Elucidating toxicological mechanisms of current flame retardants using a bacterial gene profiling assay.
Flame retardants are ubiquitously used chemicals that have been shown to contaminate environments. Toxicological data is largely limited, with little insight into their molecular modes of action that may give rise to their toxic phenotypes. Such insight would aid more effective risk assessments concerning these compounds, while also improving molecular design. We therefore used a bacterial stress-gene profiling assay to screen twelve currently-used flame retardants to obtain mechanistic insights of toxicity. Both brominated and organophosphate flame retardants were tested. All compounds showed statistically significant inductions of several stress genes when compared to control treatments. Triphenyl phosphate, tris(2-butoxyethyl) phosphate, tris(1,3-dichloro-2-propyl)phosphate, tris(butyl)phosphate, and tetrabromobisphenol A elicited (at least) two-fold inductions for any of the stress genes. When looking at absolute induction levels, the promoters induced are indicative of protein perturbation, DNA integrity and membrane integrity. However, normalising for the different induction potentials of the different stress genes and clustering using hierarchical and k-means algorithms indicated that in addition to protein and DNA damage, some compounds also resulted in growth arrest and oxidative damage. This research shows that this assay allows for the determination of toxicological modes-of-action while clustering and accounting for induction potentials of the different genes aids better risk assessment.
Department of Biology, Systemic Physiological & Ecotoxicological Research, University of Antwerp, Antwerp, Belgium. Electronic address: boris.krivochiev@uantwerpen.be.
Boris V
BV
Krivoshiev
Department of Biology, Systemic Physiological & Ecotoxicological Research, University of Antwerp, Antwerp, Belgium.
Freddy
F
Dardenne
Department of Biology, Systemic Physiological & Ecotoxicological Research, University of Antwerp, Antwerp, Belgium.
Ronny
R
Blust
Department of Pharmaceutical Science, Toxicological Centre, University of Antwerp, Antwerp, Belgium.
Adrian
A
Covaci
Department of Biology, Systemic Physiological & Ecotoxicological Research, University of Antwerp, Antwerp, Belgium.
Steven J
SJ
Husson
D015374:Biosensing Techniques / Q000379:methods*; D049109:Cell Proliferation / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism*; D005411:Flame Retardants / Q000633:toxicity*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D013312:Stress, Physiological / Q000187:drug effects; D059467:Transcriptome / Q000187:drug effects*
D005411:Flame Retardants
Bacterial stress genes; Escherichia coli; Flame retardants; Mode of action; Reporter assay