---
_id: '12891'
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."
acknowledged_ssus:
- _id: Bio
- _id: LifeSc
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Alexandra
full_name: Schauer, Alexandra
id: 30A536BA-F248-11E8-B48F-1D18A9856A87
last_name: Schauer
orcid: 0000-0001-7659-9142
citation:
ama: 'Schauer A. Mesendoderm formation in zebrafish gastrulation: The role of extraembryonic
tissues. 2023. doi:10.15479/at:ista:12891'
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'
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.'
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.'
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.'
short: 'A. Schauer, Mesendoderm Formation in Zebrafish Gastrulation: The Role of
Extraembryonic Tissues, Institute of Science and Technology Austria, 2023.'
date_created: 2023-05-05T08:48:20Z
date_published: 2023-05-05T00:00:00Z
date_updated: 2023-08-21T06:25:48Z
day: '05'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: GradSch
- _id: CaHe
doi: 10.15479/at:ista:12891
ec_funded: 1
file:
- access_level: closed
checksum: 59b0303dc483f40a96a610a90aab7ee9
content_type: application/pdf
creator: aschauer
date_created: 2023-05-05T13:01:14Z
date_updated: 2023-05-05T13:01:14Z
embargo: 2024-05-05
embargo_to: open_access
file_id: '12907'
file_name: Thesis_Schauer_final.pdf
file_size: 31434230
relation: main_file
- access_level: closed
checksum: 25f54e12479b6adaabd129a20568e6c1
content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
creator: aschauer
date_created: 2023-05-05T13:04:15Z
date_updated: 2023-05-05T13:04:15Z
file_id: '12908'
file_name: Thesis_Schauer_final.docx
file_size: 43809109
relation: source_file
file_date_updated: 2023-05-05T13:04:15Z
has_accepted_license: '1'
language:
- iso: eng
month: '05'
oa_version: Published Version
page: '190'
project:
- _id: 260F1432-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '742573'
name: Interaction and feedback between cell mechanics and fate specification in
vertebrate gastrulation
- _id: 26B1E39C-B435-11E9-9278-68D0E5697425
grant_number: '25239'
name: 'Mesendoderm specification in zebrafish: The role of extraembryonic tissues'
publication_identifier:
issn:
- 2663 - 337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '8966'
relation: part_of_dissertation
status: public
- id: '7888'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: 'Mesendoderm formation in zebrafish gastrulation: The role of extraembryonic
tissues'
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '12368'
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\x02mediated 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\x02cadherin 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."
acknowledged_ssus:
- _id: LifeSc
- _id: Bio
- _id: NanoFab
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Feyza N
full_name: Arslan, Feyza N
id: 49DA7910-F248-11E8-B48F-1D18A9856A87
last_name: Arslan
orcid: 0000-0001-5809-9566
citation:
ama: Arslan FN. Remodeling of E-cadherin-mediated contacts via cortical flows.
2022. doi:10.15479/at:ista:12153
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
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.
ieee: F. N. Arslan, “Remodeling of E-cadherin-mediated contacts via cortical flows,”
Institute of Science and Technology Austria, 2022.
ista: Arslan FN. 2022. Remodeling of E-cadherin-mediated contacts via cortical
flows. Institute of Science and Technology Austria.
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.
date_created: 2023-01-25T10:43:24Z
date_published: 2022-09-29T00:00:00Z
date_updated: 2023-08-08T13:14:10Z
day: '29'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: GradSch
- _id: CaHe
doi: 10.15479/at:ista:12153
ec_funded: 1
file:
- access_level: open_access
checksum: e54a3e69b83ebf166544164afd25608e
content_type: application/pdf
creator: cchlebak
date_created: 2023-01-25T10:52:46Z
date_updated: 2023-01-25T10:52:46Z
file_id: '12369'
file_name: THESIS_FINAL_FArslan_pdfa.pdf
file_size: 14581024
relation: main_file
success: 1
file_date_updated: 2023-01-25T10:52:46Z
has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '113'
project:
- _id: 260F1432-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '742573'
name: Interaction and feedback between cell mechanics and fate specification in
vertebrate gastrulation
publication_identifier:
isbn:
- ' 978-3-99078-025-1 '
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '9350'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: Remodeling of E-cadherin-mediated contacts via cortical flows
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: dissertation
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2022'
...
