Aluminium Induced DNA-damage and Oxidative Stress in Cultures of the Marine Sponge Hymeniacidon perlevis

Abstract

Aluminium is the most abundant element in the earth crust, and has no known biological function. However, it is an established neurotoxicant in its trivalent oxidation state, with exposure resulting in neurodegenerative diseases like Parkinson’s disease and presenile dementia. Although, the potential genotoxic and carcinogenic effects of aluminium are established in mammalian and other model system, there is however very limited information on aluminium genotoxicity in aquatic invertebrates. Mechanism of aluminium toxicity is also largely unclear. With a concentration range between 0.001– 0.05mg/L in near neutral pH water, and up to 0.5-1mg/L in an acidic water , aluminium poses a potential threat to the marine ecosystem, however it is poorly studied. This study, therefore presents for the first time, aluminium-induced DNA damage using the comet assay and reactive oxygen Species (ROS) formation using 2’, 7’-dichlorodihydrofluorescein diacetate (H2DCF-DA) assay as biomarkers of genotoxicity and oxidative stress in the inter-tidal marine sponge Hymeniacidon perlevis, respectively. H. perlevis is widely distributed in the British Isles, Mediterranean and the Arctic sea and has been reported as a model for environmental biomonitoring in aquatic ecosystem and as a suitable alternative to bivalves. In this study, cryopreserved single sponge cells of H. perlevis were cultured as viable aggregates and were thereafter treated with 0.1, 0.2, 0.3 and 0.4mg/L aluminium chloride (AlCl3) for 12 hours. Cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Our results showed that non-cytotoxic concentrations of AlCl3 caused a statistically significant concentration-dependent increase in the level of DNA-strand break and reactive oxygen species formation single sponge cells of H. perlevis. There was also a statistically significant positive linear correlation between aluminium-induced DNA strand break and ROS formation suggesting the involvement of ROS in the causative mechanism of the aluminium induced DNA-strand breaks observed.