Per- and polyfluoroalkyl substances (PFAS) are man- made, highly persistent and harmful chemicals. These substances have various industrial and commercial applications and eventually get released into the environment. PFAS have emerged as a concerning class of contaminants with over 4700 variants found worldwide. Despite growing concerns due to their bio accumulative and toxic properties, there are significant knowledge gap regarding biota exposure to different PFASs.
In this research, the impact of PFAS is assessed by exposing the blue mussels, Mytilus spp, to PFAS mixtures in three conditions- control (no exposure), foodborne route via microalgae- Tisochrysis lutea and both food and water exposure , mimicking environment in controlled tanks. The enzyme activities were measured in three different organs of mussels (mantle, gills and digestive gland). The analysis compared control mussels with PFAS-exposed ones, evaluating health effects using various enzymes as biomarkers for oxidative stress, detoxification and neurotoxicity. Early molecular responses were investigated by measuring the relative expression of genes, associated with cell proliferation, apoptosis, cellular stress, and energy metabolism through RT-qPCR analysis. The study revealed significant differences in enzyme levels and gene expressions across tissues under various PFAS exposure conditions. Gills exhibited significantly higher GST activity under dietary exposure. At the molecular level, there was a significant downregulation of energy metabolism genes, with ATP synthase and citrate synthase expressions markedly reduced, indicating a substantial impact on metabolic capacity. Additionally, the AKT signalling pathway was significantly altered, with AKT expression downregulated in PFAS-exposed mussels. These findings highlight the complex biological responses of blue mussels to PFAS contamination.
Thus, the results indicate that PFAS at environmental concentrations appears to cause a specific biochemical response in blue mussels. By enhancing our understanding of the risks associated with these contaminants, the findings shed light on the biochemical and molecular effects of distinct routes of PFAS exposures, contributing to the field of ecotoxicology and aiding in the development of more effective management strategies.