Mitochondrial DNA polymorphisms in Nepalese Achhami cattle

Achhami cattle is claimed to be the world's smallest cattle which is found in Achham district of Sudur Paschim Province of Nepal. A study was carried out to investigate the polymorphism in the control region of the mitochondrial DNA polymorphism in these Achhami cattle. Thirty-seven blood samples were collected from different pocket areas of in Achham district. Our study revealed that Achhami cattle lie significantly within the indicine haplogroups rather than taurine (34 out of 37 samples) manifesting the later introgression by taurine cattle population. The taurine haplogroup, found within Achhami was different than Lulu cattle, which might be from the independent domestication event. Within indicine haplogroup, I1 type haplogroup (64.7%) was found dominant over I2 type haplogroup (35.3%). Achhami cattle revealed its uniqueness as it segregates from Indian cattle for indicine type as well as Chinese cattle for taurine type. In order to understand its ancestry, the whole genome should be studied together with the consideration of more population of cattle from the Asian region. Bang. J. Anim. Sci. 2020. 49 (1): 22-28

Genetic markers on the distribution of ancient marine hunters in Priokhotye

This is a review of studies on the genetic polymorphism of modern and ancient populations of the north of Asia and America, with the aim of reconstructing the history of migrations of ancient marine hunters in the Okhotsk Sea region. The data on mitochondrial DNA polymorphism and the “Arctic” mutation distribution – the rs80356779-A variant of the CPT1A gene – were analyzed. It is known that the “Arctic” variant of the CPT1A gene is widely distributed in modern populations of the Eskimos, Chukchis, Koryaks, and other peoples of the Okhotsk Sea region, whose economic structure is associated with marine hunting. According to paleogenomic data, the earliest cases of the “Arctic” variant of the CPT1A gene were found in the Greenland and Canadian Paleoeskimos (4 thousand years ago), among representatives of the Tokarev culture of the Northern Priokhotye (3 thousand years ago), and among the bearers of the culture of the late Jomon of Hokkaido (3.5–3.8 thousand years ago). The results of the analysis revealed several migration events associated with the spread of marine hunters in the Okhotsk Sea region. The latest migration, which left traces on bearers of the Epi-Jomon culture (2.0–2.5 thousand years ago), introduced the mitochondrial haplogroup G1b and the “Arctic” variant of the CPT1A gene from the north of Priokhotye to Hokkaido and neighboring territories of the Amur Region. Traces of earlier migration, which also brought the “Arctic” mutation, were recorded in the Hokkaido population of the late Jomon period (3.5–3.8 thousand years ago). A phylogenetic analysis of mitochondrial genomes belonging to the rare haplogroup C1a, found in populations of the Far East and Japan, but phylogenetically related to the C1-haplogroups of the Amerindians, was carried out. The results of the analysis showed that the divergence of mitochondrial lineages within the C1a haplogroup occurred in the range from 7.9 to 6.6 thousand years ago, and the age of the Japanese branch of the C1a haplogroup is approximately 5.2 thousand years. It is not yet known whether this migration is associated with the spread of the “Arctic” variant of the CPT1A gene or the presence of C1a haplotypes in the population of the Japanese islands marks another, earlier, episode of the migration history linking the populations of Northwest Pacific and North America.

Mitochondrial genome variability in sudden cardiac death

Проведено исследование полиморфизма митохондриального генома и числа копий мтДНК в клетке при внезапной сердечной смерти (ВСС). Выявлено более низкое значение числа копий мтДНК в миокарде умерших ВСС. Анализ полиморфизма мтДНК показал более высокую частоту гаплогруппы Н1 в выборке ВСС, по сравнению с популяцией, а также более высокую частоту миссенс-варианта Ala177Thr в гене ATP6 у лиц, переживших остановку сердца. Результаты исследования указывают на связь полиморфизма мтДНК и числа копий мтДНК в клетке с риском внезапной сердечной смерти. We studied mitochondrial DNA polymorphism and mtDNA copy number in sudden cardiac death (SCD). In the SCD group, a lower mtDNA copy number was found in the myocardium. Analysis of mtDNA polymorphism revealed a higher frequency of H1 haplogroup in the SCD samples, compared with the population, as well as higher frequency of missense variant Ala177Thr in ATP6 gene in the group of cardiac arrest survivors. The results of the study suggest association of mtDNA polymorphism and mtDNA copy number with the risk of sudden cardiac death.

