An Interplasmid Transposition Assay Reveals That the piggyBac Transposon Can Be Used in the Eri Silkworm Samia ricini

抄録

We conducted an extrachromosomal interplasmid transposition assay using the lepidopteran piggyBac transposon in embryos of the eri silkworm Samia ricini. To construct the transposition assay system, expression of the piggyBac transposase in embryos is required. We first measured the promoter activity of the upstream region of the cytoplasmic actin 3 gene (BmA3) of the mulberry silkworm (Bombyx mori) in eri embryos by the luciferase assay and found that the BmA3 promoter worked well in eri silkworms. We then constructed a helper plasmid expressing piggyBac transposase in eri embryos using the BmA3 promoter and tested for transposition activity in interplasmid transposition assays to determine whether or not the piggyBac element works. The piggyBac element was inserted into the TTAA sequences on the acceptor plasmid and the frequency of transposition was high. Based on these results, we concluded that the piggyBac transposon can serve as an effective vector for germ-line transformation in the eri silkworm.