Functional characterization of the vitellogenin promoter in the silkworm, B ombyx mori

Genetic transformation and genome editing technologies have been successfully established in the lepidopteran insect model, the domesticated silkworm, B ombyx mori , providing great potential for functional genomics and practical applications. However, the current lack of cis ‐regulatory elements in B . mori gene manipulation research limits further exploitation in functional gene analysis. In the present study, we characterized a B . mori endogenous promoter, B mvgp , which is a 798‐bp DNA sequence adjacent to the 5′‐end of the vitellogenin gene ( B mvg ). P iggy B ac ‐based transgenic analysis shows that B mvgp precisely directs expression of a reporter gene, enhanced green fluorescent protein ( EGFP ), in a sex‐, tissue‐ and stage‐specific manner. In transgenic animals, EGFP expression can be detected in the female fat body from larval−pupal ecdysis to the following pupal and adult stage. Furthermore, in vitro and in vivo experiments revealed that EGFP expression can be activated by 20‐hydroxyecdysone, which is consistent with endogenous B mvg expression. These data indicate that B mvgp is an effective endogenous cis ‐regulatory element in B . mori .