Exposure to Hg also oxidized glutathione (GSH) to glutathione disulfide (GSSG) however, goslings were capable of maintaining the redox balance by de novo synthesis of GSH. Hg exposure upregulated the expression of proinflammatory genes in the spleen, including inducible nitric oxide synthase (iNOS) and interleukin 18 (IL18), suggesting Hg-induced inflammatory effects. Increased exposure to both environmental as well as supplemental Hg reduced the level of natural antibodies, suggesting impaired humoral immunity. Our results indicated that Hg exposure modulated the immune responses in Arctic barnacle goslings upon a viral-like immune challenge. Upon immune challenge with double-stranded RNA (dsRNA) injection, endpoints for immune responses and oxidative stress were measured after 24 h. Hepatic total Hg concentrations differed significantly between the control (0.011 ± 0.002 mg/kg dw), mine (0.043 ± 0.011 mg/kg dw), and supplementary feed (0.713 ± 0.137 mg/kg dw) gosling groups (average ± standard deviation). An additional group at the mining site was exposed to extra inorganic Hg(II) via supplementary feed. To address the potential immunomodulatory effects of environmental Hg on Arctic organisms, we collected newborn barnacle goslings ( Branta leucopsis) and herded them in either a control or mining site, differing in Hg levels.
Historical mining activities in Svalbard (79°N/12☎) have caused local mercury (Hg) contamination.
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