Pyrosequencer Miniaturized with Capillaries to Deliver Deoxynucleotides

Abstract

As the human genome project proceeds, various types of DNA analysis tools are required for life sciences and medical sciences including DNA diagnostics. For example, a small DNA sequencer for sequencing a short DNA is required for bedside DNA testing as well as DNA analysis in a small laboratory. Here, a new handy DNA sequencing system (pyrosequencer) based on the detection of inorganic pyrophosphate (PPi) released by polymerase incorporation is demonstrated. The system uses the bioluminescence detection system. The key point for the miniaturized DNA sequencer is to make a deoxynucleotide triphosphate (dNTP) delivery system small and inexpensive. It has been realized by using narrow capillaries to connect a reaction chamber and four dNTP reservoirs. Each dNTP is introduced into the reaction chamber by applying a pressure to the reservoir. Compared with other microdispensers, it is much cheaper and easier. By optimizing the conditions, an excellent sequencing ability is achieved while it is a simple and inexpensive system. In most cases, more than 40 bases can be successfully sequenced. A homopolymeric region, which cannot be easily sequenced by a conventional gel-based DNA sequencer, is readily sequenced with this system. The new system is successfully applied to sequence a GC-rich region or a region close to a priming region where misreading frequently occurs. A rapid analysis for a short DNA was easily achieved with this small instrument.