Biology subjects

Streichan, S.

Publications and source records attributed to Streichan, S..

3 recordsLinked to original sources

bioRxiv2020

Tissue topography steers migrating Drosophila border cells

Moving cells can sense and respond to physical features of the microenvironment, however in vivo the significance of tissue topography is mostly unknown. Here we use the Drosophila border cells, an established model for in vivo cell migration, to study how chemical and physical information influence migration path selection. Live imaging, genetics, modeling, and simulations show that, although chemical cues were thought to be sufficient, microtopography is also important. Chemoattractants promote predominantly posterior movement, whereas tissue architecture presents orthogonal information, a path of least resistance concentrated near the center of the egg chamber. E-cadherin supplies a permissive haptotactic cue. Our results provide insight into how cells integrate and prioritize topographical, adhesive, and chemoattractant cues to choose one path amongst many.

developmental biology↗

bioRxiv2019

Dynamic Morphoskeletons in Development

Morphogenetic flows in developmental biology are characterized by the coordinated motion of thousands of cells that organize into tissues, naturally raising the question of how this collective organization arises. Using only the Lagrangian kinematics of tissue deformation, which naturally integrates local and global mechanisms along cell paths, we can identifying the Dynamic Morphoskeletons (DM) behind morphogenesis, i.e., the evolving centerpieces of multi-cellular trajectory patterns. The DM is model and parameter-free, frame-invariant, robust to measurement errors, and can be computed from unfiltered cell velocity data. It reveals the spatial attractors and repellers of the embryo, objects that cannot be identified by simple trajectory inspection or Eulerian methods that are local and typically frame-dependent. Computing the DM underlying primitive streak formation in chicken embryo and early gastrulation in the whole fly embryo, we find that the DM captures the early footprint of known morphogenetic features, and reveals new ones, providing a geometric framework to analyze tissue organization.

developmental biology↗

bioRxiv2018

EGFR SIGNALING COORDINATES PATTERNING WITH CELL SURVIVAL DURING DROSOPHILA EPIDERMAL DEVELOPMENT

Extensive apoptosis is often seen in patterning mutants, suggesting that tissues can detect and eliminate potentially harmful mis-specified cells. Here we show that the pattern of apoptosis in the embryonic epidermis of Drosophila is not a response to fate mis-specification but can instead be explained by the limiting availability of pro-survival signalling molecules released from locations determined by patterning information. In wild type embryos, the segmentation cascade elicits the segmental production of several EGFR ligands, including the TGF-alpha, Spitz and the Neuregulin, Vein. This leads to an undulating pattern of signalling activity, which prevents expression of the pro-apoptotic gene hid throughout the epidermis. In segmentation mutants, where specific peaks of EGFR ligands fail to form, gaps in signalling activity appear, leading to coincident hid upregulation and subsequent cell death. These data provide a mechanistic understanding of how cell survival, and thus appropriate tissue size, is made contingent on correct patterning.

developmental biology↗