Redesigning the body plan of Drosophila by ectopic expression of the homoeotic gene Antennapedia

Abstract

Genetic and molecular studies on the expression of Antennapedia (Antp) have suggested that this gene specifies mainly the second thoracic segment. On the basis of our molecular analysis of dominant gain-of-function mutants we have postulated that the transformation of antennae into second legs is due to the ectopic overexpression of the Antp+ protein. This hypothesis was tested by inserting the complementary DNA encoding the normal Antp protein into a heat-shock expression vector and subsequent germ-line transformation. As predicted, heat induction at defined larval stages leads to the transformation of antennae into second legs. The dorsal part of the head can also be transformed into second thoracic structures (scutum) indicating that Antp indeed specifies the second thoracic segment. By ectopic overexpression of the Antp protein the body plan of the fruit fly can be altered in a predictable way.

The three postblastoderm cell cycles of Drosophila embryogenesis are regulated in G2 by string

“…This fragment was cloned into the Kpnl site of pWH1 (Schneuwly et al, 1987) and into the polylinker of pRK261 (R. Kostriken, personal communication). Stable lines carrying these genes were made by standard P element-mediated transformation of y, Df(w)67 host flies Spradling and Rubin, 1982).…”

The mouse Hox-1.3 gene is functionally equivalent to the Drosophila Sex combs reduced gene.

“…5C), suggesting that the ectopic legs have T1 leg identity. In contrast, ectopic expression of Antp (hs-Antp) induces transformation of antenna toward T2 leg, as indicated by the presence of an apical bristle on the ectopic leg (Schneuwly et al 1987;Gibson and Gehring 1988) . We have never observed an apical bristle on the hs-Hox-l.3-in-…”

“…In addition to antennal transformations, both Scr and Hox-l.3 induce a Ctx-like transformation in adult flies (swollen occiputs with many dark ectopic bristles in the dorsal aspect of hindhead; Duncan and Lewis 1982;Schneuwly et al 1987;Gibson and Gehring 1988). At present, we are unable to determine the segmental identity of this transformation and, thus, cannot distinguish between Antp-and Scr-induced effects on these structures.…”

Quantitative genetic background effects on the Antennapaedia phenotype in Drosophila melanogaster

“…Antp73b is dominant, and is caused by an inversion affecting a regulatory region of the Antennapaedia complex (Schneuwly el a!., 1987a). The transformation of antennae to legs by this allele appears to be the result of ectopic production ofAntennapaedia gene product (Schneuwly et aL, 1987b). This transformation follows the sequential homology described for Antp' by Postlethwaite and Schneiderman (1971). Proximally, Antp73b does not appear to transform the first antennal segment (Al) towards coxa, but causes a hybrid second antennal segment (All) mixed with trochanter structures.…”