TY - JOUR
T1 - Comparative analysis of the intergenic spacer regions and population structure of the species complex of the pathogenic yeast Cryptococcus neoformans
AU - Diaz, Mara R.
AU - Boekhout, Teun
AU - Kiesling, Traci
AU - Fell, Jack W.
N1 - Funding Information:
Our sincere gratitude to B. Theelen and A. Statzell-Tallman for their assistance in DNA isolation and to Drs. M. Lazera, F. Coenjaerts, K.J. Kwon-Chung, S. Hamdan, J. Torres-Rodriguez, D. Swinne, W. Meyer, A. van Belkum, M.T. Barreto de Oliviera, and F. Frommer for providing strains. This work was funded by National Institutes of Health Grant 1-UO1 AI53879-01.
PY - 2005/12
Y1 - 2005/12
N2 - Cryptococcus neoformans is an opportunistic basidiomycete responsible for the high incidence of cryptococcosis in patients with AIDS and in other immune-compromised individuals. This study, which focused on the molecular structure and genetic variability of the two varieties in the C. neoformans and Cryptococcus gattii species complex, employed sequence analysis of the intergenic spacer regions, IGSI and IGSII. The IGS region is the most rapidly evolving region of the rDNA families. The IGSI displayed the most genetic variability represented by nucleotide base substitutions and the presence of long insertions/deletions (indels). In contrast, the IGSII region exhibited less heterogeneity and the indels were not as extensive as those displayed in the IGSI region. Both intergenic spacers contained short, interspersed repeat motifs, which can be related to length polymorphisms observed between sequences. Phylogenetic analysis undertaken in the IGSI, IGSII and IGSI + 5S rRNA + IGSII regions revealed the presence of six major phylogenetic lineages, some of which segregated into subgroups. The major lineages are represented by genotypes 1 (C. neoformans var. grubii), genotype 2 (C. neoformans var. neoformans), and genotypes 3, 4, 5 and 6 represented by C. gattii. Genotype 6 is a newly described IGS genotypic group within the C. neoformans species complex. With the inclusion of IGS subgenotypic groups, our sequence analysis distinguished 12 different lineages. Sequencing of clones, which was performed to determine the presence of multiple alleles at the IGS locus in several hybrid strains, yielded a single IGS sequence type per isolate, thus suggesting that the selected group of cloned strains was mono-allelic at this locus. IGS sequence analyses proved to be a powerful technique for the delineation of the varieties of C. neoformans and C. gattii at genotypic and subgenotypic levels.
AB - Cryptococcus neoformans is an opportunistic basidiomycete responsible for the high incidence of cryptococcosis in patients with AIDS and in other immune-compromised individuals. This study, which focused on the molecular structure and genetic variability of the two varieties in the C. neoformans and Cryptococcus gattii species complex, employed sequence analysis of the intergenic spacer regions, IGSI and IGSII. The IGS region is the most rapidly evolving region of the rDNA families. The IGSI displayed the most genetic variability represented by nucleotide base substitutions and the presence of long insertions/deletions (indels). In contrast, the IGSII region exhibited less heterogeneity and the indels were not as extensive as those displayed in the IGSI region. Both intergenic spacers contained short, interspersed repeat motifs, which can be related to length polymorphisms observed between sequences. Phylogenetic analysis undertaken in the IGSI, IGSII and IGSI + 5S rRNA + IGSII regions revealed the presence of six major phylogenetic lineages, some of which segregated into subgroups. The major lineages are represented by genotypes 1 (C. neoformans var. grubii), genotype 2 (C. neoformans var. neoformans), and genotypes 3, 4, 5 and 6 represented by C. gattii. Genotype 6 is a newly described IGS genotypic group within the C. neoformans species complex. With the inclusion of IGS subgenotypic groups, our sequence analysis distinguished 12 different lineages. Sequencing of clones, which was performed to determine the presence of multiple alleles at the IGS locus in several hybrid strains, yielded a single IGS sequence type per isolate, thus suggesting that the selected group of cloned strains was mono-allelic at this locus. IGS sequence analyses proved to be a powerful technique for the delineation of the varieties of C. neoformans and C. gattii at genotypic and subgenotypic levels.
KW - Cryptococcus neoformans
KW - Intergenic spacer (IGS)
KW - Length polymorphism
KW - Repeated motifs
KW - Yeast
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U2 - 10.1016/j.femsyr.2005.05.005
DO - 10.1016/j.femsyr.2005.05.005
M3 - Article
C2 - 16061425
AN - SCOPUS:27744502920
VL - 5
SP - 1129
EP - 1140
JO - FEMS Yeast Research
JF - FEMS Yeast Research
SN - 1567-1356
IS - 12
ER -
