DNA: Postmortem Stability in Various Human Organ Tissues
The detection of DNA polymorphisms considerably expanded the means of discrimination of individuals based on small tissue samples. So-called ”DNA-fingerprints“, a banding pattern generated by hypervariable minisatellites are unique for every individual, except for monozygotic twins (Jeffreys et al., 1985a, 1985b). The bands are inherited according to the law of Mendel, hence familial relationship is reconstructible by comparing fingerprints of the parents or close relatives with the one of the unknown (Jeffreys, 1986). Questions of identity in forensic cases often concern remains of humans who have been dead for a shorter or longer time. Since high-molecular-weight DNA is a prerequisite to obtain reliable RFLP-patterns, it is important to investigate the postmortem stability of DNA under various conditions. Reports of Pääbo in 1985 on isolation of DNA from mummies of 2000 years of age amplified the enthusiasm to “raise (genetically) the dead and buried” as Jeffreys expressed it 1984. However, only short length DNA-fragments or none at all were recoverable so far (Huges et al., 1986). Postmortem decay of human bodies is an extremely complex and not yet fully understood process which consists of an aerobic and bacterial decomposition of organic material. It starts with autolysis followed by putrefaction. Autolysis is a nonbacterial autodigestion of tissue by enzymes liberated from the lysosomes whereas putrefaction is an anaerobic bacterial decomposition of proteins which is often accompanied by production of gas. However, the two processes usually cannot be clearly separated and both show a maximum of activity at temperatures between 34–40° Centigrade. In autolysis, loss of enzyme regulation and lactic acidosis enhance the activity of some enzymes, e.g of the hydrolases, whereas other’s activity is reduced.
KeywordsFormalin Phenol Agarose Polyethylene Sodium Chloride
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