---
_id: '9397'
abstract:
- lang: eng
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.
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Karla
full_name: Huljev, Karla
id: 44C6F6A6-F248-11E8-B48F-1D18A9856A87
last_name: Huljev
citation:
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
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
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.
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.
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.
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.
date_created: 2021-05-17T12:31:30Z
date_published: 2021-05-18T00:00:00Z
date_updated: 2023-09-07T13:32:32Z
day: '18'
ddc:
- '571'
degree_awarded: PhD
department:
- _id: CaHe
- _id: GradSch
doi: 10.15479/at:ista:9397
file:
- access_level: closed
checksum: 7f98532f5324a0b2f3fa8de2967baa19
content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
creator: khuljev
date_created: 2021-05-17T12:29:12Z
date_updated: 2022-05-21T22:30:04Z
embargo_to: open_access
file_id: '9398'
file_name: KHuljev_Thesis_corrections.docx
file_size: 47799741
relation: source_file
- access_level: open_access
checksum: bf512f8a1e572a543778fc4b227c01ba
content_type: application/pdf
creator: khuljev
date_created: 2021-05-18T14:50:28Z
date_updated: 2022-05-21T22:30:04Z
embargo: 2022-05-20
file_id: '9401'
file_name: new_KHuljev_Thesis_corrections.pdf
file_size: 16542131
relation: main_file
file_date_updated: 2022-05-21T22:30:04Z
has_accepted_license: '1'
language:
- iso: eng
month: '05'
oa: 1
oa_version: Published Version
page: '101'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: Coordinated spatiotemporal reorganization of interstitial fluid is required
for axial mesendoderm migration in zebrafish gastrulation
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2021'
...
---
_id: '9623'
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"
acknowledged_ssus:
- _id: Bio
- _id: EM-Fac
- _id: NanoFab
- _id: M-Shop
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Silvia
full_name: Caballero Mancebo, Silvia
id: 2F1E1758-F248-11E8-B48F-1D18A9856A87
last_name: Caballero Mancebo
orcid: 0000-0002-5223-3346
citation:
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
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
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.
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.
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.
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.
date_created: 2021-07-01T14:50:17Z
date_published: 2021-07-01T00:00:00Z
date_updated: 2023-09-07T13:33:27Z
ddc:
- '570'
degree_awarded: PhD
department:
- _id: GradSch
- _id: CaHe
doi: 10.15479/at:ista:9623
file:
- access_level: closed
checksum: e039225a47ef32666d59bf35ddd30ecf
content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
creator: scaballe
date_created: 2021-07-01T14:48:54Z
date_updated: 2022-07-02T22:30:06Z
embargo_to: open_access
file_id: '9624'
file_name: PhDThesis_SCM.docx
file_size: 131946790
relation: source_file
- access_level: open_access
checksum: dd4d78962ea94ad95e97ca7d9af08f4b
content_type: application/pdf
creator: scaballe
date_created: 2021-07-01T14:46:25Z
date_updated: 2022-07-02T22:30:06Z
embargo: 2022-07-01
file_id: '9625'
file_name: PhDThesis_SCM.pdf
file_size: 17094958
relation: main_file
file_date_updated: 2022-07-02T22:30:06Z
has_accepted_license: '1'
language:
- iso: eng
month: '07'
oa: 1
oa_version: Published Version
page: '111'
publication_identifier:
isbn:
- 978-3-99078-012-1
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '9750'
relation: part_of_dissertation
status: public
- id: '9006'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: Fertilization-induced deformations are controlled by the actin cortex and a
mitochondria-rich subcortical layer in ascidian oocytes
tmp:
image: /images/cc_by_nc_nd.png
legal_code_url: https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode
name: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
(CC BY-NC-ND 4.0)
short: CC BY-NC-ND (4.0)
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2021'
...
---
_id: '8350'
abstract:
- lang: eng
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."
acknowledged_ssus:
- _id: PreCl
- _id: Bio
- _id: EM-Fac
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."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Shayan
full_name: Shamipour, Shayan
id: 40B34FE2-F248-11E8-B48F-1D18A9856A87
last_name: Shamipour
citation:
ama: Shamipour S. Bulk actin dynamics drive phase segregation in zebrafish oocytes
. 2020. doi:10.15479/AT:ISTA:8350
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
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.
ieee: S. Shamipour, “Bulk actin dynamics drive phase segregation in zebrafish oocytes
,” Institute of Science and Technology Austria, 2020.
ista: Shamipour S. 2020. Bulk actin dynamics drive phase segregation in zebrafish
oocytes . Institute of Science and Technology Austria.
