title: The effect of a low iron diet and early life methylmercury exposure in Daphnia pulex.
abstract: Iron (Fe) deficiency increases risk for adverse health outcomes in humans; however little is known about the potential interaction with methylmercury (MeHg) exposure. Studies testing multiple stressor hypotheses are expensive and time consuming in mammalian model systems; therefore, determining relevance of alternative models is important. Daphnia pulex were fed standard or low-Fe diets of freshwater algae, Ankistrodesmus falcatus. MeHgCl (1600 ng/L) or vehicle was added to culture media for 24 h during early life, and the combinatorial effects of a low-Fe diet and MeHg exposure on lifespan, maturation time, and reproduction were evaluated. Lipid storage effects were measured using image analysis of Oil Red O staining and triacylglyceride quantification. Our results show a dose-dependent reduction in lifespan in D. pulex fed low Fe diets. Lipid analysis suggests an interactive effect of diet and MeHg exposure, with MeHg exposure increasing lipid storage in D. pulex fed a low-Fe diet. These findings suggest the effects of dietary iron intake and early life MeHg exposure in D. pulex may be mediated by changes in energetics that result in differential lipid storage. Therefore, lipid storage in D. pulex may be a useful screen for detecting long-term effects of multiple stressors early in life.
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Sherri L
authors.initials: SL
authors.lastname: Hudson
authors.affiliation: Department of Environment and Resource Studies, University for Development Studies, Wa, Ghana.
authors.forename: Dzigbodi A
authors.initials: DA
authors.lastname: Doke
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Department of Population Health Sciences, Virginia Tech, Blacksburg, VA 24061, USA. Electronic address: jgohlke@vt.edu.
authors.forename: Julia M
authors.initials: JM
authors.lastname: Gohlke
mesh_terms: D000818:Animals; D003621:Daphnia / Q000187:drug effects*; D004032:Diet; D004781:Environmental Exposure; D007501:Iron / Q000008:administration & dosage*; D008055:Lipids / Q000032:analysis; D008767:Methylmercury Compounds / Q000633:toxicity*; D023421:Models, Animal; D012098:Reproduction / Q000187:drug effects
chemical_list: D008055:Lipids; D008767:Methylmercury Compounds; D007501:Iron
keywords: Daphnia; Iron deficiency; Lipid storage; Metals; Methylmercury