Azoxystrobin and
pyraclostrobin are broad spectrum
strobilurin fungicides that have been measured in the aquatic environment.
Strobilurins inhibit mitochondrial respiration by binding to the mitochondrial respiratory
complex III. The goal of this study was to investigate
mitochondrial dysfunction and oxidative stress in the developing zebrafish from exposure to
azoxystrobin and
pyraclostrobin. Exposure studies were performed where zebrafish embryos were exposed to
azoxystrobin and
pyraclostrobin at 0.1, 10, 100 μg/L from 4 hpf to 48 hpf to measure
mitochondrial dysfunction and oxidative stress
mRNA transcripts, and 5 dpf to measure movement, growth, oxygen consumption, enzymatic activities, and
mRNA transcripts. Results from this study indicated that there was a significant reduction in both basal and maximal respiration at 48 hpf in zebrafish exposed to 100 μg/L of
pyraclostrobin. There was no difference in oxidative stress or apoptotic
mRNA transcripts at 48 hpf, indicating that the two
strobilurins were acting first on mitochondrial function and not directly through oxidative stress. At 5 dpf, standard body length was significantly reduced with exposure to
pyraclostrobin and
azoxystrobin exposure as compared to the control. These reductions in apical endpoints corresponded with increases in oxidative stress and apoptotic
mRNA transcripts in treatment groups at 5 dpf indicating that
strobilurins' exposure followed the adverse outcome pathway for mito-toxicants. Our results indicate that
strobilurins can decrease mitochondrial function, which in turn lead to diminished growth and movement.