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Unisexual reproduction of Cryptococcus gattii.

Phadke SS, Feretzaki M, Clancey SA, Mueller O, Heitman J - PLoS ONE (2014)

Bottom Line: Cryptococcus gattii is a basidiomycetous human fungal pathogen that typically causes infection in tropical and subtropical regions and is responsible for an ongoing outbreak in immunocompetent individuals on Vancouver Island and in the Pacific Northwest of the US.A marked predominance of only one mating type (α) in clinical and environmental isolates suggests that a-α opposite-sex reproduction may be infrequent or geographically restricted, raising the possibility of an alternative unisexual cycle involving cells of only α mating type, as discovered previously in the related pathogenic species Cryptococcus neoformans.Our results are consistent with population genetic evidence of recombination in the largely unisexual populations of C. gattii and provide a useful genetic model for understanding how novel modes of sexual reproduction may contribute to evolution and virulence in this species.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America.

ABSTRACT
Cryptococcus gattii is a basidiomycetous human fungal pathogen that typically causes infection in tropical and subtropical regions and is responsible for an ongoing outbreak in immunocompetent individuals on Vancouver Island and in the Pacific Northwest of the US. Pathogenesis of this species may be linked to its sexual cycle that generates infectious propagules called basidiospores. A marked predominance of only one mating type (α) in clinical and environmental isolates suggests that a-α opposite-sex reproduction may be infrequent or geographically restricted, raising the possibility of an alternative unisexual cycle involving cells of only α mating type, as discovered previously in the related pathogenic species Cryptococcus neoformans. Here we report observation of hallmark features of unisexual reproduction in a clinical isolate of C. gattii (isolate 97/433) and describe genetic and environmental factors conducive to this sexual cycle. Our results are consistent with population genetic evidence of recombination in the largely unisexual populations of C. gattii and provide a useful genetic model for understanding how novel modes of sexual reproduction may contribute to evolution and virulence in this species.

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Hallmarks of unisexual reproduction in VGIIIa mating type α strain 97/433.From left to right, (Top panel) Peripheral hyphae and basidium (inset), basidiospores, unfused clamp cells (arrow); (Middle panel) DAPI stained basidiospores, monokaryotic hyphae; (Bottom panel) SEM of basidiospores, unfused clamps; Scale bar = 1 µm; except for top left image (10 µm).
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pone-0111089-g002: Hallmarks of unisexual reproduction in VGIIIa mating type α strain 97/433.From left to right, (Top panel) Peripheral hyphae and basidium (inset), basidiospores, unfused clamp cells (arrow); (Middle panel) DAPI stained basidiospores, monokaryotic hyphae; (Bottom panel) SEM of basidiospores, unfused clamps; Scale bar = 1 µm; except for top left image (10 µm).

Mentions: We tested various combinations of media, temperatures, and light conditions, including V8 pH = 5.0 agar, Murashige Skoog (MS) medium, and filament agar and found 97/433 to produce hyphae on V8 pH 5.0 and MS media at room temperature (24°C) in the dark. When solo cultured under these conditions for up to ∼2 months, 97/433 develops hyphae at isolated spots along the periphery of the yeast colony (Figure 2). Although, the hyphal formation phenotype was highly reproducible, not every colony of 97/433 tested produced hyphae or to the same extent.


Unisexual reproduction of Cryptococcus gattii.

Phadke SS, Feretzaki M, Clancey SA, Mueller O, Heitman J - PLoS ONE (2014)

Hallmarks of unisexual reproduction in VGIIIa mating type α strain 97/433.From left to right, (Top panel) Peripheral hyphae and basidium (inset), basidiospores, unfused clamp cells (arrow); (Middle panel) DAPI stained basidiospores, monokaryotic hyphae; (Bottom panel) SEM of basidiospores, unfused clamps; Scale bar = 1 µm; except for top left image (10 µm).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206507&req=5

pone-0111089-g002: Hallmarks of unisexual reproduction in VGIIIa mating type α strain 97/433.From left to right, (Top panel) Peripheral hyphae and basidium (inset), basidiospores, unfused clamp cells (arrow); (Middle panel) DAPI stained basidiospores, monokaryotic hyphae; (Bottom panel) SEM of basidiospores, unfused clamps; Scale bar = 1 µm; except for top left image (10 µm).
Mentions: We tested various combinations of media, temperatures, and light conditions, including V8 pH = 5.0 agar, Murashige Skoog (MS) medium, and filament agar and found 97/433 to produce hyphae on V8 pH 5.0 and MS media at room temperature (24°C) in the dark. When solo cultured under these conditions for up to ∼2 months, 97/433 develops hyphae at isolated spots along the periphery of the yeast colony (Figure 2). Although, the hyphal formation phenotype was highly reproducible, not every colony of 97/433 tested produced hyphae or to the same extent.

Bottom Line: Cryptococcus gattii is a basidiomycetous human fungal pathogen that typically causes infection in tropical and subtropical regions and is responsible for an ongoing outbreak in immunocompetent individuals on Vancouver Island and in the Pacific Northwest of the US.A marked predominance of only one mating type (α) in clinical and environmental isolates suggests that a-α opposite-sex reproduction may be infrequent or geographically restricted, raising the possibility of an alternative unisexual cycle involving cells of only α mating type, as discovered previously in the related pathogenic species Cryptococcus neoformans.Our results are consistent with population genetic evidence of recombination in the largely unisexual populations of C. gattii and provide a useful genetic model for understanding how novel modes of sexual reproduction may contribute to evolution and virulence in this species.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America.

ABSTRACT
Cryptococcus gattii is a basidiomycetous human fungal pathogen that typically causes infection in tropical and subtropical regions and is responsible for an ongoing outbreak in immunocompetent individuals on Vancouver Island and in the Pacific Northwest of the US. Pathogenesis of this species may be linked to its sexual cycle that generates infectious propagules called basidiospores. A marked predominance of only one mating type (α) in clinical and environmental isolates suggests that a-α opposite-sex reproduction may be infrequent or geographically restricted, raising the possibility of an alternative unisexual cycle involving cells of only α mating type, as discovered previously in the related pathogenic species Cryptococcus neoformans. Here we report observation of hallmark features of unisexual reproduction in a clinical isolate of C. gattii (isolate 97/433) and describe genetic and environmental factors conducive to this sexual cycle. Our results are consistent with population genetic evidence of recombination in the largely unisexual populations of C. gattii and provide a useful genetic model for understanding how novel modes of sexual reproduction may contribute to evolution and virulence in this species.

Show MeSH
Related in: MedlinePlus