Mathematical modeling predicts enhanced growth of X-ray irradiated pigmented fungi

Ionizing radiation is known for its cytotoxic and mutagenic properties. However, recent evidence suggests that chronic sub-lethal irradiation stimulates the growth of melanin-pigmented (melanized) fungi, supporting the hypothesis that interactions between melanin and ionizing photons generate energy...

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Bibliographic Details
Published in:PloS one 2014-01, Vol.9 (1), p.e85561
Main Authors: Shuryak, Igor, Bryan, Ruth A, Nosanchuk, Joshua D, Dadachova, Ekaterina
Format: Article
Language:English
Subjects:
Analysis
Animal models
Biology
Cell cycle
Cell growth
Cell proliferation
Cryptococcus neoformans
Cytotoxicity
Drug dosages
Energy
Exposure
Free radicals
Fungal infections
Fungi
Fungi - growth & development
Fungi - metabolism
Growth
Immunology
Ionizing radiation
Irradiated
Irradiation
Laboratories
Mathematical models
Mathematics
Medicine
Melanin
Melanization
Models, Statistical
Nuclear power plants
Photons
Physics
Pigments, Biological - metabolism
Radiation
Radiation dosage
Radiation effects
X rays
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Summary:Ionizing radiation is known for its cytotoxic and mutagenic properties. However, recent evidence suggests that chronic sub-lethal irradiation stimulates the growth of melanin-pigmented (melanized) fungi, supporting the hypothesis that interactions between melanin and ionizing photons generate energy useful for fungal growth, and/or regulate growth-promoting genes. There are no quantitative models of how fungal proliferation is affected by ionizing photon energy, dose rate, and presence versus absence of melanin on the same genetic background. Here we present such a model, which we test using experimental data on melanin-modulated radiation-induced proliferation enhancement in the fungus Cryptococcus neoformans, exposed to two different peak energies (150 and 320 kVp) over a wide range of X-ray dose rates. Our analysis demonstrates that radiation-induced proliferation enhancement in C. neoformans behaves as a binary "on/off" phenomenon, which is triggered by dose rates 5000 mGy/h. Proliferation enhancement of irradiated cells compared with unirradiated controls occurs at both X-ray peak energies, but its magnitude is modulated by X-ray peak energy and cell melanization. At dose rates
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0085561