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At least 577 records · Page 32Linked to original sources
PubMed2002

[Effects of mtDNA deletion associated with abnormal expression in rat cochlear with presbycusis].

OBJECTIVE: To investigate the effects of the common deletion (4834-bp) of mitochondrial DNA (mtDNA) in rat cochlear with presbycusis. METHODS: The mtDNA 4834-bp deletion was analyzed by PCR. The mitochondrial-encoded cytochrome c oxidase subunit I (COXI) transcript level and cytochrome c oxidase (COX) activity were measured by RT-PCR and histochemical methods respectively. RESULTS: The 4834-bp deletion occurred in all the senescent rat cochlear. The COXI transcript level was decreased associated with the decline of COX activity. CONCLUSION: The mtDNA 4834-bp deletion presented in the rat cochlear with presbycusis, which lead to the decrease of COXI transcript level and COX activity, may play an important role in the pathogens of presbycusis.

Animals↗
PubMed2003

[MtDNA and Y-chromosome lineages in the Yakut population].

The structure of female (mtDNA) and male (Y-chromosome haplotypes) lineages in the Yakut population was examined. To determine mtDNA haplotypes, sequencing of hypervariable segment I and typing of haplotype-specific point substitutions in the other parts of the mtDNA molecule were performed. Y haplogroups were identified through typing of biallelic polymorphisms in the nonrecombining part of the chromosome. Haplotypes within haplogroups were analyzed with seven microsatellite loci. Mitochondrial gene pool of Yakuts is mainly represented by the lineages of eastern Eurasian origin (haplogroups A, B, C, D, G, and F). In Yakuts haplogroups C and D showing the total frequency of almost 80% and consisting of 12 and 10 different haplopypes, respectively, were the most frequent and diverse. The total part of the lineages of western Eurasian origin ("Caucasoid") was about 6% (4 haplotypes, haplogroups H, J, and U). Most of Y chromosomes in the Yakut population (87%) belonged to haplogroup N3 (HG16), delineated by the T-C substitution at the Tat locus. Chromosomes of haplogroup N3 displayed the presence of 19 microsatellite haplotypes, the most frequent of which encompassed 54% chromosomes of this haplogroup. Median network of haplogroup N3 in Yakuts demonstrated distinct "starlike phylogeny". Male lineages of Yakuts were shown to be closest to those of Eastern Evenks.

Asian People↗
PubMed2004

A novel mtDNA point mutation in tRNA(Val) is associated with hypertrophic cardiomyopathy and MELAS.

BACKGROUND: Pathological mutations of mitochondrial (mt) DNA may cause specific diseases such as cardiomyopathies or hearing loss, or syndromes such as mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode (MELAS) syndrome. We describe a novel mtDNA mutation in a patient with severe hypertrophic cardiomyopathy associated with MELAS. The familial phenotype included 1) hypertrophic cardiomyopathy and MELAS, 2) clinically mild cardiac hypertrophy, and 3) deafness. METHODS: The proband and her first degree relatives underwent echo and electrocardiograms, and biochemical tests. Magnetic resonance imaging of the brain was performed in the proband. mtDNA was fully analyzed by sequencing. DNA purification, polymerase chain reaction and direct automated sequencing were performed following standard procedures. Heteroplasmy of the novel mutation was quantified by densitometric analysis. RESULTS: A novel G1644A transition affecting the tRNA(Val) was identified in the proband and maternal relatives. The mutation has been interpreted as pathological because the G at the 1644 position is a highly conserved base, is heteroplasmic with higher levels of mutant DNA in the proband than in the relatives, is located in the unique tRNA(Val), is very close to a mutation described as causative of MELAS, and finally has not been found in 100 healthy controls. CONCLUSIONS: Although it is rare for patients with MELAS to be referred to cardiological evaluation because of coexisting cardiomyopathy, cardiologists should be aware of this association as well as of the non cardiac signs that may address the diagnosis to mtDNA defect-related disease in families with a variable phenotype.

