---
_id: '12716'
abstract:
- lang: eng
text: "The process of detecting and evaluating sensory information to guide behaviour
is termed perceptual decision-making (PDM), and is critical for the ability of
an organism to interact with its external world. Individuals with autism, a neurodevelopmental
condition primarily characterised by social and communication difficulties, frequently
exhibit altered sensory processing and PDM difficulties are widely reported. Recent
technological advancements have pushed forward our understanding of the genetic
changes accompanying this condition, however our understanding of how these mutations
affect the function of specific neuronal circuits and bring about the corresponding
behavioural changes remains limited. Here, we use an innate PDM task, the looming
avoidance response (LAR) paradigm, to identify a convergent behavioural abnormality
across three molecularly distinct genetic mouse models of autism (Cul3, Setd5
and Ptchd1). Although mutant mice can rapidly detect threatening visual stimuli,
their responses are consistently delayed, requiring longer to initiate an appropriate
response than their wild-type siblings. Mutant animals show abnormal adaptation
in both their stimulus- evoked escape responses and exploratory dynamics following
repeated stimulus presentations. Similarly delayed behavioural responses are observed
in wild-type animals when faced with more ambiguous threats, suggesting the mutant
phenotype could arise from a dysfunction in the flexible control of this PDM process.\r\nOur
knowledge of the core neuronal circuitry mediating the LAR facilitated a detailed
dissection of the neuronal mechanisms underlying the behavioural impairment. In
vivo extracellular recording revealed that visual responses were unaffected within
a key brain region for the rapid processing of visual threats, the superior colliculus
(SC), indicating that the behavioural delay was unlikely to originate from sensory
impairments. Delayed behavioural responses were recapitulated in the Setd5 model
following optogenetic stimulation of the excitatory output neurons of the SC,
which are known to mediate escape initiation through the activation of cells in
the underlying dorsal periaqueductal grey (dPAG). In vitro patch-clamp recordings
of dPAG cells uncovered a stark hypoexcitability phenotype in two out of the three
genetic models investigated (Setd5 and Ptchd1), that in Setd5, is mediated by
the misregulation of voltage-gated potassium channels. Overall, our results show
that the ability to use visual information to drive efficient escape responses
is impaired in three diverse genetic mouse models of autism and that, in one of
the models studied, this behavioural delay likely originates from differences
in the intrinsic excitability of a key subcortical node, the dPAG. Furthermore,
this work showcases the use of an innate behavioural paradigm to mechanistically
dissect PDM processes in autism."
acknowledged_ssus:
- _id: PreCl
- _id: Bio
- _id: LifeSc
- _id: M-Shop
- _id: CampIT
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Laura
full_name: Burnett, Laura
id: 3B717F68-F248-11E8-B48F-1D18A9856A87
last_name: Burnett
orcid: 0000-0002-8937-410X
citation:
ama: Burnett L. To flee, or not to flee? Using innate defensive behaviours to investigate
rapid perceptual decision-making through subcortical circuits in mouse models
of autism. 2023. doi:10.15479/at:ista:12716
apa: Burnett, L. (2023). To flee, or not to flee? Using innate defensive behaviours
to investigate rapid perceptual decision-making through subcortical circuits in
mouse models of autism. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:12716
chicago: Burnett, Laura. “To Flee, or Not to Flee? Using Innate Defensive Behaviours
to Investigate Rapid Perceptual Decision-Making through Subcortical Circuits in
Mouse Models of Autism.” Institute of Science and Technology Austria, 2023. https://doi.org/10.15479/at:ista:12716.
ieee: L. Burnett, “To flee, or not to flee? Using innate defensive behaviours to
investigate rapid perceptual decision-making through subcortical circuits in mouse
models of autism,” Institute of Science and Technology Austria, 2023.
ista: Burnett L. 2023. To flee, or not to flee? Using innate defensive behaviours
to investigate rapid perceptual decision-making through subcortical circuits in
mouse models of autism. Institute of Science and Technology Austria.
mla: Burnett, Laura. To Flee, or Not to Flee? Using Innate Defensive Behaviours
to Investigate Rapid Perceptual Decision-Making through Subcortical Circuits in
Mouse Models of Autism. Institute of Science and Technology Austria, 2023,
doi:10.15479/at:ista:12716.
short: L. Burnett, To Flee, or Not to Flee? Using Innate Defensive Behaviours to
Investigate Rapid Perceptual Decision-Making through Subcortical Circuits in Mouse
Models of Autism, Institute of Science and Technology Austria, 2023.
date_created: 2023-03-08T15:19:45Z
date_published: 2023-03-10T00:00:00Z
date_updated: 2023-04-05T10:59:04Z
day: '10'
ddc:
- '599'
- '573'
degree_awarded: PhD
department:
- _id: GradSch
- _id: MaJö
doi: 10.15479/at:ista:12716
ec_funded: 1
file:
- access_level: closed
checksum: 6c6d9cc2c4cdacb74e6b1047a34d7332
content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
creator: lburnett
date_created: 2023-03-08T15:08:46Z
date_updated: 2023-03-08T15:08:46Z
file_id: '12717'
file_name: Burnett_Thesis_2023.docx
file_size: 23029260
relation: source_file
- access_level: open_access
checksum: cebc77705288bf4382db9b3541483cd0
content_type: application/pdf
creator: lburnett
date_created: 2023-03-08T15:08:46Z
date_updated: 2023-03-08T15:08:46Z
file_id: '12718'
file_name: Burnett_Thesis_2023_pdfA.pdf
file_size: 11959869
relation: main_file
success: 1
file_date_updated: 2023-03-08T15:08:46Z
has_accepted_license: '1'
language:
- iso: eng
month: '03'
oa: 1
oa_version: Published Version
page: '178'
project:
- _id: 2634E9D2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '756502'
name: Circuits of Visual Attention
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
status: public
supervisor:
- first_name: Maximilian A
full_name: Jösch, Maximilian A
id: 2BD278E6-F248-11E8-B48F-1D18A9856A87
last_name: Jösch
orcid: 0000-0002-3937-1330
title: To flee, or not to flee? Using innate defensive behaviours to investigate rapid
perceptual decision-making through subcortical circuits in mouse models of autism
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '12781'
abstract:
- lang: eng
text: "Most energy in humans is produced in form of ATP by the mitochondrial respiratory
chain consisting of several protein assemblies embedded into lipid membrane (complexes
I-V). Complex I is the first and the largest enzyme of the respiratory chain which
is essential for energy production. It couples the transfer of two electrons from
NADH to ubiquinone with proton translocation across bacterial or inner mitochondrial
membrane. The coupling mechanism between electron transfer and proton translocation
is one of the biggest enigma in bioenergetics and structural biology. Even though
the enzyme has been studied for decades, only recent technological advances in
cryo-EM allowed its extensive structural investigation. \r\n\r\nComplex I from
E.coli appears to be of special importance because it is a perfect model system
with a rich mutant library, however the structure of the entire complex was unknown.
