Mercury may occur naturally in the environment (mineral deposits, volcanoes, forest fires, oceanic emission, and crust degassing), or be released by human activities such as mining, mineral processing, chloroalkali production, and combustion of fossil fuels. The inorganic mercury species could be methylated in the aquatic environment. Methyl mercury (MeHg) is the most abundant and also the most toxic form of mercury in the environment. Methyl mercury is also the only mercury compound that is bioaccumulated and biomagnified in the food chain. Beluga (Huso huso) is a critically endangered sturgeon fish species that is carnivorous and feeds on benthic and pelagic fish. Because of its feeding habits, Beluga is at risk of bioaccumulating environmental contaminants. It has been reported that Beluga shows a higher concentration of mercury than other sturgeon in the Caspian Sea. In order to obtain a preliminary scope of the MeHg toxicity at the molecular level, we used a proteomics approach to analyze the changes in the brain proteome of beluga exposed to dietary MeHg. The juvenile Beluga were fed a diet containing 0.8 ppm MeHg for 70 days. Proteins of the brain tissue were analyzed using two-dimensional electrophoresis and MALDI-TOF/TOF mass spectrometry. MeHg caused a differential expression of brain tissue proteins including glycerol-3-phosphate dehydrogenase, β-tubulin, aldo/keto reductase, calmodulin, keratin 8, 70-kDa heat shock protein, aconitase, and hydrolase. These proteins are involved in metabolism, protein folding, cell division, and signal transduction in the cell.

Our results support the idea that MeHg exerts its toxicity through oxidative stress induction and apoptotic effects. They also suggest that chronic MeHg exposure would induce an important metabolic deficiency in the brain. These findings provide basic information to understand possible mechanisms of MeHg toxicity in aquatic ecosystems.


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  • Received: 15 May 2012
  • Accepted: 15 May 2012
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