354V Poster Online - Virtual Posters
Wednesday April 06, 4:00 PM - 7:00 PM

Authors:
ANKUSH AURADKAR ^1,2; Emily A. Bulger ³; Sushil Devkota ¹; William McGinnis ¹; Ethan Bier ^1,2

Affiliations:
1) Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA; 2) Tata Institute for Genetics and Society-UCSD, La Jolla, CA 92093-0335, USA; 3) Developmental and Stem Cell Biology Graduate Program, University of California San Francisco, and Gladstone Institutes, San Francisco, CA, USA

Keywords:
l. evo-devo; n. tissue specification

Hox genes determine positional codes along the head-to-tail axis. Here, we replaced the entire Drosophila melanogaster proboscipedia (pb) Hox locus, which controls the development of the proboscis and maxillary palps, with that from Drosophila mimica, a related species with highly modified mouthparts. The D. mimica replacement rescues most aspects of adult proboscis morphology; however, the shape and orientation of maxillary palps were modified, resembling D. mimica and closely related species. Expressing the D. mimica Pb protein in the D. melanogaster pattern fully rescued D. melanogaster morphology. In contrast, expression of the pb locus directed by D. mimica pb cis-regulatory sequences was reduced from that of D. melanogaster pb in cells that produce altered maxillary structures, potentially altering the balance between pb and a competing Hox gene Deformed (Dfd). This hypothesis is consistent with the observation that over-expression of Dfd in D. melanogaster results in altered maxillary palp orientation similar to that in D. mimica replacement. These findings suggest that pb regulatory sequences evolved in related species to alter mouthpart morphology.

Auradkar, A., Bulger, E. A., Devkota, S., McGinnis, W. & Bier, E. Dissecting the evolutionary role of the Hox gene proboscipedia in Drosophila mouthpart diversification by full locus replacement.
Sci. Adv. 7, 1003(2021).