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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.
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]
Oxidative stress mechanisms in tissue injury. Free radical toxicity induced by xenobiotics and the subsequent detoxification by cellular enzymes (termination).. Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. [1]
Thus on this view, the adaptive advantage of meiosis is that it facilitates recombinational repair of DNA damage that is otherwise difficult to repair, and that occurs as a result of stress, particularly oxidative stress. [19] [20] If left unrepaired, this damage would likely be lethal to gametes and inhibit production of viable progeny.
10 Ways That Chronic Stress Affects Your Brain. Cortisol is the stress hormone that does all the damage to our brain and body. Physical health problems that are a result of chronic stress include ...
When there is DNA damage, Mdm2 is phosphorylated, most likely caused by ATM. The phosphorylation of Mdm2 leads to a reduction in the activity of Mdm2, thus preventing the degradation of p53. Normal, undamaged cell, usually has low levels of p53 while cells under stress and DNA damage, will have high levels of p53. [13]
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 ...
The human body was not built for spaceflight, with its microgravity conditions, exposure to high-energy radiation and other issues. ... This can lead to DNA damage, increased cancer risk ...