Identifying Genetic Players in Cell Sheet Morphogenesis Using a Drosophila Deficiency Screen for Genes on Chromosome 2R involved in dorsal closure

Cell sheet morphogenesis characterizes key developmental transitions throughout phylogeny. As such, it plays a crucial role in developmental milestones in vertebrate morphogenesis including gastrulation, neural tube formation, and palate formation. It also plays important roles in wound healing. Dorsal closure, a process during Drosophila embryogenesis, has emerged as a model for cell sheet morphogenesis due to the ability to image embryos in-vivo the genetic tractability of Drosophila. While 140 genes are currently published to affect dorsal closure, new genes are identified each year. In addition our understanding of dorsal closure is far from complete with many questions remaining regarding the molecular mechanisms involved in this complex process. To identify a more complete list of genes involved in dorsal closure, we used a set of large deletions (deficiencies), which collectively remove 98.5% of the genes on the right arm of the 2nd chromosome. Through two crosses, we unambiguously identified homozygous deficiencies and imaged them for the duration of dorsal closure. Images were then analyzed for defects in the cell shapes and morphogenesis. 48 deficiencies were identified to have notable defects on dorsal closure. We anticipate these deficiencies will lead to the identification of at least 31 novel dorsal closure genes. We expect the large number of novel dorsal closure will identify links to pathways already known to coordinate various aspects of closure in addition to new processes and pathways that are currently unidentified as involved in closure.