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.
short: S. Shamipour, Bulk Actin Dynamics Drive Phase Segregation in Zebrafish Oocytes
, Institute of Science and Technology Austria, 2020.
date_created: 2020-09-09T11:12:10Z
date_published: 2020-09-09T00:00:00Z
date_updated: 2023-09-27T14:16:45Z
day: '09'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: BjHo
- _id: CaHe
doi: 10.15479/AT:ISTA:8350
file:
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checksum: 6e47871c74f85008b9876112eb3fcfa1
content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
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date_updated: 2021-09-11T22:30:05Z
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file_size: 65194814
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date_updated: 2021-09-11T22:30:05Z
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file_id: '8352'
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file_size: 23729605
relation: main_file
file_date_updated: 2021-09-11T22:30:05Z
has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: None
page: '107'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '661'
relation: part_of_dissertation
status: public
- id: '6508'
relation: part_of_dissertation
status: public
- id: '7001'
relation: part_of_dissertation
status: public
- id: '735'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
- first_name: Björn
full_name: Hof, Björn
id: 3A374330-F248-11E8-B48F-1D18A9856A87
last_name: Hof
orcid: 0000-0003-2057-2754
title: 'Bulk actin dynamics drive phase segregation in zebrafish oocytes '
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2020'
...
---
_id: '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."
acknowledged_ssus:
- _id: Bio
- _id: LifeSc
- _id: EM-Fac
- _id: SSU
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Cornelia
full_name: Schwayer, Cornelia
id: 3436488C-F248-11E8-B48F-1D18A9856A87
last_name: Schwayer
orcid: 0000-0001-5130-2226
citation:
ama: Schwayer C. Mechanosensation of tight junctions depends on ZO-1 phase separation
and flow. 2019. doi:10.15479/AT:ISTA:7186
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
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.
ieee: C. Schwayer, “Mechanosensation of tight junctions depends on ZO-1 phase separation
and flow,” Institute of Science and Technology Austria, 2019.
ista: Schwayer C. 2019. Mechanosensation of tight junctions depends on ZO-1 phase
separation and flow. Institute of Science and Technology Austria.
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.
short: C. Schwayer, Mechanosensation of Tight Junctions Depends on ZO-1 Phase Separation
and Flow, Institute of Science and Technology Austria, 2019.
date_created: 2019-12-16T14:26:14Z
date_published: 2019-12-16T00:00:00Z
date_updated: 2023-09-07T12:56:42Z
day: '16'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: CaHe
doi: 10.15479/AT:ISTA:7186
file:
- access_level: closed
checksum: 585583c1c875c5d9525703a539668a7c
content_type: application/zip
creator: cschwayer
date_created: 2019-12-19T15:18:11Z
date_updated: 2020-07-14T12:47:52Z
file_id: '7194'
file_name: DocumentSourceFiles.zip
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checksum: 9b9b24351514948d27cec659e632e2cd
content_type: application/pdf
creator: cschwayer
date_created: 2019-12-19T15:19:21Z
date_updated: 2020-07-14T12:47:52Z
file_id: '7195'
file_name: Thesis_CS_final.pdf
file_size: 19226428
relation: main_file
file_date_updated: 2020-07-14T12:47:52Z
has_accepted_license: '1'
language:
- iso: eng
month: '12'
oa: 1
oa_version: Published Version
page: '107'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '1096'
relation: dissertation_contains
status: public
- id: '7001'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: Mechanosensation of tight junctions depends on ZO-1 phase separation and flow
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2019'
...
---
_id: '50'
abstract:
- lang: eng
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.
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Daniel
full_name: Capek, Daniel
id: 31C42484-F248-11E8-B48F-1D18A9856A87
last_name: Capek
orcid: 0000-0001-5199-9940
citation:
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
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
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.
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.
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.
