Evo-devo Study On Drosophila Scute And Its Homologues In Human,Mouse And Housefly

Bristles on Diptera body are part of peripheral nervous system which are efficient phenotypical marker during evo-devo study.The mechanism of Diptera bristle development is well investigated,and Achaete-scute complex plays a dominant role during bristle development by specific spatio-temporal expression in embryo.However,unlike function of achaete-scute complex,functional evolution of these genes in Diptera and mammal is bearly known.In this study,we chose Drosophila as a model to investigate functional evolution of achaete-scute complex homologues in mammal by overexpression,luciferase reporter assay.On the other hand,we took a look into the evolution of post-transcriptional modification of Diptera achaete-scute complex.We indentified phosphorylation sites in Dipteara scute gene by bioinformatics and mass spectrometry,and investigated their function by overexpression and CRISPR-Cas9 system.The main results are indicates as follows: From the phylogenetic tree of 37 mammals,we recognized that all the mammalian ASH1 genes have experienced a lower rate of divergence when comparing between species,whilst ASH2-5 are each indicative of having experienced greater divergence.Furthermore,we found mammalian ASH1 and ASH2 share sequence identity and are derived from a relatively recent duplication,whilst ASH3 and ASH5 are derived from another.(1)Overexpression of mammalian ASH1 in Drosophila indicated that function of mammalian ASH1 is conserved for the regulation of bristle placement.(2)Luciferase reporter assay was used for mammalian ASH1 enhancer identifying.The result demonstrated that cis-regulation of ASH1 through the presence of GATA binding sites may have been conserved during evolution.(3)Mouse ASH4 has lost proneural function due to lack of a complete C-terminal domain.In contract,human ASH4 inhibits Drosophila bristle development by inhibiting neuron precursor cell determination.(4)We identified a series of serine phosphorylation sites in downstream of bHLH domain of Diptera scute by bioinformatics and mass spectrometry.The number of phosphorylation sites was positively correlated with the number of birstles in Diptera notum.(5)Cdc2-induced phosphorylation sites could regulate Diptera bristle development by dose effect.PKC-induced phosphorylation sites are not involved in bristle development.(6)We constructed a chimeric form of Drosophila scute harbouring phosphorylation sites of Musca domestica by CRISPR-Cas9 system.We observed a housefly-like bristle pattern in gene editing Drosophila,implying post-transcriptional modification could involve in animal phenotype evolution.