Short‑term mercury exposure disrupts muscular and hepatic lipid metabolism in a migrant songbird

Authors: Chad L. Seewagen, Cory R. Elowe, Alexander R. Gerson, Derrick J. E. Groom, Yanju Ma, Mustafa Yildirim, & Christopher G. Guglielmo

Year: 2022

Publication: Scientific Reports:

Publication Link:

Abstract: Methylmercury (MeHg) is a global pollutant that can cause metabolic disruptions in animals and
thereby potentially compromise the energetic capacity of birds for long-distance migration, but its
effects on avian lipid metabolism pathways that support endurance flight and stopover refueling have
never been studied. We tested the effects of short-term (14-d), environmentally relevant (0.5 ppm)
dietary MeHg exposure on lipid metabolism markers in the pectoralis and livers of yellow-rumped
warblers (Setophaga coronata) that were found in a previous study to have poorer flight endurance in a
wind tunnel than untreated conspecifics. Compared to controls, MeHg-exposed birds displayed lower
muscle aerobic and fatty acid oxidation capacity, but similar muscle glycolytic capacity, fatty acid
transporter expression, and PPAR expression. Livers of exposed birds indicated elevated energy costs,
lower fatty acid uptake capacity, and lower PPAR-γ expression. The lower muscle oxidative enzyme
capacity of exposed birds likely contributed to their weaker endurance in the prior study, while the
metabolic changes observed in the liver have potential to inhibit lipogenesis and stopover refueling.
Our findings provide concerning evidence that fatty acid catabolism, synthesis, and storage pathways
in birds can be dysregulated by only brief exposure to MeHg, with potentially significant consequences
for migratory performance.

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