古人类骨骼DNA降解影响因素分析

Degradative factor analysis of ancient DNA preserved in human bones

古DNA是古代人类最重要的遗传信息载体,已用于人类起源、进化、族群特征、迁移、古代人类疾病等方面的研究,由此导致了分子考古学的兴起.由于骨骼组织独特的结构和物理特性,其常常被选作较理想的古DNA研究组织样品.在长期的埋藏和暴露过程中,受外界物理因素、化学因素、酶解及微生物侵染等作用,古人类骨骼DNA分子将发生一定程度的降解.通过分析骨骼组织结构及其物理特性,探讨了骨骼组织的保存及影响其分解的环境因素,阐述了骨骼无机相羟基磷灰石与有机胶原质形成的嵌合结构对DNA片段的吸附保护作用.在分析DNA分子的特点和稳定性的基础上,探讨了水解反应、氧化反应、酶解及微生物分解作用对古DNA分子造成的降解,研究了温度、湿度、pH值、微生物等环境因素对古DNA降解速率的影响.在此基础上,分析了在不同条件下古DNA仍得以幸存的年代范围,提出了有利于古DNA保存的环境条件,从而为古DNA样品保存、研究取样、提取及真实性评估提供理论依据.

The ancient DNA （aDNA）, the most important genetic information of ancient human, has been widely used in the studies of human origin, evolution, racial character, migration and diseases, and herefrom the molecular archaeology has developed rapidly. By virtue of its special structure and physical specialty, the bones have often been selected as the ideal aDNA sampies. Effected by the outside physical and chemical factors, enzymes and microorganism, the aDNA preserved in human bones will get degraded into small fragments during a long buried or exposed time. By analyzing the structure and specialty of bones, we discussed the preservation of bone structure and the effects of environmental factors on its decomposition and investigated the adsorption effect of matrix framework formed by bone inorganic phase hydroxyapatite and collagen via calcium bridge on aDNA fragments. Based on the analysis of the characteristics and stability of DNA, we discussed the damages of hydrolyzation, oxidation, enzyme and microorganism to aDNA and studied the influences of the environmental factors inclusive of temperature, humidity, pH value and microorganism on aDNA degrading rate. In the end, the survival age limit and the favorable preservation conditions of aDNA were suggested to provide theoretical evidences for the extraction, preservation, sampling and authenticity evaluation of aDNA.