[{"publication_identifier":{"issn":["2663 - 337X"]},"month":"05","project":[{"_id":"260F1432-B435-11E9-9278-68D0E5697425","grant_number":"742573","name":"Interaction and feedback between cell mechanics and fate specification in vertebrate gastrulation","call_identifier":"H2020"},{"name":"Mesendoderm specification in zebrafish: The role of extraembryonic tissues","_id":"26B1E39C-B435-11E9-9278-68D0E5697425","grant_number":"25239"}],"doi":"10.15479/at:ista:12891","language":[{"iso":"eng"}],"supervisor":[{"full_name":"Heisenberg, Carl-Philipp J","id":"39427864-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0912-4566","first_name":"Carl-Philipp J","last_name":"Heisenberg"}],"degree_awarded":"PhD","acknowledged_ssus":[{"_id":"Bio"},{"_id":"LifeSc"}],"ec_funded":1,"file_date_updated":"2023-05-05T13:04:15Z","year":"2023","department":[{"_id":"GradSch"},{"_id":"CaHe"}],"publisher":"Institute of Science and Technology Austria","publication_status":"published","related_material":{"record":[{"id":"8966","relation":"part_of_dissertation","status":"public"},{"id":"7888","relation":"part_of_dissertation","status":"public"}]},"author":[{"first_name":"Alexandra","last_name":"Schauer","id":"30A536BA-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-7659-9142","full_name":"Schauer, Alexandra"}],"date_updated":"2023-08-21T06:25:48Z","date_created":"2023-05-05T08:48:20Z","article_processing_charge":"No","has_accepted_license":"1","day":"05","citation":{"apa":"Schauer, A. (2023). Mesendoderm formation in zebrafish gastrulation: The role of extraembryonic tissues. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:12891","ieee":"A. Schauer, “Mesendoderm formation in zebrafish gastrulation: The role of extraembryonic tissues,” Institute of Science and Technology Austria, 2023.","ista":"Schauer A. 2023. Mesendoderm formation in zebrafish gastrulation: The role of extraembryonic tissues. Institute of Science and Technology Austria.","ama":"Schauer A. Mesendoderm formation in zebrafish gastrulation: The role of extraembryonic tissues. 2023. doi:10.15479/at:ista:12891","chicago":"Schauer, Alexandra. “Mesendoderm Formation in Zebrafish Gastrulation: The Role of Extraembryonic Tissues.” Institute of Science and Technology Austria, 2023. https://doi.org/10.15479/at:ista:12891.","short":"A. Schauer, Mesendoderm Formation in Zebrafish Gastrulation: The Role of Extraembryonic Tissues, Institute of Science and Technology Austria, 2023.","mla":"Schauer, Alexandra. Mesendoderm Formation in Zebrafish Gastrulation: The Role of Extraembryonic Tissues. Institute of Science and Technology Austria, 2023, doi:10.15479/at:ista:12891."},"page":"190","date_published":"2023-05-05T00:00:00Z","type":"dissertation","alternative_title":["ISTA Thesis"],"abstract":[{"lang":"eng","text":"The tight spatiotemporal coordination of signaling activity determining embryo\r\npatterning and the physical processes driving embryo morphogenesis renders\r\nembryonic development robust, such that key developmental processes can unfold\r\nrelatively normally even outside of the full embryonic context. For instance, embryonic\r\nstem cell cultures can recapitulate the hallmarks of gastrulation, i.e. break symmetry\r\nleading to germ layer formation and morphogenesis, in a very reduced environment.\r\nThis leads to questions on specific contributions of embryo-specific features, such as\r\nthe presence of extraembryonic tissues, which are inherently involved in gastrulation\r\nin the full embryonic context. To address this, we established zebrafish embryonic\r\nexplants without the extraembryonic yolk cell, an important player as a signaling\r\nsource and for morphogenesis during gastrulation, as a model of ex vivo development.\r\nWe found that dorsal-marginal determinants are required and sufficient in these\r\nexplants to form and pattern all three germ layers. However, formation of tissues,\r\nwhich require the highest Nodal-signaling levels, is variable, demonstrating a\r\ncontribution of extraembryonic tissues for reaching peak Nodal signaling levels.\r\nBlastoderm explants also undergo gastrulation-like axis elongation. We found that this\r\nelongation movement shows hallmarks of oriented mesendoderm cell intercalations\r\ntypically associated with dorsal tissues in the intact embryo. These are disrupted by\r\nuniform upregulation of BMP signaling activity and concomitant explant ventralization,\r\nsuggesting that tight spatial control of BMP signaling is a prerequisite for explant\r\nmorphogenesis. This control is achieved by Nodal signaling, which is critical for\r\neffectively downregulating BMP signaling in the mesendoderm, highlighting that Nodal\r\nsignaling is not only directly required for mesendoderm cell fate specification and\r\nmorphogenesis, but also by maintaining low levels of BMP signaling at the dorsal side.\r\nCollectively, we provide insights into the capacity and organization of signaling and\r\nmorphogenetic domains to recapitulate features of zebrafish gastrulation outside of\r\nthe full embryonic context."}],"user_id":"8b945eb4-e2f2-11eb-945a-df72226e66a9","_id":"12891","title":"Mesendoderm formation in zebrafish gastrulation: The role of extraembryonic tissues","status":"public","ddc":["570"],"oa_version":"Published Version","file":[{"relation":"main_file","embargo":"2024-05-05","file_id":"12907","checksum":"59b0303dc483f40a96a610a90aab7ee9","date_updated":"2023-05-05T13:01:14Z","date_created":"2023-05-05T13:01:14Z","access_level":"closed","embargo_to":"open_access","file_name":"Thesis_Schauer_final.pdf","content_type":"application/pdf","file_size":31434230,"creator":"aschauer"},{"date_updated":"2023-05-05T13:04:15Z","date_created":"2023-05-05T13:04:15Z","checksum":"25f54e12479b6adaabd129a20568e6c1","file_id":"12908","relation":"source_file","creator":"aschauer","content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","file_size":43809109,"file_name":"Thesis_Schauer_final.docx","access_level":"closed"}]},{"license":"https://creativecommons.org/licenses/by/4.0/","file_date_updated":"2023-01-25T10:52:46Z","ec_funded":1,"date_created":"2023-01-25T10:43:24Z","date_updated":"2023-08-08T13:14:10Z","author":[{"full_name":"Arslan, Feyza N","first_name":"Feyza N","last_name":"Arslan","id":"49DA7910-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-5809-9566"}],"related_material":{"record":[{"id":"9350","status":"public","relation":"part_of_dissertation"}]},"publication_status":"published","publisher":"Institute of Science and Technology Austria","department":[{"_id":"GradSch"},{"_id":"CaHe"}],"year":"2022","month":"09","publication_identifier":{"isbn":[" 978-3-99078-025-1 "],"issn":["2663-337X"]},"supervisor":[{"full_name":"Heisenberg, Carl-Philipp J","orcid":"0000-0002-0912-4566","id":"39427864-F248-11E8-B48F-1D18A9856A87","last_name":"Heisenberg","first_name":"Carl-Philipp J"}],"acknowledged_ssus":[{"_id":"LifeSc"},{"_id":"Bio"},{"_id":"NanoFab"}],"degree_awarded":"PhD","language":[{"iso":"eng"}],"doi":"10.15479/at:ista:12153","project":[{"_id":"260F1432-B435-11E9-9278-68D0E5697425","grant_number":"742573","call_identifier":"H2020","name":"Interaction and feedback between cell mechanics and fate specification in vertebrate gastrulation"}],"tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","short":"CC BY (4.0)","image":"/images/cc_by.png"},"oa":1,"abstract":[{"lang":"eng","text":"Metazoan development relies on the formation and remodeling of cell-cell contacts. The \r\nbinding of adhesion receptors and remodeling of the actomyosin cell cortex at cell-cell \r\ninteraction sites have been implicated in cell-cell contact formation. Yet, how these two \r\nprocesses functionally interact to drive cell-cell contact expansion and strengthening \r\nremains unclear. Here, we study how primary germ layer progenitor cells from zebrafish \r\nbind to supported lipid bilayers (SLB) functionalized with E-cadherin ectodomains as an \r\nassay system for monitoring cell-cell contact formation at high spatiotemporal resolution. \r\nWe show that cell-cell contact formation represents a two-tiered process: E-cadherin\u0002mediated downregulation of the small GTPase RhoA at the forming contact leads to both \r\ndepletion of Myosin-2 and decrease of F-actin. This is followed by centrifugal actin \r\nnetwork flows at the contact triggered by a sharp gradient of Myosin-2 at the rim of the \r\ncontact zone, with Myosin-2 displaying higher cortical localization outside than inside of \r\nthe contact. These centrifugal cortical actin flows, in turn, not only further dilute the actin \r\nnetwork at the contact disc, but also lead to an accumulation of both F-actin and E\u0002cadherin at the contact rim. Eventually, this combination of actomyosin downregulation \r\nand flows at the contact contribute to the characteristic molecular organization implicated \r\nin contact formation and maintenance: depletion of cortical actomyosin at the contact disc, \r\ndriving contact expansion by lowering interfacial tension at the contact, and accumulation \r\nof both E-cadherin and F-actin at the contact rim, mechanically linking the contractile \r\ncortices of the adhering cells. Thus, using a biomimetic assay, we exemplify how \r\nadhesion signaling and cell mechanics function together to modulate the spatial \r\norganization of cell-cell contacts."}],"alternative_title":["ISTA Thesis"],"type":"dissertation","file":[{"file_size":14581024,"content_type":"application/pdf","creator":"cchlebak","access_level":"open_access","file_name":"THESIS_FINAL_FArslan_pdfa.pdf","checksum":"e54a3e69b83ebf166544164afd25608e","success":1,"date_updated":"2023-01-25T10:52:46Z","date_created":"2023-01-25T10:52:46Z","relation":"main_file","file_id":"12369"}],"oa_version":"Published Version","title":"Remodeling of E-cadherin-mediated contacts via cortical flows","ddc":["570"],"status":"public","_id":"12368","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","day":"29","article_processing_charge":"No","has_accepted_license":"1","date_published":"2022-09-29T00:00:00Z","page":"113","citation":{"ama":"Arslan FN. Remodeling of E-cadherin-mediated contacts via cortical flows. 2022. doi:10.15479/at:ista:12153","ista":"Arslan FN. 2022. Remodeling of E-cadherin-mediated contacts via cortical flows. Institute of Science and Technology Austria.","ieee":"F. N. Arslan, “Remodeling of E-cadherin-mediated contacts via cortical flows,” Institute of Science and Technology Austria, 2022.","apa":"Arslan, F. N. (2022). Remodeling of E-cadherin-mediated contacts via cortical flows. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:12153","mla":"Arslan, Feyza N. Remodeling of E-Cadherin-Mediated Contacts via Cortical Flows. Institute of Science and Technology Austria, 2022, doi:10.15479/at:ista:12153.","short":"F.N. Arslan, Remodeling of E-Cadherin-Mediated Contacts via Cortical Flows, Institute of Science and Technology Austria, 2022.","chicago":"Arslan, Feyza N. “Remodeling of E-Cadherin-Mediated Contacts via Cortical Flows.” Institute of Science and Technology Austria, 2022. https://doi.org/10.15479/at:ista:12153."}},{"has_accepted_license":"1","article_processing_charge":"No","date_published":"2021-07-01T00:00:00Z","citation":{"chicago":"Caballero Mancebo, Silvia. “Fertilization-Induced Deformations Are Controlled by the Actin Cortex and a Mitochondria-Rich Subcortical Layer in Ascidian Oocytes.” Institute of Science and Technology Austria, 2021. https://doi.org/10.15479/at:ista:9623.","short":"S. Caballero Mancebo, Fertilization-Induced Deformations Are Controlled by the Actin Cortex and a Mitochondria-Rich Subcortical Layer in Ascidian Oocytes, Institute of Science and Technology Austria, 2021.","mla":"Caballero Mancebo, Silvia. Fertilization-Induced Deformations Are Controlled by the Actin Cortex and a Mitochondria-Rich Subcortical Layer in Ascidian Oocytes. Institute of Science and Technology Austria, 2021, doi:10.15479/at:ista:9623.","apa":"Caballero Mancebo, S. (2021). Fertilization-induced deformations are controlled by the actin cortex and a mitochondria-rich subcortical layer in ascidian oocytes. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:9623","ieee":"S. Caballero Mancebo, “Fertilization-induced deformations are controlled by the actin cortex and a mitochondria-rich subcortical layer in ascidian oocytes,” Institute of Science and Technology Austria, 2021.","ista":"Caballero Mancebo S. 2021. Fertilization-induced deformations are controlled by the actin cortex and a mitochondria-rich subcortical layer in ascidian oocytes. Institute of Science and Technology Austria.","ama":"Caballero Mancebo S. Fertilization-induced deformations are controlled by the actin cortex and a mitochondria-rich subcortical layer in ascidian oocytes. 2021. doi:10.15479/at:ista:9623"},"page":"111","abstract":[{"lang":"eng","text":"Cytoplasmic reorganizations are essential for morphogenesis. In large cells like oocytes, these reorganizations become crucial in patterning the oocyte for later stages of embryonic development. Ascidians oocytes reorganize their cytoplasm (ooplasm) in a spectacular manner. Ooplasmic reorganization is initiated at fertilization with the contraction of the actomyosin cortex along the animal-vegetal axis of the oocyte, driving the accumulation of cortical endoplasmic reticulum (cER), maternal mRNAs associated to it and a mitochondria-rich subcortical layer – the myoplasm – in a region of the vegetal pole termed contraction pole (CP). Here we have used the species Phallusia mammillata to investigate the changes in cell shape that accompany these reorganizations and the mechanochemical mechanisms underlining CP formation.\r\nWe report that the length of the animal-vegetal (AV) axis oscillates upon fertilization: it first undergoes a cycle of fast elongation-lengthening followed by a slow expansion of mainly the vegetal pole (VP) of the cell. We show that the fast oscillation corresponds to a dynamic polarization of the actin cortex as a result of a fertilization-induced increase in cortical tension in the oocyte that triggers a rupture of the cortex at the animal pole and the establishment of vegetal-directed cortical flows. These flows are responsible for the vegetal accumulation of actin causing the VP to flatten. \r\nWe find that the slow expansion of the VP, leading to CP formation, correlates with a relaxation of the vegetal cortex and that the myoplasm plays a role in the expansion. We show that the myoplasm is a solid-like layer that buckles under compression forces arising from the contracting actin cortex at the VP. Straightening of the myoplasm when actin flows stops, facilitates the expansion of the VP and the CP. Altogether, our results present a previously unrecognized role for the myoplasm in ascidian ooplasmic segregation. \r\n"}],"type":"dissertation","alternative_title":["ISTA Thesis"],"file":[{"date_created":"2021-07-01T14:48:54Z","date_updated":"2022-07-02T22:30:06Z","checksum":"e039225a47ef32666d59bf35ddd30ecf","file_id":"9624","relation":"source_file","creator":"scaballe","file_size":131946790,"content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","file_name":"PhDThesis_SCM.docx","embargo_to":"open_access","access_level":"closed"},{"file_id":"9625","embargo":"2022-07-01","relation":"main_file","date_created":"2021-07-01T14:46:25Z","date_updated":"2022-07-02T22:30:06Z","checksum":"dd4d78962ea94ad95e97ca7d9af08f4b","file_name":"PhDThesis_SCM.pdf","access_level":"open_access","creator":"scaballe","content_type":"application/pdf","file_size":17094958}],"oa_version":"Published Version","_id":"9623","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","title":"Fertilization-induced