In this thesis I have resolved structures of the minimal complex I version from
E. coli in different states including reduced, inhibited, under reaction turnover
and several others. Extensive structural analyses of these structures and comparison
to structures from other species allowed to derive general features of conformational
dynamics and propose a universal coupling mechanism. The mechanism is straightforward,
robust and consistent with decades of experimental data available for complex
I from different species. \r\n\r\nCyanobacterial NDH (cyanobacterial complex I)
is a part of broad complex I superfamily and was studied as well in this thesis.
It plays an important role in cyclic electron transfer (CET), during which electrons
are cycled within PSI through ferredoxin and plastoquinone to generate proton
gradient without NADPH production. Here, I solved structure of NDH and revealed
additional state, which was not observed before. The novel “resting” state allowed
to propose the mechanism of CET regulation. Moreover, conformational dynamics
of NDH resembles one in complex I which suggest more broad universality of the
proposed coupling mechanism.\r\n\r\nIn summary, results presented here helped
to interpret decades of experimental data for complex I and contributed to fundamental
mechanistic understanding of protein function.\r\n"
acknowledged_ssus:
- _id: EM-Fac
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Vladyslav
full_name: Kravchuk, Vladyslav
id: 4D62F2A6-F248-11E8-B48F-1D18A9856A87
last_name: Kravchuk
citation:
ama: Kravchuk V. Structural and mechanistic study of bacterial complex I and its
cyanobacterial ortholog. 2023. doi:10.15479/at:ista:12781
apa: Kravchuk, V. (2023). Structural and mechanistic study of bacterial complex
I and its cyanobacterial ortholog. Institute of Science and Technology Austria.
https://doi.org/10.15479/at:ista:12781
chicago: Kravchuk, Vladyslav. “Structural and Mechanistic Study of Bacterial Complex
I and Its Cyanobacterial Ortholog.” Institute of Science and Technology Austria,
2023. https://doi.org/10.15479/at:ista:12781.
ieee: V. Kravchuk, “Structural and mechanistic study of bacterial complex I and
its cyanobacterial ortholog,” Institute of Science and Technology Austria, 2023.
ista: Kravchuk V. 2023. Structural and mechanistic study of bacterial complex I
and its cyanobacterial ortholog. Institute of Science and Technology Austria.
mla: Kravchuk, Vladyslav. Structural and Mechanistic Study of Bacterial Complex
I and Its Cyanobacterial Ortholog. Institute of Science and Technology Austria,
2023, doi:10.15479/at:ista:12781.
short: V. Kravchuk, Structural and Mechanistic Study of Bacterial Complex I and
Its Cyanobacterial Ortholog, Institute of Science and Technology Austria, 2023.
date_created: 2023-03-31T12:24:42Z
date_published: 2023-03-23T00:00:00Z
date_updated: 2023-08-04T08:54:51Z
day: '23'
ddc:
- '570'
- '572'
degree_awarded: PhD
department:
- _id: GradSch
- _id: LeSa
doi: 10.15479/at:ista:12781
ec_funded: 1
file:
- access_level: closed
checksum: 5ebb6345cb4119f93460c81310265a6d
content_type: application/pdf
creator: vkravchu
date_created: 2023-04-19T14:33:41Z
date_updated: 2023-04-19T14:33:41Z
embargo: 2024-04-20
embargo_to: local
file_id: '12852'
file_name: VladyslavKravchuk_PhD_Thesis_PostSub_Final_1.pdf
file_size: 6071553
relation: main_file
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content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
creator: vkravchu
date_created: 2023-04-19T14:33:52Z
date_updated: 2023-04-20T07:02:59Z
embargo: 2024-04-20
embargo_to: local
file_id: '12853'
file_name: VladyslavKravchuk_PhD_Thesis_PostSub_Final.docx
file_size: 19468766
relation: source_file
file_date_updated: 2023-04-20T07:02:59Z
has_accepted_license: '1'
language:
- iso: eng
month: '03'
oa_version: Published Version
page: '127'
project:
- _id: 238A0A5A-32DE-11EA-91FC-C7463DDC885E
grant_number: '25541'
name: 'Structural characterization of E. coli complex I: an important mechanistic
model'
- _id: 627abdeb-2b32-11ec-9570-ec31a97243d3
call_identifier: H2020
grant_number: '101020697'
name: Structure and mechanism of respiratory chain molecular machines
publication_identifier:
isbn:
- 978-3-99078-029-9
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '12138'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Leonid A
full_name: Sazanov, Leonid A
id: 338D39FE-F248-11E8-B48F-1D18A9856A87
last_name: Sazanov
orcid: 0000-0002-0977-7989
title: Structural and mechanistic study of bacterial complex I and its cyanobacterial
ortholog
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '13074'
abstract:
- lang: eng
text: "Deep learning has become an integral part of a large number of important
applications, and many of the recent breakthroughs have been enabled by the ability
to train very large models, capable to capture complex patterns and relationships
from the data. At the same time, the massive sizes of modern deep learning models
have made their deployment to smaller devices more challenging; this is particularly
important, as in many applications the users rely on accurate deep learning predictions,
but they only have access to devices with limited memory and compute power. One
solution to this problem is to prune neural networks, by setting as many of their
parameters as possible to zero, to obtain accurate sparse models with lower memory
footprint. Despite the great research progress in obtaining sparse models that
preserve accuracy, while satisfying memory and computational constraints, there
are still many challenges associated with efficiently training sparse models,
as well as understanding their generalization properties.\r\n\r\nThe focus of
this thesis is to investigate how the training process of sparse models can be
made more efficient, and to understand the differences between sparse and dense
models in terms of how well they can generalize to changes in the data distribution.
We first study a method for co-training sparse and dense models, at a lower cost
compared to regular training. With our method we can obtain very accurate sparse
networks, and dense models that can recover the baseline accuracy. Furthermore,
we are able to more easily analyze the differences, at prediction level, between
the sparse-dense model pairs. Next, we investigate the generalization properties
of sparse neural networks in more detail, by studying how well different sparse
models trained on a larger task can adapt to smaller, more specialized tasks,
in a transfer learning scenario. Our analysis across multiple pruning methods
and sparsity levels reveals that sparse models provide features that can transfer
similarly to or better than the dense baseline. However, the choice of the pruning
method plays an important role, and can influence the results when the features
are fixed (linear finetuning), or when they are allowed to adapt to the new task
(full finetuning). Using sparse models with fixed masks for finetuning on new
tasks has an important practical advantage, as it enables training neural networks
on smaller devices. However, one drawback of current pruning methods is that the
entire training cycle has to be repeated to obtain the initial sparse model, for
every sparsity target; in consequence, the entire training process is costly and
also multiple models need to be stored. In the last part of the thesis we propose
a method that can train accurate dense models that are compressible in a single
step, to multiple sparsity levels, without additional finetuning. Our method results
in sparse models that can be competitive with existing pruning methods, and which
can also successfully generalize to new tasks."
acknowledged_ssus:
- _id: ScienComp
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Elena-Alexandra
full_name: Peste, Elena-Alexandra
id: 32D78294-F248-11E8-B48F-1D18A9856A87
last_name: Peste
citation:
ama: Peste E-A. Efficiency and generalization of sparse neural networks. 2023. doi:10.15479/at:ista:13074
apa: Peste, E.-A. (2023). Efficiency and generalization of sparse neural networks.
Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:13074
chicago: Peste, Elena-Alexandra. “Efficiency and Generalization of Sparse Neural
Networks.” Institute of Science and Technology Austria, 2023. https://doi.org/10.15479/at:ista:13074.
ieee: E.-A. Peste, “Efficiency and generalization of sparse neural networks,” Institute
of Science and Technology Austria, 2023.
ista: Peste E-A. 2023. Efficiency and generalization of sparse neural networks.
Institute of Science and Technology Austria.
mla: Peste, Elena-Alexandra. Efficiency and Generalization of Sparse Neural Networks.
Institute of Science and Technology Austria, 2023, doi:10.15479/at:ista:13074.
short: E.-A. Peste, Efficiency and Generalization of Sparse Neural Networks, Institute
of Science and Technology Austria, 2023.
date_created: 2023-05-23T17:07:53Z
date_published: 2023-05-23T00:00:00Z
date_updated: 2023-08-04T10:33:27Z
day: '23'
ddc:
- '000'
degree_awarded: PhD
department:
- _id: GradSch
- _id: DaAl
- _id: ChLa
doi: 10.15479/at:ista:13074
ec_funded: 1
file:
- access_level: open_access
checksum: 6b3354968403cb9d48cc5a83611fb571
content_type: application/pdf
creator: epeste
date_created: 2023-05-24T16:11:16Z
date_updated: 2023-05-24T16:11:16Z
file_id: '13087'
file_name: PhD_Thesis_Alexandra_Peste_final.pdf
file_size: 2152072
relation: main_file
success: 1
- access_level: closed
checksum: 8d0df94bbcf4db72c991f22503b3fd60
content_type: application/zip
creator: epeste
date_created: 2023-05-24T16:12:59Z
date_updated: 2023-05-24T16:12:59Z
file_id: '13088'
file_name: PhD_Thesis_APeste.zip
file_size: 1658293
relation: source_file
file_date_updated: 2023-05-24T16:12:59Z
has_accepted_license: '1'
language:
- iso: eng
month: '05'
oa: 1
oa_version: Published Version
page: '147'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '665385'
name: International IST Doctoral Program
- _id: 268A44D6-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '805223'
name: Elastic Coordination for Scalable Machine Learning
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '11458'
relation: part_of_dissertation
status: public
- id: '13053'
relation: part_of_dissertation
status: public
- id: '12299'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Christoph
full_name: Lampert, Christoph
id: 40C20FD2-F248-11E8-B48F-1D18A9856A87
last_name: Lampert
orcid: 0000-0001-8622-7887
- first_name: Dan-Adrian
full_name: Alistarh, Dan-Adrian
id: 4A899BFC-F248-11E8-B48F-1D18A9856A87
last_name: Alistarh
orcid: 0000-0003-3650-940X
title: Efficiency and generalization of sparse neural networks
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '12964'
abstract:
- lang: eng
text: "Pattern formation is of great importance for its contribution across different
biological behaviours. During developmental processes for example, patterns of
chemical gradients are\r\nestablished to determine cell fate and complex tissue
patterns emerge to define structures such\r\nas limbs and vascular networks. Patterns
are also seen in collectively migrating groups, for\r\ninstance traveling waves
of density emerging in moving animal flocks as well as collectively migrating
cells and tissues. To what extent these biological patterns arise spontaneously
through\r\nthe local interaction of individual constituents or are dictated by
higher level instructions is\r\nstill an open question however there is evidence
for the involvement of both types of process.\r\nWhere patterns arise spontaneously
there is a long standing interest in how far the interplay\r\nof mechanics, e.g.
force generation and deformation, and chemistry, e.g. gene regulation\r\nand signaling,
contributes to the behaviour. This is because many systems are able to both\r\nchemically
regulate mechanical force production and chemically sense mechanical deformation,\r\nforming
mechano-chemical feedback loops which can potentially become unstable towards\r\nspatio
and/or temporal patterning.\r\nWe work with experimental collaborators to investigate
the possibility that this type of\r\ninteraction drives pattern formation in biological
systems at different scales. We focus first on\r\ntissue-level ERK-density waves
observed during the wound healing response across different\r\nsystems where many
previous studies have proposed that patterns depend on polarized cell\r\nmigration
and arise from a mechanical flocking-like mechanism. By combining theory with\r\nmechanical
and optogenetic perturbation experiments on in vitro monolayers we instead find\r\nevidence
for mechanochemical pattern formation involving only scalar bilateral feedbacks\r\nbetween
ERK signaling and cell contraction. We perform further modeling and experiment\r\nto
study how this instability couples with polar cell migration in order to produce
a robust\r\nand efficient wound healing response. In a following chapter we implement
ERK-density\r\ncoupling and cell migration in a 2D active vertex model to investigate
the interaction of\r\nERK-density patterning with different tissue rheologies
and find that the spatio-temporal\r\ndynamics are able to both locally and globally
fluidize a tissue across the solid-fluid glass\r\ntransition. In a last chapter
we move towards lower spatial scales in the context of subcellular\r\npatterning
of the cell cytoskeleton where we investigate the transition between phases of\r\nspatially
homogeneous temporal oscillations and chaotic spatio-temporal patterning in the\r\ndynamics
of myosin and ROCK activities (a motor component of the actomyosin cytoskeleton\r\nand
its activator). Experimental evidence supports an intrinsic chemical oscillator
which we\r\nencode in a reaction model and couple to a contractile active gel
description of the cell cortex.\r\nThe model exhibits phases of chemical oscillations
and contractile spatial patterning which\r\nreproduce many features of the dynamics
seen in Drosophila oocyte epithelia in vivo. However,\r\nadditional pharmacological
perturbations to inhibit myosin contractility leaves the role of\r\ncontractile
instability unclear. We discuss alternative hypotheses and investigate the possibility\r\nof
reaction-diffusion instability."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Daniel R
full_name: Boocock, Daniel R
id: 453AF628-F248-11E8-B48F-1D18A9856A87
last_name: Boocock
orcid: 0000-0002-1585-2631
citation:
ama: Boocock DR. Mechanochemical pattern formation across biological scales. 2023.
doi:10.15479/at:ista:12964
apa: Boocock, D. R. (2023). Mechanochemical pattern formation across biological
scales. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:12964
chicago: Boocock, Daniel R. “Mechanochemical Pattern Formation across Biological
Scales.” Institute of Science and Technology Austria, 2023. https://doi.org/10.15479/at:ista:12964.
ieee: D. R. Boocock, “Mechanochemical pattern formation across biological scales,”
Institute of Science and Technology Austria, 2023.
ista: Boocock DR. 2023. Mechanochemical pattern formation across biological scales.
Institute of Science and Technology Austria.
mla: Boocock, Daniel R. Mechanochemical Pattern Formation across Biological Scales.
