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[Intraspecific chromosomal variability in human pathogenic fungi, especially in Histoplasma capsulatum]

Rafael Romero-Martínez1, Cristina Canteros, Maria Lucia Taylor

  • 1Laboratorio de Inmunología de Hongos, Departamento Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico DF, Mexico.

Revista Iberoamericana De Micologia
|February 16, 2005
PubMed

Insights

This study revises fungal ploidy and chromosome length polymorphism (CLP) in Histoplasma capsulatum, the fungus causing histoplasmosis. Electrophoresis revealed variations in chromosome number and size, suggesting CLP is linked to virulence.

Area of Science:

  • Mycology
  • Medical Mycology
  • Fungal Genetics

Background:

  • Human pathogenic fungi, particularly Histoplasma capsulatum, exhibit variations in ploidy, karyotype, and chromosome length polymorphism (CLP).
  • Electrokaryotypes (EKs) are crucial for understanding fungal genome organization and variability.
  • Histoplasma capsulatum is the primary etiological agent of histoplasmosis, a significant systemic mycosis.

Purpose of the Study:

  • To revise the understanding of ploidy, karyotype, and CLP in human pathogenic fungi, focusing on Histoplasma capsulatum.
  • To investigate the relationship between electrokaryotype variations and virulence in different H. capsulatum strains.
  • To estimate genome sizes and analyze chromosome number and size using advanced molecular techniques.

Main Methods:

  • Gel electrophoresis techniques including Contour-clamped homogeneous electric field (CHEF) and Field inversion gel electrophoresis (FIGE).
  • Southern blot analysis using various probes for detailed genomic investigation.
  • Renaturation kinetics and genomic reconstruction for genome size estimation.

Main Results:

  • Estimated genome sizes of 23 Mb (G-186AS) and 32 Mb (Downs strain) for H. capsulatum, with aneuploidy suggested for the Downs strain.
  • The low-virulence Downs strain exhibited six to seven chromosomes, while the high-virulence G-186B strain showed four chromosomes.
  • Chromosome Length Polymorphism (CLP) was observed across different H. capsulatum strains and isolates, correlating with chromosome size and mobility.

Conclusions:

  • Electrokaryotype (EK) analysis reveals significant variability in chromosome number and size within Histoplasma capsulatum.
  • Chromosome Length Polymorphism (CLP) is associated with virulence differences among H. capsulatum strains.
  • Further research is required to understand the mechanisms governing ploidy variability and its phenotypic impact in H. capsulatum.

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