湖泊沉积物中DNA提取与PCR扩增

对湖泊沉积物中保存的生物大分子—DNA进行研究分析，以探讨湖泊生态系统随环境改变而演变的过程。根据前人对土壤和海洋沉积物DNA的提取方法，针对湖泊沉积物的特点进行改进，在此基础上对太湖梅梁湾湖泊沉积岩芯进行DNA提取和扩增。结果表明：不同深度湖泊沉积物均能获得DNA，且纯度较高，OD²⁶⁰/ OD²⁸⁰均大于1.4、OD²⁶⁰/ OD²³⁰大于1.1，可直接用于PCR（polymerase chain reaction ）扩增。对微囊藻的16S rRNA基因进行PCR扩增，结果发现在前5个沉积物样品中，均得到了200 bp左右的微囊藻16S rRNA基因片段，表明微囊藻或已降解的微囊藻基因片段存在于这5个层位的湖泊沉积物中。这为利用湖泊沉积物中的生物分子来推断历史湖泊生物群落结构，判断湖泊生态演变的历史提供了新的研究思路。

Extraction and PCR Amplification of DNA from Lake Sediments

Biomacromolecules in lake sediments are very important in the indication of environmental information. DNA(Deoxyribonucleic acid) is an important biomacromolecule, and its genetic information which corresponds to organism to indicate information of biology and environmental change of lake sediments con be studied. In recent years, several approaches based on the extraction of DNA from environmental samples have been developed for the microbial diversity in soil and sea sediments. On the basis of previous work, an efficient method to extract DNA from lake sediments is reported. Samples from location in Lake Taihu were collected, and their genomic DNA with the size of 23kb was obtained from all sediment samples of Meiliang bay. Purification and efficiency of extracted DNA were evaluated through ultraviolet spectrum OD260/ OD280 and OD260/ OD230 ratios. Experimental results show that all samples mentioned above obtain quite purified genomic DNA with OD260/ OD280 ratios from 1.41 to 1.72, and OD260/ OD280 ratios from 1.13 to 1.54. The changed regulation of DNA in different sediment depth is elucidated, the distribution of organic carbon and DNA is consistent in 15cm surface sediments, and DNA keeps low contents below 15cm. The extracted DNA is sufficient enough to be served as a template for PCR amplification of specific genetic sequences. In particular, Microcystis 16S rRNA gene fragments (200bp gene fragments) were obtained from 5 samples. 