寒区环境中的古DNA分子

寒区埋藏环境常年处于负温条件下, 土壤冻结或冰的形成过程产生封闭作用, 可以隔离造成埋藏生物遗体同DNA氧化分解的氧气之间的接触. 由于液态水含量极大地减少和冰胶结作用, 使得主要依赖于液态水而发生的生物大分子的化学分解以及生物降解反应作用减慢, 有机体没有成岩过程中降解以及水解作用, 从而使古DNA分子可以得到较好的保存. 目前绝大多数关于古DNA研究的重要成果所使用生物材料均来自寒区环境, 最为引人注目的有关猛犸象、棕熊和企鹅化石古DNA的研究. 这些研究分别从个体、种群和同一种群在不同时间尺度上描绘了它们与现代生物种之间的亲缘关系、过去发生的生物迁移和空间隔离以及特定生物分子水平上的时间演化. 从目前来看, 大量的生物标本很好地保存在那里, 以至于单一考贝基因都可以获得, 因此是获取古DNA并获得相应遗传信息的理想地区.

Ancient DNA in Cold Environment Regions--A Review

The biological materials can be preserved in an extremely good state in cold environments and are often used to extract ancient DNA for genetic and evolutionary studies. Some factors are responsible for well-preserved condition, for example, low temperature which can slow down the rate of chemical and biological reactions, enclosure during soil freezing which can resist oxygen diffusing, lack of liquid water and ice-cement which can reduce the diagenesis in sedimentation. In this review, the possibility of ancient DNA retrieving from the biological remains buried in cold regions and the summarize methods for extraction, purification and amplification of ancient DNA are discussed. In the same time, many famous studies of ancient DNA on mammoth, penguin, brown bear, etc are also introduced. These studies described the genetic relationship between ancient species and their modern one, the spatial and geographic patterns about the migration and separation in past and molecular evolution rate of particular species in individual, population and time-dependent population scales. It is clear that low temperature and consequent process makes for good preservation. Thus studying the remains from cold regions is clearly a wise decision if one wants to retrieve ancient DNA.