Chromosome-breaking activity of extracts of the mushroom Paxillus involutus Fries ex Batsch.

Dry and presoaked seeds of Nigella damascena were treated with aqueous extracts of the mushroom Paxillus involutus. At the first mitosis after the onset of germination, metaphase chromosomes showed damage independent of the origin of the mushrooms. The damaging substance(s) is (are) thermostable. Except a few achromatic gaps, all the lesions observed are of the chromosome type, i.e. are induced at the pre-synthetic G1 stage.