DNA fragmentation

DNA fragmentation is the separation or breaking of DNA strands into pieces. It can be intentional by laboratory personnel or the cells, or it can be spontaneous.

Intentional

Restriction digest is the intentional laboratory breaking of DNA strands.

Apoptosis DNA fragmentation is a natural fragmentation that cells perform in apoptosis (programmed cell death)

Spontaneous

Spontaneous or accidental DNA fragmentation is fragmentation that gradually accumulates in a cell. It can be measured by e.g. Comet assay.

The degree of DNA fragmentation can predict outcomes for in vitro fertilization^[1] (IVF) and its expansion intracytoplasmic sperm injection^[2] (ICSI). The sperm chromatin dispersion test (SCD) and TUNEL assay are both effective in detecting sperm DNA damage.^[3] Using bright-field microscopy, the SCD test appears to be more sensitive than the TUNEL assay.^[3]

Its main units of measurement is DNA fragmentation index (DFI).^[2] A DFI of 20% or more significantly reduces the success rates after ICSI.^[2]

References

1. ^ Simon L, Brunborg G, Stevenson M, Lutton D, McManus J, Lewis SE (May 2010). "Clinical significance of sperm DNA damage in assisted reproduction outcome". Hum Reprod 25 (7): 1594–1608. doi:10.1093/humrep/deq103. PMID 20447937. 
2. ^ ^{a b c} 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. 
3. ^ ^{a b} Zhang LH, Qiu Y, Wang KH, Wang Q, Tao G, Wang LG (June 2009). "Measurement of sperm DNA fragmentation using bright-field microscopy: comparison between sperm chromatin dispersion test and terminal uridine nick-end labeling assay". Fertil. Steril. 94 (3): 1027–1032. doi:10.1016/j.fertnstert.2009.04.034. PMID 19505686.