The gene diversity and random match probability were 0.9989 and 0.0025, respectively. According to the pairwise comparison of the 704 control region sequences, the mean number of pairwise differences between individuals was 13.47±6.06. Based on the result of mtDNA control region sequences, pairwise FST genetic distances revealed genetic homogeneity of the Korean provinces on a peninsular level, except in samples from Jeju Island. This result indicates there may be a need to formulate a local mtDNA database for Jeju Island, to avoid bias in forensic parameter estimates caused by genetic heterogeneity of the population. Thus, the present data may help not only in personal identification but also in determining maternal lineages to provide an expanded and reliable Korean mtDNA database. These data will be available on the EMPOP database via accession number EMP00661.

P17.51 * FUNCTIONAL PREDICTION OF MITOCHONDRIAL DNA MUTATIONS IN GLIOBLASTOMA MULTIFORME

Gliobastoma multiforme (GBM) is the most common adult primary brain tumour. It is highly malignant with fewer than half of patients surviving for over one year following diagnosis. One reason for this is its highly heterogeneous nature, which renders the current standard-of-care treatment of surgical resection, radiotherapy, and temozolomide (TMZ) chemotherapy inadequate. Altered metabolism is a hallmark of cancer compared to non-cancer cells and central to this are mitochondria, which contain their own multi-copy circular DNA (mtDNA). At the heart of every mitochondrion is a collection of five large protein machines known as the respiratory chain (RC). The RC consists of approximately 70 subunits. MtDNA-encodes thirteen of the core catalytic subunits that form the RC. Variations in mtDNA can therefore directly affect metabolism and contribute to the pathology of numerous human diseases, including cancer. The acquisition of TMZ-resistance and decreased overall survival in GBM patients has been linked to altered RC activity but the contribution of mtDNA variations to this remains unexplored. To address this we have employed a novel dual approach for (1) discovering and (2) predicting the function of mtDNA variations in GBM patients using a combination of long PCR and next generation sequencing and 3D structural analysis, respectively. We have generated a set of 10 high quality mtDNAs each from GBM-biopsy derived cells with a mean depth of coverage per nucleotide of over 22,000. This enabled a total of 193 mtDNA variations to be detected, including those present at less than 1% heteroplasmy. Twenty five of these variations caused non-synonymous amino acid substitutions (AAS) in mtDNA-encoded Complex III and IV proteins. Using 3D structural analysis, we predict that 8 of these are highly likely to be functional, occurring in RC active sites, substrate/drug binding pockets and protein-protein interaction regions. The latter class will affect the assembly and stability of the RC complexes. All functional candidates were absent from the non-neoplastic astrocytic control, and mining the human mtDNA database revealed the majority never, or very rarely, occur in healthy subjects. Long PCR and next generation sequencing provides a high throughput, cost effective and sensitive method for detecting mtDNA variations in GBM. While 3D structural analysis reveals considerable insight into the functional role of mtDNA variations, including how they could affect metabolism and contribute to the differential survival and chemosensitivity of individual patients. This study forms an important first step towards determining the functional and clinical significance of mtDNA variations in GBM. The next step will be to validate the functional and clinical significance of the candidate variations so that better predictors of outcomes and more personalised therapies can be developed for patients in the future.

Mitochondriome and cholangiocellular carcinoma.

Cholangiocellular carcinoma (CCA) of the liver was the target of more interest, recently, due mainly to its increased incidence and possible association to new environmental factors. Somatic mitochondrial DNA (mtDNA) mutations have been found in several cancers. Some of these malignancies contain changes of mtDNA, which are not or, very rarely, found in the mtDNA databases. In terms of evolutionary genetics and oncology, these data are extremely interesting and may be considered a sign of poor fitness, which may conduct in some way to different cellular processes, including carcinogenesis. MitoChip analysis is a strong tool for investigations in experimental oncology and was carried out on three CCA cell lines (HuCCT1, Huh-28 and OZ) with different outcome in human and a Papova-immortalized normal hepatocyte cell line (THLE-3). Real time quantitative PCR, western blot analysis, transmission electron microscopy, confocal laser microscopy, and metabolic assays including L-Lactate and NAD+/NADH assays were meticulously used to identify mtDNA copy number, oxidative phosphorylation (OXPHOS) content, ultrastructural morphology, mitochondrial membrane potential (ΔΨm), and differential composition of metabolites, respectively. Among 102 mtDNA changes observed in the CCA cell lines, 28 were non-synonymous coding region alterations resulting in an amino acid change. Thirty-eight were synonymous and 30 involved ribosomal RNA (rRNA) and transfer RNA (tRNA) regions. We found three new heteroplasmic mutations in two CCA cell lines (HuCCT1 and Huh-28). Interestingly, mtDNA copy number was decreased in all three CCA cell lines, while complexes I and III were decreased with depolarization of mitochondria. L-Lactate and NAD+/NADH assays were increased in all three CCA cell lines. MtDNA alterations seem to be a common event in CCA. This is the first study using MitoChip analysis with comprehensive metabolic studies in CCA cell lines potentially creating a platform for future studies on the interactions between normal and neoplastic cells.

Mitochondrial DNA haplogroups and homogeneity in the Korean population

Mitochondrial DNA (mtDNA) haplogroup data provide valuable information for inferring patterns of variation and population structure of maternal lineages. In this study, we analyzed the distribution of mtDNA haplogroup variation using a 20-plex SNaPshot assay for determination of the major East Asian haplogroups to evaluate the possible genetic structure and differentiation from 708 unrelated individuals residing in six major provinces in Korea. The most common mtDNA haplogroups were found to be D4 and B4, followed by A, D4a, and M7, which are prevalent in East Asian populations. All provinces exhibited high haplogroup diversities, ranging from 0.8957 in Jeju Island to 0.9284 in Gyeongsang. Pair-wise F ST distances and AMOVA of the studied Korean provinces reflected no maternal subpopulation heterogeneity present within the population group, except for Jeju Island, showing small, but statistically significant differences between the populations (p < 0.01). This result indicates that the Jeju Island may point to the need for creating a local mtDNA database, to avoid bias in forensic parameters estimates caused by genetic heterogeneity of the population. However, since there is no geographic pattern to suggest this result represents any population heterogeneity on a peninsular level in Korea, the present data could be useful in serving as a basis for comprehensive Korean population and forensic mtDNA database.