Patent ID: 7049103

Claim:
A method of assaying the efficacy andlor toxicity of a test substance by expression of a specific gene in a cell or a microorganism, which comprises: (a) treating the cell or the microorganism with the test substance, (b) extracting nucleic acids from the cell or the microorganism to provide a reaction solution, (c) amplifying, from said reaction solution containing nucleic acids, a target RNA having a sequence homologous or complementary to a specific sequence in a target mRNA in the reaction solution which is obtained by said extracting by a method comprising, synthesizing a cDNA of the target RNA with an RNA-dependent DNA polymerase, degrading the RNA strand in the resulting RNA•DNA hydrid with ribonuclease H to leave a single-stranded DNA, forming a double-stranded DNA having a promoter sequence which can be transcribed into an RNA comprising the specific base sequence or a sequence complementary to the specific base sequence by using the single-stranded DNA as a template for a DNA-dependent DNA polymerase, transcribing the double-stranded DNA into an RNA transcript, synthesizing a cDNA from the RNA transcript as a template by catalysis of an RNA-dependent DNA polymerase, and amplifying the target RNA with a first oligonucleotide and a second oligonucleotide consisting of at least 10 consecutive bases in the cDNA, (d) determining whether the target mRNA is transcribed through the expression of the specific gene by detecting the RNA amplified by said amplifying, and (e) assessing the efficacy and/or toxicity of said test substance by expression of the specific gene compared to expression of said the specific gene when in the absence of said test substance, wherein (c) and (d) are performed simultaneously.