deformations are controlled by the actin cortex and a mitochondria-rich subcortical layer in ascidian oocytes","status":"public","ddc":["570"],"month":"07","publication_identifier":{"issn":["2663-337X"],"isbn":["978-3-99078-012-1"]},"doi":"10.15479/at:ista:9623","acknowledged_ssus":[{"_id":"Bio"},{"_id":"EM-Fac"},{"_id":"NanoFab"},{"_id":"M-Shop"}],"supervisor":[{"full_name":"Heisenberg, Carl-Philipp J","orcid":"0000-0002-0912-4566","id":"39427864-F248-11E8-B48F-1D18A9856A87","last_name":"Heisenberg","first_name":"Carl-Philipp J"}],"degree_awarded":"PhD","language":[{"iso":"eng"}],"oa":1,"tmp":{"name":"Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)","legal_code_url":"https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode","short":"CC BY-NC-ND (4.0)","image":"/images/cc_by_nc_nd.png"},"file_date_updated":"2022-07-02T22:30:06Z","license":"https://creativecommons.org/licenses/by-nc-nd/4.0/","author":[{"full_name":"Caballero Mancebo, Silvia","first_name":"Silvia","last_name":"Caballero Mancebo","id":"2F1E1758-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-5223-3346"}],"related_material":{"record":[{"status":"public","relation":"part_of_dissertation","id":"9750"},{"status":"public","relation":"part_of_dissertation","id":"9006"}]},"date_created":"2021-07-01T14:50:17Z","date_updated":"2023-09-07T13:33:27Z","year":"2021","publication_status":"published","department":[{"_id":"GradSch"},{"_id":"CaHe"}],"publisher":"Institute of Science and Technology Austria"},{"file_date_updated":"2022-05-21T22:30:04Z","author":[{"full_name":"Huljev, Karla","id":"44C6F6A6-F248-11E8-B48F-1D18A9856A87","last_name":"Huljev","first_name":"Karla"}],"date_created":"2021-05-17T12:31:30Z","date_updated":"2023-09-07T13:32:32Z","year":"2021","department":[{"_id":"CaHe"},{"_id":"GradSch"}],"publisher":"Institute of Science and Technology Austria","publication_status":"published","publication_identifier":{"issn":["2663-337X"]},"month":"05","doi":"10.15479/at:ista:9397","language":[{"iso":"eng"}],"supervisor":[{"last_name":"Heisenberg","first_name":"Carl-Philipp J","orcid":"0000-0002-0912-4566","id":"39427864-F248-11E8-B48F-1D18A9856A87","full_name":"Heisenberg, Carl-Philipp J"}],"degree_awarded":"PhD","oa":1,"abstract":[{"text":"Accumulation of interstitial fluid (IF) between embryonic cells is a common phenomenon in vertebrate embryogenesis. Unlike other model systems, where these accumulations coalesce into a large central cavity – the blastocoel, in zebrafish, IF is more uniformly distributed between the deep cells (DC) before the onset of gastrulation. This is likely due to the presence of a large extraembryonic structure – the yolk cell (YC) at the position where the blastocoel typically forms in other model organisms. IF has long been speculated to play a role in tissue morphogenesis during embryogenesis, but direct evidence supporting such function is still sparse. Here we show that the relocalization of IF to the interface between the YC and DC/epiblast is critical for axial mesendoderm (ME) cell protrusion formation and migration along this interface, a key process in embryonic axis formation. We further demonstrate that axial ME cell migration and IF relocalization engage in a positive feedback loop, where axial ME migration triggers IF accumulation ahead of the advancing axial ME tissue by mechanically compressing the overlying epiblast cell layer. Upon compression, locally induced flow relocalizes the IF through the porous epiblast tissue resulting in an IF accumulation ahead of the leading axial ME. This IF accumulation, in turn, promotes cell protrusion formation and migration of the leading axial ME cells, thereby facilitating axial ME extension. Our findings reveal a central role of dynamic IF relocalization in orchestrating germ layer morphogenesis during gastrulation.","lang":"eng"}],"type":"dissertation","alternative_title":["ISTA Thesis"],"file":[{"creator":"khuljev","file_size":47799741,"content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","file_name":"KHuljev_Thesis_corrections.docx","embargo_to":"open_access","access_level":"closed","date_updated":"2022-05-21T22:30:04Z","date_created":"2021-05-17T12:29:12Z","checksum":"7f98532f5324a0b2f3fa8de2967baa19","file_id":"9398","relation":"source_file"},{"file_size":16542131,"content_type":"application/pdf","creator":"khuljev","access_level":"open_access","file_name":"new_KHuljev_Thesis_corrections.pdf","checksum":"bf512f8a1e572a543778fc4b227c01ba","date_updated":"2022-05-21T22:30:04Z","date_created":"2021-05-18T14:50:28Z","relation":"main_file","file_id":"9401","embargo":"2022-05-20"}],"oa_version":"Published Version","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","_id":"9397","status":"public","ddc":["571"],"title":"Coordinated spatiotemporal reorganization of interstitial fluid is required for axial mesendoderm migration in zebrafish gastrulation","article_processing_charge":"No","has_accepted_license":"1","day":"18","date_published":"2021-05-18T00:00:00Z","citation":{"mla":"Huljev, Karla. Coordinated Spatiotemporal Reorganization of Interstitial Fluid Is Required for Axial Mesendoderm Migration in Zebrafish Gastrulation. Institute of Science and Technology Austria, 2021, doi:10.15479/at:ista:9397.","short":"K. Huljev, Coordinated Spatiotemporal Reorganization of Interstitial Fluid Is Required for Axial Mesendoderm Migration in Zebrafish Gastrulation, Institute of Science and Technology Austria, 2021.","chicago":"Huljev, Karla. “Coordinated Spatiotemporal Reorganization of Interstitial Fluid Is Required for Axial Mesendoderm Migration in Zebrafish Gastrulation.” Institute of Science and Technology Austria, 2021. https://doi.org/10.15479/at:ista:9397.","ama":"Huljev K. Coordinated spatiotemporal reorganization of interstitial fluid is required for axial mesendoderm migration in zebrafish gastrulation. 2021. doi:10.15479/at:ista:9397","ista":"Huljev K. 2021. Coordinated spatiotemporal reorganization of interstitial fluid is required for axial mesendoderm migration in zebrafish gastrulation. Institute of Science and Technology Austria.","apa":"Huljev, K. (2021). Coordinated spatiotemporal reorganization of interstitial fluid is required for axial mesendoderm migration in zebrafish gastrulation. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:9397","ieee":"K. Huljev, “Coordinated spatiotemporal reorganization of interstitial fluid is required for axial mesendoderm migration in zebrafish gastrulation,” Institute of Science and Technology Austria, 2021."},"page":"101"},{"article_processing_charge":"No","has_accepted_license":"1","day":"09","page":"107","citation":{"ama":"Shamipour S. Bulk actin dynamics drive phase segregation in zebrafish oocytes . 2020. doi:10.15479/AT:ISTA:8350","ieee":"S. Shamipour, “Bulk actin dynamics drive phase segregation in zebrafish oocytes ,” Institute of Science and Technology Austria, 2020.","apa":"Shamipour, S. (2020). Bulk actin dynamics drive phase segregation in zebrafish oocytes . Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:8350","ista":"Shamipour S. 2020. Bulk actin dynamics drive phase segregation in zebrafish oocytes . Institute of Science and Technology Austria.","short":"S. Shamipour, Bulk Actin Dynamics Drive Phase Segregation in Zebrafish Oocytes , Institute of Science and Technology Austria, 2020.","mla":"Shamipour, Shayan. Bulk Actin Dynamics Drive Phase Segregation in Zebrafish Oocytes . Institute of Science and Technology Austria, 2020, doi:10.15479/AT:ISTA:8350.","chicago":"Shamipour, Shayan. “Bulk Actin Dynamics Drive Phase Segregation in Zebrafish Oocytes .” Institute of Science and Technology Austria, 2020. https://doi.org/10.15479/AT:ISTA:8350."