The transcriptome analysis of early morphogenesis in Paracoccidioides brasiliensis mycelium reveals novel and induced genes potentially associated to the dimorphic process

Abstract

Background: Paracoccidioides brasiliensis is a human pathogen with a broad distribution in Latin America. The fungus is thermally dimorphic with two distinct forms corresponding to completely different lifestyles. Upon elevation of the temperature to that of the mammalian body, the fungus adopts a yeast-like form that is exclusively associated with its pathogenic lifestyle. We describe expressed sequence tags (ESTs) analysis to assess the expression profile of the mycelium to yeast transition. To identify P. brasiliensis differentially expressed sequences during conversion we performed a large-scale comparative analysis between P. brasiliensis ESTs identified in the transition transcriptome and databases.

Preferential transcription of Paracoccidioides brasiliensis genes: host niche and time-dependent expression

“…The dimorphic transition occurs simultaneously with changes in the composition of the fungal cell wall (San-Blas et al 2002). As described by Bastos et al (2007), transcription of 34-cell wall/membranerelated genes was induced upon temperature shift. The main polysaccharide of the yeast cell wall is alpha-1.3 glucan, while the mycelium contains predominantly beta-glucan (Kanetsuna et al 1969).…”

“…As inferred from transcriptional data, the most prominent events during the initial stages of the fungal transition from mycelium to yeast cells would seem to be the remodelling of the membrane and cell wall (Bastos et al 2007). The dimorphic transition occurs simultaneously with changes in the composition of the fungal cell wall (San-Blas et al 2002).…”

“…Interestingly, some genes related to cell rescue and virulence were over-induced in all conditions analyzed (Bailão et al 2006, Bastos et al 2007, Costa et al 2007. One such example is the transcript encoding a serine proteinase (E.C.3.4.21.4).…”

“…Therefore, we also analyzed ESTs to assess the expression profile during the mycelium-toyeast transition. Comparative analysis of P. brasiliensis ESTs identified in the transition from mycelium to yeast cells (http://192.168.0.5/phorestwww) and the databases cited above allowed the identification of differentiallyexpressed sequences of P. brasiliensis during the morphological conversion (Bastos et al 2007). A summary of the data from non-normalized cDNA libraries is presented in Fig.…”

“…2. A total of 1,602 unique sequences were obtained from the non-normalized cDNA libraries of yeast cells recovered from infected mouse liver and 639 were obtained from mycelium in transition to yeast cells (Costa et al 2007, Bastos et al 2007. From the 1,602 unique sequences in the cDNA library of yeast cells recovered from infected mice, 649 (40.51%) represented novel transcripts and 344 (21.47%) represented overexpressed genes.…”