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Mitochondria and Embryo Viability
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Irene Corachan Garcia, Laura Iñiguez Quiles, Antonio Diez-Juan
mtDNA encodes two rRNAs (12S and 16S), 22 tRNAs, and 13 mRNAs (18). It also has a regulatory sequence involved in replication and transcription, known as the D-loop (18). The proteins encoded by mtDNA are synthesized in the mitochondria. These proteins are essential subunits of the ETC complexes: seven subunits of complex I (20), one subunit of complex III (18), three subunits of complex IV (21), and two subunits of complex V (18). mtDNA gene mutations affect ETC functions, while mutations in the nuclear genes encoding mitochondrial proteins can affect multiple mitochondrial functions (11). Importantly, mtDNA mutates ten or more times faster than nuclear DNA due to its location near the ETC and its lack of protective histones (22). As a result, mtDNA is more prone to the deleterious effects of ROS (Figure 15.3b) (23).
Mitochondrial DNAs and Phylogenetic Relationships
Published in S. K. Dutta, DNA Systematics, 2019
Variation in relation to functional or structural differentiation of the mitochondrial genome is depicted in Table 3 for two species, Mus domesticus180 and man.200 Both studies used the sequence comparison method, i.e., restriction fragments were compared in alignment with the known mitochondrial sequence for each species. Comparisons of the two species are based on the relative ranking within each species of percent variability for the four aspects of structure or function. As expected the D-loop shows the higher variability followed by protein encoding DNA. Ribosomal and tRNA encoding regions are the least variable with some difference in species’ rank order.
A Survey of Newer Gene Probing Techniques
Published in Victor A. Bernstam, Pocket Guide to GENE LEVEL DIAGNOSTICS in Clinical Practice, 2019
An emerging approach for determining familial relationships is based on the maternal inheritance of the mitochondrial genome, and uses PCR amplification and sequencing of the D loop. So far, however, not enough population data are available to make this approach widely acceptable.
Forensic evaluation of mitochondrial DNA heteroplasmy in Gujarat population, India
Published in Annals of Human Biology, 2022
Mohammed H. M. Alqaisi, Molina Madhulika Ekka, Bhargav C. Patel
The non-coding region (D-loop) is a regulatory region that contains the origin of replication (Anderson et al. 1981; Holland and Parsons 1999; Barshad et al. 2018). It is highly polymorphic and hence referred to as a hypervariable region. There are three hypervariable regions in D-loop: hypervariable region one (HV1) at position 16024–16365, hypervariable region two (HV2) at position 73–340, and hypervariable region three (HV3) at position 340–576 (Greenberg et al. 1983; Wilkinson-Herbots et al. 1996; Ingman and Gyllensten 2003). Genetic variation in the hypervariable regions of mtDNA confers discriminating power in forensic analysis. These variations (polymorphisms) can be used by an investigator to learn more about the genealogy and ethnicity of the questioned sample (Parson and Bandelt 2007; Lee et al. 2011; Amorim et al. 2019). However, when it comes to heteroplasmy, difficulties with mtDNA analysis remain unresolved in court. Thus, it is crucial to analyse heteroplasmy when determining the forensic importance of mtDNA polymorphisms, even more so when the questioned and reference samples differ in the presence of heteroplasmy, which confers inconclusive results in forensic analysis (Nilsson 2007; Parson and Bandelt 2007a).
Role of Mitochondrial DNA (mtDNA) Variations in Cancer Development: A Systematic Review
Published in Cancer Investigation, 2020
Nisha Thakur, Amitesh Kumar Sharma, Harpreet Singh, Shalini Singh
The mitochondrial chromosome is a closed circular, ds-DNA molecule. The human mtgenome is 1.8 × 10−5 times smaller than the nuclear genome having size of 16,569 bp.The major part of the human mtgenome encrypts 13 protein subunits of the electron transport chain (ETC), two rRNA and twenty twot RNAs genes. The discplacement loop (D-Loop) region is mainly noncoding part of the mtDNA. The maximum transcription of mtDNA takes place in the heavy strand (guanines ‘G’ rich). Though, light strand (cytosine ‘C’ rich) and encodes for eight tRNA and only one protein coding gene. Interestingly, bulk of the mt proteins are encoded by the ncDNA genome and transferred to the mitochondria. Mitochondria are inherited maternally and majority of the cells contain identical copies of mtDNA. Any modification in the mtDNA sequence due to error in the replication and repair mechanism results in disease phenotype and can be of clinical importance (3,4).
The causative variants of amyloidosis in the autism
Published in International Journal of Neuroscience, 2019
Mansoureh Akouchekian, Mitra Hakim Shooshtari, Hamed Heidary, Fateme Zahedi Abghari, Parisa Moeinian
The mitochondrial genome has a total of 37 genes, 22 of them encode transfer RNAs (tRNAs), 2 genes encode ribosomal RNAs (rRNAs) and the remaining 13 genes encode subunits of complexes I and III–V of the electron transferring complex (ETC). These 13 critical genes are, respectively, involved in five complexes of ETC [7]. One of the mitochondrial complexes is cytochrome-c-oxidase (COX). COX is the terminal electron acceptor of the mitochondrial respiratory chain and catalyses the transfer of electrons from reduced cytochrome c to molecular oxygen to form water. COX deficiency is the most commonly recognized respiratory-chain defect in childhood [8]. Mitochondrial genome also consists of a non-coding sequence which is a 1121-bp region called d-loop [9]. Many common mutations have been diagnosed in the mtDNA and most of them accumulate in the regulatory region or d-loop. This region is like a promoter for both light strands (L-strand, Cytosine-rich) and heavy strand (H-strand, Guanine-rich) of mtDNA [10]. Figure 1 shows a simple map of human mitochondrial DNA gene.