Lack of protection by carotenes against gamma-radiation damage in Phycomyces

Carotenes could protect cells from radiation damage by chemically quenching the free radicals and the activated chemical species originated by the exposure. We tested this hypothesis with strains of the zygomycete Phycomyces blakesleeanus that contained different carotenes (phytoene, lycopene, beta-carotene) or different concentrations of beta-carotene. Pairs of strains were cultured together, exposed to a maximum of 73 Gy gamma-radiation from a Co source, and allowed to recover and grow further together on limited resources. Irradiation did not affect the relative abundance of each strain in the resulting spore crop. Thus, carotenes did not protect the fungal cells against gamma-radiation and did not influence their recovery from damage caused by the exposure.