Adult↗
PubMed2004

[Sequence polymorphism of mtDNA HV1, HV2 overlapping fragments and coding region 8430-8673nt in Han population of Hebei province].

OBJECTIVE: To investigate the sequence polymorphism of mtDNA HV1,HV2 overlapping fragments and coding region encompassing position 8430-8673 in Hebei Han population. METHODS: Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) combined with sequencing method was used to detect the haplotype distribution of mtDNA in 100 Hebei Han individuals. RESULTS: Ninety-one haplotypes were noted in 100 unrelated individuals. The gene diversity is 0.9985 and the random match probability is 0.0115. Compared with the Anderson sequence, 65 sites of different nucleotide sequences were noted, of which 44 sites were previously registered in MITOMAP, 12 sites were not registered and the gene mutations were different from MITOMAP at 9 positions. CONCLUSION: The obtained data suggest that these loci are valuable genetic markers for personal identification and thus could be used as basic data for the forensic application of mtDNA in Hebei province.

China↗
PubMed2005

mtDNA investigations after differential lysis.

In order to gain information regarding the ethnic origin of an unknown offender in a murder case it was necessary to sequence the HV1 and 2 regions of the mitochondrial DNA (mtDNA). The only evidentiary material that could be linked to the suspect was DNA, extracted from spermatozoa after differential lysis. The observed mtDNA sequences were identical to the sequences of the victim. Therefore, we had to check if this was a coincidence or the result of a technical limitation of the testing procedure. Subsequently, we performed a systematic study. In cases with complete separation of sperm and female cells it wasn't possible to obtain a mtDNA sequence for the sperm fraction. This phenomena is based on the loss of the sperm's flagellum and mid-piece during the first lysis step and a concomitant loss of the sperm's mitochondria. In our murder case, a minor carry-over of female cells to the sperm fraction was responsible for the sequencing result.

Chromosomes, Human, Y↗
PubMed2005

[The effect of marriage migration on the genetic structure of the Taimyr Nganasan population: genealogical analysis inferred from MtDNA markers].

The marriage structure of Nganasans during the time period from 1796 to 1991 and genealogy of carriers of mitochondrial DNA haplotypes was studied in a sample of 280 individuals. It was shown that, from the beginning of its formation to the late 1970s, the population exhibited high endogamy (1976, 83.8%; 1926, 88.4%; 1976, 74.3%). The main source of traditional marriage migration (preferentially female) was populations of Entsy and, indirectly, Nentsy. Intense assimilation of Nganasans by the immigrant population, and to a lesser extent, by Dolgans, in the second half of the 20th century resulted in a reduction of endogamy index in Avam Nganasans to 42.5% by 1991. Assimilation by the immigrants was predominantly paternal, promoting preservation of the historically formed genetic diversity of the Nganasan mitochondrial gene pool. Genealogical analysis of mtDNA haplotypes showed that a relatively high total frequency of Western Eurasian mtDNA haplogroups (20.4%) in the Mongoloid (according to anthropological type) Nganasan population is explained not only by the common ethnic origin with Entsy and Nentsy, but also by direct marriage migration from the Entsy population and indirect marriage migration, from the Nentsy population. This migration led to accumulation of Entsy-Nentsy maternal lineages in the genealogy of Avam Nganasans (38.9% of the total number). Of all mtDNA haplotypes, 28.6% were introduced to Avam Nganasans by female Entsy and Nentsy, whereas the total frequency of these haplotypes was 0.204. Genetic diversity of mitochondrial DNA haplotypes was 0.935.

DNA, Mitochondrial↗
PubMed2006

[Large-scale screening of mtDNA A1555G mutation in China and its significance in prevention of aminoglycoside antibiotic induced deafness].

