title: Toxic effects of chlortetracycline on maize growth, reactive oxygen species generation and the antioxidant response.
abstract: The toxicity of chlortetracycline (CTC) on maize (Zea mays L.) growth and reactive oxygen species (ROS) generation was studied. The root and shoot lengths and fresh weights of maize seedlings were inhibited by CTC treatment (p < 0.05). Root length was more sensitive than other parameters with the EC10 value of 0.064 mg/L. The spin trapping technique followed by electron paramagnetic resonance (EPR) analysis was used to quantify the ROS production. The ROS generated in maize roots after exposure to CTC was identified as hydroxyl radical (*OH). The EPR signal intensity correlated positively with the logarithm of CTC concentrations exposed (p < 0.05). The dynamic changes of malondialdehyde (MDA) contents and the antioxidative enzyme activities in maize roots were also determined. As compared to the control group, CTC was found to significantly increase MDA content. Treatment of maize roots with the *OH scavenger sodium benzoate (SB) reduced the MDA content and enhanced the antioxidative enzyme activities. The results demonstrated the harmfulness of CTC at high dose to maize in the early developmental stage, and clarified that the inducement of *OH is one of the mechanisms of CTC toxicity.
authors.affiliation: 1. State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. bwen@rcees.ac.cn
authors.forename: Bei
authors.initials: B
authors.lastname: Wen
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Tong
authors.initials: T
authors.lastname: Wu
authors.forename: Shuzhen
authors.initials: S
authors.lastname: Zhang
authors.forename: Xiaoquan
authors.initials: X
authors.lastname: Shan
authors.forename: Jingfen
authors.initials: J
authors.lastname: Lu
mesh_terms: D000900:Anti-Bacterial Agents / Q000633:toxicity*; D002374:Catalase / Q000378:metabolism; D002751:Chlortetracycline / Q000633:toxicity*; D008315:Malondialdehyde / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D003313:Zea mays / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D017382:Reactive Oxygen Species; D008315:Malondialdehyde; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; D002751:Chlortetracycline