The absence of metabolically favorable carbon sources in the chitin-containing media could trigger

the negative regulation of the gpdh1 gene to the detriment of the positive regulation of genes encoding the enzymes required for the use of metabolically less favorable carbon sources. The complexity of the exoskeleton that was added to the culture medium is difficult to determine. This could explain the positive regulation of the GAPDH gene in the exoskeleton-containing media, in addition to the possible host-adhesion role of GAPDH (Dutra et al., 2004; Mogensen et al., 2006). Immunofluorescence microscopy was performed to elucidate Selleckchem CDK inhibitor the subcellular protein localization. Conidia, appressoria, mycelia, blastospores and germinated blastospores were analyzed and both cytosolic and surface forms of the GAPDH protein were observed in vesicular-like structures, as reported before (Rodrigues et al., 2007, 2008; De Jesus et al., 2009). Cell-surface GAPDH localization was corroborated by Triton X-100 surface removal of the protein and the measurement of specific GAPDH activity. Surface GAPDH was also quantified by fluorescence using

a polyclonal antibody. Both methods corroborated the presence of GAPDH on the cell surface. This ‘unexpected’ localization of cytosolic enzymes is increasingly being recognized in

both eukaryotic and prokaryotic cells (Barbosa et al., 2006; Egea et al., 2007). The presence of GAPDH on the external cell surface of M. anisopliae selleck chemicals raises some questions, such as how incorporation into the cell wall occurs in the absence of a conventional N-terminal signal sequence that is responsible for targeting the protein in the secretory pathway. The vesicular-like structures presented by GAPDH would lead us to hypothesize that there is a vesicle-secretion pathway across the cell wall (Rodrigues et al., pheromone 2007); however, more studies will be needed to verify this possibility. The blastospore pole migration pattern evidenced after a 64-h cultivation and the almost complete GAPDH migration to the poles of germinated blastospore are remarkable events in GAPDH localization in M. anisopliae cells. One simple explanation for this recruitment is the increased metabolic activity in these regions of the germinating cells. On the other hand, the surface localization at the blastospore pole could have another function: inhibition of the host immune system through a molecular mimicry mechanism, because the fungal and host GAPDH share high identity, leading to a lack of recognition of the pathogen by the host immune system (Goudot-Crozel et al., 1989; Terao et al., 2006). The possible involvement of M.