title: Mobilization of mercury from lean tissues during simulated migratory fasting in a model songbird.
abstract: The pollutant methylmercury accumulates within lean tissues of birds and other animals. Migrating birds catabolize substantial amounts of lean tissue during flight which may mobilize methylmercury and increase circulating levels of this neurotoxin. As a model for a migrating songbird, we fasted zebra finches (Taeniopygia guttata) that had been dosed with 0.0, 0.1, and 0.6 parts per million (ppm) dietary methylmercury and measured changes in blood total mercury concentrations (THg) in relation to reductions in lean mass. Birds lost 6-16% of their lean mass during the fast, and THg increased an average of 12% and 11% in the 0.1 and 0.6 ppm treatments, respectively. Trace amounts of THg in the 0.0 ppm control group also increased as a result of fasting, but remained extremely low. THg increased 0.4 ppm for each gram of lean mass catabolized in the higher dose birds. Our findings indicate that methylmercury is mobilized from lean tissues during protein catabolism and results in acute increases in circulating concentrations. This is a previously undocumented potential threat to wild migratory birds, which may experience greater surges in circulating methylmercury than demonstrated here as a result of their greater reductions in lean mass.
authors.affiliation: Natural Resources Department, AKRF Inc., White Plains 10601, NY, USA.|Great Hollow Nature Preserve, New Fairfield 06812, CT, USA.
authors.forename: Chad L
authors.initials: CL
authors.lastname: Seewagen
authors.affiliation: Biology Department, College of William &Mary, Williamsburg, VA 23187, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Cristol
authors.affiliation: Department of Biology, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Gerson
mesh_terms: D025041:Animal Migration; D000818:Animals; D005215:Fasting / Q000097:blood*; D046369:Finches / Q000097:blood*; D008628:Mercury / Q000097:blood*; D008767:Methylmercury Compounds / Q000097:blood; D023421:Models, Animal; D009928:Organ Specificity
chemical_list: D008767:Methylmercury Compounds; D008628:Mercury