Project description:The goal of this gene expression profiling experiment was to identify the entire set of transcription factors expressed during late pupal wing development (~80h APF) when pigmentation genes are expressed We used Affymetrix microarrays to profile the expression of the transcription factors in late pupal wings of Oregon R flies. The staging of the flies was made by eye, based on the extent of wing pigmentation. RNA was extracted from batches of 40 flies and three biological replicates were analyzed.
Project description:The male terminalia of Drosophila melanogaster has undergone rapid morphological change between it and its closely related species, making it a useful model for studying evolution and development. In order to identify the network components that pattern the male terminalia, we isolated and sequenced whole RNA from two timepoints during pupal development, and next performed in situ hybridization for 100 highly expressed transcription factors during pupal development.
Project description:The loss of discrete morphological traits, the most common evolutionary transition, is typically driven by changes in expression of developmental genes. Mutations accumulating in regulatory elements of these genes can disrupt DNA binding sites for transcription factors patterning their spatial expression, or delete entire enhancers. Regulatory elements, however, may in principle be silenced through other mechanisms, including changes in chromatin accessibility, or the emergence of repressive elements. Here, we show that an increase in chromatin accessibility at the pigmentation gene yellow, combined with the gain of a repressor site, underlie the evolutionary loss of a spot pigmentation pattern on the wings of a Drosophila species. The evolutionary gain of accessibility of this repressive element is regulated by E93, a transcription factor governing the progress of metamorphosis. This convoluted evolutionary scenario contrasts with the classical parsimonious mutational paths generally envisioned and often documented for morphological losses. It illustrates for the first time how evolutionary changes in chromatin accessibility may directly contribute to morphological diversification. We profiled chromatin accessibility at selected stages in the pupal wings of D. melanogaster and D. biarmipes using ATAC-seq.
Project description:In order to test the hypothesis that adult hybrid misexpression results from the cascading effect of earlier-expressed developmentally important improperly regulated genes, as well as address whether Von Baer’s 3rd law (suggesting that earlier stages of development should be more similar between species than later stages) holds at the level of gene expression, we conducted whole-transcriptome Drosophila melanogaster cDNA microarray-based expression profiling of males of D. melanogaster, D. sechellia, and D. simulans, at four synchronized developmental time-points (3rd instar larval [larval], early pupal, late pupal, and newly-emerged adult [adult]). D. simulans and D. sechellia shared a most recent common ancestor (MRCA) ~0.5 to 1.0 million years ago (MYA) and form a clade that shared an MRCA with D. melanogaster approximately 5.4 MYA. In addition, we also performed the same analysis on the male interspecific F1 hybrids of the D. simulans (♀) × D. sechellia (♂) cross.
Project description:Hox genes regionalize the animal body axis by modifying complex morphogenetic and differentiation processes during development. The transformation of wings into halteres by the Hox gene Ultrabithorax (Ubx) in Drosophila melanogaster presents an excellent model system to study the transcriptional networks that control such complex developmental programmes. We have employed an inducible misexpression system to switch on Ubx in the wing epithelium at successive larval, prepupal and pupal stages, and have used microarray expression profiling to identify the primary transcriptional responses to Ubx. We find that Ubx regulates hundreds of downstream genes, mostly in a subtle manner. These targets are largely distinct at the different stages of appendage development and diversification. We have generated an experimental fly line combining the nabGal4NP3537-driver, a tub-GAL80ts transgene, and a UAS-UbxIa transgene (the control line was carrying a UAS-eGFP transgene instead). Our core microarray analysis has involved comparison of the transcriptional profile of experimental wings carrying the UAS-UbxIa transgene with that of control wings carrying the UAS-eGFP transgene. Pairwise comparisons have been carried out at three successive developmental stages, in particular at (i) the third instar larval wandering stage, about 4hrs before puparium formation at 29˚C, (ii) the prepupal stage, 6hrs after puparium formation (APF) at 29˚C, and (iii) the early pupal stage, 16hrs APF at 29˚C. Moreover, pairwise comparisons have been carried out with samples developed exclusively at 19˚C (UbxIa or eGFP expression OFF), as well as with samples collected at 16hrs after the temperature shift from 19 to 29˚C (UbxIa or eGFP expression ON). This has allowed us to distinguish the Ubx-dependent effects from the intrinsic expression differences between the fly lines used, and from the temperature-induced responses. We have carried out 4 biological replicates for each condition making a total of 48 hybridizations to Affymetrix Drosophila Genome 2.0 arrays.