Institute of Science and Technology Austria, 2023, doi:10.15479/at:ista:12964.
short: D.R. Boocock, Mechanochemical Pattern Formation across Biological Scales,
Institute of Science and Technology Austria, 2023.
date_created: 2023-05-15T14:52:36Z
date_published: 2023-05-17T00:00:00Z
date_updated: 2023-08-04T11:02:40Z
day: '17'
ddc:
- '530'
degree_awarded: PhD
department:
- _id: GradSch
- _id: EdHa
doi: 10.15479/at:ista:12964
ec_funded: 1
file:
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content_type: application/pdf
creator: dboocock
date_created: 2023-05-17T13:39:54Z
date_updated: 2023-05-19T07:04:25Z
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embargo_to: open_access
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creator: dboocock
date_created: 2023-05-17T13:39:53Z
date_updated: 2023-05-17T14:35:13Z
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relation: source_file
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has_accepted_license: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by-nc-sa/4.0/
month: '05'
oa_version: Published Version
page: '146'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '665385'
name: International IST Doctoral Program
publication_identifier:
isbn:
- 978-3-99078-032-9
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '8602'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Edouard B
full_name: Hannezo, Edouard B
id: 3A9DB764-F248-11E8-B48F-1D18A9856A87
last_name: Hannezo
orcid: 0000-0001-6005-1561
title: Mechanochemical pattern formation across biological scales
tmp:
image: /images/cc_by_nc_sa.png
legal_code_url: https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode
name: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC
BY-NC-SA 4.0)
short: CC BY-NC-SA (4.0)
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '12885'
abstract:
- lang: eng
text: 'High-performance semiconductors rely upon precise control of heat and charge
transport. This can be achieved by precisely engineering defects in polycrystalline
solids. There are multiple approaches to preparing such polycrystalline semiconductors,
and the transformation of solution-processed colloidal nanoparticles is appealing
because colloidal nanoparticles combine low cost with structural and compositional
tunability along with rich surface chemistry. However, the multiple processes
from nanoparticle synthesis to the final bulk nanocomposites are very complex.
They involve nanoparticle purification, post-synthetic modifications, and finally
consolidation (thermal treatments and densification). All these properties dictate
the final material’s composition and microstructure, ultimately affecting its
functional properties. This thesis explores the synthesis, surface chemistry and
consolidation of colloidal semiconductor nanoparticles into dense solids. In particular,
the transformations that take place during these processes, and their effect on
the material’s transport properties are evaluated. '
acknowledged_ssus:
- _id: EM-Fac
- _id: NanoFab
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Mariano
full_name: Calcabrini, Mariano
id: 45D7531A-F248-11E8-B48F-1D18A9856A87
last_name: Calcabrini
orcid: 0000-0003-4566-5877
citation:
ama: 'Calcabrini M. Nanoparticle-based semiconductor solids: From synthesis to consolidation.
2023. doi:10.15479/at:ista:12885'
apa: 'Calcabrini, M. (2023). Nanoparticle-based semiconductor solids: From synthesis
to consolidation. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:12885'
chicago: 'Calcabrini, Mariano. “Nanoparticle-Based Semiconductor Solids: From Synthesis
to Consolidation.” Institute of Science and Technology Austria, 2023. https://doi.org/10.15479/at:ista:12885.'
ieee: 'M. Calcabrini, “Nanoparticle-based semiconductor solids: From synthesis to
consolidation,” Institute of Science and Technology Austria, 2023.'
ista: 'Calcabrini M. 2023. Nanoparticle-based semiconductor solids: From synthesis
to consolidation. Institute of Science and Technology Austria.'
mla: 'Calcabrini, Mariano. Nanoparticle-Based Semiconductor Solids: From Synthesis
to Consolidation. Institute of Science and Technology Austria, 2023, doi:10.15479/at:ista:12885.'
short: 'M. Calcabrini, Nanoparticle-Based Semiconductor Solids: From Synthesis to
Consolidation, Institute of Science and Technology Austria, 2023.'
date_created: 2023-05-02T07:58:57Z
date_published: 2023-04-28T00:00:00Z
date_updated: 2023-08-14T07:25:26Z
day: '28'
ddc:
- '546'
- '541'
degree_awarded: PhD
department:
- _id: GradSch
- _id: MaIb
doi: 10.15479/at:ista:12885
ec_funded: 1
file:
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date_updated: 2023-05-02T07:43:18Z
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file_date_updated: 2023-05-02T07:43:18Z
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language:
- iso: eng
month: '04'
oa: 1
oa_version: Published Version
page: '82'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '665385'
name: International IST Doctoral Program
publication_identifier:
isbn:
- 978-3-99078-028-2
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '10806'
relation: part_of_dissertation
status: public
- id: '10042'
relation: part_of_dissertation
status: public
- id: '12237'
relation: part_of_dissertation
status: public
- id: '9118'
relation: part_of_dissertation
status: public
- id: '10123'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Maria
full_name: Ibáñez, Maria
id: 43C61214-F248-11E8-B48F-1D18A9856A87
last_name: Ibáñez
orcid: 0000-0001-5013-2843
title: 'Nanoparticle-based semiconductor solids: From synthesis to consolidation'
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '12732'
abstract:
- lang: eng
text: "Nonergodic systems, whose out-of-equilibrium dynamics fail to thermalize,
provide a fascinating research direction both for fundamental reasons and for
application in state of the art quantum devices.\r\nGoing beyond the description
of statistical mechanics, ergodicity breaking yields a new paradigm in quantum
many-body physics, introducing novel phases of matter with no counterpart at equilibrium.\r\nIn
this Thesis, we address different open questions in the field, focusing on disorder-induced
many-body localization (MBL) and on weak ergodicity breaking in kinetically constrained
models.\r\nIn particular, we contribute to the debate about transport in kinetically
constrained models, studying the effect of $U(1)$ conservation and inversion-symmetry
breaking in a family of quantum East models.\r\nUsing tensor network techniques,
we analyze the dynamics of large MBL systems beyond the limit of exact numerical
methods.\r\nIn this setting, we approach the debated topic of the coexistence
of localized and thermal eigenstates separated by energy thresholds known as many-body
mobility edges.\r\nInspired by recent experiments, our work further investigates
the localization of a small bath induced by the coupling to a large localized
chain, the so-called MBL proximity effect.\r\n\r\nIn the first Chapter, we introduce
a family of particle-conserving kinetically constrained models, inspired by the
quantum East model.\r\nThe system we study features strong inversion-symmetry
breaking, due to the nature of the correlated hopping.\r\nWe show that these models
host so-called quantum Hilbert space fragmentation, consisting of disconnected
subsectors in an entangled basis, and further provide an analytical description
of this phenomenon.\r\nWe further probe its effect on dynamics of simple product
states, showing revivals in fidelity and local observalbes.\r\nThe study of dynamics
within the largest subsector reveals an anomalous transient superdiffusive behavior
crossing over to slow logarithmic dynamics at later times.\r\nThis work suggests
that particle conserving constrained models with inversion-symmetry breaking realize
new universality classes of dynamics and invite their further theoretical and
experimental studies.\r\n\r\nNext, we use kinetic constraints and disorder to
design a model with many-body mobility edges in particle density.\r\nThis feature
allows to study the dynamics of localized and thermal states in large systems
beyond the limitations of previous studies.\r\nThe time-evolution shows typical
signatures of localization at small densities, replaced by thermal behavior at
larger densities.\r\nOur results provide evidence in favor of the stability of
many-body mobility edges, which was recently challenged by a theoretical argument.\r\nTo
support our findings, we probe the mechanism proposed as a cause of delocalization
in many-body localized systems with mobility edges suggesting its ineffectiveness
in the model studied.\r\n\r\nIn the last Chapter of this Thesis, we address the
topic of many-body localization proximity effect.\r\nWe study a model inspired
by recent experiments, featuring Anderson localized coupled to a small bath of
free hard-core bosons.\r\nThe interaction among the two particle species results
in non-trivial dynamics, which we probe using tensor network techniques.\r\nOur
simulations show convincing evidence of many-body localization proximity effect
when the bath is composed by a single free particle and interactions are strong.\r\nWe
furthter observe an anomalous entanglement dynamics, which we explain through
a phenomenological theory.\r\nFinally, we extract highly excited eigenstates of
large systems, providing supplementary evidence in favor of our findings."
