Kong W D, Zhu Y G, Liang Y C, Zhang J, Smith F A, Yang M
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Environ Pollut. 2007 May;147(1):187-93. doi: 10.1016/j.envpol.2006.08.016. Epub 2006 Oct 6.
A series of experiments were conducted in a hydroponic system to investigate the uptake of oxytetracycline (OTC) and its toxicity to alfalfa (Medicago sativa L.). OTC inhibited alfalfa shoot and root growth by up to 61% and 85%, respectively. The kinetics of OTC uptake could be well described by Michaelis-Menten equation with Vmax of 2.25 micromol g-1 fresh weight h-1, and Km of 0.036 mM. The uptake of OTC by alfalfa was strongly inhibited by the metabolic inhibitor, 2,4-DNP (2,4-dinitrophenol), at pH 3.5 and 6.0, but not by the aquaporin competitors, glycerol and Ag+. OTC uptake, however, was significantly inhibited by Hg2+, suggesting that the inhibition of influx was due to general cellular stress rather than the specific action of Hg2+ on aquaporins. Results from the present study suggested that OTC uptake into alfalfa is an energy-dependent process.
在水培系统中进行了一系列实验，以研究苜蓿（紫花苜蓿）对土霉素（OTC）的吸收及其对苜蓿的毒性。OTC分别抑制苜蓿地上部分和根部生长达61%和85%。OTC吸收动力学可用米氏方程很好地描述，Vmax为2.25微摩尔克鲜重每小时，Km为0.036毫摩尔。在pH值为3.5和6.0时，代谢抑制剂2,4-二硝基苯酚（2,4-DNP）强烈抑制苜蓿对OTC的吸收，但水通道蛋白竞争剂甘油和银离子对其无抑制作用。然而，汞离子显著抑制OTC的吸收，这表明流入的抑制是由于一般细胞应激，而非汞离子对水通道蛋白的特异性作用。本研究结果表明，苜蓿对OTC的吸收是一个能量依赖过程。
