XI International Meeting on Paracoccidioidomycosis

XI International Meeting on Paracoccidioidomycosis

Resume:142-1

Investigação

142-1	Molecular and morphological aspects of mating in Paracoccidioides: comparative studies with other dimorphic fungal pathogens
Authors:	Marcus Teixeira (UNB - Universidade de Brasilia)

Abstract

The genus Paracoccidioides includes the thermodimorphic species P. brasiliensis and P. lutzii, both of which are the etiological agents of paracoccidioidomycosis, a systemic mycosis that affects humans in Latin America. Phylogenetically, Paracoccidioides may be located in the family Ajellomycetaceae, together with other fungal pathogens. Despite the common occurrence of a sexual stage among the members of this family, this has not been observed with Paracoccidioides species, which have thus been hitherto considered asexual. Molecular evolutionary studies revealed recombination events within isolated populations in the genus Paracoccidioides, suggesting the possible existence of a sexual cycle. Comparative genomic analysis of dimorphic fungi and Saccharomyces cerevisiae demonstrated the presence of conserved genes involved in sexual reproduction, including mating regulators such as the MAT locus, α pheromone precursor gene, pheromone receptors, pheromone processing enzymes and mating signaling regulators. The expression of sex-related genes in the yeast and mycelial phases of both Paracoccidioides species was also detected by real-time polymerase chain reaction, with nearly all of these genes being preferentially expressed in the filamentous form of the pathogens. In addition, the expression of sex-related genes was responsive to the putative presence of pheromone in the supernatants obtained in previous co-cultures of two different mating-type strains. In vitro crossing of different mating-type isolates, discriminated by phylogenetic analysis of α-box (MAT1-1) and HMG (MAT1-2), led to the identification of the formation of young ascocarps with constricted coiled hypha related to the initial stage process of mating. These genomic and morphological analyses strongly support the existence of a sexual cycle in species of the genus Paracoccidioides.਀ Funding: CNPq/FAP-DF

Keyword: speciation, mating, Paracoccidioides brasiliensis, Paracoccidioides lutzii

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