},"date_published":"2020-09-09T00:00:00Z","alternative_title":["ISTA Thesis"],"type":"dissertation","abstract":[{"text":"Cytoplasm is a gel-like crowded environment composed of tens of thousands of macromolecules, organelles, cytoskeletal networks and cytosol. The structure of the cytoplasm is thought to be highly organized and heterogeneous due to the crowding of its constituents and their effective compartmentalization. In such an environment, the diffusive dynamics of the molecules is very restricted, an effect that is further amplified by clustering and anchoring of molecules. Despite the jammed nature of the cytoplasm at the microscopic scale, large-scale reorganization of cytoplasm is essential for important cellular functions, such as nuclear positioning and cell division. How such mesoscale reorganization of the cytoplasm is achieved, especially for very large cells such as oocytes or syncytial tissues that can span hundreds of micrometers in size, has only begun to be understood.\r\nIn this thesis, I focus on the recent advances in elucidating the molecular, cellular and biophysical principles underlying cytoplasmic organization across different scales, structures and species. First, I outline which of these principles have been identified by reductionist approaches, such as in vitro reconstitution assays, where boundary conditions and components can be modulated at ease. I then describe how the theoretical and experimental framework established in these reduced systems have been applied to their more complex in vivo counterparts, in particular oocytes and embryonic syncytial structures, and discuss how such complex biological systems can initiate symmetry breaking and establish patterning.\r\nSpecifically, I examine an example of large-scale reorganizations taking place in zebrafish embryos, where extensive cytoplasmic streaming leads to the segregation of cytoplasm from yolk granules along the animal-vegetal axis of the embryo. Using biophysical experimentation and theory, I investigate the forces underlying this process, to show that this process does not rely on cortical actin reorganization, as previously thought, but instead on a cell-cycle-dependent bulk actin polymerization wave traveling from the animal to the vegetal pole of the embryo. This wave functions in segregation by both pulling cytoplasm animally and pushing yolk granules vegetally. Cytoplasm pulling is mediated by bulk actin network flows exerting friction forces on the cytoplasm, while yolk granule pushing is achieved by a mechanism closely resembling actin comet formation on yolk granules. This study defines a novel role of bulk actin polymerization waves in embryo polarization via cytoplasmic segregation. Lastly, I describe the cytoplasmic reorganizations taking place during zebrafish oocyte maturation, where the initial segregation of the cytoplasm and yolk granules occurs. Here, I demonstrate a previously uncharacterized wave of microtubule aster formation, traveling the oocyte along the animal-vegetal axis. Further research is required to determine the role of such microtubule structures in cytoplasmic reorganizations therein.\r\nCollectively, these studies provide further evidence for the coupling between cell cytoskeleton and cell cycle machinery, which can underlie a core self-organizing mechanism for orchestrating large-scale reorganizations in a cell-cycle-tunable manner, where the modulations of the force-generating machinery and cytoplasmic mechanics can be harbored to fulfill cellular functions.","lang":"eng"}],"ddc":["570"],"status":"public","title":"Bulk actin dynamics drive phase segregation in zebrafish oocytes ","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","_id":"8350","file":[{"file_size":65194814,"content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","creator":"sshamip","access_level":"closed","embargo_to":"open_access","file_name":"Shayan-Thesis-Final.docx","checksum":"6e47871c74f85008b9876112eb3fcfa1","date_created":"2020-09-09T11:06:27Z","date_updated":"2021-09-11T22:30:05Z","relation":"source_file","file_id":"8351"},{"relation":"main_file","embargo":"2021-09-10","file_id":"8352","checksum":"1b44c57f04d7e8a6fe41b1c9c55a52a3","date_updated":"2021-09-11T22:30:05Z","date_created":"2020-09-09T11:06:13Z","access_level":"open_access","file_name":"Shayan-Thesis-Final.pdf","content_type":"application/pdf","file_size":23729605,"creator":"sshamip"}],"oa_version":"None","publication_identifier":{"issn":["2663-337X"]},"month":"09","oa":1,"language":[{"iso":"eng"}],"degree_awarded":"PhD","supervisor":[{"last_name":"Heisenberg","first_name":"Carl-Philipp J","orcid":"0000-0002-0912-4566","id":"39427864-F248-11E8-B48F-1D18A9856A87","full_name":"Heisenberg, Carl-Philipp J"},{"last_name":"Hof","first_name":"Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn"}],"acknowledged_ssus":[{"_id":"PreCl"},{"_id":"Bio"},{"_id":"EM-Fac"}],"doi":"10.15479/AT:ISTA:8350","file_date_updated":"2021-09-11T22:30:05Z","department":[{"_id":"BjHo"},{"_id":"CaHe"}],"publisher":"Institute of Science and Technology Austria","publication_status":"published","acknowledgement":"I would have had no fish and hence no results without our wonderful fish facility crew, Verena Mayer, Eva Schlegl, Andreas Mlak and Matthias Nowak. Special thanks to Verena for being always happy to help and dealing with our chaotic schedules in the lab. Danke auch, Verena, für deine Geduld, mit mir auf Deutsch zu sprechen. Das hat mir sehr geholfen.\r\nSpecial thanks to the Bioimaging and EM facilities at IST Austria for supporting us every day. Very special thanks would go to Robert Hauschild for his continuous support on data analysis and also to Jack Merrin for designing and building microfabricated chambers for the project and for the various discussions on making zebrafish extracts.","year":"2020","date_created":"2020-09-09T11:12:10Z","date_updated":"2023-09-27T14:16:45Z","related_material":{"record":[{"id":"661","relation":"part_of_dissertation","status":"public"},{"status":"public","relation":"part_of_dissertation","id":"6508"},{"id":"7001","relation":"part_of_dissertation","status":"public"},{"relation":"part_of_dissertation","status":"public","id":"735"}]},"author":[{"id":"40B34FE2-F248-11E8-B48F-1D18A9856A87","first_name":"Shayan","last_name":"Shamipour","full_name":"Shamipour, Shayan"}]},{"day":"16","has_accepted_license":"1","article_processing_charge":"No","date_published":"2019-12-16T00:00:00Z","page":"107","citation":{"ama":"Schwayer C. Mechanosensation of tight junctions depends on ZO-1 phase separation and flow. 2019. doi:10.15479/AT:ISTA:7186","ieee":"C. Schwayer, “Mechanosensation of tight junctions depends on ZO-1 phase separation and flow,” Institute of Science and Technology Austria, 2019.","apa":"Schwayer, C. (2019). Mechanosensation of tight junctions depends on ZO-1 phase separation and flow. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:7186","ista":"Schwayer C. 2019. Mechanosensation of tight junctions depends on ZO-1 phase separation and flow. Institute of Science and Technology Austria.","short":"C. Schwayer, Mechanosensation of Tight Junctions Depends on ZO-1 Phase Separation and Flow, Institute of Science and Technology Austria, 2019.","mla":"Schwayer, Cornelia. Mechanosensation of Tight Junctions Depends on ZO-1 Phase Separation and Flow. Institute of Science and Technology Austria, 2019, doi:10.15479/AT:ISTA:7186.","chicago":"Schwayer, Cornelia. “Mechanosensation of Tight Junctions Depends on ZO-1 Phase Separation and Flow.” Institute of Science and Technology Austria, 2019. https://doi.org/10.15479/AT:ISTA:7186."