Study On The Mechanism Of T-box Transcription Factor Midline In Regulating Tracheal Development In Drosophila

In many animals and humans,defects in the development of the tracheal system(respiratory system)can lead to fatal disease.Because of the similarities in developmental mechanism between the vertebrate vasculature and the Drosophila tracheal system,the research on tracheal development of Drosophila can be used as a reference for the pathogenesis of vertebrate vascular system diseases.Drosophila is a classical model organism,which plays an important role in the history of developmental genetics and can be used as an ideal biological model for studying the development of tracheal system.Drosophila trachea originates from 20 groups of precursor cells in the placodes,a series of complex processes have been occurred,such as cell division,differentiation,migration,changing shape,branching fusion and so on,the tracheal precursor cells finally developed into the tracheal system throughout the body.Drosophila tracheal development process is regulated by multiple factors,a variety of biological molecules and signaling pathway coordinate with others constituting a regulatory network to regulate the formation of trachea.Transcription factors of the T-box family are required both for early cell-fate decisions and for differentiation and organogenesis,and also tend to be expressed in specific organs or cell types,especially during development,and they are generally required for the development of those tissues.Midline(Mid)acts as a T-box transcriptional regulator in the early stages of Drosophila embryonic development and plays a major role in the development of various tissues and organs,such as muscles,gonads,eyes,legs,wings,heart and centre nervous system and so on.However,the function of Mid in the development of tracheal system was unknown.The study is aimed to explore the important function of mid in tracheal development.In this research,we explore the role of T-box transcriptional regulator Mid in Drosophila tracheal development by using lacZ reporter gene,in situ hybridization and immunofluorescence staining and some biotechnologies.By the expression patterns and functions analysis of Mid,we found that transcriptional regulator Mid is widely expressed in the trachea of Drosophila and plays an important role in the development of Drosophila trachea.The tracheal formation is out of order in a screen for mutants in mid,and the mutant phenotypes recover apparently by the rescue experiments.Slit has been described previously to act in Drosophila trachea developing,in this study we explore the isoform specific requirements of mid and slit and define the regulatory relationship between those two genes for the morphogenesis of trachea.Here,for the first time,our results suggest that Mid plays an important role as the direct trigger of the expression of slit to regulate tracheal development.This study can lay a theoretical foundation for the study of tracheal system(respiratory system)development in other animals and human body by exploring the molecular regulation mechanism of tracheal development of Drosophila melanogaster.At the same time,it can provide theoretical basis for studying the tracheal system(respiratory system).This study is the first insight to explore the effect of mid on tracheal development of Drosophila and we find the new function of mid in the Drosophila development,and this is of great significance.