Studying Autism Spectrum Disorder and Environmental Factors; Neurodevelopmental Effects of ChromiumExposure in Embryonic Zebrafish

Science Center A255

Autism Spectrum Disorder (ASD) is a prevalent neurodevelopmental disorder, affecting roughly 1 in 68 people worldwide (CDC). Current epidemiological evidence implicates heavy metal exposure, notably in contaminated water supplies, with an elevated incidence rate of ASD. While not establishing a causal relationship, these data motivate the study of the effects of heavy metals on the developing nervous system, including chromium. We exposed zebrafish embryos to increasing levels of chromium and identified phenotypic variation through brightfield microscopy. Embryos were exposed to chromium solutions starting at 24 hours post-fertilization hpf and observed at 48hpf and 72hpf. A titration curve of embryo survivability was created; the observed lethal dose was approximately 150mg/L, and subtle phenotypic variations became visible at 25mg/L. We observed phenotypic variations in a dose-dependent fashions, including enlarged yolk sacs, pericardial edema, and crooked spines. Ongoing experiments are assessing gene expression patterns via quantitative polymerase chain reaction (qPCR) using RNA extracted from 72hpf embryos exposed to chromium or vehicle. Genes assessed include specific neural-type cell markers and autism risk genes. Our findings may be useful for informing health and environmental policy and further understanding the impacts of heavy metal exposure on neurodevelopment.