title: Maternal transfer, distribution, and metabolism of BDE-47 and its related hydroxylated, methoxylated analogs in zebrafish (Danio rerio).
abstract: OH-PBDEs have been reported to be more potent than the postulated precursor PBDEs or corresponding MeO-PBDEs. However, there are contradictory reports for transformation of these compounds in organisms, particularly, for biotransformation of OH-PBDEs and MeO-PBDEs, only one study reported transformation of 6-OH-BDE-47 and 6-MeO-BDE-47 in Japanese medaka. In present study zebrafish (Danio rerio) were exposed to BDE-47, 6-OH-BDE-47, 6-MeO-BDE-47, 2'-OH-BDE-28 and 2'-MeO-BDE-28 in the diet for 20 d. Concentrations of each exposed compound were measured in eggs collected on days 0, 5, 10, 15 or 20. After 20 d exposure, concentrations of precursor and biotransformation products in liver and liver-free residual carcass were measured by use of GC-MS/MS. Total mass of the five compounds in bodies of adults were: 2'-MeO-BDE-28 ∼ 6-MeO-BDE-47>BDE-47>2'-OH-BDE-28>6-OH-BDE-47. MeO-PBDEs were also accumulated more into parental fish body than in liver, while OH-PBDEs accumulated in liver more than in liver-free residual carcass. Concentrations in liver of males were greater than those of females. This result suggests sex-related differences in accumulation. Ratios between concentration in eggs and liver (E/L) were: 2.9, 1.7, 0.8, 0.4 and 0.1 for 6-MeO-BDE-47, BDE-47, 6-OH-BDE-47, 2'-MeO-BDE-28 and 2'-OH-BDE-28, respectively. This result suggests transfer from adult females to eggs. BDE-47 was not transformed into OH-PBDEs or MeO-PBDEs. Inter-conversions of 6-OH-BDE-47 and 6-MeO-BDE-47, 2'-OH-BDE-28 and 2'-MeO-BDE-28 were observed, with metabolite/precursor concentration ratios for 6-OH-BDE-47, 6-MeO-BDE-47, 2'-OH-BDE-28 and 2'-MeO-BDE-28 being 3.8%, 14.6%, 2.9% and 76.0%, respectively. Congener-specific differences were observed in distributions between liver and carcass, maternal transfer and transformation. The two MeO-PBDEs were accumulated into adults, transferred to eggs, and were transformed to the structural similar OH-PBDEs, which might be more toxic. BDE-47 was accumulated into adults and transferred from females to eggs, but not transformed to MeO-PBDEs and/or OH-PBDEs. Accumulation of OH-PBDEs into adults as well as rates of transformation of OH-PBDEs to MeO-PBDEs were all several orders of magnitude less. Thus, MeO-PBDEs are likely to present more of a risk in the environment.
authors: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
authors: Quan
authors: Q
authors: Wen
authors: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China. Electronic address: hlliu@nju.edu.cn.
authors: Hong-ling
authors: HL
authors: Liu
authors: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
authors: Yu-ting
authors: YT
authors: Zhu
authors: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
authors: Xin-mei
authors: XM
authors: Zheng
authors: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
authors: Guan-yong
authors: GY
authors: Su
authors: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
authors: Xiao-wei
authors: XW
authors: Zhang
authors: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China. Electronic address: yuhx@nju.edu.cn.
authors: Hong-xia
authors: HX
authors: Yu
authors: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong, Special Administrative Regions.
authors: John P
authors: JP
authors: Giesy
authors: Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong, Special Administrative Regions.
authors: Michael H W
authors: MH
authors: Lam
mesh_terms: D000818:Animals; D000840:Anisoles / Q000032:analysis / Q000378:metabolism; D001711:Biotransformation; D004785:Environmental Pollutants / Q000032:analysis / Q000378:metabolism*; D005260:Female; D055768:Halogenated Diphenyl Ethers / Q000032:analysis / Q000378:metabolism*; D006900:Hydroxylation; D008099:Liver / Q000378:metabolism; D008297:Male; D018811:Maternal Exposure; D010063:Ovum / Q000737:chemistry; D011075:Polybrominated Biphenyls / Q000032:analysis / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D015027:Zebrafish / Q000378:metabolism*
chemical_list: C496823:2-(2',4'-dibromophenoxy)-3,5-dibromoanisole; C580599:6-OH-BDE-47; D000840:Anisoles; D004785:Environmental Pollutants; D055768:Halogenated Diphenyl Ethers; D011075:Polybrominated Biphenyls; C511295:2,2',4,4'-tetrabromodiphenyl ether; C533760:tribromodiphenyl ether 28
keywords: Body burden; Inter-conversion; Offspring; Transformation