Metal partitioning and metallothionein-mediated detoxification in different tissues of Magellanic penguins stranded...

Studies integrating metal burdens and metallothionein (MT) responses in seabirds are still scarce, and bile is still an understudied biological matrix in this sense. Herein, metal partitioning and MT-mediated detoxification were assessed in the brain, bile, liver, and muscle of Magellanic penguins (Spheniscus magellanicus) found stranded along southeastern Brazil. Metallothionein concentrations were the highest in muscle, followed by liver and bile, whereas brain levels were consistently the lowest. Preferential accumulation of Ag, Al, Cr, and Pb in muscle was noted, which may explain the higher MT levels observed in this tissue. Significant MT-metal associations involving both essential and toxic elements suggest coordinated homeostasis and detoxification processes. Correlations among elements typically associated to anthropogenic inputs indicate shared exposure pathways. Essential-to-toxic metal molar ratios were also examined, indicating potential protective interactions, particularly involving Cd (Fe × Cd = 150:1), Hg (Cu × Hg = 27:1), and Pb (Mn × Pb = 17:1). Multivariate analyses confirmed tissue-specific patterns, highlighting bile as a responsive matrix reflecting exposure and elimination, while liver and muscle reflect metabolic regulation and longer-term accumulation, respectively. These findings reinforce the relevance of integrating multiple tissue assessments to improve the understanding of metal dynamics, tissue-specific accumulation, and MT-mediated detoxification processes in seabirds.