Abstract
During Drosophila oogenesis, intercellular signaling between germ cells and somatic follicle cells establishes the further anterior-posterior and dorsal-ventral axes of embryo. This interaction is mediated by epidermal growth factor (EGF) receptor signaling. To identify the genes involved in these process, we manipulated the screening of P-element insertion lines with enhancer trap detection. Of 673 P-insertion strains, 14 strains were shown special staining pattern. Four of these strains, the lac Z expression is down-regulated at dorsal-anterior region, where the EGF receptor signaling is highly activated. Two of them, 11590 and 11606, were chosen for further examination. Ectopic EGF receptor signaling represses the lac Z expression of 11590 and 11606, but the in situ hybridization of nearby genes does not match the lac Z expression. Somatic clone analysis of 11590 and 11606 show no effect on eggshell morphology. It is suggested that the lac Z expression does not reflect the expression pattern of nearby genes. We assume that there are some DNA sequences upstream of the P-element insertion sites, which were similar to the transcription regulatory elements regulated by EGF receptor signaling. These sequences therefore regulated the lac Z expression of 11590 and 11606