There is a strong climate gradient in the Inner Mongolia region, China, with solar radiation and air temperature increasing but precipitation decreasing gradually from the northeast to the southwest. Sixteen Cara- gana species exist in the Inner Mongolia region. These Caragana species exhibit a distribution pattern across moisture zones and form a geographical replacement series. In order to examine the mechanisms responsible for Caragana species distribution pattern, we selected 12 Caragana species that exhibit a distinct distribution pattern across multiple moisture zones in the Inner Mongolia region, and determined the relationships between the leaf ecological and physiological traits of these Caragana species and the aridity index and solar radiation. Along with the climatic drought gradient and the solar radiation intensification from the northeast to the southwest, leaf eco- logical characteristics of Caragana species changed drastically, i.e. the leaf shape gradually turned from flat into tegular or tubbish; the leaf hair became denser, longer and lighter in color; the leaf area, leaf biomass and specific leaf area （SLA） decreased significantly; the leaf thickness and the ratio of leaf thickness to leaf area increased sig- nificantly; and the leaf chlorophyll content decreased significantly. As the climatic drought stress increased, osmotic potentials of the main osmotic adjustment substances and the cytoplasmic ion concentration of Caragana species increased significantly. Meanwhile, the total and free water contents and water potential of leaves decreased sig- nificantly; the ratio of bound to free water increased significantly; the stomatal conductance and transpiration rate reduced significantly; and the water use efficiency （WUE） increased significantly. In addition, with the intensification of climatic drought stress, peroxidase （POD） and superoxide dismutase （SOD） activities in leaves increased significantly. As a result, the malondialdehyde （MDA） content increased while the oxyg
[目的]探索一种快速、高效提取海底淤泥中微生物DNA的最佳方法,为开展海底淤泥微生物的分子生物学研究奠定基础。[方法]分析了不同DNA提取液浓度和不同的腐植酸去除方法对淤泥中微生物DNA提取的产率、纯度的影响,探讨天津市海底淤泥中微生物DNA提取的最佳方法。[结果]海底淤泥用焦磷酸钠和氢氧化钠混合浸提剂提取腐植酸后,再用蒸馏水洗去浸提液,用4 ml DNA提取液提取,所得DNA的产率及纯度均优于对照组。[结论]该试验结果为海底淤泥微生物的分子生物学研究奠定了基础。
