Freshwater cyanobacterium Microcystis aeruginosa (UTEX 2385) induced DNA damage in vivo and in vitro.

Microcystins are a family of potent hepatotoxins and liver tumor promoters produced by several genera of cyanobacteria including Microcystis, Nodularia, Anabena, Nostoc, etc. They are chemically very stable and represent a public health threat when they occur in water used for human consumption. We investigated the DNA damage effects of M. aeruginosa UTEX 2385 in mouse liver in vivo and also in mammalian cells in vitro. The DNA damage effect is compared with purified toxin microcystin-LR (MCLR) in non-hepatic cells viz. baby hamster kidney cells (BHK-21) and mouse embryo fibroblasts primary cells (MEF). Cell-free extracts of UTEX 2385 induced significant DNA fragmentation at 0.5, 1 and 2 LD(50) (32.7, 65.4 and 130.8 mg/kg, respectively) and it was also time dependent. M. aeruginosa UTEX 2385 and MCLR induced significant DNA fragmentation in BHK-21 and MEF cells at 100 and 1.0 μg/ml concentration. Electrophoretic analysis revealed necrotic DNA damage by UTEX 2385 in vivo. Both the toxins caused smear in agarose gel electrophoresis indicating the necrotic DNA damage in MEF cells, whereas, multiple DNA fragments in BHK-21 cells. The DNA damage effect of the toxin is supported by data on hepatotoxicity in vivo and cytotoxicity in vitro.