A supersensitive dot-hybridization method: rapid and quantitative detection of host-derived DNA in recombinant...

We have developed a highly sensitive method of DNA dot-blotting hybridization to detect host-derived DNA (nuclear DNA and plasmid DNA) in a recombinant product. This method has two distinctive features compared to the conventional hybridization method: firstly, a highly specific radioactive probe is prepared by using ultrasonicated DNA, instead of untreated DNA, as a template for the oligo-labeling reaction; secondly, the signal to noise ratio is increased by the use of lambda phage DNA as non-homologous DNA. This method enabled us to detect host-derived DNA at the one picogram level without using a radioisotope of high specific activity and long exposure times.