Adipose tissue transcriptome is related to pollutant exposure in polar bear mother-cub pairs from Svalbard, Norway.

Being at the food chain apex, polar bears (Ursus maritimus) are highly contaminated with persistent organic pollutants (POPs). Females transfer POPs to their offspring through gestation and lactation, therefore, young cubs present higher POPs concentrations than their mothers. Recent studies suggest that POPs affect lipid metabolism in female polar bears, however, the mechanisms and impact on their offspring remain unknown. Here, we hypothesized that exposure to POPs differentially alters genome-wide gene transcription in adipose tissue from mother polar bears and their cubs, highlighting molecular differences in response between adults and young. Adipose tissue biopsies were collected from 13 adult female polar bears and their twin cubs in Svalbard, Norway, in April 2011, 2012 and 2013. Total RNA extracted from biopsies was subjected to next-generation RNA sequencing. Plasma concentrations of summed PCBs, organochlorine pesticides and polybrominated diphenyl ethers in mothers ranged from 897 to 13,620 ng/g wet weight and were associated with altered adipose tissue gene expression in both mothers and cubs. In mothers, 2,502 and 2,586 genes in total were respectively positively and negatively correlated to POP exposure, whereas in cubs, 2,585 positively and 1,690 negatively genes. Between mothers and cubs, 743 positively and negatively genes overlapped between mothers and cubs suggesting partially shared molecular responses to ΣPOPs. ΣPOPs associated genes were involved in numerous metabolic pathways in mothers and cubs, indicating that POP exposure alters energy metabolism, which, in turn, may be linked to metabolic dysfunction.