OBJECTIVE: To explore the necessity of large-scale screening of mtDNA A1555G mutation in prevention of aminoglycoside antibiotic induced deafness (AAID) and to develop a feasible method to prevent AAID. METHODS: A total of 1836 patients with non-syndromic hearing impairment (NSHI), 1352 students of schools for deaf-mutes in 11 provinces and municipality in China, 413 out-patients, and 71 persons from the families with maternal relatives suffering from AAID, underwent questionnaire survey and/or PCR for A-to-G mutation at nucleotide 1555 of the mitochondrial genome. RESULTS: Sixty three patients with mtDNA A1555G mutation were found among the 1836 NSHI patients. Fifty-two maternal pedigrees were identified. 536 cases with normal hearing from these pedigrees were informed to avoid using aminoglycoside antibiotics (AmAn). CONCLUSION: Large-scale screening of mtDNA A1555G mutation and relevant health education to avoid use of AmAn are effective to prevent ototoxicity in the A1555G carriers and their maternal relatives.

Adolescent↗
PubMed2006

[The application of PCR-SSCP in forensic mtDNA typing].

OBJECTIVE: To study the application of PCR-SSCP in forensic mtDNA typing. METHODS: Primers flanking the mtDNA HV-I and HV-II regions were designed. By PCR-SSCP techniques, 70 family trios and 140 unrelated Wuhan Han individuals were investigated and analyzed. RESULTS: In 70 family trios, the SSCP profiles in region HV-I and HV-II of children were not same to that of their fathers in 98.57% and 97.13% respectively but were identical with their mothers. In 140 unrelated Wuhan Han individuals, 21 haplotypes were found in HVI, GD = 0.9556; 16 haplotypes were found in HVII, GD = 0.9356. CONCLUSION: PCR-SSCP technique may be useful in forensic mtDNA typing, especially for screening the suspects.

DNA Fingerprinting↗
PubMedDate not supplied

[Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) with the A3243G mutation of the tRNALeu(UUR) gene of mtDNA in native American haplogroup B2].

INTRODUCTION: Mitochondrial encephalopathy, lactic acidosis and cerebrovascular accident syndrome (MELAS) is, from the clinical point of view, one of the best studied mitochondrial multisystemic disorders. This disease has mainly been associated to the mitochondrial desoxyribonucleic acid (mtDNA) mutation A3243G located in the tRNALeu(UUR) gene. Although a relation between European haplogroups and the presence of the 3243 mutation has not been described, nothing is known about the presence of this mutation in native American haplogroups. CASE REPORT: A 12 year-old female Mexican patient diagnosed with MELAS is reported. Besides neurological, biochemical and cytological examination, we also analyzed the particular mtDNA mutations related to MELAS and the whole genome was sequenced to determine the mitochondrial haplogroup. The A3243G mutation was detected in the patient and maternal relatives (mother and siblings, all of them asymptomatic). The genotype corresponds to the native American haplogroup B2 and contains two private non-synonymous polymorfisms. CONCLUSION: All the members of the family studied present different percentage of the A3243G mutation, being the patient who presented the highest value. The mtDNA genotype corresponds to the native American haplogroup B2 and the private polymorphisms do not confer any phenotypic modification in MELAS syndrome.

Child↗
PubMed1991

[Studies on mtDNA of Ustilago maydis. II. Restriction mapping].

A restriction map was constructed for mtDNA of Ustilago maydis. The fragment order for each restriction enzyme was determined by DNA hybridization and fragment overlapping. The restriction sites were located by analysing the secondary digestions of the cloned mtDNA fragments. It was also found that the mtDNA of U. maydis was a circle molecule (60.7 kb), without recognizable repeat sequence.

DNA, Mitochondrial↗
PubMedDate not supplied

Genetic rearrangements of plasmids containing mtDNA inserts: possible poison sequence.

Restriction mapping of recombinant plasmids indicated the presence of poison sequence(s) in monkey mtDNA. These plasmids were constructed from a 5.2 K.b. BglII mtDNA fragment and pRSVneo or pdel9 as cloning vectors. The poison sequence(s) caused genetic rearrangement of the vectors' nucleotide sequences. Deletion of the suspected poison sequence(s) from the mtDNA fragment increased the transformation efficiency of the produced recombinant plasmids and conserved the vectors' original nucleotide sequences.

