[Intraspecific chromosomal variability in human pathogenic fungi, especially in Histoplasma capsulatum].
The ploidy, karyotype, and chromosome length polymorphism (CLP) of human pathogenic fungi were revised with emphasis on Histoplasma capsulatum, the causative agent of the systemic mycosis, histoplasmosis. Currently, different systems of gel electrophoresis are being used to determine fungal electrokaryotypes (EK). By renaturation kinetic and genomic reconstruction in H. capsulatum strains (G-186AS and Downs), estimated genome sizes of 23 and 32 Mb were determined for both strains, respectively. The haploid state was proposed for both strains, although aneuploidy was suggested for the Downs strain. Contour-clamped homogeneous electric field (CHEF), field inversion gel electrophoresis (FIGE), and Southern blot using different probes showed the presence of six to seven chromosomes in the Downs strain (low virulence), whereas four chromosomes were identified in the G-186B strain (high virulence). The use of these methods in the three major H. capsulatum reference strains (G-217B and Downs from the United States of America, G-186B from Panama) revealed distinct chromosome sizes, from 0.5 to 5.7 Mb, with CLP associated with chromosomes size and mobility. Recently, by CHEF, using 19 H. capsulatum isolates from Latin-America and the G-186B strain, five to seven chromosomes with 1.1 to 11.2 Mb molecular sizes were revealed, which again suggested CLP in H. capsulatum. However, to elucidate the EKs polymorphism in H. capsulatum and its relationship with the isolates phenotype more studies are needed to understand the mechanisms controlling ploidy variability.
Romero-Martínez
Rafael
R
Laboratorio de Inmunología de Hongos, Departamento Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico DF, Mexico.
Canteros
Cristina
C
Taylor
Maria Lucia
ML
D015825:Chromosomes, Fungal / Q000235:genetics* / Q000648:ultrastructure; D004271:DNA, Fungal / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005658:Fungi / Q000235:genetics*; D016681:Genome, Fungal; D006658:Histoplasma / Q000235:genetics*; D006801:Humans; D009181:Mycoses / Q000382:microbiology; D011003:Ploidies; D013045:Species Specificity
D004271:DNA, Fungal