Simultaneous extraction of high-quality RNA and DNA from small tissue samples

Purification of high-quality DNA and RNA from a single sample is becoming increasingly important for studies seeking both genomic and transcriptomic data. We compare different methods for isolating DNA and RNA from fish embryos (Gulf killifish; Fundulus grandis) and describe an optimal technique to extract high-quality DNA and RNA from a single embryo. The optimal method utilizes a chaotropic buffer and spin column technology. From embryos weighing approximately 4 mg, we were able to isolate an average of 6.1 microg of DNA and 1.1 microg of RNA per sample. Relative amounts of DNA and RNA can be adjusted as needed per study. Although these extraction trials were conducted on fish embryos, they can be potentially applied to small samples that typically do not yield high concentrations of nucleic acids.