Gene Activity and Cell Mechanics during Drosophila Embryonic Development

During development, cells in an embryo face two major tasks. First they must express distinct combinations of genes appropriate for specific cell fates such as muscle and skin. Once such patterns of gene expression are established, cells must change their shape and position to match those cell fates. These morphological transformations are remarkable for their speed and precision, but also for their incredible beauty. The associated cell shape changes depend on local patterns of gene activity, but how such patterns are converted into the physical properties controlling shape and motility is a major unanswered question in biology. We have approached these problems in Drosophila, where large scale mutagenesis screen have provided a detailed description of the gene activities that pattern cells in the embryo. Our initial analyses focused on the internalization of mesoderm cells during gastrulation and their subsequent epithelial to mesenchymal transition. Our genetic analyses are coupled with quantitative imaging in living embryos and experimental manipulations designed to measure physical parameters such as cytoplasmic viscosity and elastic lifetimes of the cell cortex. In one approach, we use a computational vertex model where passive volume maintenance in cells bounded by an elastic cellular membrane can account for invagination of the furrow. The second approach eliminates the role of elastic cell membranes and relies on Stokes equation to explain the invagination in terms of global flows in viscous cytoplasmic medium. A surprising feature of all morphological changes in Drosophila is that although they are driven by gene activities in individual cells, they can often be understood as global changes in the distribution of physical forces within the entire tissue. These finds open up a new perspective on the relationship between cells and organismal morphology. Support or Funding Information Howard Hughes Medical Institute This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .