Mark Hahn, Ph.D.
Woods Hole Oceanographic Institution
Low-dose exposure to domoic acid in early life altered zebrafish neurodevelopment and behavior, according to new NIEHS-funded research. The study sheds light on the mechanisms by which domoic acid affects the developing nervous system and identifies a window of susceptibility to exposure. Domoic acid is a neurotoxic compound produced by certain harmful algae. Humans are primarily exposed through eating contaminated seafood.
Domoic acid was injected into zebrafish at 1 to 4 days post fertilization (dpf), including distinct neurodevelopmental timepoints. At 5 dpf, the researchers used imagining techniques to examine the myelin sheath, which is important for proper transmission of nerve signals throughout the body. Using genetic sequencing methods, they identified altered gene expression resulting from exposure at 2 dpf. They performed behavioral tests at 7 dpf to determine the functional impact of exposure.
Fish exposed to domoic acid at 2 dpf, but not 1 or 4 dpf, showed consistent deficits in behavior, including lower responsiveness to stimuli. Similarly, only fish exposed at 2 dpf showed myelin sheath defects. Exposure at 2 dpf decreased expression of genes required for maintaining myelin sheath and nerve structure.
According to the authors, these results reveal a critical window of susceptibility to domoic acid exposure in zebrafish and identify altered gene expression and myelin structure as possible mechanisms driving behavioral deficits.
Citation: Panlilio JM, Aluru N, Hahn ME. 2020. Developmental neurotoxicity of the harmful algal bloom toxin domoic acid: cellular and molecular mechanisms underlying altered behavior in the zebrafish model. Environ Health Perspect 128(11):117002.