Bistratene A, a toxin isolated from the colonial ascidian Lissoclinum
bistratum causes a decrease in mitotic index and retardation of lympho
cyte proliferation kinetics when it is added at 48 h to 72-h human lym
phocyte cultures. In the same cultures, the incidence of sister chroma
tid exchanges was not altered by this compound. We also observed an in
crease in the number of polyploid cells in the cultures, and alteratio
ns of the beta-tubulin organization by immunocytochemistry with an ant
ibody against beta-tubulin. Bistratene A induces DNA damage in a dose-
dependent fashion in leukocytes, as measured by the alkaline single ce
ll gel electrophoresis assay. These results show that bistratene A int
erferes with microtubule assembly, is cytotoxic and cytostatic, and th
at it causes DNA damage.