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The arrest of ooctyes at the four genome copy stage appears to provide the informational redundancy needed to repair damage in the DNA of the germline. [26] The repair process used likely involves homologous recombinational repair. [26] [27] [28] Prophase arrested oocytes have a high capability for efficient repair of DNA damages. [27]
Oocyte abnormalities can be caused by a variety of genetic factors affecting different stages in meiosis. [1] Moreover, ageing is associated with oocyte abnormalities since higher maternal age is associated with oocytes with a reduced gene expression of spindle assembly checkpoints which are important in maintaining stability in the genome.
In mammalian females the period of arrest may last for years. During this period of arrest, oocytes are subject to spontaneous DNA damage including double-strand breaks. However, the oocytes can efficiently repair DNA double-strand breaks, allowing the restoration of genetic integrity and the protection of offspring health. [8]
Accumulation of DNA damage with age in the mammalian brain has been reported during the period 1971 to 2008 in at least 29 studies. [29] This DNA damage includes the oxidized nucleoside 8-oxo-2'-deoxyguanosine (8-oxo-dG), single-and double-strand breaks, DNA-protein crosslinks and malondialdehyde adducts (reviewed in Bernstein et al. [29 ...
BRCA1 and ATM proteins are employed in repair of DNA double-strand break during meiosis. These proteins appear to have a critical role in resisting ovarian aging. [25] However, homologous recombinational repair of DNA double-strand breaks mediated by BRCA1 and ATM weakens with age in oocytes of humans and other species. [25]
The SMC-5/6 complex in mouse oocytes is essential for the formation of segregation competent bivalents during meiosis. [19] In the yeast Saccharomyces cerevisiae, SMC6 is necessary for resistance to DNA damage as well as for damage-induced interchromosomal and sister chromatid recombination. [20]
The dictyate appears to be an adaptation for efficiently removing damages in germ line DNA by homologous recombinational repair. [5] Prophase arrested oocytes have a high capability for efficient repair of DNA damages. [5] DNA repair capability appears to be a key quality control mechanism in the female germ line and a critical determinant of ...
Damage to DNA that occurs naturally can result from metabolic or hydrolytic processes. Metabolism releases compounds that damage DNA including reactive oxygen species, reactive nitrogen species, reactive carbonyl species, lipid peroxidation products, and alkylating agents, among others, while hydrolysis cleaves chemical bonds in DNA. [8]