title: Bioaccumulation and degradation of pesticide fluroxypyr are associated with toxic tolerance in green alga Chlamydomonas reinhardtii.
abstract: The herbicide fluroxypyr is widely used for controlling weeds and insects but intensive use of fluroxypyr has resulted in its widespread contamination in soils and aquatic ecosystems. To evaluate the eco-toxicity of fluroxypyr to green algae, bioaccumulation and degradation of fluroxypyr in Chlamydomonas reinhardtii, a model unicellular alga, along with its biological adaptation to fluroxypyr toxicity were investigated. The microalgae were treated with fluroxypyr at 0.05-1.00 mg l(-1) for 2 days or 0.50 mg l(-1) for 1-5 days. The growth of C. reinhardtii was stimulated at low levels of fluroxypyr (0.05-0.5 mg l(-1)) but inhibited at high concentrations (0.75-1.00 mg l(-1)). Fluroxypyr was significantly accumulated by C. reinhardtii. Interestingly, the accumulated fluroxypyr could be rapidly degraded in the cells. On day 5 more than 57% of cellular fluroxypyr was degraded. Our results indicated that accumulation and degradation of fluroxypyr occurred simultaneously. Treatment with 0.05-1.00 mg l(-1) fluroxypyr for 30 min induced significant production of reactive oxygen species and as a consequence resulted in accumulation of peroxides and DNA degradation. Additionally, activities of several major antioxidant enzymes were activated in C. reinhardtii exposed to high levels of fluroxypyr. Overall, the present studies represent the initial comprehensive analyses of the green alga C. reinhardtii in adaptation to the fluroxypyr-contaminated aquatic ecosystems.
authors.affiliation: Department of Applied Chemistry, College of Science, Nanjing Agricultural University, Nanjing, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Zhang
authors.forename: Chong Bin
authors.initials: CB
authors.lastname: Qiu
authors.forename: You
authors.initials: Y
authors.lastname: Zhou
authors.forename: Zhen Peng
authors.initials: ZP
authors.lastname: Jin
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
mesh_terms: D000085:Acetates / Q000378:metabolism* / Q000633:toxicity; D000222:Adaptation, Physiological; D001673:Biodegradation, Environmental; D016825:Chlamydomonas reinhardtii / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D004361:Drug Tolerance; D006540:Herbicides / Q000378:metabolism* / Q000633:toxicity; D018384:Oxidative Stress; D011725:Pyridines / Q000378:metabolism* / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity
chemical_list: D000085:Acetates; D006540:Herbicides; D011725:Pyridines; D014874:Water Pollutants, Chemical; C416382:4,5-amino-3,5-dichloro-6-fluoro-2-pyridinyloxyacetic acid