Coexpression of the homeobox genes Distal-less and homothorax determines Drosophila antennal identity

Abstract

The Distal-less gene is known for its role in proximodistal patterning of Drosophila limbs. However, Distal-less has a second critical function during Drosophila limb development, that of distinguishing the antenna from the leg. The antenna-specifying activity of Distal-less is genetically separable from the proximodistal patterning function in that certain Distal-less allelic combinations exhibit antenna-to-leg transformations without proximodistal truncations. Here, we show that Distal-less acts in parallel with homothorax, a previously identified antennal selector gene, to induce antennal differentiation. While mutations in either Distal-less or homothorax cause antenna-to-leg transformations, neither gene is required for the others expression, and both genes are required for antennal expression of spalt. Coexpression of Distal-less and homothorax activates ectopic spalt expression and can induce the formation of ectopic antennae at novel locations in the body, including the head, the legs, the wings and the genital disc derivatives. Ectopic expression of homothorax alone is insufficient to induce antennal differentiation from most limb fields, including that of the wing. Distal-less therefore is required for more than induction of a proximodistal axis upon which homothorax superimposes antennal identity. Based on their genetic and biochemical properties, we propose that Homothorax and Extradenticle may serve as antenna-specific cofactors for Distal-less.

Regulation of the retinal determination gene dachshund in the embryonic head and developing eye of Drosophila

“…In this report, we set out to further our understanding of how the eye specification gene dac, which is distantly related to the Ski/Sno family of proto-oncogenes (Hammond et al, 1998), is regulated in the developing eye and in non-retinal contexts, particularly during embryonic development. We were interested in dac, in part, because it is expressed and controls the development of a wide range of embryonic and post-embryonic tissues (Dong et al, 2000;Keisman and Baker, 2001;Mardon et al, 1994;Martini and Davis, 2005;Martini et al, 2000b;Noveen et al, 2000a). In contrast to eye development, the full set of remaining eye specification genes are not co-expressed with dac in these developmental contexts.…”

“…The dac gene is expressed within and controls the development of several post-embryonic tissues including the developing eye, antenna, leg and genitals (Dong et al, 2000;Keisman and Baker, 2001;Mardon et al, 1994;Martini and Davis, 2005;Martini et al, 2000b;Noveen et al, 2000b;Pappu et al, 2005). In addition, dac influences the development of several embryonic tissues including the optic lobes, brain and central nervous system (Mardon et al, 1994).…”

A Single Cell Genomics Atlas of theDrosophilaLarval Eye Reveals Distinct Developmental Timelines and Novel Markers for All Photoreceptor Subtypes

“…The copyright holder for this preprint this version posted February 14, 2023. ; https://doi.org/10.1101/2023.02.14.528565 doi: bioRxiv preprint clustered using the RunUMAP, FindNeighbors and FindClusters functions in Seurat. Using known markers, we removed cells from antenna (Distal-less (dll)) 74 , glia (reversed polarity (repo)) 75 and brain (found in neurons (fne)) 76 , and 26,999 cells with a sequencing depth of ~2.1 billion reads were retained from the eye disc proper, Oc, PC and LM, and the PPD. Differential marker gene lists for all cell clusters were generated using the FindAllMarkers function with a log-fold change threshold value of 0.25 and a minimum percentage of cells in which the gene is detected of 25%.…”

Identification of the molecular changes underlying head morphology variation in closely related Drosophila species

“…Cut and Ey/Toy repress each other to pattern the antenna and eye primordia, respectively (Punzo et al, 2004). Cut activates expression of Distalles (Dll) and hth, which together promote antennal fate (Casares and Mann, 1998;Dong et al, 2000). In parallel to these events, during late LII stage, in the eye region of the imaginal disc the expression of "early retinal genes" starts to promote retinal differentiation (Kenyon et al, 2003;Kumar and Moses, 2001).…”