},"abstract":[{"lang":"eng","text":"Tissue morphogenesis in developmental or physiological processes is regulated by molecular\r\nand mechanical signals. While the molecular signaling cascades are increasingly well\r\ndescribed, the mechanical signals affecting tissue shape changes have only recently been\r\nstudied in greater detail. To gain more insight into the mechanochemical and biophysical\r\nbasis of an epithelial spreading process (epiboly) in early zebrafish development, we studied\r\ncell-cell junction formation and actomyosin network dynamics at the boundary between\r\nsurface layer epithelial cells (EVL) and the yolk syncytial layer (YSL). During zebrafish epiboly,\r\nthe cell mass sitting on top of the yolk cell spreads to engulf the yolk cell by the end of\r\ngastrulation. It has been previously shown that an actomyosin ring residing within the YSL\r\npulls on the EVL tissue through a cable-constriction and a flow-friction motor, thereby\r\ndragging the tissue vegetal wards. Pulling forces are likely transmitted from the YSL\r\nactomyosin ring to EVL cells; however, the nature and formation of the junctional structure\r\nmediating this process has not been well described so far. Therefore, our main aim was to\r\ndetermine the nature, dynamics and potential function of the EVL-YSL junction during this\r\nepithelial tissue spreading. Specifically, we show that the EVL-YSL junction is a\r\nmechanosensitive structure, predominantly made of tight junction (TJ) proteins. The process\r\nof TJ mechanosensation depends on the retrograde flow of non-junctional, phase-separated\r\nZonula Occludens-1 (ZO-1) protein clusters towards the EVL-YSL boundary. Interestingly, we\r\ncould demonstrate that ZO-1 is present in a non-junctional pool on the surface of the yolk\r\ncell, and ZO-1 undergoes a phase separation process that likely renders the protein\r\nresponsive to flows. These flows are directed towards the junction and mediate proper\r\ntension-dependent recruitment of ZO-1. Upon reaching the EVL-YSL junction ZO-1 gets\r\nincorporated into the junctional pool mediated through its direct actin-binding domain.\r\nWhen the non-junctional pool and/or ZO-1 direct actin binding is absent, TJs fail in their\r\nproper mechanosensitive responses resulting in slower tissue spreading. We could further\r\ndemonstrate that depletion of ZO proteins within the YSL results in diminished actomyosin\r\nring formation. This suggests that a mechanochemical feedback loop is at work during\r\nzebrafish epiboly: ZO proteins help in proper actomyosin ring formation and actomyosin\r\ncontractility and flows positively influence ZO-1 junctional recruitment. Finally, such a\r\nmesoscale polarization process mediated through the flow of phase-separated protein\r\nclusters might have implications for other processes such as immunological synapse\r\nformation, C. elegans zygote polarization and wound healing."}],"alternative_title":["ISTA Thesis"],"type":"dissertation","file":[{"file_id":"7194","relation":"source_file","checksum":"585583c1c875c5d9525703a539668a7c","date_updated":"2020-07-14T12:47:52Z","date_created":"2019-12-19T15:18:11Z","access_level":"closed","file_name":"DocumentSourceFiles.zip","creator":"cschwayer","file_size":19431292,"content_type":"application/zip"},{"access_level":"open_access","file_name":"Thesis_CS_final.pdf","content_type":"application/pdf","file_size":19226428,"creator":"cschwayer","relation":"main_file","file_id":"7195","checksum":"9b9b24351514948d27cec659e632e2cd","date_updated":"2020-07-14T12:47:52Z","date_created":"2019-12-19T15:19:21Z"}],"oa_version":"Published Version","ddc":["570"],"status":"public","title":"Mechanosensation of tight junctions depends on ZO-1 phase separation and flow","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","_id":"7186","month":"12","publication_identifier":{"issn":["2663-337X"]},"supervisor":[{"full_name":"Heisenberg, Carl-Philipp J","id":"39427864-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0912-4566","first_name":"Carl-Philipp J","last_name":"Heisenberg"}],"degree_awarded":"PhD","acknowledged_ssus":[{"_id":"Bio"},{"_id":"LifeSc"},{"_id":"EM-Fac"},{"_id":"SSU"}],"language":[{"iso":"eng"}],"doi":"10.15479/AT:ISTA:7186","oa":1,"file_date_updated":"2020-07-14T12:47:52Z","date_created":"2019-12-16T14:26:14Z","date_updated":"2023-09-07T12:56:42Z","author":[{"last_name":"Schwayer","first_name":"Cornelia","orcid":"0000-0001-5130-2226","id":"3436488C-F248-11E8-B48F-1D18A9856A87","full_name":"Schwayer, Cornelia"}],"related_material":{"record":[{"relation":"dissertation_contains","status":"public","id":"1096"},{"status":"public","relation":"part_of_dissertation","id":"7001"}]},"publication_status":"published","department":[{"_id":"CaHe"}],"publisher":"Institute of Science and Technology Austria","year":"2019"},{"publication_identifier":{"issn":["2663-337X"]},"month":"06","doi":"10.15479/AT:ISTA:TH_1031","language":[{"iso":"eng"}],"supervisor":[{"id":"39427864-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0912-4566","first_name":"Carl-Philipp J","last_name":"Heisenberg","full_name":"Heisenberg, Carl-Philipp J"}],"degree_awarded":"PhD","oa":1,"publist_id":"8004","file_date_updated":"2021-02-11T23:30:21Z","related_material":{"record":[{"id":"1100","status":"public","relation":"part_of_dissertation"},{"id":"661","relation":"part_of_dissertation","status":"public"},{"id":"676","status":"public","relation":"part_of_dissertation"}]},"author":[{"full_name":"Capek, Daniel","last_name":"Capek","first_name":"Daniel","orcid":"0000-0001-5199-9940","id":"31C42484-F248-11E8-B48F-1D18A9856A87"}],"date_created":"2018-12-11T11:44:21Z","date_updated":"2023-09-07T12:48:16Z","year":"2018","department":[{"_id":"CaHe"}],"publisher":"Institute of Science and Technology Austria","publication_status":"published","article_processing_charge":"No","has_accepted_license":"1","day":"22","date_published":"2018-06-22T00:00:00Z","citation":{"apa":"Capek, D. (2018). Optogenetic Frizzled 7 reveals a permissive function of Wnt/PCP signaling in directed mesenchymal cell migration. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:TH_1031","ieee":"D. Capek, “Optogenetic Frizzled 7 reveals a permissive function of Wnt/PCP signaling in directed mesenchymal cell migration,” Institute of Science and Technology Austria, 2018.","ista":"Capek D. 2018. Optogenetic Frizzled 7 reveals a permissive function of Wnt/PCP signaling in directed mesenchymal cell migration. Institute of Science and Technology Austria.","ama":"Capek D. Optogenetic Frizzled 7 reveals a permissive function of Wnt/PCP signaling in directed mesenchymal cell migration. 2018. doi:10.15479/AT:ISTA:TH_1031","chicago":"Capek, Daniel. “Optogenetic Frizzled 7 Reveals a Permissive Function of Wnt/PCP Signaling in Directed Mesenchymal Cell Migration.” Institute of Science and Technology Austria, 2018. https://doi.org/10.15479/AT:ISTA:TH_1031.","short":"D. Capek, Optogenetic Frizzled 7 Reveals a Permissive Function of Wnt/PCP Signaling in Directed Mesenchymal Cell Migration, Institute of Science and Technology Austria, 2018.","mla":"Capek, Daniel. Optogenetic Frizzled 7 Reveals a Permissive Function of Wnt/PCP Signaling in Directed Mesenchymal Cell Migration. Institute of Science and Technology Austria, 2018, doi:10.15479/AT:ISTA:TH_1031."