Demethylation of Methylmercury in Bird, Fish, and Earthworm

Toxicity of methylmercury (MeHg) to wildlife and humans results from its binding cysteine residues proteins, forming MeHg-cysteinate (MeHgCys) complexes that hinder biological functions. MeHgCys can be detoxified in vivo, yet how this occurs is unknown. We report are transformed into selenocysteinate [Hg(Sec)4] multiple animals two phyla (a waterbird, freshwater fish, earthworms) sampled different geographical areas contaminated by Hg sources. In addition, high energy-resolution X-ray absorption spectroscopy (HR-XANES) chromatography-inductively coupled plasma mass spectrometry the waterbird liver support Hg(Sec)4 selenoprotein P biomineralization chemically inert nanoparticulate mercury selenide (HgSe). The provide a foundation for understanding detoxification higher organisms suggest identified demethylation pathway common nature.