A Simple Genome Walking Strategy to Isolate Unknown Genomic Regions Using Long Primer and RAPD Primer

Genome walking is a DNA-cloning methodology that is used to isolate unknown genomic regions adjacent to known sequences. However, the existing genome-walking methods have their own limitations. Our aim was to provide a simple and efficient genome-walking technology. In this paper, we developed a novel PCR strategy (termed SLRA PCR) that uses a single long primer (SLP), a set of gene specific primers (GSP), and a random amplified polymorphic DNA (RAPD) primer for genome walking. SLRA PCR consists of two processes: the first amplification using SLP, and three successive rounds of nested PCR amplified by GSP and RAPD primer. The novelty of the approach lies in the use of long primers (SLP and GSP) and same annealing and extension temperature 68℃ in combination. This method offers higher amplification efficiency, superior versatility, and greater simplicity compared with conventional randomly primed PCR methods for genome walking. The promoter regions and the first introns of theinsulin-like androgenic gland hormone (IAG) gene and the hemocyanin gene of Macrobrachium nipponense were cloned using SLRA PCR, respectively. This genome walking strategy can be applied to a wide range of genomes.