LACK OF PROTECTION BY CAROTENES AGAINST GAMMA-RADIATION DAMAGE IN PHYCOMYCES

Carotenes could protect cells from radiation damage by chemically quen ching the free radicals and the activated chemical species originated by the exposure. We tested this hypothesis with strains of the zygomyc ete Phycomyces blakesleeanus that contained different carotenes (phyto ene, lycopene, beta-carotene) or different concentra tions of beta-car otene. Pairs of strains were cultured together, exposed to a maximum o f 73 Gy gamma-radiation from a Co-60 source, and allowed to recover an d grow further together on limited resources. Irradiation did not affe ct the relative abundance of each strain in the resulting spore crop. Thus, carotenes did not protect the fungal cells against gamma-radiati on and did not influence their recovery from damage caused by the expo sure.