title: Chromosomal damage and EROD induction in tree swallows (Tachycineta bicolor) along the Upper Mississippi River, Minnesota, USA.
abstract: The health of tree swallows, Tachycineta bicolor, on the Upper Mississippi River (UMR) was assessed in 2010 and 2011 using biomarkers at six sites downriver of Minneapolis/St. Paul, MN metropolitan area, a tributary into the UMR, and a nearby lake. Chromosomal damage was evaluated in nestling blood by measuring the coefficient of variation of DNA content (DNA CV) using flow cytometry. Cytochrome P450 1A activity in nestling liver was measured using the ethoxyresorufin-O-dealkylase (EROD) assay, and oxidative stress was estimated in nestling livers via determination of thiobarbituric acid reacting substances (TBARS), reduced glutathione (GSH), oxidized glutathione (GSSG), the ratio GSSG/GSH, total sulfhydryl, and protein bound sulfhydryl (PBSH). A multilevel regression model (DNA CV) and simple regressions (EROD and oxidative stress) were used to evaluate biomarker responses for each location. Chromosomal damage was significantly elevated at two sites on the UMR (Pigs Eye and Pool 2) relative to the Green Mountain Lake reference site, while the induction of EROD activity was only observed at Pigs Eye. No measures of oxidative stress differed among sites. Multivariate analysis confirmed an increased DNA CV at Pigs Eye and Pool 2, and elevated EROD activity at Pigs Eye. These results suggest that the health of tree swallows has been altered at the DNA level at Pigs Eye and Pool 2 sites, and at the physiological level at Pigs Eye site only.
authors.affiliation: Department of Environmental Science and the Center for Reservoir and Aquatic Systems Research (CRASR), Baylor University, Waco, TX, 76798, USA.
authors.forename: Emilie
authors.initials: E
authors.lastname: Bigorgne
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Custer
authors.forename: Paul M
authors.initials: PM
authors.lastname: Dummer
authors.forename: Richard A
authors.initials: RA
authors.lastname: Erickson
authors.forename: Natalie
authors.initials: N
authors.lastname: Karouna-Renier
authors.forename: Sandra
authors.initials: S
authors.lastname: Schultz
authors.forename: Christine M
authors.initials: CM
authors.lastname: Custer
authors.forename: Wayne E
authors.initials: WE
authors.lastname: Thogmartin
authors.forename: Cole W
authors.initials: CW
authors.lastname: Matson
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism*; D004249:DNA Damage / Q000235:genetics*; D005434:Flow Cytometry; D008099:Liver / Q000378:metabolism; D008910:Minnesota; D015999:Multivariate Analysis; D018384:Oxidative Stress / Q000502:physiology*; D012044:Regression Analysis; D045483:Rivers; D046388:Swallows / Q000235:genetics* / Q000502:physiology
chemical_list: D015415:Biomarkers; D019363:Cytochrome P-450 CYP1A1