Variability on tolerance to UVB radiation of melanized and non-melanized cells of Cryptococcus neoformans strains and Cryptococcus laurentii strains / Viariabilidade na tolerância à radiação UVB de células melanizadas e não melanizadas entre linhagens de Cryptococcus neoformanse entre linhagens de Cryptococcus laurentii

AUTOR(ES)

Letícia Aparecida Schiave

DATA DE PUBLICAÇÃO

2007

RESUMO

Solar radiation is one of the major factors responsible for the control of fungus populations in the environment. The inactivation of dispersal and infection structures by UVA and UVB radiation is even more important for the control of fungi that disperse through the air and that can produce melanin in the presence of oxogeneous substrates such as L-dopa. Melanization can protect the fungus against various biotic and abiotic factors. In the present study, we investigated the effect of exposure to an environmental intensity of UVB radiation of 1,000 mWm-2 on the survival of melanized and non-melanized cells of four strains of Cryptococcus neoformans and of four strains of Cryptococcus laurentii. The relative survival (survival of cells exposed to radiation in relation to cells not exposed) of 2, 4, 6 and 8 day cells grown on medium with and without L-dopa was determinated after exposure to doses of 1.8 and 3.6kJ m-2. Both irradiance and these doses are observed in the environment even in temperate regions. Difference in tolerance to UVB radiation were observed both in the C. neoformans and C. laurentii strains. The C. neofarmans strains were more sensitive to radiation than the C. laurentii strains. In C. neoformans, diferences in tolerance to radiation were observed during development both in melanized and non-melanized cells. For most features (strains, time of growth and UVB dose) there was no difference in tolerance between melanized and non-melanized cell and when differences occurred they were smaller than those previously observed with UVC. In C. laurentii, there was no difference in tolerance to radiation during development between melanized and non-melanized cells., Also, no significant differences in tolerance were observed between melanized and non-melanized cells of any strain

ASSUNTO(S)

cryptococcus laurentii cryptococcus neoformans cryptococcus laurentii melanização em fungos fungal melanization uvb tolerance tolerância à radiação uv fungal photobiology fotobiologia de fungos cryptococcus neoformans

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