Abstract
1219
Introduction: Black fungi withstand extreme environmental stresses partly due to the presence of melanin pigment within their cell walls. Melanin has been associated with structural integrity and resistance to chemical and radiological stresses. This provides a select survival advantage for these species of melanized fungi. Our goal was to utilize the radiation sensing nature of the melanized fungi to develop novel radioadapted strains capable of responding to radiation in the environment as radioprotectors and sensors of radioactive fallout.
Methods: Our model was melanized fungus Wangiella dermatitidis which was exposed in a protracted fashion to mixed sources of gamma, beta and alpha radiation. As control, we used W. dermatitidis albino melanin deficient mutant strain wdpsk1. We then tested the growth response of each strain in response to radiation in the environment with shielding to direct exposure to radiation. The radioadapted strains were subjected to genomic analysis. Results: After protracted exposure to a chronic mixed radiation melanized W. dermatitidis showed altered electron transport properties. In contrast to this, the albino melanin deficient mutant strain wdpsk1 showed no response.. Gamma radiation caused growth in all strain irrespective of previous exposure. Beta particles inhibited growth in all strains. Previously exposed melanized strains showed the strongest growth response to alpha particles. Alpha particles have high linear energy transfer, which produces more reactive oxygen species. The exposed melanized strains showed resistance to the toxic effects of H2O2, while naïve and albino mutants were sensitive. We propose that previous radiation exposure introduces adaptations that allow melanized fungi to tolerate, sense and respond to radiation by-products in the environment. Genomic analysis of the these cultures will provide insights into whether these adaptations are genetic or epigenetic in nature.
Conclusions: By understanding the correlation between the presence of melanin and varied radiation responses of our fungal cultures, we hope to further our knowledge of radiation sensing and shielding in order to develop innovative means of radiation protection and sensing the radioactive fallout.