Germline transformation of the silkworm Bombyx mori L. by sperm-mediated gene transfer.

The domesticated silkworm Bombyx mori L. has important roles in basic biological research and applied science. To explore the practical use of transgenic technology in agricultural silkworm varieties, we fused the neomycin-resistance gene (Neo(R)) and the green fluorescent protein gene (gfp) into the piggyBac-based transposon vector and transduced it into silkworms by sperm-mediated gene transfer (SMGT). Fluorescence observation indicated the positive rate of G0 egg-batches is 72.7%. After screening against the antibiotic G418, development of individual larvae in the same brood showed significant size differences. PCR detection indicated the existence of gfp and Neo(R) and confirmed the positive rate of transgenesis as 0.47%. Southern blot analysis confirmed the presence of the exogenous genes in the genome of G7 larvae. These results show that our strategy is practical and markedly improves the efficiency of SMGT.