},"page":"95","abstract":[{"text":"The Wnt/planar cell polarity (Wnt/PCP) pathway determines planar polarity of epithelial cells in both vertebrates and invertebrates. The role that Wnt/PCP signaling plays in mesenchymal contexts, however, is only poorly understood. While previous studies have demonstrated the capacity of Wnt/PCP signaling to polarize and guide directed migration of mesenchymal cells, it remains unclear whether endogenous Wnt/PCP signaling performs these functions instructively, as it does in epithelial cells. Here we developed a light-switchable version of the Wnt/PCP receptor Frizzled 7 (Fz7) to unambiguously distinguish between an instructive and a permissive role of Wnt/PCP signaling for the directional collective migration of mesendoderm progenitor cells during zebrafish gastrulation. We show that prechordal plate (ppl) cell migration is defective in maternal-zygotic fz7a and fz7b (MZ fz7a,b) double mutant embryos, and that Fz7 functions cell-autonomously in this process by promoting ppl cell protrusion formation and directed migration. We further show that local activation of Fz7 can direct ppl cell migration both in vitro and in vivo. Surprisingly, however, uniform Fz7 activation is sufficient to fully rescue the ppl cell migration defect in MZ fz7a,b mutant embryos, indicating that Wnt/PCP signaling functions permissively rather than instructively in directed mesendoderm cell migration during zebrafish gastrulation.","lang":"eng"}],"type":"dissertation","alternative_title":["ISTA Thesis"],"pubrep_id":"1031","file":[{"file_id":"6238","embargo":"2019-06-25","relation":"main_file","checksum":"d3eca3dcacb67bffdde6e6609c31cdd0","date_updated":"2021-02-11T11:17:17Z","date_created":"2019-04-08T13:42:26Z","access_level":"open_access","file_name":"2018_Thesis_Capek.pdf","creator":"dernst","content_type":"application/pdf","file_size":31576521},{"file_size":38992956,"content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","creator":"dernst","access_level":"closed","embargo_to":"open_access","file_name":"2018_Thesis_Capek_source.docx","checksum":"876deb14067e638aba65d209668bd821","date_created":"2019-04-08T13:42:27Z","date_updated":"2021-02-11T23:30:21Z","relation":"source_file","file_id":"6239"}],"oa_version":"Published Version","_id":"50","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","ddc":["570","591","596"],"status":"public","title":"Optogenetic Frizzled 7 reveals a permissive function of Wnt/PCP signaling in directed mesenchymal cell migration"},{"page":"109","citation":{"ama":"Barone V. Cell adhesion and cell fate: An effective feedback loop during zebrafish gastrulation. 2017. doi:10.15479/AT:ISTA:th_825","apa":"Barone, V. (2017). Cell adhesion and cell fate: An effective feedback loop during zebrafish gastrulation. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:th_825","ieee":"V. Barone, “Cell adhesion and cell fate: An effective feedback loop during zebrafish gastrulation,” Institute of Science and Technology Austria, 2017.","ista":"Barone V. 2017. Cell adhesion and cell fate: An effective feedback loop during zebrafish gastrulation. Institute of Science and Technology Austria.","short":"V. Barone, Cell Adhesion and Cell Fate: An Effective Feedback Loop during Zebrafish Gastrulation, Institute of Science and Technology Austria, 2017.","mla":"Barone, Vanessa. Cell Adhesion and Cell Fate: An Effective Feedback Loop during Zebrafish Gastrulation. Institute of Science and Technology Austria, 2017, doi:10.15479/AT:ISTA:th_825.","chicago":"Barone, Vanessa. “Cell Adhesion and Cell Fate: An Effective Feedback Loop during Zebrafish Gastrulation.” Institute of Science and Technology Austria, 2017. https://doi.org/10.15479/AT:ISTA:th_825."},"date_published":"2017-03-01T00:00:00Z","day":"01","article_processing_charge":"No","has_accepted_license":"1","title":"Cell adhesion and cell fate: An effective feedback loop during zebrafish gastrulation","status":"public","ddc":["570","590"],"_id":"961","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","file":[{"file_id":"6205","relation":"source_file","date_created":"2019-04-05T08:36:52Z","date_updated":"2020-07-14T12:48:16Z","checksum":"242f88c87f2cf267bf05049fa26a687b","file_name":"2017_Barone_thesis_final.docx","access_level":"closed","creator":"dernst","content_type":"application/vnd.openxmlformats-officedocument.wordprocessingml.document","file_size":14497822},{"file_size":14995941,"content_type":"application/pdf","creator":"dernst","file_name":"2017_Barone_thesis_.pdf","access_level":"open_access","date_created":"2019-04-05T08:36:52Z","date_updated":"2020-07-14T12:48:16Z","checksum":"ba5b0613ed8bade73a409acdd880fb8a","relation":"main_file","file_id":"6206"}],"oa_version":"Published Version","pubrep_id":"825","alternative_title":["ISTA Thesis"],"type":"dissertation","abstract":[{"text":"Cell-cell contact formation constitutes the first step in the emergence of multicellularity in evolution, thereby allowing the differentiation of specialized cell types. In metazoan development, cell-cell contact formation is thought to influence cell fate specification, and cell fate specification has been implicated in cell-cell contact formation. However, remarkably little is yet known about whether and how the interaction and feedback between cell-cell contact formation and cell fate specification affect development. Here we identify a positive feedback loop between cell-cell contact duration, morphogen signaling and mesendoderm cell fate specification during zebrafish gastrulation. We show that long lasting cell-cell contacts enhance the competence of prechordal plate (ppl) progenitor cells to respond to Nodal signaling, required for proper ppl cell fate specification. We further show that Nodal signalling romotes ppl cell-cell contact duration, thereby generating an effective positive feedback loop between ppl cell-cell contact duration and cell fate specification. Finally, by using a combination of theoretical modeling and experimentation, we show that this feedback loop determines whether anterior axial mesendoderm cells become ppl progenitors or, instead, turn into endoderm progenitors. Our findings reveal that the gene regulatory networks leading to cell fate diversification within the developing embryo are controlled by the interdependent activities of cell-cell signaling and contact formation.","lang":"eng"}],"tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","short":"CC BY (4.0)","image":"/images/cc_by.png"},"oa":1,"supervisor":[{"first_name":"Carl-Philipp J","last_name":"Heisenberg","id":"39427864-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0912-4566","full_name":"Heisenberg, Carl-Philipp J"}],"degree_awarded":"PhD","language":[{"iso":"eng"}],"doi":"10.15479/AT:ISTA:th_825","month":"03","publication_identifier":{"issn":["2663-337X"]},"publication_status":"published","department":[{"_id":"CaHe"}],"publisher":"Institute of Science and Technology Austria","year":"2017","acknowledgement":"Many people accompanied me during this trip: I would not have reached my destination nor \r\nenjoyed the travelling without them. First of all, thanks to CP. Thanks for making me part of \r\nyour team, always full of diverse, interesting and incredibly competent people and thanks for \r\nall the good science I witnessed and participated in. It has been a \r\nblast, an incredibly \r\nexciting one! Thanks to JLo, for teaching me how to master my pipettes and showing me \r\nthat science is a lot of fun. Many, many thanks to Gabby for teaching me basically everything \r\nabout zebrafish and being always there to advice, sugge\r\nst, support...and play fussball! \r\nThank you to Julien, for the critical eye on things, Pedro, for all the invaluable feedback and \r\nthe amazing kicker matches, and Keisuke, for showing me the light, and to the three of them \r\ntogether for all the good laughs we\r\nhad. My start in Vienna would have been a lot more \r\ndifficult without you guys. Also it would not have been possible without Elena and Inês: \r\nthanks for helping setting up this lab and for the dinners in Gugging. Thanks to Martin, for \r\nhelping me understand \r\nthe physics behind biology. Thanks to Philipp, for the interest and \r\nadvice, and to Michael, for the Viennise take on things. Thanks to Julia, for putting up with \r\nbeing our technician and becoming a friend in the process. And now to the newest members \r\nof th\r\ne lab. Thanks to Daniel for the enthusiasm and the neverending energy and for all your \r\nhelp over the years: thank you! To Jana, for showing me that one doesn’t give up, no matter \r\nwhat. To Shayan, for being such a motivated student. To