Image via Tohru Murakami

Researchers from North Carolina State University (NCSU) and Oregon State University have identified a genetic factor in zebrafish that appears to explain why organisms react differently to the same environmental chemicals. The work, which was published last week in Environmental Health Perspectives, could help us to understand previously unexplained differences in the way we react to chemicals.

“We believe that the interplay between an individual’s genetics and the environment is a key to answering questions like, ‘Why do some drugs work well for some people but not others?’ or ‘Why does pollution affect people differently?’” said David Reif, PhD, one of the authors of the study and Associate Professor of Biology at NCSU. “We wanted to address two related problems: Of all the tens of thousands of chemicals to which we are exposed, do some elicit differential sensitivity? And are there genetic factors that explain differential sensitivity?”

Specifically, the team were investigation the affect abamectin had on zebrafish during the early stages of development. Abamectin is a natural fermentation product produced by certain types of bacteria that is primarily used as an insecticide for agriculture, while zebrafish are considered to be genetically similar (relatively) to humans; understanding how and when this chemical could affect the organisms is an important factor in making large-scale food production safer.

Using a series of assays, the team compared the genomes of any affected zebrafish with those that developed normally despite the presence of the chemical. The team found that the organisms most affected by the insecticide were carrying a variant of the Sox7 gene that wasn’t present in unaffected individuals and, in follow up experiments, were expressing the gene at a lower level than their healthy brethren.  

“This study is a starting point to confirm that individuals may react differently to chemicals in the environment based upon genetic profile,” said Dr Reif. “Our high throughput screening approach allows us to quickly sort through the ‘exposome’ of chemicals to which we are exposed and look for relationships between genetics and environmental exposure, rather than be limited to preselected candidate exposures. The work has implications for precision medicine, disease prevention and understanding how risk may differ across communities.”

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