Methylmercury-induced changes in gene transcription associated with neuroendocrine disruption in largemouth bass (Micropterus salmoides).
Methyl-mercury (MeHg) is a potent neuroendocrine disruptor that impairs reproductive processes in fish. The objectives of this study were to (1) characterize transcriptomic changes induced by MeHg exposure in the female largemouth bass (LMB) hypothalamus under controlled laboratory conditions, (2) investigate the health and reproductive impacts of MeHg exposure on male and female largemouth bass (LMB) in the natural environment, and (3) identify MeHg-associated gene expression patterns in whole brain of female LMB from MeHg-contaminated habitats. The laboratory experiment was a single injection of 2.5 μg MeHg/g body weight for 96 h exposure. The field survey compared river systems in Florida, USA with comparably lower concentrations of MeHg (Wekiva, Santa Fe, and St. Johns Rivers) in fish and one river system with LMB that contained elevated concentrations of MeHg (St. Marys River). Microarray analysis was used to quantify transcriptomic responses to MeHg exposure. Although fish at the high-MeHg site did not show overt health or reproductive impairment, there were MeHg-responsive genes and pathways identified in the laboratory study that were also altered in fish from the high-MeHg site relative to fish at the low-MeHg sites. Gene network analysis suggested that MeHg regulated the expression targets of neuropeptide receptor and steroid signaling, as well as structural components of the cell. Disease-associated gene networks related to MeHg exposure, based upon expression data, included cerebellum ataxia, movement disorders, and hypercalcemia. Gene responses in the CNS are consistent with the documented neurotoxicological and neuroendocrine disrupting effects of MeHg in vertebrates.
U.S. Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201, USA.
Catherine A
CA
Richter
Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32611, USA.
Christopher J
CJ
Martyniuk
U.S. Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201, USA.
Mandy L
ML
Annis
U.S. Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201, USA.
William G
WG
Brumbaugh
U.S. Geological Survey, Florida Integrated Science Center, 2639 North Monroe Street, Suite A-200, Tallahassee, FL 32303, USA.
Lia C
LC
Chasar
Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32611, USA.
Nancy D
ND
Denslow
U.S. Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65201, USA.
Donald E
DE
Tillitt
D000818:Animals; D001492:Bass / Q000235:genetics*; D052244:Endocrine Disruptors / Q000633:toxicity*; D005260:Female; D005431:Florida; D005786:Gene Expression Regulation / Q000187:drug effects*; D008297:Male; D008767:Methylmercury Compounds / Q000633:toxicity*; D009490:Neurosecretory Systems / Q000187:drug effects*; D012098:Reproduction / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D052244:Endocrine Disruptors; D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; C004925:methylmercuric chloride
Fish; Movement disorders; Neuroendocrine disruption; Neurotoxicity; Sub-network enrichment analysis; Transcriptomics