Spatial and temporal expression of an Antennapedia/lac Z gene construct integrated into the endogenous Antennapedia gene of Drosophila melanogaster.

In order to study the regulation of spatial and temporal expression of the homeotic gene Antennapedia (Antp) in Drosophila melanogaster, we have constructed fusion genes which contain Antp sequences linked to the reporter gene lac Z of Escherichia coli. In one case of P-element transformation, a fusion gene construct integrated into the endogenous Antp gene close to one of the two promoters (P1). The spatial expression from the reporter gene in this transformant line, as analysed by the detection of β-galactosidase activity, was found to exactly mimic the normal expression from the P1 promoter of the Antp gene. We have used this unique transformant as a tool for studying the expression of the P1 promoter in embryonic, larval and adult development. Parallel lines transformed with the same fusion gene construct did not confer a correct P1 pattern of expression. The position in the genome was, therefore, crucial for the expression pattern of the reporter gene. Experiments aiming at the detection of autoregulatory control of Antp gene expression were designed. The results did not, however, support models of positive or negative autoregulation of P1 expression by Amp protein.