Matt, for helping out\r\nwith coding \r\nand for finding punk solutions to data analysis problems. Thanks to all the members of the \r\nlab, Verena, Hitoshi, Silvia, Conny, Karla, Nicoletta, Zoltan, Peng, Benoit, Roland, Yuuta and \r\nFeyza, for the wonderful atmosphere in the lab. Many than\r\nks to Koni and Deborah: doing \r\nexperiments would have been much more difficult without your help. Special thanks to Katjia \r\nfor setting up an amazing imaging facility and for building the best team, Robert, Nasser, \r\nAnna and Doreen: thank you for putting up w\r\nith all the late sortings and for helping with all \r\nthe technical problems. Thanks to Eva, Verena and Matthias for keeping the fish happy. Big \r\nthanks to Harald Janovjak for being a present and helpful committee member over the years \r\nand to Patrick Lemaire f\r\nor the helpful insight and extremely interesting discussion we had \r\nabout the project. Also, this journey would not have been the same without all the friends \r\nthat I met in Dresden and then in Vienna: Daniele, Claire, Kuba, Steffi, Harold, Dejan, Irene, \r\nFab\r\nienne, Hande, Tiago, Marianne, Jon, Srdjan, Branca, Uli, Murat, Alex, Conny, Christoph, \r\nCaro, Simone, Barbara, Felipe, Dama, Jose, Hubert and many others that filled my days with \r\nfun and support. A special thank to my family, always close even if they are \r\nkilometers away. \r\nGrazie ai miei fratelli, Nunzio e William, e alla mia mamma, per essermi sempre vicini pur \r\nvivendo a chilometri di distanza. And, last but not least, thanks to Moritz, for putting up with \r\nthe crazy life of a scientist, the living apart for\r\nso long, never knowing when things are going \r\nto happen. Thanks for being a great partner and my number one fan!","date_updated":"2023-09-27T14:16:45Z","date_created":"2018-12-11T11:49:25Z","author":[{"full_name":"Barone, Vanessa","id":"419EECCC-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-2676-3367","first_name":"Vanessa","last_name":"Barone"}],"related_material":{"record":[{"status":"public","relation":"part_of_dissertation","id":"1100"},{"id":"1537","relation":"part_of_dissertation","status":"public"},{"status":"public","relation":"part_of_dissertation","id":"1912"},{"id":"2926","status":"public","relation":"part_of_dissertation"},{"id":"3246","relation":"part_of_dissertation","status":"public"},{"id":"676","relation":"part_of_dissertation","status":"public"},{"relation":"part_of_dissertation","status":"public","id":"735"}]},"file_date_updated":"2020-07-14T12:48:16Z","publist_id":"6444"},{"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","_id":"1403","year":"2014","title":"Forces driving epithelial spreading in zebrafish epiboly","status":"public","publication_status":"published","department":[{"_id":"CaHe"}],"publisher":"IST Austria","author":[{"full_name":"Behrndt, Martin","last_name":"Behrndt","first_name":"Martin","id":"3ECECA3A-F248-11E8-B48F-1D18A9856A87"}],"related_material":{"record":[{"id":"2282","relation":"part_of_dissertation","status":"public"},{"status":"public","relation":"part_of_dissertation","id":"2950"},{"relation":"part_of_dissertation","status":"public","id":"3373"}]},"date_updated":"2023-10-17T12:16:58Z","date_created":"2018-12-11T11:51:49Z","oa_version":"None","type":"dissertation","alternative_title":["IST Austria Thesis"],"abstract":[{"text":"A variety of developmental and disease related processes depend on epithelial cell sheet spreading. In order to gain insight into the biophysical mechanism(s) underlying the tissue morphogenesis we studied the spreading of an epithelium during the early development of the zebrafish embryo. In zebrafish epiboly the enveloping cell layer (EVL), a simple squamous epithelium, spreads over the yolk cell to completely engulf it at the end of gastrulation. Previous studies have proposed that an actomyosin ring forming within the yolk syncytial layer (YSL) acts as purse string that through constriction along its circumference pulls on the margin of the EVL. Direct biophysical evidence for this hypothesis has however been missing. The aim of the thesis was to understand how the actomyosin ring may generate pulling forces onto the EVL and what cellular mechanism(s) may facilitate the spreading of the epithelium. Using laser ablation to measure cortical tension within the actomyosin ring we found an anisotropic tension distribution, which was highest along the circumference of the ring. However the low degree of anisotropy was incompatible with the actomyosin ring functioning as a purse string only. Additionally, we observed retrograde cortical flow from vegetal parts of the ring into the EVL margin. Interpreting the experimental data using a theoretical distribution that models the tissues as active viscous gels led us to proposen that the actomyosin ring has a twofold contribution to EVL epiboly. It not only acts as a purse string through constriction along its circumference, but in addition constriction along the width of the ring generates pulling forces through friction-resisted cortical flow. Moreover, when rendering the purse string mechanism unproductive EVL epiboly proceeded normally indicating that the flow-friction mechanism is sufficient to drive the process. Aiming to understand what cellular mechanism(s) may facilitate the spreading of the epithelium we found that tension-oriented EVL cell divisions limit tissue anisotropy by releasing tension along the division axis and promote epithelial spreading. Notably, EVL cells undergo ectopic cell fusion in conditions in which oriented-cell division is impaired or the epithelium is mechanically challenged. Taken together our study of EVL epiboly suggests a novel mechanism of force generation for actomyosin rings through friction-resisted cortical flow and highlights the importance of tension-oriented cell divisions in epithelial morphogenesis.","lang":"eng"}],"publist_id":"5804","citation":{"mla":"Behrndt, Martin. Forces Driving Epithelial Spreading in Zebrafish Epiboly. IST Austria, 2014.","short":"M. Behrndt, Forces Driving Epithelial Spreading in Zebrafish Epiboly, IST Austria, 2014.","chicago":"Behrndt, Martin. “Forces Driving Epithelial Spreading in Zebrafish Epiboly.” IST Austria, 2014.","ama":"Behrndt M. Forces driving epithelial spreading in zebrafish epiboly. 2014.","ista":"Behrndt M. 2014. Forces driving epithelial spreading in zebrafish epiboly. IST Austria.","ieee":"M. Behrndt, “Forces driving epithelial spreading in zebrafish epiboly,” IST Austria, 2014.","apa":"Behrndt, M. (2014). Forces driving epithelial spreading in zebrafish epiboly. IST Austria."},"page":"91","date_published":"2014-08-01T00:00:00Z","supervisor":[{"full_name":"Heisenberg, Carl-Philipp J","first_name":"Carl-Philipp J","last_name":"Heisenberg","id":"39427864-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0912-4566"}],"acknowledged_ssus":[{"_id":"SSU"}],"language":[{"iso":"eng"}],"day":"01","month":"08"},{"day":"01","month":"10","publication_identifier":{"issn":["2663-337X"]},"article_processing_charge":"No","page":"123","citation":{"ista":"Campinho P. 2013. Mechanics of zebrafish epiboly: Tension-oriented cell divisions limit anisotropic tissue tension in epithelial spreading. Institute of Science and Technology Austria.","apa":"Campinho, P. (2013). Mechanics of zebrafish epiboly: Tension-oriented cell divisions limit anisotropic tissue tension in epithelial spreading. Institute of Science and Technology Austria.","ieee":"P. Campinho, “Mechanics of zebrafish epiboly: Tension-oriented cell divisions limit anisotropic tissue tension in epithelial spreading,” Institute of Science and Technology Austria, 2013.","ama":"Campinho P. Mechanics of zebrafish epiboly: Tension-oriented cell divisions limit anisotropic tissue tension in epithelial spreading. 