Cyclin G: looking for the causes of developmental noise

International audienceDrosophila melanogaster Cyclin G (dCycG) controls transcription and regulates the cell cycle. We previously determined that dCycG shares many transcriptional targets with the Polycomb PRC1 and PR-DUB complexes1. Overexpression of a potentially more stable form of dCycG down-regulates genes involved in mitochondrial activity. Interestingly, it also induces a high developmental noise, as estimated by an increase of wing fluctuating asymmetry (FA) in adults2. Overexpression of dCycG in background mutants for the Polycomb complexes PRC1 or PR-DUB leads to a previously unseen FA1. We show here that dCycG directly interacts with dRing, the ubiquitine-ligase of PRC1 and Calypso, the deubiquitinase of PR-DUB. Our resullts suggest that dCycG undergoes a ubiquitination/deubiquitination cycle driven by these complexes and bookmarks its transcriptional targets during mitosis. We have produced a dCycG mutant by CRISPR/Cas9. This mutant displays a high FA. Although its amount of mitochondrial DNA does not vary, wing imaginal disc respiration unexpectedly increases. The next step will be to check the amount of Reactive Oxygen Species in these tissues and address whether an increase in ROS is causal to developmental noise

Altering the Temporal Regulation of One Transcription Factor Drives Evolutionary Trade-Offs between Head Sensory Organs

International audienceSize trade-offs of visual versus olfactory organs is a pervasive feature of animal evolution. This could result from genetic or functional constraints. We demonstrate that head sensory organ size trade-offs in Drosophila are genetically encoded and arise through differential subdivision of the head primordium into visual versus non-visual fields. We discover that changes in the temporal regulation of the highly conserved eyeless/Pax6 gene expression during development is a conserved mechanism for sensory trade-offs within and between Drosophila species. We identify a natural single nucleotide polymorphism in the cis-regulatory region of eyeless in a binding site of its repressor Cut that is sufficient to alter its temporal regulation and eye size. Because eyeless/Pax6 is a conserved regulator of head sensory placode subdivision, we propose that its temporal regulation is key to define the relative size of head sensory organs

Coplas d'os Mayos 1955 : segunda parte

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