title: Effects of triclosan and triclocarban on the growth inhibition, cell viability, genotoxicity and multixenobiotic resistance responses of Tetrahymena thermophila.
abstract: The information about adverse effects of emerging contaminants on aquatic protozoa is very scarce. The growth inhibition effect, cell viability, genotoxicity and multixenobiotic resistance (MXR) responses of two commonly used antimicrobial agents, triclosan (TCS) and triclocarban (TCC) to protozoan Tetrahymena thermophila were investigated in this study. The results revealed that TCS and TCC can inhibit the growth of T. thermophila with 24h EC50 values of 1063 and 295μgL(-1), respectively. The impairment of plasma membrane was observed after 2h exposure of TCS or TCC at the level of mg/L. Furthermore, it is noticeable that at environmentally relevant concentration (1.0μgL(-1)), both TCS and TCC can lead to statistically significant DNA damage in T. thermophila, while the inhibition of growth and change of cell viability cannot be observed. Our results firstly provide the evidence for genotoxic effects of TCS and TCC on the freshwater protozoan. Additionally, both TCS and TCC were found to inhibit the efflux transporter activities, with the inhibitory potencies of 39% and 40% (using verapamil as a model inhibitor), respectively. Particularly, TCC could significantly down-regulate the expression of MXR related gene Abcb15, which encodes the membrane efflux protein that acting as P-gp in T. thermophila. The results raise the awareness of potential aquatic ecological and human health risks from the exposure of TCS and TCC, as they might potentiate the toxic effects by chemosensitizing with co-existing toxicants.
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; School of Resource and Environment, Ningxia University, Yinchuan 750021, China.
authors.forename: Li
authors.initials: L
authors.lastname: Gao
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: taoyuan@sjtu.edu.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Yuan
authors.affiliation: School of Life Science, Hubei University, Wuhan 430062, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Cheng
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Qifeng
authors.initials: Q
authors.lastname: Bai
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Chuanqi
authors.initials: C
authors.lastname: Zhou
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Ao
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Wenhua
authors.initials: W
authors.lastname: Wang
authors.affiliation: School of Life Science, Hubei University, Wuhan 430062, China.
authors.forename: Haimou
authors.initials: H
authors.lastname: Zhang
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D002224:Carbanilides / Q000633:toxicity*; D002470:Cell Survival / Q000187:drug effects; D004347:Drug Interactions; D004351:Drug Resistance / Q000187:drug effects*; D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000737:chemistry; D009153:Mutagens / Q000633:toxicity; D016808:Tetrahymena thermophila / Q000166:cytology* / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D014260:Triclosan / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity; D015262:Xenobiotics / Q000378:metabolism / Q000633:toxicity*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002224:Carbanilides; D009153:Mutagens; D014874:Water Pollutants, Chemical; D015262:Xenobiotics; D014260:Triclosan; C009540:triclocarban
keywords: Gene expression; Genotoxicity; Growth inhibition; Multixenobiotic resistance; Triclocarban; Triclosan