Chromosome Coiling: Abnormalities Induced by Polyamines

P UTRESCINE has been found to induce chromosome aberrations in cells undergoing meiosis in Oenothera [8] but not in cells undergoing mitosis in roots of Vicia faba [9]. In re-examining the action of putrescine and cadaverine in less toxic concentrations [cf. 91, we have tested the ability of these polyamines either to induce chromosome breakage or to upset the process of chromosome condensation. Our results confirm that the diamines, putrescine and cadaverine, do not induce chromosome breakage in cells of Vicia faba roots, and a similar result has been found for a tetramine, spermine. They also show that polyamines do induce chromosome abnormalities, which seem to be attributable to disturbances in the cycle of chromosome coiling and uncoiling occurring during mitosis. The view that chromosomal condensation is a reflection of a change in configuration of DNA molecules has been previously presented [2, 31. The polyanionic DNA molecules appear to be bound end-to-end by protein to form long strands [5] that are loosely cross-linked in the nucleus to form an open gelwork. It has been proposed [4] that polycations such as putrescine, spermidine, and spermine, which would have a profound condensing effect on such a system [7], may function in this capacity during prophase. These compounds are widely distributed in animal and plant cells [6] and have now been found in association with viral DNA [l]. The observations to be reported here indicate that polyamines present from late interphase to telophase affect the processes of chromosome coiling and uncoiling. Materials and methods.-Beans (Vicia faba) were grown in aerated distilled water until lateral roots had formed. They were placed in aerated solutions of putrescine-2 HCI, cadaverine-2 HCI and spermine-4 HCl, 0.5 mM, for 3, 6, or 24 hours. After treatment, the beans were returned to distilled water. Roots were fixed in La COW’S 2BD at the end of the treatment and after a 24-hour period of recovery. They were