Prolonged exposure to particulate Cr(VI) is cytotoxic and genotoxic to fin whale cells

• Published in: Journal of Trace Elements in Medicine and Biology
• Main Authors: Meaza, Idoia, Speer, Rachel M., Toyoda, Jennifer H., Lu, Haiyan, Wise, Sandra S., Croom-Perez, Tayler J., Aboueissa, Abou El-Makarim, Wise, John Pierce
• Format: Text
• Language: English
• Published: 2020
• Subjects: Article; Balaenoptera physalus; Fin whale
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7655514/; http://www.ncbi.nlm.nih.gov/pubmed/32570008; https://doi.org/10.1016/j.jtemb.2020.126562

BACKGROUND: Hexavalent chromium [Cr(VI)] is a human lung carcinogen and global marine pollutant. High Cr concentrations, resembling the ones observed in occupationally exposed workers, have been observed in fin whales (Balaenoptera physalus) in the Gulf of Maine. This outcome suggests Cr might be disrupting the health of fin whale populations. Indeed, Cr in acute (24 h) exposure does cause toxicity in fin whale cells. However, human cell culture data indicate prolonged exposures (120 h) induce a higher amount of toxicity compared to 24 h exposure due to an inhibition of homologous recombination repair. However, whether prolonged exposure causes similar outcomes in fin whale cells is unknown. OBJECTIVE: Due to the importance of assessing prolonged exposure toxicity, this study focuses on characterizing acute and prolonged exposure of Cr(VI) in male and female fin whale cells. METHODS: Cytotoxicity was measured by the clonogenic assay, also known as colony forming assay, which measures the ability of cells to proliferate and form colonies after the treatment. DNA double strand breaks were analyzed by neutral comet assay. Clastogenicity was measured using the chromosome aberration assay. Intracellular Cr levels were measured with Graphite Furnace Atomic Absorption Spectrometry (GFAAS) with Syngistix Software. RESULTS: In this study, we demonstrate that particulate Cr(VI) induces cytotoxicity and genotoxicity in a treatment-dependent manner after 24 h and 120 h exposures. Cytotoxicity levels were generally low with relative survival above 72%. DNA double strand break data and chromosome aberration data were elevated after a 24 h exposure, but decreased after a 120 h exposure. While cytotoxicity was similar after 24 h and 120 h exposures, less DNA double strand breaks and chromosomal instability occurred with prolonged exposure. CONCLUSION: Particulate Cr(VI) is cytotoxic and genotoxic to fin whale cells after acute and prolonged exposures. The reduction of genotoxicity we have observed after 120 h exposure may be ...