The impact of in vivo and in vitro exposure to base analogue 5-FU on the level of DNA damage in haemocytes of freshwater mussels Unio pictorum and Unio tumidus

• In vivo and in vitro exposure to 5-FU was studied on haemocytes of freshwater mussels.
• The effects were measured by the level of DNA damage assessed with the comet assay.
• In vivo and in vitro CdCl2 treatment (positive control) resulted in increase of DNA damage.
• 5-FU treatment induced significant increase of DNA damage in vivo, but not in vitro.

The impact of in vivo and in vitro exposure to anticancer drug 5-Fluorouracil (5-FU) on the level of DNA damage was evaluated using comet assay on haemocytes of freshwater mussels Unio pictorum and Unio tumidus. For the in vivo experiment, the groups of 5 mussels per concentration were exposed for 72 h to 5-FU (0.04, 0.4, 4, 40 and 100 μM) with 0.4 μM being the lowest concentration to induce significant DNA damage. For the in vitro experiment, the primary cultures of haemocytes were treated with 0.04, 0.4, 4 and 40 μM 5-FU for 22 h and the treatment with CdCl2 was used as a positive control. In contrast to in vivo exposure, 5-FU did not induce significant increase of DNA damage in vitro, possibly because of the absence of haemocytes proliferation in primary cultures.