Blastomyces dermatitidis: SREB null mutant versus wild type at 37oC and 6, 24, and 48-hrs 22oC. Blastomyces dermatitidis

The goal of this study was to capture the transcriptional response regulated by the GATA transcription factor encoded by SREB during the first 48-hours of the temperature-dependent shift from yeast (37oC) to mycelia (22oC). Gene expression microarrays were used to compare an SREB null mutant (SREBΔ) to an isogenic wild type strain (ATCC 26199). SREB null mutants fail to fully complete the conversion from yeast to sporulating mycelia after a drop in temperature from 37oC to 22oC, and under iron-replete conditions cannot properly repress siderophore biosynthesis. Deletion of SREB in ATCC 26199 produced SREBΔ. The isogenic wild-type strain is ATCC 26199. Overall design: Total RNA was isolated from 3 biological replicates of SREBΔ and the isogenic wild-type control (ATCC 26199) at 37oC and 6, 24, and 48-hrs at 22oC (24 total samples). All cultures were grown in liquid HMM (Histoplasma macrophage media) under iron replete conditions (10 uM FeSO4). All glassware was pre-treated with 2N HCl and extensively washed with ddH2O.