DNA fragmentation

DNA fragmentation is the separation or breaking of DNA strands into pieces. It can be done intentionally by laboratory personnel or by cells, or can occur spontaneously. Spontaneous or accidental DNA fragmentation is fragmentation that gradually accumulates in a cell. It can be measured by e.g. the Comet assay or by the TUNEL assay.

Its main units of measurement is the DNA Fragmentation Index (DFI).^[1] A DFI of 20% or more significantly reduces the success rates after ICSI.^[1]

DNA fragmentation was first documented by Williamson in 1970 when he observed discrete oligomeric fragments occurring during cell death in primary neonatal liver cultures. He described the cytoplasmic DNA isolated from mouse liver cells after culture as characterized by DNA fragments with a molecular weight consisting of multiples of 135 kDa. This finding was consistent with the hypothesis that these DNA fragments were a specific degradation product of nuclear DNA.^[2]

^ ^a ^b Speyer BE, Pizzey AR, Ranieri M, Joshi R, Delhanty JD, Serhal P (May 2010). "Fall in implantation rates following ICSI with sperm with high DNA fragmentation". Hum Reprod. 25 (7): 1609–1618. doi:10.1093/humrep/deq116. PMID 20495207.
^ Williamson, Robert (1970). "Properties of rapidly labelled deoxyribonucleic acid fragments isolated from the cytoplasm of primary cultures of embryonic mouse liver cells". Journal of Molecular Biology. 51 (1): 157–168. doi:10.1016/0022-2836(70)90277-9. PMID 5481278.

[speyer-1] Speyer BE, Pizzey AR, Ranieri M, Joshi R, Delhanty JD, Serhal P (May 2010). "Fall in implantation rates following ICSI with sperm with high DNA fragmentation". Hum Reprod. 25 (7): 1609–1618. doi:10.1093/humrep/deq116. PMID 20495207.

[2] Williamson, Robert (1970). "Properties of rapidly labelled deoxyribonucleic acid fragments isolated from the cytoplasm of primary cultures of embryonic mouse liver cells". Journal of Molecular Biology. 51 (1): 157–168. doi:10.1016/0022-2836(70)90277-9. PMID 5481278.

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