Open AccessStrain-Dependent Variation in 18S Ribosomal DNA Copy Numbers in Aspergillus fumigatus
Author(s) -
Mónica Herrera,
Ana C. Vallor,
Jonathan Gelfond,
Thomas F. Patterson,
Brian L. Wickes
Publication year - 2009
Publication title -
journal of clinical microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.349
H-Index - 255
eISSN - 1070-633X
pISSN - 0095-1137
DOI - 10.1128/jcm.02073-08
Subject(s) - biology , copy number variation , ribosomal dna , ribosomal rna , gene dosage , aspergillus fumigatus , low copy number , strain (injury) , gene , enumeration , genetics , dna , genome , microbiology and biotechnology , phylogenetics , gene expression , mathematics , anatomy , combinatorics
EnumeratingAspergillus fumigatus CFU can be challenging since CFU determination by plate count can be difficult. CFU determination by quantitative real-time PCR (qPCR), however, is becoming increasingly common and usually relies on detecting one of the subunits of the multicopy rRNA genes. This study was undertaken to determine if ribosomal DNA (rDNA) copy number was constant or variable among differentA. fumigatus isolates.FKS1 was used as a single-copy control gene and was validated against single-copy (pyrG andARG4 ) and multicopy (arsC ) controls. The copy numbers of the 18S rDNA subunit were then determined for a variety of isolates and were found to vary with the strain, from 38 to 91 copies per genome. Investigation of the stability of the 18S rDNA copy number after exposure to a number of different environmental and growth conditions revealed that the copy number was stable, varying less than one copy across all conditions, including in isolates recovered from an animal model. These results suggest that while the ribosomal genes are excellent targets for enumeration by qPCR, the copy number should be determined prior to using them as targets for quantitative analysis.