Assessment of Developmental Toxicity Potential of Glyphosate-Based Herbicides Using Drosophila melanogaster Primary Embryonic Stem Cell Cultures

Glyphosate-based herbicides (GBH) are widely and most commonly used in the world of agriculture. A number of earlier developmental toxicity studies, utilizing a number of model organisms, have indicated that GBH exposure can result in neural defects and cranial malformations in the developing fetus. The Drosophila melanogaster embryonic cell culture system has been established as a robust in vitro assay to identify developmental toxicants (teratogens). The assay utilizes gastrula-staged Drosophila embryos which are homogenized into single cells, diluted into an appropriate cell density with Schneider’s Drosophila medium that has been supplemented with FCS, and plated into 35mm dishes. Over the course of 24 hours, the embryonic stem cells go on to differentiate into a number of different cell types, but predominantly give rise to neuronal clusters (mostly cholinergic neurons) and myotubes. In this study, Drosophila melanogaster embryos were collected, cultured, and exposed to GBH at concentrations of 1x10-5mM, 5x10-5mM, and 1x10-4mM. Concentrations above 1x10-5mM yielded a significant decrease in the numbers of terminally differentiated neuronal clusters and myotubes and therefore identified GBH as a potential teratogen. Future studies will include identifying if GBH targets only cholinergic neurons and if GBH exposure results in the induction of hsp 70 (a major stress protein). It is hoped that this assay can be used, along with a battery of other in vitro assays, as a screen for the large number of insecticides and pesticides awaiting comprehensive testing of their teratogenic potential