Toxin-Induced Changes in Gene Expression: New Findings in Zebrafish

 An RNA-sequencing investigation of zebrafish exposed to the environmental contaminant, Aroclor 1254.

Figure 1: Zebrafish, Danio rerio, are a common freshwater fish, frequently used in biomedical research for their rapid development, as an ethical alternative to mammals, and high genetic homology to humans.

    Aroclor 1254 is an environmental contaminant present in aquatic environments, made up of various PCBs (polychlorinated biphenyls), sourced from old shipwrecks, antifreeze, and plasticizers. Last year, a study from the University of North Texas determined that exposure to Aroclor 1254 in zebrafish embryos caused induced eye tremors in larvae. To further investigate this difference in gene expression, a group of geneticists from UC Riverside and the University of North Texas studied the molecular signaling pathways responsible for this impaired sensory system. 

    The updated study affirmed that, upon exposure to this environmental factor, an eye-tremor response was induced in 7ph Zebrafish. Specifically, at 173 micrograms per liter of this contaminant, impaired optokinetic responses and decreased eye diameter were observed in the fish. Specific doses of the contaminant were found to directly impact the species's equivalent to a Parkinson's signaling pathway. This presents further implications for humans, due to our 70% shared genome with Zebrafish. Long-term or early life exposure to pollutants could directly interfere with neurological development and function.

Sources:

Magnuson, Jason T., et al. “Aroclor 1254 Impairs Visual and Neurosensory Signaling Pathways Independent of the Aryl Hydrocarbon Receptor in Larval Zebrafish.” Aquatic Toxicology, vol. 291, 2026, p. 107695. https://www.sciencedirect.com/science/article/pii/S0166445X2500459X?via%3Dihub#sec0017 

National Oceanic and Atmospheric Administration (NOAA). “New Research Identifies Impacts to Developing Zebrafish Exposed to Contaminants.” NOAA Office of Response and Restoration, 12 Mar. 2026. https://response.restoration.noaa.gov/new-research-identifies-impacts-developing-zebrafish-exposed-contaminants