acknowledged_ssus:
- _id: ScienComp
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Pietro
full_name: Brighi, Pietro
id: 4115AF5C-F248-11E8-B48F-1D18A9856A87
last_name: Brighi
orcid: 0000-0002-7969-2729
citation:
ama: Brighi P. Ergodicity breaking in disordered and kinetically constrained quantum
many-body systems. 2023. doi:10.15479/at:ista:12732
apa: Brighi, P. (2023). Ergodicity breaking in disordered and kinetically constrained
quantum many-body systems. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:12732
chicago: Brighi, Pietro. “Ergodicity Breaking in Disordered and Kinetically Constrained
Quantum Many-Body Systems.” Institute of Science and Technology Austria, 2023.
https://doi.org/10.15479/at:ista:12732.
ieee: P. Brighi, “Ergodicity breaking in disordered and kinetically constrained
quantum many-body systems,” Institute of Science and Technology Austria, 2023.
ista: Brighi P. 2023. Ergodicity breaking in disordered and kinetically constrained
quantum many-body systems. Institute of Science and Technology Austria.
mla: Brighi, Pietro. Ergodicity Breaking in Disordered and Kinetically Constrained
Quantum Many-Body Systems. Institute of Science and Technology Austria, 2023,
doi:10.15479/at:ista:12732.
short: P. Brighi, Ergodicity Breaking in Disordered and Kinetically Constrained
Quantum Many-Body Systems, Institute of Science and Technology Austria, 2023.
date_created: 2023-03-17T13:30:48Z
date_published: 2023-03-21T00:00:00Z
date_updated: 2023-09-20T10:44:12Z
day: '21'
ddc:
- '530'
degree_awarded: PhD
department:
- _id: GradSch
- _id: MaSe
doi: 10.15479/at:ista:12732
ec_funded: 1
file:
- access_level: closed
checksum: 5d2de651ef9449c1b8dc27148ca74777
content_type: application/zip
creator: pbrighi
date_created: 2023-03-23T16:42:56Z
date_updated: 2023-03-23T16:42:56Z
file_id: '12753'
file_name: Thesis_sub_PBrighi.zip
file_size: 42167561
relation: source_file
- access_level: open_access
checksum: 7caa153d4a5b0873a79358787d2dfe1e
content_type: application/pdf
creator: pbrighi
date_created: 2023-03-23T16:43:14Z
date_updated: 2023-03-23T16:43:14Z
file_id: '12754'
file_name: Thesis_PBrighi.pdf
file_size: 13977000
relation: main_file
success: 1
file_date_updated: 2023-03-23T16:43:14Z
has_accepted_license: '1'
language:
- iso: eng
month: '03'
oa: 1
oa_version: None
page: '158'
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
call_identifier: H2020
grant_number: '850899'
name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '11470'
relation: part_of_dissertation
status: public
- id: '8308'
relation: part_of_dissertation
status: public
- id: '11469'
relation: part_of_dissertation
status: public
- id: '12750'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
title: Ergodicity breaking in disordered and kinetically constrained quantum many-body
systems
tmp:
image: /images/cc_by_nc_sa.png
legal_code_url: https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode
name: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC
BY-NC-SA 4.0)
short: CC BY-NC-SA (4.0)
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '12726'
abstract:
- lang: eng
text: "Most motions of many-body systems at any scale in nature with sufficient
degrees\r\nof freedom tend to be chaotic; reaching from the orbital motion of
planets, the air\r\ncurrents in our atmosphere, down to the water flowing through
our pipelines or\r\nthe movement of a population of bacteria. To the observer
it is therefore intriguing\r\nwhen a moving collective exhibits order. Collective
motion of flocks of birds, schools\r\nof fish or swarms of self-propelled particles
or robots have been studied extensively\r\nover the past decades but the mechanisms
involved in the transition from chaos to\r\norder remain unclear. Here, the interactions,
that in most systems give rise to chaos,\r\nsustain order. In this thesis we investigate
mechanisms that preserve, destabilize\r\nor lead to the ordered state. We show
that endothelial cells migrating in circular\r\nconfinements transition to a collective
rotating state and concomitantly synchronize\r\nthe frequencies of nucleating
actin waves within individual cells. Consequently,\r\nthe frequency dependent
cell migration speed uniformizes across the population.\r\nComplementary to the
WAVE dependent nucleation of traveling actin waves, we\r\nshow that in leukocytes
the actin polymerization depending on WASp generates\r\npushing forces locally
at stationary patches. Next, in pipe flows, we study methods\r\nto disrupt the
self–sustaining cycle of turbulence and therefore relaminarize the\r\nflow. While
we find in pulsating flow conditions that turbulence emerges through a\r\nhelical
instability during the decelerating phase. Finally, we show quantitatively in\r\nbrain
slices of mice that wild-type control neurons can compensate the migratory\r\ndeficits
of a genetically modified neuronal sub–population in the developing cortex."
acknowledged_ssus:
- _id: M-Shop
- _id: Bio
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Michael
full_name: Riedl, Michael
id: 3BE60946-F248-11E8-B48F-1D18A9856A87
last_name: Riedl
orcid: 0000-0003-4844-6311
citation:
ama: Riedl M. Synchronization in collectively moving active matter. 2023. doi:10.15479/at:ista:12726
apa: Riedl, M. (2023). Synchronization in collectively moving active matter.
Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:12726
chicago: Riedl, Michael. “Synchronization in Collectively Moving Active Matter.”
Institute of Science and Technology Austria, 2023. https://doi.org/10.15479/at:ista:12726.
ieee: M. Riedl, “Synchronization in collectively moving active matter,” Institute
of Science and Technology Austria, 2023.
ista: Riedl M. 2023. Synchronization in collectively moving active matter. Institute
of Science and Technology Austria.
mla: Riedl, Michael. Synchronization in Collectively Moving Active Matter.
