Investigation of the Genotoxic Potential of the Marine Toxin C17-SAMT Using the In Vivo Comet and Micronucleus Assays

Abstract

The contaminant responsible for the atypical toxicity reported in mussels from Bizerte Lagoon (Northern Tunisia) during the last decade has been characterized as C17-sphinganine analog mycotoxin (C17-SAMT). This neurotoxin showed common mouse toxic symptoms, including flaccid paralysis and severe dyspnea, followed by rapid death. For hazard assessment on human health, in this work we aimed to evaluate the in vivo genotoxic effects of this marine biotoxin using the classical alkaline and modified Fpg comet assays performed to detect DNA breaks and alkali-labile sites as well as oxidized bases. The micronucleus assay was used on bone marrow to detect chromosome and genome damage. C17-SAMT induces a statistically insignificant increase in DNA tail intensity at all doses in the duodenum, and in the spleen contrary to the liver, the percentage of tail DNA increased significantly at the mid dose of 300 µg/kg b.w/d. C17-SAMT did not affect the number of micronuclei in the bone marrow. Microscopic observations of the liver showed an increase in the number of mitosis and hepatocytes’ cytoplasm clarification. At this level of study, we confirm that C17-SAMT induced DNA damage in the liver but there was no evidence of effects causing DNA oxidation or chromosome and genome damage.

An Evaluation of the Cytotoxic and Genotoxic Effects of the Marine Toxin C17-SAMT in Human TK6 and HepaRG Cell Lines

“…In proliferating cells, a slight induction of DNA double-strand breaks was observed, as well as an induction of MN formation in TK6 cells, with a strong cytotoxic effect at the highest concentration. In a previous study [18], we have shown that C17-SAMT induced primary DNA damage in the liver of mice treated at a dose of 300 µg/kg b.w/day (three oral administrations in 45 h), which was associated with an elevated number of hepatocytes in mitosis and was an indicator of a regeneration process. The results from both the in vivo and the current in vitro studies are strongly correlated, and further investigation is clearly necessary in order to elucidate the precise molecular mechanisms associated with the toxicity of C17-SAMT; in particular, the effects of this toxin on mitochondrial function.…”

“…Cells were grown in William's E medium supplemented with 10% fetal calf serum (FCS), 100 U/mL penicillin, 100 µg/mL streptomycin, 2 mM glutamine, 5 µg/mL insulin, and 50 µM hydrocortisone hemisuccinate. HepaRG cells (passages [13][14][15][16][17][18][19] were seeded at a density of 26,000 cells/cm 2 in 96-well plates.…”

“…Following treatment of mice with the purified toxin through intracerebroventricular, intraperitoneal, and oral routes, LD50 values of 150, 750, and 900 µg/kg b.w were observed, respectively [17]. Recently, an in vivo genotoxicity study showed that C17-SAMT induced equivocal results of DNA damage in the liver with the comet assay, whereas the bone marrow micronucleus assay was negative but without evidence of bone marrow exposure [18].…”