Data for effects of MeHg on avian lipid metabolism

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) MeHg exposure on multiple lipid
metabolism markers in the pectoralis and livers of yellow-rumped warblers
(Setophaga coronata) that were previously found 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 dosed birds
indicated elevated energy costs, lower fatty acid uptake capacity, and
lower PPAR-γ expression. The lower muscle oxidative enzyme capacity of
dosed birds may have caused or 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.