High-Resolution Respirometry for the Assessment of Teratogenic Chemicals

Pesticides are often used in agriculture and residential areas to mitigate pests and weeds. These chemicals can enter aquatic ecosystems via runoff and rain events, exerting negative effects on aquatic species. In rapidly developing fish embryos, metabolic disruption can alter the developmental trajectory and alter ATP levels. Therefore, it is important to quantify mitochondrial integrity in organisms following exposure to pesticides. To achieve this, a high throughput method to assess pesticide effects on oxidative phosphorylation and mitochondria has been optimized for fish embryos. Fish embryos are first exposed to pesticides for 24 or 48 h, and oxygen consumption rates are measured using the Seahorse XFe24/96 Flux Analyzer (formerly Seahorse Biosciences, now Agilent). The assay utilizes a single embryo and precisely measures oxygen consumption and extracellular acidification. Based upon these measurements, characteristics related to mitochondrial bioenergetics are calculated to provide information on mitochondrial integrity. Using this approach, one can identify pesticides affecting the electron transport chain and ultimately ATP production. In this chapter, we describe the mitochondrial stress test to understand mitochondrial dysfunction and metabolic shifts within the fish embryo.