IDENTIFICATION OF DIFFERENTIALLY EXPRESSED GENES IN LAUGHING GULL (Larus atricilla) HATCHLINGS EXPOSED TO MERCURY

Abstract

Genomic markers have become an invaluable tool for analyzing the physiological mechanisms affected by xenobiotics in a variety of organisms and are an important pathway for exploring the genetic basis of sensitivity. To understand the molecular effects of methylmercury (MeHg) in birds, genes expressed in liver tissue from laughing gull hatchlings in response to MeHg were investigated. Genes that were differentially expressed were found to be involved in processes associated with glutathione synthesis, iron transport and storage, cellular respiration, and thyroid hormone regulation. Analysis of gene expression patterns for all genes, except DI02 and THRSP, suggested protective mechanisms against reactive oxygen species at high treatments of MeHg. At low exposure levels, results indicated that MeHg was sequestered by GSH and ferritin as defenses against MeHg toxicity. At the highest dose, genetic responses returned to baseline levels, which may play a role in the laughing gull's low survival rate at that dose.