Studies on DNA extracted from postmortem tissues

1. 使用多位点探针mz1.3 （MZ）对死后24小时内从各种死后组织中提取的DNA进行分析。肺部的DNA显示出最明显的条带模式。脾脏、肾脏和肌肉的DNA也显示出明显的条带模式，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。当每月提取一次DNA时，我们观察到DNA的产量与冷冻时间有关。当从肌肉中提取的DNA在4‰的温度下保存时，没有观察到产量的下降。每天从小条的肌肉中提取DNA，这些肌肉在+20 C的条件下储存在潮湿的房间里。DNA产量在前3-6天稳步下降。随后，产量逐渐增加。然而，在储存超过3天的肌肉DNA中无法检测到MZ的片段模式。这在一定程度上可以用人类基因组DNA的降解和微生物基因组DNA的替代来解释。从几种细菌中提取DNA，用限制性限制蛋白酶消化，并用MZ分析。一些细菌的DNA不能完全被消化，另一些细菌的DNA显示出更宽和更弱的条带，这与人类的高变片段模式明显不同。从同一标本中采用不同方法提取DNA时，可采用饱和氯化钠法、液氮法、干冰法以及常用的苯酚-氯仿法提取足够数量和质量的DNA。无论提取方法如何，其谱带模式几乎相同。

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.