Differential expression of an <i>hsp70</i> gene during transition from the mycelial to the infective yeast form of the human pathogenic fungus <i>Paracoccidioides brasiliensis</i>

Silva, Silvana Petrofeza da; Borges-Walmsley, M. Inês; Silva-Pereira, Ildinete; Soares, Célia Maria de Almeida; Walmsley, Adrian R.; Felipe, Maria Sueli Soares

doi:10.1046/j.1365-2958.1999.01236.x

Cited by 66 publications

(55 citation statements)

References 42 publications

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“…In addition, some HSPs are also involved in signal transduction to regulate morphogenic variation (Rutherford, 2003). For example, differential expression of an HSP70 gene has been observed during transition from the mycelial to the yeast form in the human pathogenic fungus Paracoccidioides brasiliensis (Da Silva et al, 1999). Consequently, HSPs could be involved in the morphological change from densesporulating to fluffy-mycelial type.…”

Section: Discussionmentioning

confidence: 99%

Colony sectorization of Metarhizium anisopliae is a sign of ageing

2005

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Spontaneous phenotypic degeneration resulting in sterile sectors is frequently observed when culturing filamentous fungi on artificial medium. Sterile sectors from two different strains of the insect pathogenic fungus Metarhizium anisopliae were investigated and found to contain reduced levels of cAMP and destruxins (insecticidal peptides). Microarray analysis using slides printed with 1730 clones showed that compared to wild-type, sterile sectors down-regulated 759 genes and upregulated 27 genes during growth in Sabouraud glucose broth or on insect cuticle. The differentially expressed genes are largely involved in cell metabolism (18?8 %), cell structure and function (13?6 %) and protein metabolism (8?8 %). Strong oxidative stress was demonstrated in sectorial cultures using the nitro blue tetrazolium assay and these cultures show other syndromes associated with ageing, including mitochondrial DNA alterations. However, genes involved in deoxidation and self-protection (e.g. heat-shock proteins, HSPs) were also upregulated. Further evidence of physiological adaptation by the degenerative sectorial cultures included cell-structure reorganization and the employment of additional signalling pathways. In spite of their very similar appearance, microarray analysis identified 181 genes differentially expressed between the two sectors, and the addition of exogenous cAMP only restored conidiation in one of them. Most of the differentially expressed genes were involved in catabolic or anabolic pathways, but the latter included genes for sporulation. Compared to the mammalian ageing process, sectorization in M. anisopliae showed many similarities, including similar patterns of cAMP production, oxidative stress responses and the involvement of HSPs. Thus, a common molecular machinery for ageing may exist throughout the eukaryotes. INTRODUCTIONThe ascomycete Metarhizium anisopliae is a widespread, soil-borne pathogen of insects, ticks and mites (Roberts & St Leger, 2004). Strains of this fungus are being developed for the control of pest species (Butt et al., 2001). Like many other fungi (Morrow et al., 1989;Kale & Bennett, 1992;Li et al., 1994), it frequently shows culture degeneration (sterile sectorization): a loss or reduction in sporulation and virulence with a fluffy-mycelium type growth. Fungal culture degeneration is usually irreversible and inheritable, and can result in great commercial losses (Li et al., 1994;Horgen et al., 1996;Ryan et al., 2003).Apart from the reports of secondary metabolite decline in degenerative fungal cultures (Wing et al., 1995; Guzman-dePena & Ruiz-Herrera, 1997;Ryan et al., 2002; Kale et al., 2003), little information is available to explain fungal culture instability at the molecular level. However, genomic DNA methylation was reported in a sector of Fusarium oxysporum after successive subculturing (Kim, 1997). In another case, fungal morphological instability was linked to dsRNA virus infection (Dawe & Nuss, 2001).In this study, the spontaneous sterile sectors from two genetically di...

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Section: Discussionmentioning

confidence: 99%

Colony sectorization of Metarhizium anisopliae is a sign of ageing

2005

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“…In Histoplasma capsulatum and Paracoccidioides brasiliensis, the morphological change from filamentous forms to yeast forms is essential for their pathogenicity (Maresca and Kobayashi, 2000;Da Silva, 1999). However, in C. albicans, both yeast and filamentous forms are important for infection (Calderone and Fonzi, 2001;Mitchell, 1998).…”

Section: Introductionmentioning

confidence: 99%

Molecular cloning and characterization of WdTUP1, a gene that encodes a potential transcriptional repressor important for yeast-hyphal transitions in Wangiella (Exophiala) dermatitidis

Liu

Abramczyk

Cooper

et al. 2008

Fungal Genetics and Biology

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The general transcriptional repressor Tup1p is known to influence cell development in many fungi. To determine whether the Tup1p ortholog (WdTup1p) of Wangiella dermatitidis also influences cellular development in this melanized, polymorphic human pathogen, the gene (WdTUP1) that encodes this transcription factor was isolated, sequenced and disrupted. Phylogenetic analysis showed that the WdTup1p sequence was closely related to homologues in other polymorphic, conidiogenous fungi. Disruption of WdTUP1 produced mutants (wdtup1Δ) with pronounced growth and cellular abnormalities, including slow growth on various agar media and exclusively as a filamentous morphotype in liquid media. We concluded that WdTup1p represents an important switch regulator that controls the yeast-to-filamentous growth transition. However, detailed observations of the filamentous growth of the disruption mutant showed that the hyphae produced by the wdtup1Δ mutants, unlike those of the wild type, were arrested at a stage prior to the formation of true hyphae and subsequent conidia production.

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“…Early work from our laboratory using metabolically labelled cells has led to a group of heat-induced proteins (Silva et al, 1994). Our group also isolated and characterized the genes encoding the heat-induced proteins 70 and 60 (Silva et al, 1999;Salem-Izaac et al, 2001). Recently the cloning and characterization of the gene encoding the heat-inducible Lon protease of P. brasiliensis has been described by Barros and Puccia (2001).…”

Section: Introductionmentioning

confidence: 98%