Direct exponential amplification and sequencing (DEXAS) of genomic DNA.

In order to supply a sufficient amount of template molecules for DNA sequence determination, cloning into plasmids and subsequent plasmid purification, or amplification via the PCR, are generally used. Here, we present a method-'direct exponential amplification and sequencing' or 'DEXAS'-that permits direct sequence determination from whole genomic DNA and thus eliminates the need for template amplification and preparation. It relies on the simultaneous amplification of a target sequence and the determination of its sequence using dideoxyterminators in a two-step cycling reaction. DEXAS can be applied to single as well as multi-copy genomic sequences, and can easily be automated.