[Constructing tandem-repeated sequence of nucleic acid and evaluating its signal amplification action]

Tandem-repeated sequence of nucleic acid was constructed by splicing 4 fragments which contain the same sequence in the central part, using overlap extension polymerase chain reaction and then repeatedly cloning it in the same vector at different site of restriction endonuclease. Its signal amplification action was evaluated using electrophoresis of hybridized product and dot hybridization assay. 24-repeat sequence was successfully constructed and confirmed by restriction endonuclease digestion analysis. The construct was 25-repeat actually since the vector itself had the same basic sequence. Hybridized product electrophoresis revealed that the 25-repeat sequence could combine with several secondary probes. Dot hybridization assay demonstrated that tandem-repeated sequence was 16-fold more sensitive than that of non-repeated sequence. Tandem-repeated sequence had good effect on signal amplification. It could be easily cheaply prepared in large amount after cloning. Thus, it might be useful in clinical examinations and biological researches.