588B Poster - 08. Patterning, morphogenesis and organogenesis
Friday April 08, 2:00 PM - 4:00 PM

Authors:
Daniel S. Alber ^1,2; Maria Avdeeva ³; Liu Yang ²; Shannon E. Keenan ^1,2; Eric F. Wieschaus ^2,4; Stanislav Y. Shvartsman ^2,3,4

Affiliations:
1) Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA; 2) The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA; 3) Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, NY, USA; 4) Department of Molecular Biology, Princeton University, Princeton, NJ, USA

Keywords:
k. gut; f. pattern formation

The organogenesis of the Drosophila posterior midgut (PMG) offers a genetic and morphological model system to study the fundamentals of tissue patterning and morphogenesis in a highly conserved and broadly relevant tissue. ERK-mediated signaling acts primarily through two key regulators, Tailless (Tll) and Huckebein (Hkb), to pattern the posterior region of the embryo prior to gastrulation. We use immunostaining to follow the expression patterns of 16 potential targets of these regulators, including overlapping domains of Brachyenteron (Byn), a highly conserved T-box transcription factor, and Wingless (Wg). We elaborate on the conventional model of specification to include effects of Tll and Hkb mutants on the expression patterns of these 16 targets and establish a hierarchy of expression. We reveal the dynamics of this signaling network via transcriptional live reporters created via CRISPR and live imaging using light-sheet microscopy. Using a novel computational method to fuse imaging datasets of the individual components of posterior patterning into a common multivariable trajectory, we show a low intrinsic dimensionality of posterior patterning. Additionally, we classify the morphological changes as the primordial mid- and hind-gut invaginates and involutes into distinct geometric transformation events and connect it to spatiotemporal expression patterns of key PMG-specifying markers. We focus on the morphological effects of Byn, which plays a key role in the cell shape changes and rearrangements in zebrafish and frog embryogenesis, by studying PMG morphogenesis in various mutant backgrounds. Our analysis supplements the existing understanding of epistatic relationships within the PMG-specifying gene regulatory network and describes PMG morphogenesis in the context of gene expression patterns.