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近年来,有学者通过古DNA方法成功地重建了海洋沉积记录中古微生物群落变化,并借此反演了当地古环境—气候变化。然而,此种方法对于陆地湖泊沉积记录是否适用仍然有待研究。采用聚合酶链式反应(PCR,Polymerase Chain Reaction)、变性梯度凝胶电泳(DGGE,Denaturing Gradient Gel Electrophoresis)与实时荧光定量聚合酶链式反应(Q-PCR,Quantitative PCR)相结合的综合分析技术手段,系统研究青海湖5.8 m(时间跨度为~18 500 a)沉积柱中的甲藻(Dinoflagellate)多样性和丰度变化。研究结果显示,青海湖Dinoflagellate藻18S rRNA基因序列主要与海洋型藻类Woloszynskiahalophila和Scrippsiellahangoei相近(~98%序列相似性)。定量Q-PCR结果显示,每克沉积物含有dinoflagellate藻类18S rRNA基因丰度范围为2.27×10~3~8.55×10~6拷贝。另外,Dinoflagellate藻类18S rRNA基因丰度与总有机碳含量成显著正相关(R=0.408,p=0.0001)。对比分析揭示,较高的藻类丰度对应高总有机碳含量和较低的可溶解性盐电导率;反之,较低的藻类丰度对应较高的可溶解性盐电导率和较低的总有机碳含量。在青海湖区,总有机碳指示着季风降雨变化,并间接地指示着外源输入和湖泊营养状况变化,然而可溶性盐电导率则指示着湖泊盐度变化。综上所述,青海湖沉积柱Dinoflagellate藻类丰度可能反应了历史时期湖泊营养状况和盐度波动情况。
In recent years, some scholars successfully reconstructed the changes of paleoclimate communities in marine sedimentary records through ancient DNA methods, and thus retrieved the ancient paleoenvironment - climate change. However, the applicability of this method to sedimentary records of terrestrial lakes remains to be studied. A comprehensive analytical technique such as polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (Q-PCR) Means to systematically study the diversity and abundance changes of dinoflagellate in the sedimentary column of Qinghai Lake at 5.8 m (~ 18 500 a). The results showed that the 18S rRNA gene sequence of Dinoflagellate algae in Qinghai Lake was similar to that of marine algae Woloszynskiahalophila and Scrippsiellahangoei (~ 98% sequence similarity). Quantitative Q-PCR results showed that the abundance of 18S rRNA gene in dinoflagellate sediment per gram of sediment ranged from 2.27 × 10 ~ 3 to 8.55 × 10 ~ 6 copies. In addition, the abundance of 18S rRNA gene in Dinoflagellate algae was positively correlated with total organic carbon (R = 0.408, p = 0.0001). A comparative analysis revealed that higher algal abundances correspond to higher total organic carbon content and lower soluble salt conductivity; conversely, lower algal abundances correspond to higher salt conductivity and lower total salt conductivity Organic carbon content. In the Qinghai Lake area, total organic carbon is indicative of monsoon rainfall changes and indirectly indicates exogenous inputs and lake nutrient status changes, whereas soluble salt conductivity is indicative of changes in lake salinity. In summary, the algal abundance of Dinoflagellate sediments in Qinghai Lake may reflect the changes of lake nutrition status and salinity during the historical period.