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.
date_created: 2018-12-11T11:44:21Z
date_published: 2018-06-22T00:00:00Z
date_updated: 2023-09-07T12:48:16Z
day: '22'
ddc:
- '570'
- '591'
- '596'
degree_awarded: PhD
department:
- _id: CaHe
doi: 10.15479/AT:ISTA:TH_1031
file:
- access_level: open_access
checksum: d3eca3dcacb67bffdde6e6609c31cdd0
content_type: application/pdf
creator: dernst
date_created: 2019-04-08T13:42:26Z
date_updated: 2021-02-11T11:17:17Z
embargo: 2019-06-25
file_id: '6238'
file_name: 2018_Thesis_Capek.pdf
file_size: 31576521
relation: main_file
- access_level: closed
checksum: 876deb14067e638aba65d209668bd821
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creator: dernst
date_created: 2019-04-08T13:42:27Z
date_updated: 2021-02-11T23:30:21Z
embargo_to: open_access
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file_name: 2018_Thesis_Capek_source.docx
file_size: 38992956
relation: source_file
file_date_updated: 2021-02-11T23:30:21Z
has_accepted_license: '1'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
page: '95'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '8004'
pubrep_id: '1031'
related_material:
record:
- id: '1100'
relation: part_of_dissertation
status: public
- id: '661'
relation: part_of_dissertation
status: public
- id: '676'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: Optogenetic Frizzled 7 reveals a permissive function of Wnt/PCP signaling in
directed mesenchymal cell migration
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2018'
...
---
_id: '961'
abstract:
- lang: eng
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.
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!"
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Vanessa
full_name: Barone, Vanessa
id: 419EECCC-F248-11E8-B48F-1D18A9856A87
last_name: Barone
orcid: 0000-0003-2676-3367
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'
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.'
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.'
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.'
short: 'V. Barone, Cell Adhesion and Cell Fate: An Effective Feedback Loop during
Zebrafish Gastrulation, Institute of Science and Technology Austria, 2017.'
date_created: 2018-12-11T11:49:25Z
date_published: 2017-03-01T00:00:00Z
date_updated: 2023-09-27T14:16:45Z
day: '01'
ddc:
- '570'
- '590'
degree_awarded: PhD
department:
- _id: CaHe
doi: 10.15479/AT:ISTA:th_825
file:
- access_level: closed
checksum: 242f88c87f2cf267bf05049fa26a687b
content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
creator: dernst
date_created: 2019-04-05T08:36:52Z
date_updated: 2020-07-14T12:48:16Z
file_id: '6205'
file_name: 2017_Barone_thesis_final.docx
file_size: 14497822
relation: source_file
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checksum: ba5b0613ed8bade73a409acdd880fb8a
content_type: application/pdf
creator: dernst
date_created: 2019-04-05T08:36:52Z
date_updated: 2020-07-14T12:48:16Z
file_id: '6206'
file_name: 2017_Barone_thesis_.pdf
file_size: 14995941
relation: main_file
file_date_updated: 2020-07-14T12:48:16Z
has_accepted_license: '1'
language:
- iso: eng
month: '03'
oa: 1
oa_version: Published Version
page: '109'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '6444'
pubrep_id: '825'
related_material:
record:
- id: '1100'
relation: part_of_dissertation
status: public
- id: '1537'
relation: part_of_dissertation
status: public
- id: '1912'
relation: part_of_dissertation
status: public
- id: '2926'
relation: part_of_dissertation
status: public
- id: '3246'
relation: part_of_dissertation
status: public
- id: '676'
relation: part_of_dissertation
status: public
- id: '735'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: 'Cell adhesion and cell fate: An effective feedback loop during zebrafish gastrulation'
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2017'
...
---
_id: '1403'
abstract:
- lang: eng
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.
acknowledged_ssus:
- _id: SSU
alternative_title:
- IST Austria Thesis
author:
- first_name: Martin
full_name: Behrndt, Martin
id: 3ECECA3A-F248-11E8-B48F-1D18A9856A87
last_name: Behrndt
citation:
ama: Behrndt M. Forces driving epithelial spreading in zebrafish epiboly. 2014.
apa: Behrndt, M. (2014). Forces driving epithelial spreading in zebrafish epiboly.
IST Austria.
chicago: Behrndt, Martin. “Forces Driving Epithelial Spreading in Zebrafish Epiboly.”
IST Austria, 2014.
ieee: M. Behrndt, “Forces driving epithelial spreading in zebrafish epiboly,” IST
Austria, 2014.
ista: Behrndt M. 2014. Forces driving epithelial spreading in zebrafish epiboly.
