Characterization of the Fundulus heteroclitus embryo transcriptional response and development of a gene expression-based fingerprint of exposure for the alternative flame retardant, TBPH (bis (2-ethylhexyl)-tetrabromophthalate). (April 2019)

• Record Type: Journal Article
• Authors: Huang, Weichun; Bencic, David C.; Flick, Robert L.; Nacci, Diane E.; Clark, Bryan W.; Burkhard, Lawrence; Lahren, Tylor; Biales, Adam D.
• Is Part Of: Environmental pollution. Volume 247(2019)
• Page Start: 696
• Page End: 705
• Publication Date: 2019-04
• Subjects: TBPH -- Transcriptomics -- Killifish -- AHR -- RNA-seq; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2019.01.010
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Although alternative Flame Retardant (FR) chemicals are expected to be safer than the legacy FRs they replace, their risks to human health and the environment are often poorly characterized. This study used a small volume, fish embryo system to reveal potential mechanisms of action and diagnostic exposure patterns for TBPH (bis (2-ethylhexyl)-tetrabromophthalate), a component of several widely-used commercial products. Two different concentration of TBPH were applied to sensitive early life stages of an ecologically important test species, Fundulus heteroclitus (Atlantic killifish), with a well-annotated genome. Exposed fish embryos were sampled for transcriptomics or chemical analysis of parent compound and primary metabolite or observed for development and survival through larval stage. Global transcript profiling using RNA-seq was conducted (n = 16 per treatment) to provide a non-targeted and statistically robust approach to characterize TBPH gene expression patterns. Transcriptomic analysis revealed a dose-response in the expression of genes associated with a surprisingly limited number of biological pathways, but included the aryl hydrocarbon receptor signal transduction pathway, which is known to respond to several toxicologically-important chemical classes. A transcriptional fingerprint using Random Forests was developed that was able to perfectly discriminate exposed vs. non-exposed individuals in test sets. These results suggest that TBPH has a relatively low potential for developmental toxicity (at least in fishes), despite concerns related to its structural similarities to endocrine disrupting chemicals and that the early life stage Fundulus system may provide a convenient test system for exposure characterization. More broadly, this study advances the usefulness of a biological testing and analysis system utilizing non-targeted transcriptomics profiling and early developmental endpoints that complements current screening methods to characterize chemicals of ecological and human health concern. Graphical abstract: Image 1 Highlights: Minimal metabolism of TBPH was observed in Fundulus hetericlitus embryos. No observed developmental effects observed in Fundulus embryos following TBPH exposure. Non-targeted RNA-seq strongly suggests TBPH initiates a dose-dependent TCDD-like effect. A transcriptional fingerprint of TBPH exposure was able to perfectly differentiate exposed vs. non-exposed Fundulus embryos. Abstract : No developmental effects were observed in Fundulus heteroclitus exposed to the alternative flame retardant, TBPH; however, RNA-seq analysis strongly suggested a TCDD-like transcriptional response.