@article {64847, title = {Attachment of the blastoderm to the vitelline envelope affects gastrulation of insects.}, journal = {Nature}, year = {2019}, month = {2019 Mar 27}, abstract = {

During gastrulation, physical forces reshape the simple embryonic tissue to form the complex body plans of multicellular organisms. These forces often cause large-scale asymmetric movements of the embryonic tissue. In many embryos, the gastrulating tissue is surrounded by a rigid protective shell. Although it is well-recognized that gastrulation movements depend on forces that are generated by tissue-intrinsic contractility,\ it is not known whether interactions between the tissue and the protective shell provide additional forces that affect gastrulation. Here we show that a particular part of the blastoderm tissue of the red flour beetle (Tribolium castaneum) tightly adheres in a temporally coordinated manner to the vitelline envelope that surrounds the embryo. This attachment generates an additional force that counteracts tissue-intrinsic contractile forces to create asymmetric tissue movements. This localized attachment depends on an αPS2 integrin (inflated), and the knockdown of this integrin leads to a gastrulation phenotype that is consistent with complete loss of attachment. Furthermore, analysis of another integrin (the αPS3 integrin, scab) in the fruit fly (Drosophila melanogaster) suggests that gastrulation in this organism also relies on adhesion between the blastoderm and the vitelline envelope. Our findings reveal a conserved mechanism through which the spatiotemporal pattern of tissue adhesion to the vitelline envelope provides controllable, counteracting forces that shape gastrulation movements in insects.

}, doi = {10.1038/s41586-019-1044-3}, author = {Muenster, Stefan and Jain, Akanksha and Mietke, Alexander and Pavlopoulos, Anastasios and Grill, Stephan W and Tomancak, Pavel} } @article {65111, title = {Regionalized tissue fluidization by an actomyosin cable is required for epithelial gap closure during insect gastrulation.}, journal = {Nature Communications}, volume = {11}, year = {2019}, month = {2020 Aug 22}, pages = {5604}, abstract = {

Many animal embryos face early on in development the problem of having to pull and close an epithelial sheet around the spherical yolk-sac. During this gastrulation process, known as epiboly, the spherical geometry of the egg dictates that the epithelial sheet first expands and subsequently compacts to close around the sphere. While it is well recognized that contractile actomyosin cables can drive epiboly movements, it is unclear how pulling on the leading edge can lead to simultaneous tissue expansion and compaction. Moreover, the epithelial sheet spreading over the sphere is mechanically stressed and this stress needs to be dissipated for seamless closure. While oriented cell division is known to dissipate tissue stresses during epiboly, it is unclear how this can be achieved without cell division. Here we show that during extraembryonic tissue (serosa) epiboly in the red flour beetle Tribolium castaneum, the non-proliferative serosa becomes regionalized into two distinct territories: a dorsal region under higher tension away from the leading edge with larger, isodiametric and non-rearranging cells, and a more fluid ventral region under lower tension surrounding the leading edge with smaller, anisotropic cells undergoing cell intercalation. Our results suggest that fluidization of the leading edge is effected by a heterogeneous actomyosin cable that drives sequential eviction and intercalation of individual cells away from the serosa margin. Since this developmental solution utilized during epiboly resembles the mechanism of wound healing in other systems, we propose actomyosin cable-driven local tissue fluidization as a conserved morphogenetic module for closure of epithelial gaps.

}, doi = {https://doi.org/10.1101/744193}, author = {Jain, Akanksha and Ulman, Vladimir and Mukherjee, Argo and Prakash, Mangal and Pimpale, Lokesh and Munster, Stefan and Panfilio, Kristen A. and Jug, Florian and Grill, Stephan WA. and Tomancak, Pavel and Pavlopoulos, Anastasios} } @article {49451, title = {Integrin-mediated attachment of the blastoderm to the vitelline envelope impacts gastrulation of insects.}, journal = {bioRxiv}, year = {2018}, month = {2018 Oct 2}, abstract = {

During gastrulation, physical forces reshape the simple embryonic tissue to form a complex body plan of multicellular organisms. These forces often cause large-scale asymmetric movements of the embryonic tissue. In many embryos, the tissue undergoing gastrulation movements is surrounded by a rigid protective shell. While it is well recognized that gastrulation movements depend on forces generated by tissue-intrinsic contractility, it is not known if interactions between the tissue and the protective shell provide additional forces that impact gastrulation. Here we show that a particular part of the blastoderm tissue of the red flour beetle Tribolium castaneum tightly adheres in a temporally coordinated manner to the vitelline envelope surrounding the embryo. This attachment generates an additional force that counteracts the tissue-intrinsic contractile forces to create asymmetric tissue movements. Furthermore, this localized attachment is mediated by a specific integrin, and its knock-down leads to a gastrulation phenotype consistent with complete loss of attachment. Moreover, analysis of another integrin in the fruit fly Drosophila melanogaster suggests that gastrulation in this organism also relies on adhesion between the blastoderm and the vitelline. Together, our findings reveal a conserved mechanism whereby the spatiotemporal pattern of tissue adhesion to the vitelline envelope provides controllable counter-forces that shape gastrulation movements in insects.

}, doi = {10.1101/421701}, author = {Muenster, Stefan and Jain, Akanksha and Mietke, Alexander and Pavlopoulos, Anastasios and Grill, Stephan W and Tomancak, Pavel} }