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Characterizing the in vitro hepatic biotransformation of the flame retardant BDE 99 by common carp.

Publication ,  Journal Article
Noyes, PD; Kelly, SM; Mitchelmore, CL; Stapleton, HM
Published in: Aquatic toxicology (Amsterdam, Netherlands)
April 2010

Polybrominated diphenyl ethers (PBDEs) are a class of flame retardant chemicals known to biomagnify in aquatic foodwebs. However, significant biotransformation of some congeners via reductive dehalogenation has been observed during in vivo and in vitro laboratory exposures, particularly in fish models. Little information is available on the enzyme systems responsible for catalyzing this metabolic pathway in fish. This study was undertaken to characterize the biotransformation of one primary BDE congener, 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), using in vitro techniques. Hepatic sub-cellular fractions were first prepared from individual adult common carp (Cyprinus carpio) to examine metabolism in both microsomal and cytosolic sub-cellular fractions. Debromination rates (i.e. BDE-99 biotransformation to BDE-47) were generally higher in the microsomal fraction than in the cytosolic fraction, and some intra-species variability was observed. Further experiments were conducted to determine the biotransformation kinetics and the influence of specific co-factors, inhibitors and competitive substrates on metabolism using pooled carp liver microsomes. The apparent K(m) and V(max) values were 19.4microM and 1120pmolesh(-1)mgprotein(-1), respectively. Iodoacetate (IaC) and the two thyroid hormones, reverse triodothyronine (rT3) and thyroxine (T4), significantly inhibited the debromination of BDE-99 in microsomal sub-cellular fractions with IC(50) values of 2.2microM, 0.83microM, and >1.0microM, respectively. These results support our hypothesis that deiodinase enzymes may be catalyzing the metabolism of PBDEs in fish liver tissues. Further studies are needed to evaluate metabolic activity in other species and tissues that contain these enzymes.

Duke Scholars

Published In

Aquatic toxicology (Amsterdam, Netherlands)

DOI

EISSN

1879-1514

ISSN

0166-445X

Publication Date

April 2010

Volume

97

Issue

2

Start / End Page

142 / 150

Related Subject Headings

  • Water Pollutants, Chemical
  • Triiodothyronine, Reverse
  • Toxicology
  • Thyroxine
  • Subcellular Fractions
  • Propylthiouracil
  • Male
  • Liver
  • Linear Models
  • Kinetics
 

Citation

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Noyes, P. D., Kelly, S. M., Mitchelmore, C. L., & Stapleton, H. M. (2010). Characterizing the in vitro hepatic biotransformation of the flame retardant BDE 99 by common carp. Aquatic Toxicology (Amsterdam, Netherlands), 97(2), 142–150. https://doi.org/10.1016/j.aquatox.2009.12.013
Noyes, Pamela D., Shannon M. Kelly, Carys L. Mitchelmore, and Heather M. Stapleton. “Characterizing the in vitro hepatic biotransformation of the flame retardant BDE 99 by common carp.Aquatic Toxicology (Amsterdam, Netherlands) 97, no. 2 (April 2010): 142–50. https://doi.org/10.1016/j.aquatox.2009.12.013.
Noyes PD, Kelly SM, Mitchelmore CL, Stapleton HM. Characterizing the in vitro hepatic biotransformation of the flame retardant BDE 99 by common carp. Aquatic toxicology (Amsterdam, Netherlands). 2010 Apr;97(2):142–50.
Noyes, Pamela D., et al. “Characterizing the in vitro hepatic biotransformation of the flame retardant BDE 99 by common carp.Aquatic Toxicology (Amsterdam, Netherlands), vol. 97, no. 2, Apr. 2010, pp. 142–50. Epmc, doi:10.1016/j.aquatox.2009.12.013.
Noyes PD, Kelly SM, Mitchelmore CL, Stapleton HM. Characterizing the in vitro hepatic biotransformation of the flame retardant BDE 99 by common carp. Aquatic toxicology (Amsterdam, Netherlands). 2010 Apr;97(2):142–150.
Journal cover image

Published In

Aquatic toxicology (Amsterdam, Netherlands)

DOI

EISSN

1879-1514

ISSN

0166-445X

Publication Date

April 2010

Volume

97

Issue

2

Start / End Page

142 / 150

Related Subject Headings

  • Water Pollutants, Chemical
  • Triiodothyronine, Reverse
  • Toxicology
  • Thyroxine
  • Subcellular Fractions
  • Propylthiouracil
  • Male
  • Liver
  • Linear Models
  • Kinetics