Effects of experimental warming on soil microbial communities in two contrasting subalpine forest ecosystems,eastern Tibetan Plateau,China

Soil microbial communities are primarily regulated by environmental temperature. Our study investigated the effects of global warming on soil microbial community composition as measured via phospholipid fatty acid(PLFA) analysis and soil chemical characteristics in relation to soil depth in a dragon spruce plantation and a spruce-fir-dominated natural forestin the Eastern Tibetan Plateau. Opentop chambers were utilized to increase the soil and air temperature. Soil samples were collected from the 0-10 cm, 10-20 cm, and 20-30 cm layers after a 4-year warming. Our results showed that the soil microbial community and the contents of TC(Total carbon), TN(Total nitrogen), NO_3^-, and NH_4^+ responded differently to warming in the two contrasting forests, especially at the 0-10 cm soil depth. Warming increased soil microbial biomass at the 0-20 cm depth of soil in natural forest but reduced it at the 0-10 cm depth ofsoil in the plantation. In contrast, the TC and TN contents were reduced in most soil layers of a natural forest but increased in all of the soil layers of the plantation under warming conditions. This result suggested that the effects of warming on soil microbial community and soil C and N pools would differ according to soil depth and forest types; thus, the two contrasting forests would under go differing changes following the future climate warming in this region.

全自动二维高效液相色谱测定霉酚酸血药浓度的研究

目的:采用全自动二维液相色谱(2D-LC-UV)建立测定霉酚酸(MPA)血药浓度的方法,并应用于临床。方法:样品去除蛋白后直接进样,待测物在一维柱AstonSC2T(3.5 mm×50 mm,5μm)上初步分离,通过中间柱Aston SBR(3.0 mm×10 mm,5μm)截取保留,转移到二维柱Aston SBX4(4.6 mm×150 mm,5μm)上进一步分离。一维流动相为MPA-1A移动相,流速0.8 mL·min-1;二维流动相为MPA-2A移动相,流速1.2 mL·min-1;柱温40℃;紫外检测波长304 nm。结果:在所建立的色谱条件下,霉酚酸与各杂质分离良好,在0.32~25.03μg·mL-1范围内与峰面积呈良好的线性关系(r=0.9999),可在13 min内完整出峰,方法回收率高于95%;日内、日间的精密度RSD值均小于5%;稳定性试验RSD小于5%。结论:本方法简便快速、结果准确、稳定性良好、自动化程度高、检测成本低,适用于临床霉酚酸快速检测。