Animals↗
PubMed1995

Polynesian genetic affinities with Southeast Asian populations as identified by mtDNA analysis.

Polynesian genetic affinities to populations of Asia were studied using mtDNA markers. A total of 1,037 individuals from 12 populations were screened for a 9-bp deletion in the intergenic region between the COII and tRNA(Lys) genes that approaches fixation in Polynesians. Sequence-specific oligonucleotide probes that identify specific mtDNA control region nucleotide substitutions were used to describe variation in individuals with the 9-bp deletion. The 9-bp deletion was not observed in northern Indians, Bangladeshis, or Pakistanis but was seen at low to moderate frequencies in the nine other Southeast Asian populations. Three substitutions in the control region at positions 16217, 16247, and 16261 have previously been observed at high frequency in Polynesian mtDNAs; this "Polynesian motif" was observed in 20% of east Indonesians with the 9-bp deletion but was observed in only one additional individual. mtDNA types related to the Polynesian motif are highest in frequency in the corridor from Taiwan south through the Philippines and east Indonesia, and the highest diversity for these types is in Taiwan. These results are consistent with linguistic evidence of a Taiwanese origin for the proto-Polynesian expansion, which spread throughout Oceania by way of Indonesia.

Asia, Southeastern↗
PubMed1994

mtDNA and Y-chromosome polymorphisms in four Native American populations from southern Mexico.

mtDNA sequence variation was examined in 60 Native Americans (Mixtecs from the Alta, Mixtecs from the Baja, Valley Zapotecs, and Highland Mixe) from southern Mexico by PCR amplification and high-resolution restriction endonuclease analysis. Four groups of mtDNA haplotypes (haplogroups A, B, C, and D) characterize Amerind populations, but only three (haplogroups A, B, and C) were observed in these Mexican populations. The comparison of their mtDNA variation with that observed in other populations from Mexico and Central America permits a clear distinction among the different Middle American tribes and raises questions about some of their linguistic affiliations. The males of these population samples were also analyzed for Y-chromosome RFLPs with the probes 49a, 49f, and 12f2. This analysis suggests that certain Y-chromosome haplotypes were brought from Asia during the colonization of the Americas, and a differential gene flow was introduced into Native American populations from European males and females.

DNA, Mitochondrial↗
PubMed1996

An autosomal locus predisposing to multiple deletions of mtDNA on chromosome 3p.

Autosomal dominant progressive external ophthalmoplegia (adPEO) is a disorder characterized by ptosis, progressive weakness of the external eye muscles, and general muscle weakness. The patients have multiple deletions of mtDNA on Southern blots or in PCR analysis of muscle DNA and a mild deficiency of one or more respiratory-chain enzymes carrying mtDNA-encoded subunits. The pattern of inheritance indicates a nuclear gene defect predisposing to secondary mtDNA deletions. Recently, in one Finnish family, we assigned an adPEO locus to chromosome 10q 23.3-24.3 but also excluded linkage to this same locus in two Italian adPEO families with a phenotype closely resembling the Finnish one. We applied a random mapping approach to informative non-10q-linked Italian families to assign the second locus for adPEO and found strong evidence for linkage on chromosome 3p 14.1-21.2 in three Italian families, with a maximum two-point lod score of 4.62 at a recombination fraction of .0. However, in three additional families, linkage to the same chromosomal region was clearly absent, indicating further genetic complexity of the adPEO trait.

Adult↗
PubMed1996

mtDNA variation in the Yanomami: evidence for additional New World founding lineages.

