An evaluation of transcriptomic points of departure and gene expression profiles for larval fathead minnows (Pimephales promelas) exposed to 22 chemicals with known modes of action

One day post hatch fathead minnows were exposed to eight concentrations of two piscicides, three herbicides, four insecticides, seven fungicides, two statins, and four PPAR agonists for 24 h. Following exposures, whole body homogenates were sent for targeted RNA sequencing using TempO-Seq. Concentration response modeling, using measured concentrations where feasible, was applied to all sequencing results to estimate benchmark concentrations and derive tPODs.

The derived tPODs were lower than concentrations that impacted apical endpoints in fish collected from the ECOTOX Knowledgebase in most cases. However, this was not the case when compared to apical effects in other taxa (crustaceans, insects, algae). To investigate the relationships of chemicals within the same mode of action (MoA), exploratory principal component analysis was used as was examining differentially expressed genes between chemicals within modes of action.

Our results showed that the individual genes impacted by chemical exposure rarely clustered within modes of action. The results of this study provide additional data that can be used to examine the applicability of high-throughput assay for possible use in ecological hazard screening