[Effects of some physical and chemical factors on both human hair DNA and results of sex determination by PCR].

The present study aims at observation of the effects of some physical and chemical factors on both human hair DNA and the results of sex determination by PCR. After the hairs were treated with varying pH solutions, the quantity of the DNA extracted was decreased. High-molecular-weight (HMW) DNA was determined in the hairs treated with pH 1, 3, 5 and 7 solutions for 2 hours, but no DNA was demonstrated by agarose gel electrophoresis in the hairs treated with pH 1 and 3 solution for 24 hours, and the quantity of DNA was decreased in the hairs treated with pH 5 for 24 hours. The quantity of DNA was decreased in the hairs treated with pH 9 for 2 hours and no DNA was demonstrated for 24 hours. No DNA was found in the hairs treated with pH 11 for 2 or 24 hours. No changes of DNA were observed in hairs treated with 75% ethanol or methanol for 2 or 24 hours and exposed to UV light for 24 hours. No DNA but RNA was observed in the hairs treated with 10% formalin (pH 7 or pH 5) for 2 or 24 hours. The quantity of DNA was decreased obviously in the hairs treated in 100 degrees C water for 5 or 10 minutes. The quantity of DNA was not decreased in the hairs heated at 50 degrees C for 24 hours, and only little decrease was noted at 100 degrees C for 24 hours. Both fragments of PCR products were obtained in most hairs except the hairs treated with pH 11 solution for 24 hours. Although no DNA was observed in some treated hairs, specific bands were detected after PCR. PCR is a very sensitive and specific technique of DNA amplification, which can be used for sex determination in forensic medicine.