Cryptococcus neoformans population includes hybrid strains homozygous at mating-type locus |
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Authors: | Cogliati Massimo Esposto Maria Carmela Tortorano Anna Maria Viviani Maria Anna |
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Affiliation: | Istituto di Igiene e Medicina Preventiva, Università degli Studi di Milano - IRCCS Ospedale Maggiore di Milano, Milan, Italy. |
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Abstract: | Recent attempts to characterise the hybrid strains of Cryptococcus neoformans have led to the identification of a cryptic population of hybrid strains ('H strains') with double DNA content but only a single mating-type allele. To verify a set of hypotheses concerning their origin, we investigated 14 previously isolated H strains and ten F1-progeny strains arising from H99 and JEC20 mating. The double DNA content was tested by flow cytometry; the presence of only one mating type was tested by amplifying 12 mating-type-specific genes and one gene unlinked with the mating-type locus (URA5). Analysis of the F1 progeny identified two H strains, and electrophoretic karyotyping confirmed the occurrence of genetic recombination. The simultaneous presence of the homozygous and heterozygous loci, and the fact that all of the F1-progeny strains presented a recombinant karyotype, suggest that the H strains originated from the post-meiotic random fusion of two of the four recombinant nuclei. Further studies are required to elucidate the role of the homozygous mating-type loci in the virulence of C. neoformans. |
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Keywords: | Cryptococcus neoformans hybrid strains mating type |
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