A previously unrecorded property of actinomycin D, a well-known antibiotic, was discovered in the course of long-term genetic research on the amoeba Amoeba proteus and the ciliate Dileptus anser. In these protists actinomycin D can induce an unusual type of hereditary variation, which we refer to as the inheritable destabilization of characters. A number of features indicate that this variation is epigenetic, that is, not caused by mutations in the DNA. Therefore, actinomycin D may be considered as an inducer of epigenetic inheritable changes, in other words, as an epimutagen.
