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A double-strand break repair model refers to the various models of pathways that cells undertake to repair double strand-breaks (DSB). DSB repair is an important cellular process, as the accumulation of unrepaired DSB could lead to chromosomal rearrangements, tumorigenesis or even cell death. [ 1 ]
Another type of DNA double-strand breaks originates from the DNA heat-sensitive or heat-labile sites. These DNA sites are not initial DSBs. However, they convert to DSB after treating with elevated temperature. Ionizing irradiation can induces a highly complex form of DNA damage as clustered damage.
Homology-directed repair (HDR) is a mechanism in cells to repair double-strand DNA lesions. [1] The most common form of HDR is homologous recombination . The HDR mechanism can only be used by the cell when there is a homologous piece of DNA present in the nucleus , mostly in G2 and S phase of the cell cycle .
The MRN complex (MRX complex in yeast) is a protein complex consisting of Mre11, Rad50 and Nbs1 (also known as Nibrin [1] in humans and as Xrs2 in yeast). In eukaryotes, the MRN/X complex plays an important role in the initial processing of double-strand DNA breaks prior to repair by homologous recombination or non-homologous end joining.
Meiotic recombination can be initiated by a double-strand break (DSB) in DNA. The 5’ ends of the break are degraded, leaving long 3’ overhangs of several hundred nucleotides (see Figure). One of these 3’ single stranded DNA segments then invades a homologous sequence on the homologous chromosome, forming an intermediate which can be ...
By pairing Cas proteins with a designed guide RNA CRISPR/Cas9 can be used to induce double-stranded breaks at specific points within DNA sequences. The break gets repaired by cellular DNA repair enzymes, creating a small insertion/deletion type mutation in most cases. Targeted DNA repair is possible by providing a donor DNA template that ...
Bile acids cause DNA damage, including oxidative DNA damage, double-strand DNA breaks, aneuploidy and chromosome breakage. [55] High-normal levels of the bile acid deoxycholic acid cause apoptosis in human colon cells, [ 56 ] but may also lead to colon cancer if repair and apoptotic defenses are insufficient.
The formation of a bivalent occurs during the first division of meiosis (in the zygotene stage of meiotic prophase 1). In most organisms, each replicated chromosome (composed of two identical sister chromatids [1] [2]) elicits formation of DNA double-strand breaks during the leptotene phase. [3]