Melanin and Resistance to Ionizing Radiation in Fungi
Constant exposure to ionizing radiation is a “fact of life” for all life forms on Earth – for example, 90% of the annual radiation dose for a person living in the US comes from natural sources such as cosmic radiation and radioactive rocks (Early and Sodee 1995). However, fungi seem to interact with the ionizing radiation in a manner that may differ from other life forms. Large quantities of highly melanized fungal spores have been found in early Cretaceous period deposits when many species of animals and plants died out. This time period coincides with Earth’s crossing the “magnetic zero” resulting in the loss of its “shield” against cosmic radiation (Hulot and Gallet 2003). When exposed to high doses of ionizing radiation under experimental conditions, fungi in general, and especially melanized ones, are highly radioresistant (Saleh et al. 1988; Dembitzer et al. 1972; Dadachova et al. 2004; Mirchink et al. 1972). As ionizing radiation is perceived to be harmful to life,...
KeywordsHigh Performance Liquid Chromatography Electron Paramagnetic Resonance Stable Free Radical Deinococcus Radiodurans Cladosporium Cladosporioides
E. Dadachova is supported by the National Institute of Allergy and Infectious Disease (NIAID) grant AI60507; A. Casadevall – by NIAID grants AI033142 and AI033774.
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