Studies on DNA extracted from postmortem tissues

1.使用多位点探针MZ 1.3（MZ）分析了从死亡后24小时内的各种死后组织中提取的DNA。来自肺的DNA显示出最突出的带型。脾、肾和肌肉的DNA也显示出明显的带型，而血液、肝脏和胰腺的DNA由于高分子量DNA的快速降解而不适合用于DNA指纹图谱。2.从-20 ℃冷冻的肌肉样品中每月提取DNA时，观察到DNA产量随冷冻时间的延长而逐渐下降。从肌肉中提取的DNA在4 ℃保存时，产量的下降并不明显.每天从储存在+20 ° C潮湿室中的小条肌肉中提取DNA。DNA的产量稳定下降，直到前3-6天。随后，产量逐渐增加。然而，MZ的片段模式不能检测到的肌肉中存储超过3天。这可以部分解释为人类基因组DNA的降解和微生物基因组DNA的取代。从几种细菌中提取的DNA用限制性内切酶消化，用MZ分析，有些细菌的DNA不能完全消化，而另一些细菌的DNA显示出较宽较弱的条带，可以清楚地与人类高变片段模式区分开来.当用各种方法从相同的标本中提取DNA时，用饱和NaCl法、液氮法和干冰法以及常用的酚-氯仿法可获得足够数量和质量的DNA。无论提取方法如何，条带模式几乎相同。

1. DNA extracted from various postmortem tissues up to 24 hours after death was analyzed using a multi-locus probe, MZ 1.3 (MZ). DNA from lungs showed the most prominent band patterns. DNA from spleen, kidneys and muscles also showed prominent band patterns, whereas DNA from blood, liver and pancreas was found to be not suitable for DNA fingerprinting because of rapid degradation of high-molecular-weight DNA.2.When DNA was extracted monthly from muscle specimens which were frozen at -20ﾟC, a steady decline of the yields of DNA was observed in relation to frozen periods. When DNA extracted from muscles was preserved at 4ﾟC, the decline of the yields was not observed.3. DNA was extracted daily from small strips of muscles that were stored at +20ﾟC in moist chambers. The yields of DNA steadily decreased up to first 3-6 days. Subsequently, the yields gradually increased. However, the fragment patterns of MZ could not be detected in DNA from muscles stored for more than 3 days. This mnay in part be explained by the degradation of human genomic DNA and its substitution by genomic DNA of microorganisms.4. DNA which was extracted from several bacteria was digested with a restrictoin enzyme and analyzed using MZ.DNA from some bacteria could not be digested completely and DNA from the other bacteria showed wider and fainter bands which could clearly be distinguished from the human hypervariable fragment patterns.5. When DNA was extracted from the same specimens by using various procedures, DNA of sufficient quantity an quality was obtained by a saturated NaCl method, a liquid nitrogen method and a dry ice method as well as by a usual phenol-chloroform method. The band patterns were almost identical regardless of the extraction methods.