Analysis of the DNase I-hypersensitive site of a developmentally regulated 25-kDa protein gene of Sarcophaga peregrina.

Change in chromatin structure of a developmentally regulated gene of Sarcophaga peregrina (flesh fly) during development was investigated. This gene (25-kDa protein gene) was specifically activated in the fat body, but not the hemocytes of larvae in the middle of the third instar. The mRNA level in the fat body decreased thereafter, reaching one-fifth of the maximum level in the late third instar to early pupal stage. In the chromatin of fat body nuclei, a DNase I-hypersensitive site was found about 300 base pairs upstream from the transcription initiation site of the 25-kDa protein gene. This DNase I-hypersensitive site appeared before activation of the 25-kDa protein gene, and it was conserved until the late third instar, but disappeared in the early pupal stage. Since activity of the 25-kDa protein gene decreases significantly in the early pupal stage, it is likely that disappearance of this DNase I-hypersensitive site coincides with inactivation of the 25-kDa protein gene.