Copyright information:Taken from "Doxycycline-regulated gene expression in the opportunistic fungal pathogen "BMC Microbiology 2005;5():1-1.Published online 13 Jan 2005PMCID:PMC546209.Copyright © 2005 Vogt et al; licensee BioMed Central Ltd. Total RNA was isolated from an overnight culture of the tTA-1 transformant (Fig. 4) growing in minimal medium supplemented with one tenth the normal concentration of iron and the indicated concentrations of doxycycline (0–50 μg/ml). RNA was fractionated by agarose gel electrophoresis, transferred to nylon membranes, and probed with a P-labeled probe. Wild type is included in the first lane as a negative hybridization control. Hybridization intensity was normalized to levels of SYBR-green II-stained rRNA by phosphorimager analysis and is presented in the graph as a percentage of the signal obtained in the tTA-1 strain in the absence of doxycycline (0).