No Effect of Lifelong Methylmercury Exposure on Oxidative Status in Zebra Finches (Taeniopygia guttata): A Demonstration of Methylmercury-Induced Selection?
Songbirds exposed to methylmercury (MeHg) often exhibit reduced reproductive success and cognitive abilities. To better understand whether oxidative stress plays a role, we dosed zebra finches (Taeniopygia guttata) with a contaminated (1.2 ppm MeHg-cysteine) or control diet for their entire lives, including during development in the egg. Levels of antioxidant enzymes [superoxide dismutase (SOD1 and SOD2)], oxidative damage (4-hydroxynonenal; 4-HNE), and antioxidant transcription factors [nuclear factor (erythroid-derived 2)-like 2; Nrf2] were measured in the liver and pectoralis muscle of adults. MeHg treatment did not affect levels of 4-HNE or liver SOD2 or Nrf2. Birds in the MeHg treatment differed significantly from controls in pectoralis SOD1 and Nrf2, and tended to differ in liver SOD1 and pectoralis SOD2; however, we detected no overall pattern of effect of MeHg on oxidative status in dosed finches. We suspect that this is a consequence of the differential survival of MeHg-tolerant birds.
Bulletin of Environmental Contamination and Toxicology
Finger, J., Botero, J., Zhang, Y., Still, S., Hoffman, A., Kavazis, A., Cristol, D., & Wada, H. (2017). No Effect of Lifelong Methylmercury Exposure on Oxidative Status in Zebra Finches (Taeniopygia guttata): A Demonstration of Methylmercury-Induced Selection?. Bulletin of Environmental Contamination and Toxicology, 99 (6), 668-672. https://doi.org/10.1007/s00128-017-2202-7