Native Americans have been classified into four founding haplogroups with as many as seven founding lineages based on mtDNA RFLPs and DNA sequence data. mtDNA analysis was completed for 83 Yanomami from eight villages in the Surucucu and Catrimani Plateau regions of Roraima in northwestern Brazil. Samples were typed for 15 polymorphic mtDNA sites (14 RFLP sites and 1 deletion site), and a subset was sequenced for both hypervariable regions of the mitochondrial D-loop. Substantial mitochondrial diversity was detected among the Yanomami, five of seven accepted founding haplotypes and three others were observed. Of the 83 samples, 4 (4.8%) were lineage B1, 1 (1.2%) was lineage B2, 31 (37.4%) were lineage C1, 29 (34.9%) were lineage C2, 2 (2.4%) were lineage D1, 6 (7.2%) were lineage D2, 7 (8.4%) were a haplotype we designated "X6," and 3 (3.6%) were a haplotype we designated "X7." Sequence analysis found 43 haplotypes in 50 samples. B2, X6, and X7 are previously unrecognized mitochondrial founding lineage types of Native Americans. The widespread distribution of these haplotypes in the New World and Asia provides support for declaring these lineages to be New World founding types.

Adult↗
PubMed1997

A new mtDNA mutation showing accumulation with time and restriction to skeletal muscle.

We have identified a new mutation in mtDNA, involving tRNALeu(CUN) in a patient manifesting an isolated skeletal myopathy. This heteroplasmic A-->G transition at position 12320 affects the T psi C loop at a conserved site and was not found in 120 controls. Analysis of cultured fibroblasts, white blood cells/platelets, and skeletal muscle showed that only skeletal muscle contained the mutation and that only this tissue demonstrated a biochemical defect of respiratory-chain activity. In a series of four muscle-biopsy specimens taken over a 12-year period, there was a gradual increase, from 70% to 90%, in the overall level of mutation, as well as a marked clinical deterioration. Single-fiber PCR confirmed that the proportion of mutant mtDNA was highest in cytochrome c oxidase-negative fibers. This study, which reports a mutation involving tRNALeu(CUN), demonstrates clearly that mtDNA point mutations can accumulate over time and may be restricted in their tissue distribution. Furthermore, clinical deterioration seemed to follow the increase in the level of mutation, although, interestingly, the appearance of fibers deficient in respiratory-chain activity showed a lag period.

Base Sequence↗
PubMed1997

[The correlation of the heteroplasmy of mtDNA and clinicopathological findings in the patients with mitochondrial encephalomyopathies].

In most cases of the mitochondrial encephalomyopathies, the mutations of mtDNA usually appear in heteroplasmic states. The degree of mtDNA heteroplasmy has been suggested to play an important role in determining the clinical phenotype and the organ-specific defects. We had devised a novel method for quantitative analysis of heteroplasmy using PCR-SSCP, this method is useful to accurately quantitate heteroplasmy of very small amount of samples. Using this method, we analyzed the heteroplasmy of skeletal muscle or leucocyte from 12 cases of MERRF and 5 cases of MELAS. And we analyzed autopsied cases (2 MERRF and 2 MELAS patients), and the cellular or organellar distributions of heteroplasmy of CNS in MERRF patients, and discussed the correlation of heteroplasmy of mtDNA and clinicopathological findings.

Adolescent↗
PubMed1998

Siberian population of the New Stone Age: mtDNA haplotype diversity in the ancient population from the Ust'-Ida I burial ground, dated 4020-3210 BC by 14C.

On the basis of analysis of mtDNA from skeletal remains, dated by 14C 4020-3210 BC, from the Ust'-Ida I Neolithic burial ground in Cis-Baikal area of Siberia, we obtained genetic characteristics of the ancient Mongoloid population. Using the 7 restriction enzymes for the analysis of site's polymorphism in 16,106-16,545 region of mtDNA, we studied the structure of the most frequent DNA haplotypes, and estimated the intrapopulational nucleotide diversity of the Neolithic population. Comparison of the Neolithic and modern indigeneous populations from Siberia, Mongolia and Ural showed, that the ancient Siberian population is one of the ancestors of the modern population of Siberia. From genetic distance, in the assumption of constant nucleotide substitution rate, we estimated the divergence time between the Neolithic and the modern Siberian population. This divergence time (5572 years ago) is conformed to the age of skeletal remains (5542-5652 years). With use of the 14C dates of the skeletal remains, nucleotide substitution rate in mtDNA was estimated as 1% sequence divergence for 8938-9115 years.

Asian People↗