Assessment of mitochondrial DNA damage in little brown bats (Myotis lucifugus) collected near a mercury-contaminated river
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Historical discharges of Hg into the South River near the town of Waynesboro, VA, USA, have resulted in persistently elevated Hg concentrations in sediment, surface water, ground water, soil, and wildlife downstream of the discharge site. In the present study, we examined mercury (Hg) levels in in little brown bats (Myotis lucifugus) from this location and assessed the utility of a non-destructively collected tissue sample (wing punch) for determining mitochondrial DNA (mtDNA) damage in Hg exposed bats. Bats captured 1 and 3 km from the South River, exhibited significantly higher levels of total Hg (THg) in blood and fur than those from the reference location. We compared levels of mtDNA damage using real-time quantitative PCR (qPCR) analysis of two distinct regions of mtDNA. Genotoxicity is among the many known toxic effects of Hg, resulting from direct interactions with DNA or from oxidative damage. Because it lacks many of the protective protein structures and repair mechanisms associated with nuclear DNA, mtDNA is more sensitive to the effects of genotoxic chemicals and therefore may be a useful biomarker in chronically exposed organisms. Significantly higher levels of damage were observed in both regions of mtDNA in bats captured 3 km from the river than in controls. However, levels of mtDNA damage exhibited weak correlations with fur and blood THg levels, suggesting that other factors may play a role in the site-specific differences.
KeywordsMercury DNA damage Wildlife Biomarkers Little brown bats Myotis lucifugus
Funding and support for this work was provided by the U.S. Fish and Wildlife Service, DuPont ™, the South River Science Team, and the U.S. Geological Survey. The use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service. We would like to thank the many biologists that helped obtain samples for this study, Tim Divoll, Lucas Savoy, Dustin Meatty, Pedro Ardapple, Casey Huck, Patrick Keenan, Rick Reynolds (VADGF) and all the field technicians who put in countless hours. We also thank Catherine Maddox and Kelly Hallinger for their assistance in the laboratory.
Conflict of interest
The authors declare that they have no conflict of interest.
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