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  1. Article ; Online: The Role of Mitochondria in Oocyte Maturation

    Anastasia Kirillova / Johan E. J. Smitz / Gennady T. Sukhikh / Ilya Mazunin

    Cells, Vol 10, Iss 2484, p

    2021  Volume 2484

    Abstract: With the nucleus as an exception, mitochondria are the only animal cell organelles containing their own genetic information, called mitochondrial DNA (mtDNA). During oocyte maturation, the mtDNA copy number dramatically increases and the distribution of ... ...

    Abstract With the nucleus as an exception, mitochondria are the only animal cell organelles containing their own genetic information, called mitochondrial DNA (mtDNA). During oocyte maturation, the mtDNA copy number dramatically increases and the distribution of mitochondria changes significantly. As oocyte maturation requires a large amount of ATP for continuous transcription and translation, the availability of the right number of functional mitochondria is crucial. There is a correlation between the quality of oocytes and both the amount of mtDNA and the amount of ATP. Suboptimal conditions of in vitro maturation (IVM) might lead to changes in the mitochondrial morphology as well as alternations in the expression of genes encoding proteins associated with mitochondrial function. Dysfunctional mitochondria have a lower ability to counteract reactive oxygen species (ROS) production which leads to oxidative stress. The mitochondrial function might be improved with the application of antioxidants and significant expectations are laid on the development of new IVM systems supplemented with mitochondria-targeted reagents. Different types of antioxidants have been tested already on animal models and human rescue IVM oocytes, showing promising results. This review focuses on the recent observations on oocytes’ intracellular mitochondrial distribution and on mitochondrial genomes during their maturation, both in vivo and in vitro. Recent mitochondrial supplementation studies, aiming to improve oocyte developmental potential, are summarized.
    Keywords oocyte maturation ; mtDNA copy number ; mitochondria distribution ; IVM ; mitochondrial supplementation reagents ; Biology (General) ; QH301-705.5
    Subject code 570
    Language English
    Publishing date 2021-09-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Targeted Modification of Mammalian DNA by a Novel Type V Cas12a Endonuclease from Ruminococcus bromii

    Ruslan Vasilev / Natalia Gunitseva / Regina Shebanova / Aleksei Korzhenkov / Anna Vlaskina / Marta Evteeva / Irina Polushkina / Natalia Nikitchina / Stepan Toshchakov / Piotr Kamenski / Maxim Patrushev / Ilya Mazunin

    International Journal of Molecular Sciences, Vol 23, Iss 16, p

    2022  Volume 9289

    Abstract: Type V Cas12a nucleases are DNA editors working in a wide temperature range and using expanded protospacer-adjacent motifs (PAMs). Though they are widely used, there is still a demand for discovering new ones. Here, we demonstrate a novel ortholog from ... ...

    Abstract Type V Cas12a nucleases are DNA editors working in a wide temperature range and using expanded protospacer-adjacent motifs (PAMs). Though they are widely used, there is still a demand for discovering new ones. Here, we demonstrate a novel ortholog from Ruminococcus bromii sp. entitled RbCas12a, which is able to efficiently cleave target DNA templates, using the particularly high accessibility of PAM 5′-YYN and a relatively wide temperature range from 20 °C to 42 °C. In comparison to Acidaminococcus sp. (AsCas12a) nuclease, RbCas12a is capable of processing DNA more efficiently, and can be active upon being charged by spacer-only RNA at lower concentrations in vitro. We show that the human-optimized RbCas12a nuclease is also active in mammalian cells, and can be applied for efficient deletion incorporation into the human genome. Given the advantageous properties of RbCas12a, this enzyme shows potential for clinical and biotechnological applications within the field of genome editing.
    Keywords Cas endonuclease ; CRISPR ; genome editing ; mammalian cells ; site-directed mutagenesis ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 612
    Language English
    Publishing date 2022-08-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Secondary structure of the human mitochondrial genome affects formation of deletions

    Victor Shamanskiy / Alina A. Mikhailova / Evgenii O. Tretiakov / Kristina Ushakova / Alina G. Mikhailova / Sergei Oreshkov / Dmitry A. Knorre / Natalia Ree / Jonathan B. Overdevest / Samuel W. Lukowski / Irina Gostimskaya / Valerian Yurov / Chia-Wei Liou / Tsu-Kung Lin / Wolfram S. Kunz / Alexandre Reymond / Ilya Mazunin / Georgii A. Bazykin / Jacques Fellay /
    Masashi Tanaka / Konstantin Khrapko / Konstantin Gunbin / Konstantin Popadin

    BMC Biology, Vol 21, Iss 1, Pp 1-

    2023  Volume 13

    Abstract: Abstract Background Aging in postmitotic tissues is associated with clonal expansion of somatic mitochondrial deletions, the origin of which is not well understood. Such deletions are often flanked by direct nucleotide repeats, but this alone does not ... ...

    Abstract Abstract Background Aging in postmitotic tissues is associated with clonal expansion of somatic mitochondrial deletions, the origin of which is not well understood. Such deletions are often flanked by direct nucleotide repeats, but this alone does not fully explain their distribution. Here, we hypothesized that the close proximity of direct repeats on single-stranded mitochondrial DNA (mtDNA) might play a role in the formation of deletions. Results By analyzing human mtDNA deletions in the major arc of mtDNA, which is single-stranded during replication and is characterized by a high number of deletions, we found a non-uniform distribution with a “hot spot” where one deletion breakpoint occurred within the region of 6–9 kb and another within 13–16 kb of the mtDNA. This distribution was not explained by the presence of direct repeats, suggesting that other factors, such as the spatial proximity of these two regions, can be the cause. In silico analyses revealed that the single-stranded major arc may be organized as a large-scale hairpin-like loop with a center close to 11 kb and contacting regions between 6–9 kb and 13–16 kb, which would explain the high deletion activity in this contact zone. The direct repeats located within the contact zone, such as the well-known common repeat with a first arm at 8470–8482 bp (base pair) and a second arm at 13,447–13,459 bp, are three times more likely to cause deletions compared to direct repeats located outside of the contact zone. A comparison of age- and disease-associated deletions demonstrated that the contact zone plays a crucial role in explaining the age-associated deletions, emphasizing its importance in the rate of healthy aging. Conclusions Overall, we provide topological insights into the mechanism of age-associated deletion formation in human mtDNA, which could be used to predict somatic deletion burden and maximum lifespan in different human haplogroups and mammalian species.
    Keywords Mitochondrial DNA ; Deletions ; Aging ; Single-stranded DNA ; Global secondary structure ; Contact zone ; Biology (General) ; QH301-705.5
    Subject code 612
    Language English
    Publishing date 2023-05-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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    Inter-library loan at ZB MED

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