Institute of Science and Technology Austria, 2023, doi:10.15479/at:ista:12726.
short: M. Riedl, Synchronization in Collectively Moving Active Matter, Institute
of Science and Technology Austria, 2023.
date_created: 2023-03-15T13:22:13Z
date_published: 2023-03-23T00:00:00Z
date_updated: 2023-11-30T10:55:13Z
day: '23'
ddc:
- '530'
degree_awarded: PhD
department:
- _id: GradSch
- _id: BjHo
doi: 10.15479/at:ista:12726
file:
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checksum: eba0e19fe57a8c15e7aeab55a845efb7
content_type: application/pdf
creator: cchlebak
date_created: 2023-03-23T12:49:23Z
date_updated: 2023-11-24T11:57:46Z
description: the main file is missing the bibliography. See new thesis record 14530
for updated files.
file_id: '12745'
file_name: Thesis_Riedl_2023.pdf
file_size: 63734746
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creator: cchlebak
date_created: 2023-03-23T12:54:34Z
date_updated: 2023-09-24T22:30:03Z
embargo_to: open_access
file_id: '12746'
file_name: Thesis_Riedl_2023_source.rar
file_size: 339473651
relation: source_file
file_date_updated: 2023-11-24T11:57:46Z
has_accepted_license: '1'
language:
- iso: eng
month: '03'
oa_version: None
page: '260'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '10703'
relation: part_of_dissertation
status: public
- id: '10791'
relation: part_of_dissertation
status: public
- id: '7932'
relation: part_of_dissertation
status: public
- id: '461'
relation: part_of_dissertation
status: public
- id: '14530'
relation: new_edition
status: public
status: public
supervisor:
- first_name: Björn
full_name: Hof, Björn
id: 3A374330-F248-11E8-B48F-1D18A9856A87
last_name: Hof
orcid: 0000-0003-2057-2754
title: Synchronization in collectively moving active matter
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '14058'
abstract:
- lang: eng
text: "Females and males across species are subject to divergent selective pressures
arising\r\nfrom di↵erent reproductive interests and ecological niches. This often
translates into a\r\nintricate array of sex-specific natural and sexual selection
on traits that have a shared\r\ngenetic basis between both sexes, causing a genetic
sexual conflict. The resolution of\r\nthis conflict mostly relies on the evolution
of sex-specific expression of the shared genes,\r\nleading to phenotypic sexual
dimorphism. Such sex-specific gene expression is thought\r\nto evolve via modifications
of the genetic networks ultimately linked to sex-determining\r\ntranscription
factors. Although much empirical and theoretical evidence supports this\r\nstandard
picture of the molecular basis of sexual conflict resolution, there still are
a\r\nfew open questions regarding the complex array of selective forces driving
phenotypic\r\ndi↵erentiation between the sexes, as well as the molecular mechanisms
underlying sexspecific adaptation. I address some of these open questions in my
PhD thesis.\r\nFirst, how do patterns of phenotypic sexual dimorphism vary within
populations,\r\nas a response to the temporal and spatial changes in sex-specific
selective forces? To\r\ntackle this question, I analyze the patterns of sex-specific
phenotypic variation along\r\nthree life stages and across populations spanning
the whole geographical range of Rumex\r\nhastatulus, a wind-pollinated angiosperm,
in the first Chapter of the thesis.\r\nSecond, how do gene expression patterns
lead to phenotypic dimorphism, and what\r\nare the molecular mechanisms underlying
the observed transcriptomic variation? I\r\naddress this question by examining
the sex- and tissue-specific expression variation in\r\nnewly-generated datasets
of sex-specific expression in heads and gonads of Drosophila\r\nmelanogaster.
I additionally used two complementary approaches for the study of the\r\ngenetic
basis of sex di↵erences in gene expression in the second and third Chapters of\r\nthe
thesis.\r\nThird, how does intersex correlation, thought to be one of the main
aspects constraining the ability for the two sexes to decouple, interact with
the evolution of sexual\r\ndimorphism? I develop models of sex-specific stabilizing
selection, mutation and drift\r\nto formalize common intuition regarding the patterns
of covariation between intersex\r\ncorrelation and sexual dimorphism in the fourth
Chapter of the thesis.\r\nAlltogether, the work described in this PhD thesis provides
useful insights into the\r\nlinks between genetic, transcriptomic and phenotypic
layers of sex-specific variation,\r\nand contributes to our general understanding
of the dynamics of sexual dimorphism\r\nevolution."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Gemma
full_name: Puixeu Sala, Gemma
id: 33AB266C-F248-11E8-B48F-1D18A9856A87
last_name: Puixeu Sala
orcid: 0000-0001-8330-1754
citation:
ama: 'Puixeu Sala G. The molecular basis of sexual dimorphism: Experimental and
theoretical characterization of phenotypic, transcriptomic and genetic patterns
of sex-specific adaptation. 2023. doi:10.15479/at:ista:14058'
apa: 'Puixeu Sala, G. (2023). The molecular basis of sexual dimorphism: Experimental
and theoretical characterization of phenotypic, transcriptomic and genetic patterns
of sex-specific adaptation. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:14058'
chicago: 'Puixeu Sala, Gemma. “The Molecular Basis of Sexual Dimorphism: Experimental
and Theoretical Characterization of Phenotypic, Transcriptomic and Genetic Patterns
of Sex-Specific Adaptation.” Institute of Science and Technology Austria, 2023.
https://doi.org/10.15479/at:ista:14058.'
ieee: 'G. Puixeu Sala, “The molecular basis of sexual dimorphism: Experimental and
theoretical characterization of phenotypic, transcriptomic and genetic patterns
of sex-specific adaptation,” Institute of Science and Technology Austria, 2023.'
ista: 'Puixeu Sala G. 2023. The molecular basis of sexual dimorphism: Experimental
and theoretical characterization of phenotypic, transcriptomic and genetic patterns
of sex-specific adaptation. Institute of Science and Technology Austria.'
mla: 'Puixeu Sala, Gemma. The Molecular Basis of Sexual Dimorphism: Experimental
and Theoretical Characterization of Phenotypic, Transcriptomic and Genetic Patterns
of Sex-Specific Adaptation. Institute of Science and Technology Austria, 2023,
doi:10.15479/at:ista:14058.'
short: 'G. Puixeu Sala, The Molecular Basis of Sexual Dimorphism: Experimental and
Theoretical Characterization of Phenotypic, Transcriptomic and Genetic Patterns
of Sex-Specific Adaptation, Institute of Science and Technology Austria, 2023.'
