Abstract: A method for preparing a DNA library from a sample containing RNA includes ligating a first DNA linker to the 3? end of at least one RNA molecule in a sample containing RNA to obtain an RNA molecule having the first DNA linker, hybridizing a first oligonucleotide with the RNA molecule having the first DNA linker to obtain the RNA molecule having a double-stranded DNA promoter region, obtaining a complementary strand of the RNA molecule having the first DNA linker (complementary RNA) by in vitro transcription using the RNA molecule having the double-stranded DNA promoter region as a template and an RNA polymerase that recognizes the promoter sequence and initiates transcription; and ligating a second DNA linker to the 3? end of the complementary RNA and further obtaining a single-stranded DNA by reverse transcription using the complementary RNA having the second DNA linker as a template.

Abstract: An object of the present invention is to provide a method for producing a non-ribosomal RNA-containing sample, which comprises a novel step for removing ribosomes. According to the present invention, there is provided a method for producing a non-ribosomal RNA-containing sample, which comprises the step (a) of splitting subunits of ribosomes and mRNAs in a sample containing mRNAs and ribosomes, and the step (b) of removing the subunits of ribosomes split in the step (a).