2013.","chicago":"Campinho, Pedro. “Mechanics of Zebrafish Epiboly: Tension-Oriented Cell Divisions Limit Anisotropic Tissue Tension in Epithelial Spreading.” Institute of Science and Technology Austria, 2013.","mla":"Campinho, Pedro. Mechanics of Zebrafish Epiboly: Tension-Oriented Cell Divisions Limit Anisotropic Tissue Tension in Epithelial Spreading. Institute of Science and Technology Austria, 2013.","short":"P. Campinho, Mechanics of Zebrafish Epiboly: Tension-Oriented Cell Divisions Limit Anisotropic Tissue Tension in Epithelial Spreading, Institute of Science and Technology Austria, 2013."},"degree_awarded":"PhD","supervisor":[{"orcid":"0000-0002-0912-4566","id":"39427864-F248-11E8-B48F-1D18A9856A87","last_name":"Heisenberg","first_name":"Carl-Philipp J","full_name":"Heisenberg, Carl-Philipp J"}],"acknowledged_ssus":[{"_id":"Bio"},{"_id":"PreCl"}],"language":[{"iso":"eng"}],"date_published":"2013-10-01T00:00:00Z","alternative_title":["ISTA Thesis"],"type":"dissertation","abstract":[{"text":"Epithelial spreading is a critical part of various developmental and wound repair processes. Here we use zebrafish epiboly as a model system to study the cellular and molecular mechanisms underlying the spreading of epithelial sheets. During zebrafish epiboly the enveloping cell layer (EVL), a simple squamous epithelium, spreads over the embryo to eventually cover the entire yolk cell by the end of gastrulation. The EVL leading edge is anchored through tight junctions to the yolk syncytial layer (YSL), where directly adjacent to the EVL margin a contractile actomyosin ring is formed that is thought to drive EVL epiboly. The prevalent view in the field was that the contractile ring exerts a pulling force on the EVL margin, which pulls the EVL towards the vegetal pole. However, how this force is generated and how it affects EVL morphology still remains elusive. Moreover, the cellular mechanisms mediating the increase in EVL surface area, while maintaining tissue integrity and function are still unclear. Here we show that the YSL actomyosin ring pulls on the EVL margin by two distinct force-generating mechanisms. One mechanism is based on contraction of the ring around its circumference, as previously proposed. The second mechanism is based on actomyosin retrogade flows, generating force through resistance against the substrate. The latter can function at any epiboly stage even in situations where the contraction-based mechanism is unproductive. Additionally, we demonstrate that during epiboly the EVL is subjected to anisotropic tension, which guides the orientation of EVL cell division along the main axis (animal-vegetal) of tension. The influence of tension in cell division orientation involves cell elongation and requires myosin-2 activity for proper spindle alignment. Strikingly, we reveal that tension-oriented cell divisions release anisotropic tension within the EVL and that in the absence of such divisions, EVL cells undergo ectopic fusions. We conclude that forces applied to the EVL by the action of the YSL actomyosin ring generate a tension anisotropy in the EVL that orients cell divisions, which in turn limit tissue tension increase thereby facilitating tissue spreading.","lang":"eng"}],"publist_id":"5801","publication_status":"published","title":"Mechanics of zebrafish epiboly: Tension-oriented cell divisions limit anisotropic tissue tension in epithelial spreading","status":"public","department":[{"_id":"CaHe"}],"publisher":"Institute of Science and Technology Austria","_id":"1406","year":"2013","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","date_created":"2018-12-11T11:51:50Z","date_updated":"2023-09-07T11:36:07Z","oa_version":"None","author":[{"full_name":"Campinho, Pedro","id":"3AFBBC42-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-8526-5416","first_name":"Pedro","last_name":"Campinho"}]},{"date_published":"2011-12-12T00:00:00Z","degree_awarded":"PhD","supervisor":[{"id":"39427864-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0912-4566","first_name":"Carl-Philipp J","last_name":"Heisenberg","full_name":"Heisenberg, Carl-Philipp J"}],"language":[{"iso":"eng"}],"citation":{"ama":"Maître J-L. Mechanics of adhesion and de‐adhesion in zebrafish germ layer progenitors. 2011.","ista":"Maître J-L. 2011. Mechanics of adhesion and de‐adhesion in zebrafish germ layer progenitors. Institute of Science and Technology Austria.","apa":"Maître, J.-L. (2011). Mechanics of adhesion and de‐adhesion in zebrafish germ layer progenitors. Institute of Science and Technology Austria.","ieee":"J.-L. Maître, “Mechanics of adhesion and de‐adhesion in zebrafish germ layer progenitors,” Institute of Science and Technology Austria, 2011.","mla":"Maître, Jean-Léon. Mechanics of Adhesion and De‐adhesion in Zebrafish Germ Layer Progenitors. Institute of Science and Technology Austria, 2011.","short":"J.-L. Maître, Mechanics of Adhesion and De‐adhesion in Zebrafish Germ Layer Progenitors, Institute of Science and Technology Austria, 2011.","chicago":"Maître, Jean-Léon. “Mechanics of Adhesion and De‐adhesion in Zebrafish Germ Layer Progenitors.” Institute of Science and Technology Austria, 2011."},"day":"12","month":"12","article_processing_charge":"No","publication_identifier":{"issn":["2663-337X"]},"author":[{"full_name":"Maître, Jean-Léon","id":"48F1E0D8-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-3688-1474","first_name":"Jean-Léon","last_name":"Maître"}],"date_updated":"2023-09-07T11:30:16Z","date_created":"2018-12-11T12:02:23Z","oa_version":"None","_id":"3273","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","year":"2011","publication_status":"published","status":"public","title":"Mechanics of adhesion and de‐adhesion in zebrafish germ layer progenitors","department":[{"_id":"CaHe"}],"publisher":"Institute of Science and Technology Austria","publist_id":"3373","type":"dissertation","alternative_title":["ISTA Thesis"]},{"_id":"3962","year":"2010","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","department":[{"_id":"CaHe"},{"_id":"GradSch"}],"publisher":"Institute of Science and Technology Austria","title":"Dendritic cell migration across basement membranes in the skin","publication_status":"published","status":"public","author":[{"id":"CAA57A9A-5B61-11E9-B130-E0C1E1F2C83D","last_name":"Pflicke","first_name":"Holger","full_name":"Pflicke, Holger"}],"oa_version":"None","date_updated":"2023-09-07T11:28:47Z","date_created":"2018-12-11T12:06:08Z","type":"dissertation","alternative_title":["ISTA Thesis"],"publist_id":"2165","citation":{"ama":"Pflicke H. Dendritic cell migration across basement membranes in the skin. 2010.","ista":"Pflicke H. 2010. Dendritic cell migration across basement membranes in the skin. Institute of Science and Technology Austria.","ieee":"H. Pflicke, “ Dendritic cell migration across basement membranes in the skin,” Institute of Science and Technology Austria, 2010.","apa":"Pflicke, H. (2010). Dendritic cell migration across basement membranes in the skin. Institute of Science and Technology Austria.","mla":"Pflicke, Holger. Dendritic Cell Migration across Basement Membranes in the Skin. Institute of Science and Technology Austria, 2010.","short":"H. Pflicke, Dendritic Cell Migration across Basement Membranes in the Skin, Institute of Science and Technology Austria, 2010.","chicago":"Pflicke, Holger. “ Dendritic Cell Migration across Basement Membranes in the Skin.” Institute of Science and Technology Austria, 2010."},"date_published":"2010-07-01T00:00:00Z","language":[{"iso":"eng"}],"degree_awarded":"PhD","supervisor":[{"full_name":"Heisenberg, Carl-Philipp J","last_name":"Heisenberg","first_name":"Carl-Philipp J","orcid":"0000-0002-0912-4566","id":"39427864-F248-11E8-B48F-1D18A9856A87"}],"publication_identifier":{"issn":["2663-337X"]},"article_processing_charge":"No","day":"01","month":"07"}]