No evidence for Wolbachia infection (Alphaproteobacteria: Rickettsiales) in the threatened freshwater crustacean AeglaLeach, 1820 (Decapoda: Anomura: Aeglidae)

Wolbachia bacteria (Alphaproteobacteria, Rickettsiales) are worldwide endosymbionts infecting arthropods and nematodes, which, among other effects, interfere with reproduction and the mitochondrial DNA polymorphism of their hosts. Among crustaceans, the bacteria have been mainly found in isopods, but its complete range of hosts is still unknown. We investigated the presence of Wolbachia in 10 species of AeglaLeach, 1820, a freshwater anomuran endemic to southern South America. We found no evidence for the presence of the bacteria, ensuring the reliability of studies employing mitochondrial DNA as molecular markers in aeglids.

The study on the modifying role of mitochondrial DNA polymorphism in the Brugada syndrome manifestation

Background: Brugada syndrome is a hereditary disease with genetic and phenotypic variability characterized by a high risk for arrhythmia and sudden cardiac death. It is assumed that modifying genetic factors contribute to the variability of the phenotype. Mitochondrial DNA (mtDNA) polymorphism can be considered among such factors, since mitochondrial dysfunction, including that associated with mtDNA variants, can have an arrhythmogenic effect. Aim: To study possible association between mtDNA polymorphism with the phenotype in the Russian patients with Brugada syndrome. Materials and methods: We have studied mtDNA polymorphism in 36 Russian probands with Brugada syndrome. Common “European” haplogroups of mtDNA were assigned using sequencing of the hypervariable segment 1 in mtDNA D-loop. Results: In the study sample, the frequencies of the mtDNA haplogroups generally correspond to the distribution common for the Russian populations, except the J haplogroup, which was not found in the studied probands. The results contradict with previously published data on the J and T haplogroups as risk factors for Brugada syndrome manifestation. Conclusion: The study did not reveal the role of mtDNA polymorphism (J and T haplogroups) in the formation of the Brugada syndrome phenotype.

Mitochondrial DNA polymorphism and cardiovascular continuum diseases

Митохондриальный геном кодирует жизненно важные белки субъединиц дыхательной цепи и характеризуется высоким уровнем полиморфизма в популяциях человека. Однако работы по поиску генов предрасположенности к многофакторным заболеваниям, в том числе сердечно-сосудистым, часто ограничиваются анализом ядерного генома. В то же время показано, что отдельные генотипы мтДНК могут отличаться более высокой или низкой эффективностью окислительного фосфорилирования. Выявлены ассоциации популяционного полиморфизма мтДНК с сердечно-сосудистыми заболеваниями. Согласно результатам наших исследований, а также опубликованных другими авторами результатам ассоциативных и функциональных исследований, можно говорить о том, что эффект полиморфизма мтДНК проявляется чаще не в предрасположенности к сердечно-сосудистым заболеваниям в целом, а в риске развития осложнений и коморбидных фенотипов в пределах синтропии сердечно-сосудистого континуума. Mitochondrial genome, encoding respiratory chain subunits, is characterized by high polymorphism level in human populations. In most studies for susceptibility genes for common diseases, including cardiovascular diseases, the analysis is limited to the nuclear genome. It was shown that particular mtDNA genotypes may differ by oxidative phosphorylation efficiency. Some associations of mtDNA polymorphisms with cardiovascular diseases have been found. According to our results and published data, we suggest that mtDNA effect on cardiovascular system does not manifest in predisposition to cardiovascular diseases themselves but rather in risk of complications and comorbidities in the cardiovascular continuum.