A fluorescence-based method for quantitative determination of RNA and DNA in probes containing both nucleic acids has been
developed. The total concentration of nucleic acids is determined using SYBR Green II dye under conditions providing independent
binding of the fluorophore with DNA and RNA. The concentration of DNA is specifically measured using the Hoechst 33258 dye
and the RNA concentration is calculated from these data. The procedure allows for accurate determination of DNA concentration
in the range 10–1000 ng/ml in the presence of 200-fold excess of RNA and determination of RNA concentrations in the range 10–
1000 ng/ml in the presence of large excess of DNA. An absence of the treatment of mixed samples with RNase-free DNase I provides
rapid, reproducible, and accurate RNA quantification.
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