date_created: 2023-08-15T10:20:40Z
date_published: 2023-08-15T00:00:00Z
date_updated: 2023-12-13T12:15:36Z
day: '15'
ddc:
- '576'
degree_awarded: PhD
department:
- _id: GradSch
- _id: NiBa
- _id: BeVi
doi: 10.15479/at:ista:14058
ec_funded: 1
file:
- access_level: closed
checksum: 4e44e169f2724ee8c9324cd60bcc2b71
content_type: application/zip
creator: gpuixeus
date_created: 2023-08-16T18:15:17Z
date_updated: 2023-08-17T06:55:24Z
file_id: '14075'
file_name: Thesis_latex_forpdfa.zip
file_size: 10891454
relation: source_file
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checksum: e10b04cd8f3fecc0d9ef6e6868b6e1e8
content_type: application/pdf
creator: gpuixeus
date_created: 2023-08-18T10:47:55Z
date_updated: 2023-08-18T10:47:55Z
file_id: '14079'
file_name: PhDThesis_PuixeuG.pdf
file_size: 19856686
relation: main_file
success: 1
file_date_updated: 2023-08-18T10:47:55Z
has_accepted_license: '1'
language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
page: '230'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '665385'
name: International IST Doctoral Program
- _id: 9B9DFC9E-BA93-11EA-9121-9846C619BF3A
grant_number: '25817'
name: 'Sexual conflict: resolution, constraints and biomedical implications'
publication_identifier:
isbn:
- 978-3-99078-035-0
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '9803'
relation: research_data
status: public
- id: '12933'
relation: research_data
status: public
- id: '6831'
relation: part_of_dissertation
status: public
- id: '14077'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Beatriz
full_name: Vicoso, Beatriz
id: 49E1C5C6-F248-11E8-B48F-1D18A9856A87
last_name: Vicoso
orcid: 0000-0002-4579-8306
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
title: 'The molecular basis of sexual dimorphism: Experimental and theoretical characterization
of phenotypic, transcriptomic and genetic patterns of sex-specific adaptation'
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: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '14280'
abstract:
- lang: eng
text: "Cell division in Escherichia coli is performed by the divisome, a multi-protein
complex composed of more than 30 proteins. The divisome spans from the cytoplasm
through the inner membrane to the cell wall and the outer membrane. Divisome assembly
is initiated by a cytoskeletal structure, the so-called Z-ring, which localizes
at the center of the E. coli cell and determines the position of the future cell
septum. The Z-ring is composed of the highly conserved bacterial tubulin homologue
FtsZ, which forms treadmilling filaments. These filaments are recruited to the
inner membrane by FtsA, a highly conserved bacterial actin homologue. FtsA interacts
with other proteins in the periplasm and thus connects the cytoplasmic and periplasmic
components of the divisome. \r\nA previous model postulated that FtsA regulates
maturation of the divisome by switching from an oligomeric, inactive state to
a monomeric and active state. This model was based mostly on in vivo studies,
as a biochemical characterization of FtsA has been hampered by difficulties in
purifying the protein. Here, we studied FtsA using an in vitro reconstitution
approach and aimed to answer two questions: (i) How are dynamics from cytoplasmic,
treadmilling FtsZ filaments coupled to proteins acting in the periplasmic space
and (ii) How does FtsA regulate the maturation of the divisome?\r\nWe found that
the cytoplasmic peptides of the transmembrane proteins FtsN and FtsQ interact
directly with FtsA and can follow the spatiotemporal signal of FtsA/Z filaments.
When we investigated the underlying mechanism by imaging single molecules of FtsNcyto,
we found the peptide to interact transiently with FtsA. An in depth analysis of
the single molecule trajectories helped to postulate a model where PG synthases
follow the dynamics of FtsZ by a diffusion and capture mechanism. \r\nFollowing
up on these findings we were interested in how the self-interaction of FtsA changes
when it encounters FtsNcyto and if we can confirm the proposed oligomer-monomer
switch. For this, we compared the behavior of the previously identified, hyperactive
mutant FtsA R286W with wildtype FtsA. The mutant outperforms WT in mirroring and
transmitting the spatiotemporal signal of treadmilling FtsZ filaments. Surprisingly
however, we found that this was not due to a difference in the self-interaction
strength of the two variants, but a difference in their membrane residence time.
Furthermore, in contrast to our expectations, upon binding of FtsNcyto the measured
self-interaction of FtsA actually increased. \r\nWe propose that FtsNcyto induces
a rearrangement of the oligomeric architecture of FtsA. In further consequence
this change leads to more persistent FtsZ filaments which results in a defined
signalling zone, allowing formation of the mature divisome. The observed difference
between FtsA WT and R286W is due to the vastly different membrane turnover of
the proteins. R286W cycles 5-10x faster compared to WT which allows to sample
FtsZ filaments at faster frequencies. These findings can explain the observed
differences in toxicity for overexpression of FtsA WT and R286W and help to understand
how FtsA regulates divisome maturation."
acknowledged_ssus:
- _id: Bio
- _id: LifeSc
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Philipp
full_name: Radler, Philipp
id: 40136C2A-F248-11E8-B48F-1D18A9856A87
last_name: Radler
orcid: '0000-0001-9198-2182 '
citation:
ama: Radler P. Spatiotemporal signaling during assembly of the bacterial divisome.
2023. doi:10.15479/at:ista:14280
apa: Radler, P. (2023). Spatiotemporal signaling during assembly of the bacterial
divisome. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:14280
chicago: Radler, Philipp. “Spatiotemporal Signaling during Assembly of the Bacterial
Divisome.” Institute of Science and Technology Austria, 2023. https://doi.org/10.15479/at:ista:14280.
ieee: P. Radler, “Spatiotemporal signaling during assembly of the bacterial divisome,”
Institute of Science and Technology Austria, 2023.
ista: Radler P. 2023. Spatiotemporal signaling during assembly of the bacterial
divisome. Institute of Science and Technology Austria.
mla: Radler, Philipp. Spatiotemporal Signaling during Assembly of the Bacterial
Divisome. Institute of Science and Technology Austria, 2023, doi:10.15479/at:ista:14280.
short: P. Radler, Spatiotemporal Signaling during Assembly of the Bacterial Divisome,
Institute of Science and Technology Austria, 2023.
date_created: 2023-09-06T10:58:25Z
date_published: 2023-09-25T00:00:00Z
date_updated: 2024-02-21T12:35:18Z
day: '25'
ddc:
- '572'
degree_awarded: PhD
department:
- _id: GradSch
- _id: MaLo
doi: 10.15479/at:ista:14280
ec_funded: 1
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date_created: 2023-10-04T10:11:53Z
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file_size: 37838778
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file_date_updated: 2023-10-04T10:28:35Z
has_accepted_license: '1'
keyword:
- Cell Division
- Reconstitution
- FtsZ
- FtsA
- Divisome
- E.coli
language:
- iso: eng
month: '09'
oa_version: Published Version
page: '156'
project:
- _id: 2595697A-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '679239'
name: Self-Organization of the Bacterial Cell
- _id: fc38323b-9c52-11eb-aca3-ff8afb4a011d
grant_number: P34607
name: "Understanding bacterial cell division by in vitro\r\nreconstitution"
- _id: 2596EAB6-B435-11E9-9278-68D0E5697425
grant_number: ALTF 2015-1163
name: Synthesis of bacterial cell wall
- _id: 259B655A-B435-11E9-9278-68D0E5697425
grant_number: LT000824/2016
name: Reconstitution of bacterial cell wall sythesis
publication_identifier:
isbn:
- 978-3-99078-033-6
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '11373'
relation: part_of_dissertation
status: public
- id: '7387'
relation: part_of_dissertation
status: public
- id: '10934'
relation: research_data
status: public
status: public
supervisor:
- first_name: Martin
full_name: Loose, Martin
id: 462D4284-F248-11E8-B48F-1D18A9856A87
last_name: Loose
orcid: 0000-0001-7309-9724
title: Spatiotemporal signaling during assembly of the bacterial divisome
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: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '12491'
abstract:
- lang: eng
text: "The extracellular matrix (ECM) is a hydrated and complex three-dimensional
network consisting of proteins, polysaccharides, and water. It provides structural
scaffolding for the cells embedded within it and is essential in regulating numerous
physiological processes, including cell migration and proliferation, wound healing,
and stem cell fate. \r\nDespite extensive study, detailed structural knowledge
of ECM components in physiologically relevant conditions is still rudimentary.