IST Austria.
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.
date_created: 2018-12-11T11:51:49Z
date_published: 2014-08-01T00:00:00Z
date_updated: 2023-10-17T12:16:58Z
day: '01'
department:
- _id: CaHe
language:
- iso: eng
month: '08'
oa_version: None
page: '91'
publication_status: published
publisher: IST Austria
publist_id: '5804'
related_material:
record:
- id: '2282'
relation: part_of_dissertation
status: public
- id: '2950'
relation: part_of_dissertation
status: public
- id: '3373'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: Forces driving epithelial spreading in zebrafish epiboly
type: dissertation
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2014'
...
---
_id: '1406'
abstract:
- lang: eng
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.
acknowledged_ssus:
- _id: Bio
- _id: PreCl
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Pedro
full_name: Campinho, Pedro
id: 3AFBBC42-F248-11E8-B48F-1D18A9856A87
last_name: Campinho
orcid: 0000-0002-8526-5416
citation:
ama: 'Campinho P. Mechanics of zebrafish epiboly: Tension-oriented cell divisions
limit anisotropic tissue tension in epithelial spreading. 2013.'
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.'
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.'
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.'
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.'
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.'
date_created: 2018-12-11T11:51:50Z
date_published: 2013-10-01T00:00:00Z
date_updated: 2023-09-07T11:36:07Z
day: '01'
degree_awarded: PhD
department:
- _id: CaHe
language:
- iso: eng
month: '10'
oa_version: None
page: '123'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '5801'
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: 'Mechanics of zebrafish epiboly: Tension-oriented cell divisions limit anisotropic
tissue tension in epithelial spreading'
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2013'
...
---
_id: '3273'
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Jean-Léon
full_name: Maître, Jean-Léon
id: 48F1E0D8-F248-11E8-B48F-1D18A9856A87
last_name: Maître
orcid: 0000-0002-3688-1474
citation:
ama: Maître J-L. Mechanics of adhesion and de‐adhesion in zebrafish germ layer progenitors.
2011.
apa: Maître, J.-L. (2011). Mechanics of adhesion and de‐adhesion in zebrafish
germ layer progenitors. Institute of Science and Technology Austria.
chicago: Maître, Jean-Léon. “Mechanics of Adhesion and De‐adhesion in Zebrafish
Germ Layer Progenitors.” Institute of Science and Technology Austria, 2011.
ieee: J.-L. Maître, “Mechanics of adhesion and de‐adhesion in zebrafish germ layer
progenitors,” Institute of Science and Technology Austria, 2011.
ista: Maître J-L. 2011. Mechanics of adhesion and de‐adhesion in zebrafish germ
layer progenitors. Institute of Science and Technology Austria.
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.
date_created: 2018-12-11T12:02:23Z
date_published: 2011-12-12T00:00:00Z
date_updated: 2023-09-07T11:30:16Z
day: '12'
degree_awarded: PhD
department:
- _id: CaHe
language:
- iso: eng
month: '12'
oa_version: None
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '3373'
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: Mechanics of adhesion and de‐adhesion in zebrafish germ layer progenitors
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2011'
...
---
_id: '3962'
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Holger
full_name: Pflicke, Holger
id: CAA57A9A-5B61-11E9-B130-E0C1E1F2C83D
last_name: Pflicke
citation:
ama: Pflicke H. Dendritic cell migration across basement membranes in the skin.
2010.
apa: Pflicke, H. (2010). Dendritic cell migration across basement membranes
in the skin. Institute of Science and Technology Austria.
chicago: Pflicke, Holger. “ Dendritic Cell Migration across Basement Membranes
in the Skin.” Institute of Science and Technology Austria, 2010.
ieee: H. Pflicke, “ Dendritic cell migration across basement membranes in the skin,”
Institute of Science and Technology Austria, 2010.
ista: 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.
date_created: 2018-12-11T12:06:08Z
date_published: 2010-07-01T00:00:00Z
date_updated: 2023-09-07T11:28:47Z
day: '01'
degree_awarded: PhD
department:
- _id: CaHe
- _id: GradSch
language:
- iso: eng
month: '07'
oa_version: None
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '2165'
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: "\uFEFF\uFEFFDendritic cell migration across basement membranes in the skin"
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2010'
...