Gamma Radiation Effects on <Emphasis Type="Italic">Sporothrix schenckii</Emphasis> Yeast Cells |
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Authors: | Camila Maria de Souza Lacerda Estefânia Mara do Nascimento Martins Maria Aparecida de Resende Antero Silva Ribeiro de Andrade |
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Institution: | 1.Laboratório de Radiobiologia,Centro de Desenvolvimento da Tecnologia Nuclear (CDTN),Belo Horizonte,Brazil;2.Departamento de Microbiologia,Universidade Federal de Minas Gerais (UFMG),Belo Horizonte,Brazil |
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Abstract: | Sporotrichosis is a subcutaneous mycosis caused by Sporothrix schenckii. Zoonotic transmission to man can occur after scratches or bites of animals, mainly cats. In this study, the gamma radiation
effects on yeast of S. schenckii were analyzed with a view of developing a radioattenuated vaccine for veterinary use. The cultures were irradiated at doses
ranging from 1.0 to 9.0 kGy. The reproductive capacity was measured by the ability of cells to form colonies. No colonies
could be recovered above 8.0 kGy, using inocula up to 107 cells. Nevertheless, yeast cells irradiated with 7.0 kGy already were unable to produce infection in immunosuppressed mice.
Evaluation by the FungaLight™ Kit (Invitrogen) indicated that yeast cells remained viable up to 9.0 kGy. At 7.0 kGy, protein
synthesis, estimated by the incorporation of L-35S] methionine, continues at levels slightly lower than the controls, but a significant decrease was observed at 9.0 kGy. The
DNA of 7.0 kGy irradiated cells, analyzed by electrophoresis in agarose gel, was degraded. Cytoplasmic vacuolation was the
main change verified in these cells by transmission electron microscopy. The dose of 7.0 kGy was considered satisfactory for
yeast attenuation since irradiated cells were unable to produce infection but retained viability, metabolic activity, and
morphology. |
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