This is due to methodological limitations in specimen preparation protocols which
are incompatible with keeping large samples, such as the ECM, in their native
state for subsequent imaging. Conventional electron microscopy (EM) techniques
rely on fixation, dehydration, contrasting, and sectioning. This results in the
alteration of a highly hydrated environment and the potential introduction of
artifacts. Other structural biology techniques, such as nuclear magnetic resonance
(NMR) spectroscopy and X-ray crystallography, allow high-resolution analysis of
protein structures but only work on homogenous and purified samples, hence lacking
contextual information. Currently, no approach exists for the ultrastructural
and structural study of extracellular components under native conditions in a
physiological, 3D environment. \r\nIn this thesis, I have developed a workflow
that allows for the ultrastructural analysis of the ECM in near-native conditions
at molecular resolution. The developments I introduced include implementing a
novel specimen preparation workflow for cell-derived matrices (CDMs) to render
them compatible with ion-beam milling and subsequent high-resolution cryo-electron
tomography (ET). \r\nTo this end, I have established protocols to generate CDMs
grown over several weeks on EM grids that are compatible with downstream cryo-EM
sample preparation and imaging techniques. Characterization of these ECMs confirmed
that they contain essential ECM components such as collagen I, collagen VI, and
fibronectin I in high abundance and hence represent a bona fide biologically-relevant
sample. I successfully optimized vitrification of these specimens by testing various
vitrification techniques and cryoprotectants. \r\nIn order to obtain high-resolution
molecular insights into the ultrastructure and organization of CDMs, I established
cryo-focused ion beam scanning electron microscopy (FIBSEM) on these challenging
and complex specimens. I explored different approaches for the creation of thin
cryo-lamellae by FIB milling and succeeded in optimizing the cryo-lift-out technique,
resulting in high-quality lamellae of approximately 200 nm thickness. \r\nHigh-resolution
Cryo-ET of these lamellae revealed for the first time the architecture of native
CDM in the context of matrix-secreting cells. This allowed for the in situ visualization
of fibrillar matrix proteins such as collagen, laying the foundation for future
structural and ultrastructural characterization of these proteins in their near-native
environment. \r\nIn summary, in this thesis, I present a novel workflow that combines
state-of-the-art cryo-EM specimen preparation and imaging technologies to permit
characterization of the ECM, an important tissue component in higher organisms.
This innovative and highly versatile workflow will enable addressing far-reaching
questions on ECM architecture, composition, and reciprocal ECM-cell interactions."
acknowledged_ssus:
- _id: EM-Fac
- _id: LifeSc
- _id: Bio
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Bettina
full_name: Zens, Bettina
id: 45FD126C-F248-11E8-B48F-1D18A9856A87
last_name: Zens
orcid: 0000-0002-9561-1239
citation:
ama: Zens B. Ultrastructural characterization of natively preserved extracellular
matrix by cryo-electron tomography. 2023. doi:10.15479/at:ista:12491
apa: Zens, B. (2023). Ultrastructural characterization of natively preserved
extracellular matrix by cryo-electron tomography. Institute of Science and
Technology Austria. https://doi.org/10.15479/at:ista:12491
chicago: Zens, Bettina. “Ultrastructural Characterization of Natively Preserved
Extracellular Matrix by Cryo-Electron Tomography.” Institute of Science and Technology
Austria, 2023. https://doi.org/10.15479/at:ista:12491.
ieee: B. Zens, “Ultrastructural characterization of natively preserved extracellular
matrix by cryo-electron tomography,” Institute of Science and Technology Austria,
2023.
ista: Zens B. 2023. Ultrastructural characterization of natively preserved extracellular
matrix by cryo-electron tomography. Institute of Science and Technology Austria.
mla: Zens, Bettina. Ultrastructural Characterization of Natively Preserved Extracellular
Matrix by Cryo-Electron Tomography. Institute of Science and Technology Austria,
2023, doi:10.15479/at:ista:12491.
short: B. Zens, Ultrastructural Characterization of Natively Preserved Extracellular
Matrix by Cryo-Electron Tomography, Institute of Science and Technology Austria,
2023.
date_created: 2023-02-02T14:50:20Z
date_published: 2023-02-02T00:00:00Z
date_updated: 2024-03-25T23:30:05Z
day: '02'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: GradSch
- _id: FlSc
doi: 10.15479/at:ista:12491
file:
- access_level: open_access
checksum: 069d87f025e0799bf9e3c375664264f2
content_type: application/pdf
creator: bzens
date_created: 2023-02-07T13:07:38Z
date_updated: 2024-02-08T23:30:04Z
embargo: 2024-02-07
file_id: '12527'
file_name: PhDThesis_BettinaZens_2023_final.pdf
file_size: 23082464
relation: main_file
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date_updated: 2024-02-08T23:30:04Z
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file_id: '12528'
file_name: PhDThesis_BettinaZens_2023_final.docx
file_size: 106169509
relation: source_file
file_date_updated: 2024-02-08T23:30:04Z
has_accepted_license: '1'
keyword:
- cryo-EM
- cryo-ET
- FIB milling
- method development
- FIBSEM
- extracellular matrix
- ECM
- cell-derived matrices
- CDMs
- cell culture
- high pressure freezing
- HPF
- structural biology
- tomography
- collagen
language:
- iso: eng
month: '02'
oa: 1
oa_version: Published Version
page: '187'
project:
- _id: eba3b5f6-77a9-11ec-83b8-cf0905748aa3
name: Integrated visual proteomics of reciprocal cell-extracellular matrix interactions
- _id: 059B463C-7A3F-11EA-A408-12923DDC885E
name: NÖ-Fonds Preis für die Jungforscherin des Jahres am IST Austria
publication_identifier:
isbn:
- 978-3-99078-027-5
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '8586'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Florian KM
full_name: Schur, Florian KM
id: 48AD8942-F248-11E8-B48F-1D18A9856A87
last_name: Schur
orcid: 0000-0003-4790-8078
title: Ultrastructural characterization of natively preserved extracellular matrix
by cryo-electron tomography
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...