Glyphosate induces cardiovascular toxicity in Danio rerio

• Glyphosate causes changes to the atria and ventricle and decreases heartrate.
• Glyphosate causes alteration to the vasculature in the body.
• Glyphosate alters expression of Mef2 in early myocardial precursors.

Glyphosate is a broad spectrum herbicide used aggressively in agricultural practices as well as home garden care. Although labeled “safe” by the chemical industry, doses tested by industry do not mimic chronic exposures to sublethal doses that organisms in the environment are exposed to over long periods of time. Given the widespread uses of and exposure to glyphosate, studies on developmental toxicity are needed. Here we utilize the zebrafish vertebrate model system to study early effects of glyphosate on the developing heart. Treatment by embryo soaking with 50 μg/ml glyphosate starting at gastrulation results in structural abnormalities in the atrium and ventricle, irregular heart looping, situs inversus as well as decreased heartbeats by 48 h as determined by live imaging and immunohistochemistry. Vasculature in the body was also affected as determined using fli-1 transgenic embryos. To determine if the effects noted at 48 h post fertilization are due to early stage alterations in myocardial precursors, we also investigate cardiomyocyte development with a Mef2 antibody and by mef2ca in situ hybridization and find alterations in the Mef2/mef2ca staining patterns during early cardiac patterning stages. We conclude that glyphosate is developmentally toxic to the zebrafish heart.