The Lucilia sericata bottleneck (Lsbnk) promoter is derived from the bottleneck (bnk) gene, a cellularization gene expressed during early embryonic development. The bnk gene is involved in cytoskeletal organization during cellularization of the blastoderm.
The Lsbnk promoter drives high levels of gene expression during early embryonic development and has been used in transgenic calliphorid flies to control expression of genes during this developmental stage. In transgenic sexing systems, the promoter has been used to drive expression of the tetracycline-controlled transactivator (tTA), enabling activation of effector genes during early embryogenesis. Promoter activity has also been detected at later developmental stages, including in adult female ovaries.

An approximately 860-bp DNA fragment containing the Lsbnk promoter has been amplified from L. sericata genomic DNA and characterized for its ability to direct gene expression in transgenic flies.