Temporal-responsiveness of the epidermal enhancer of the deformed gene in the adult Drosophila melanogaster

Date of Completion

January 1998


Biology, Molecular|Biology, Entomology|Biology, Genetics




The Deformed gene is a member of the Antennapedia complex of Drosophila that is expressed in the maxillary and mandibular segments during embryogenesis. Deformed is also expressed in the adult antenna in unique spatial and temporal patterns, as analyzed by the expression of $\beta$-galactosidase reporters; these P-element constructs contain the intact epidermal enhancer, or restriction fragments thereof, linked to a minimal promoter and the lacZ gene. The 2.7 kilobase epidermal autoregulatory enhancer of the Deformed gene confers a reproducible pattern of expression with time in the adult fly. The E region, a 120 base pair DNA restriction fragment from this epidermal regulatory region, also shows reproducible temporal and spatial regulation of $\beta$-gal expression, the patterns of which closely resemble those of the intact epidermal enhancer.^ Adult and embryonic expression of the 1085 enhancer trap gene and the epidermal enhancer of the Deformed gene are differentially regulated. The regulation of the enhancer trap line 1085 in the adult fly is not affected by alterations of ambient temperature during larval development and pupation, suggesting a separation of the genetic programs of aging within these two distinct developmental periods, larval development and adult maturation, respectively. Although the binding site of the Deformed protein is essential for proper temporal and spatial regulation of gene expression during embryogenesis, the presence of Deformed binding sites is insufficient to confer adult expression, and mutations of this region which prohibit embryonic expression do not entirely eliminate adult expression.^ Data also suggest that both the epidermal enhancer and the smaller E restriction fragment thereof are unresponsive to the relative age of the adult fly; unlike many genes, Deformed gene expression does not appear to adjust in accordance with physiological age when life span is altered by changes in ambient temperature. The apparent age-insensitivity of expression of the Deformed epidermal enhancer, the E restriction fragment of this enhancer, and substitutional mutants of this restriction fragment, suggests that they are closely linked to internal cycles of periodicity. ^