Thioguanine

Metabolomics measures low molecular weight endogenous metabolites and changes linked to contaminant exposure in biota. However, few studies have explored the relationship between metabolomics and contaminants in Arctic wildlife. We analyzed 239 endogenous metabolites and ∼150 persistent organic pollutants (POPs), including total mercury (THg), in the liver of polar bears and their ringed seal prey harvested from low Canadian Arctic (western Hudson Bay; WHB) and high Arctic (HA) locations during 2015-2016. Polar bears from the HA had different metabolomic profiles compared to those from WHB, particularly in several phosphatidylcholines (PCs), with the HA bears having higher concentrations of longer chain PCs. Similarly, HA and WHB ringed seals also had metabolomic profile differences in five PCs related to fat catabolism and transport. The metabolites with the highest impact on discriminating metabolomic profiles between the two species, based on VIP scores, were: tauroursodeoxycholic Acid (TUDCA), histamine, serotonin, lithocholic acid (LCA), and taurolithocholic acid (TLCA). Higher TUDCA levels in polar bears likely reflect their blubber-rich diet, while higher histamine in seal liver may indicate inflammatory responses. Significant correlations were found between liver metabolites and several per- and polyfluoroalkyl substances (PFAS) in both species, including PFOA, PFNA, PFDA, PFEtCHxS, PFOS, and/or PFDS that moderately correlated to PCs. THg in seals and bears was negatively correlated with sarcosine. This study revealed significant correlations and differences in metabolite profiles of polar bears and ringed seals, suggesting that PFAS impacted several pathways related to lipid metabolism, bile acid synthesis, antioxidant defenses, arginine biosynthesis, histidine metabolism, and sphingolipid metabolism, with ringed seals showing greater sensitivity to PFAS. These results indicate that PFAS may influence metabolic processes in Arctic wildlife, although further research is needed to understand the full impact on Arctic wildlife health.

In marine ecosystems, arsenic (As) and total mercury (T-Hg) represent two of the major pollutants, particularly in fish due to their ecology and the affinity of these metal(loid)s with biological cycles. This study assessed the influence of total length, total weight, relative condition factor, and trophic levels of ten marine fish species from the Colombian Caribbean on As and T-Hg accumulation in muscle tissue, as well as the differentiation in accumulated amounts based on fish habitat type. In this context, Balistes capriscus exhibited the highest As median (7949.08 μg/kg), along with Thunnus atlanticus (1567.15 μg/kg), Haemulon flavolineatum (1469.26 μg/kg), and Euthynnus alletteratus (1191.55 μg/kg), exceeding the maximum permissible limit of 1000 μg/kg for human consumption. Evaluated factors displayed complex and non-linear influences on As accumulation: trophic level > total length > relative condition factor > total weight, where all factors except total weight described a negative effect. Conversely, for T-Hg, influences were markedly linear and monotonic: trophic level > total length > total weight > relative condition factor, with all factors exerting a positive effect. The habitat plays a crucial role in the cumulative patterns of As, with demersal fish significantly differing from pelagic and reef-associated species. Results indicate that the accumulation of As and T-Hg in muscle tissue may be mediated by a multiplicity of factors inherent to the species' morpho-physiology and the chemical activity of each pollutant in the ecosystem, along with the feeding ecology and niche occupied by these organisms.