DNA Adductomics for the Biological Effect Assessment of Contaminant Exposure in Marine Sediments

Exposure to chemical pollution can induce genetic andepigeneticalterations, developmental changes, and reproductive disorders, leadingto population declines in polluted environments. These effects aretriggered by chemical modifications of DNA nucleobases (DNA adducts)and epigenetic dysregulation. However, linking DNA adducts to thepollution load in situ remains challenging, and thelack of evidence-based DNA adductome response to pollution hampersthe development and application of DNA adducts as biomarkers for environmentalhealth assessment. Here, we provide the first evidence for pollutioneffects on the DNA modifications in wild populations of Baltic sentinelspecies, the amphipod Monoporeia affinis. A workflow based on high-resolution mass spectrometry to screenand characterize genomic DNA modifications was developed, and itsapplicability was demonstrated by profiling DNA modifications in theamphipods collected in areas with varying pollution loads. Then, thecorrelations between adducts and the contaminants level (polycyclicaromatic hydrocarbons (PAHs), trace metals, and pollution indices)in the sediments at the collection sites were evaluated. A total of119 putative adducts were detected, and some (5-me-dC, N-6-me-dA, 8-oxo-dG, and dI) were structurally characterized. The DNAadductome profiles, including epigenetic modifications, differed betweenthe animals collected in areas with high and low contaminant levels.Furthermore, the correlations between the adducts and PAHs were similaracross the congeners, indicating possible additive effects. Also,high-mass adducts had significantly more positive correlations withPAHs than low-mass adducts. By contrast, correlations between theDNA adducts and trace metals were stronger and more variable thanfor PAHs, indicating metal-specific effects. These associations betweenDNA adducts and environmental contaminants provide a new venue forcharacterizing genome-wide exposure effects in wild populations andapply DNA modifications in the effect-based assessment of chemicalpollution. DNA adductome analysis identifiesexposure to environmentalcontaminants in a sentinel species in the Baltic Sea.