Abstract: The fibroin light-chain gene (fib-L) of the silkworm Bombyx mori is tissue-specifically expressed in the posterior silk glands at high-level. To establish a silk gland bio-factory to produce foreign gene in B. mori under the control of the promoter of fibroin light-chain gene (fib-L), the activity of the promoter was investigated. The fib-L promoter obtained by PCR was cloned and sequenced. The sequence analysis showed that the promoter of fib-L was constituted of the TATA box (－33-－35) and the characteristic sequence GTCAATTT(－128-－121). The reporter gene DsRed driven by fibroin light-chain gene promoter was transiently expressed in the BmN cells and the posterior silk gland. The result showed that the fibroin light-chain gene promoter could drive the report gene transiently expressing both in the BmN cells and the posterior silk gland of silkworm B. mori.  

Key words: Bombyx mori, fib-L gene, promoter, DsRed, transient expression