Dworkin, I.M.*; Larsen, E.W: Temporal dynamics of the interaction between homothorax and Antennapedia in D. melanogaster

The antenna to leg transformations induced by dominant alleles of Antennapedia (Antp) have become classic examples of homeotic transformation in D. melanogaster. It has recently been suggested that this transformation is due to Antp mediated repression of the homothorax (hth) gene. Loss of hth activity from the antennal imaginal disc results in transformation to leg identity, and results of co-expression of Antp and hth have been interpreted as rescuing the antennal phenotype. While Antp activity in the antennal disc does seem to repress hth transcription, several inconsistencies have lead us to investigate the interactions between these two genes in a more quantitative manner. We have investigated how short pulses of Antp via a heat shock mediated transgene (HS-Antp) induces morphological transformations, and represses hth expression. As well, we have employed a HS-hth transgene to examine the temporal dynamics of rescue of the Antp mediated transformation. Our results indicate that there is only a weak correlation between loss of hth expression and morphological transformation. Short pulses of hth appear to be sufficient to induce partial rescue of the Antp mediated transformation. These results will be discussed in terms of the presumed roles of hth in the antennal disc.