Dear colleagues, The following article has just been published on line in PLOS ONE: Lailson-Brito J, Cruz R, Dorneles PR, Andrade L, Azevedo AdF, et al. (2012) Mercury-Selenium Relationships in Liver of Guiana Dolphin: The Possible Role of Kupffer Cells in the Detoxification Process by Tiemannite Formation. PLoS ONE 7(7): e42162. doi:10.1371/journal.pone.0042162 Abstract: Top marine predators present high mercury concentrations in their tissues as consequence of biomagnification of the most toxic form of this metal, methylmercury (MeHg). The present study concerns mercury accumulation by Guiana dolphins (Sotalia guianensis), highlighting the selenium-mediated methylmercury detoxification process. Liver samples from 19 dolphins incidentally captured within Guanabara Bay (Rio de Janeiro State, Brazil) from 1994 to 2006 were analyzed for total mercury (THg), methylmercury (MeHg), total organic mercury (TOrgHg) and selenium (Se). X-ray microanalyses were also performed. The specimens, including from fetuses to 30-year-old dolphins, comprising 8 females and 11 males, presented high THg (0.53–132 mg/g wet wt.) and Se concentrations (0.17–74.8 mg/g wet wt.). Correlations between THg, MeHg, TOrgHg and Se were verified with age (p,0.05), as well as a high and positive correlation was observed between molar concentrations of Hg and Se (p,0.05). Negative correlations were observed between THg and the percentage of MeHg contribution to THg (p,0.05), which represents a consequence of the selenium-mediated methylmercury detoxification process. Accumulation of Se-Hg amorphous crystals in Kupffer Cells was demonstrated through ultra-structural analysis, which shows that Guiana dolphin is capable of carrying out the demethylation process via mercury selenide formation. The article is available online at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0042162 Best regards, Jose Lailson -- -- Dr. José Lailson Brito Junior Professor Adjunto Universidade do Estado do Rio de Janeiro Faculdade de Oceanografia Laboratório de Mamíferos Aquáticos e Bioindicadores Rua São Francisco Xavier, 524 4º andar sala 4002 bloco E Maracanã, Rio de Janeiro - RJ CEP 20.550-013 Tel:21-2334-0065 / 2334-0795 Fax:21-2334-0621 / 23340795 email: lailson@uerj.br ou joselailson@gmail.com