@phdthesis{19903, abstract = {Cooperation, that is, one person paying a cost for another's benefit, is a fundamental principle without which no form of society could exist. The extent to which humans cooperate with each other is also an essential feature that differentiates them from other animals. Cooperation occurs even in the absence of altruistic motivations, when it is selfishly incentivised by the expectation of a future reward. For example, many economic interactions are well described that way. This kind of cooperation requires that people exhibit reciprocal behaviour that acts as a mechanism that rewards cooperation. With game-theoretic models, it is possible to formally study potential such mechanisms and under what conditions they can exist. This thesis contributes to this effort by analysing recently introduced models of cooperation that advance on previous work by taking into account the potential for pre-existing inequality among cooperating individuals as well as the different forms that reciprocity can take. Individuals may differ both intrinsically, in their abilities, as well as extrinsically, in the amount of resources they have available. Allowing for such differences in a model of cooperation helps to understand how inequality affects the potential for, and outcomes of, cooperation among unequals. In this thesis, it is shown that in the presence of intrinsic inequality, a similar unequal distribution of resources can increase the potential for cooperation. This effect is stronger the smaller the group is in which cooperation takes place. It is also shown that under particular assumptions, if the unequal members of a group vary the size of their contributions to a cooperative effort over time, they can thereby increase their efficiency and improve the collective outcome. Cooperative behaviour in a two-person interaction can be rewarded either by direct reciprocation whenever the same two people interact again, or indirectly by a third party who observed the interaction. In the latter case of indirect reciprocity, individuals are proximally rewarded by a good reputation, which ultimately translates to being rewarded with cooperative behaviour by others. This mechanism can enable selfishly motivated cooperation even in circumstances where individuals are unlikely to meet again, akin to how money facilitates trade. While these two forms of reciprocity have mostly been studied in isolation, this thesis analyses both direct and indirect reciprocity in a general model in order to compare their relative effectiveness under different circumstances. The contribution of this thesis is an extension of previous work regarding a specific kind of interaction, whose parameters allow for convenient mathematical analysis, to the most general set of possible interactions.}, author = {Hübner, Valentin}, issn = {2663-337X}, pages = {157}, publisher = {Institute of Science and Technology Austria}, title = {{Reciprocity and inequality in social dilemmas}}, doi = {10.15479/AT-ISTA-19903}, year = {2025}, } @phdthesis{20138, abstract = {The evolution shapes the world around us. Not only in biology, where the fittest individuals spread their genes but also in physics and social dynamics, the evolutionary forces determine the development of a state of matter or public opinions. Many models describe these dynamics. This thesis examines the role of the structure in the models of selection. The population structure is represented as a graph or a network, and each vertex is occupied by one individual. Every individual has a type and fitness that represents the reproductive potential and depends on the type, occupied vertex, and the arrangement of the neighbors. The evolution is modeled in discrete steps; in one step, one individual is replaced by a neighbor selected randomly with the influence of fitness. The role of the networks is widely examined in the literature. The structures that promote the spread of the desired type compared to the structureless case are called amplifiers. The existence of amplifiers in various settings is an intensively studied topic, and in some settings, the amplifiers have been identified. Moreover, there are other important questions about the number of steps until one type spreads over the whole network (fixation time), the computational complexity, and the questions about the robustness of these processes. This thesis explores the role of structure in evolution from many perspectives. First, it introduces different models and various choices that can be made in the models of evolution. It highlights the role of the structure in the real world and how this is reflected in these models. Then, it describes the previous results and open problems. Second, the thesis describes an amplifier for two variants of the Moran process: one with a constant birth rate and the other with a constant death rate. This is an important contribution to the robustness of the amplification. Third, the thesis determines the complexity of spatial games. These are processes where the fitness comes from a game, and the strength of selection is high. It shows that determining the fate of cooperation in these games is a PSPACE-complete problem. Fourth, the thesis describes the amplifier of cooperation for spatial games. This is the first amplifier in this setting. Fifth, the thesis examines the coexistence in the Moran process with environmental heterogeneity. In this setting, the fitness depends not only on the type of the individual but also on the occupied vertex. The chapter determines the relationship between the interactions of vertices of different types and the coexistence time. Sixth, the thesis examines the social balance on networks and proposes a stochastic dynamic partially aware of the state of the graph, which reaches a balanced position quickly. Finally, the thesis presents conclusions and outlines the directions for future work. }, author = {Svoboda, Jakub}, issn = {2663-337X}, pages = {167}, publisher = {Institute of Science and Technology Austria}, title = {{Structural properties of games on graphs}}, doi = {10.15479/AT-ISTA-20138}, year = {2025}, } @phdthesis{20575, abstract = {This thesis deals with eigenvalue and eigenvector universality results for random matrix ensembles equipped with non-trivial spatial structure. We consider both mean-field models with a general variance profile (Wigner-type matrices) and correlation structure (correlated matrices) among the entries, as well as non-mean-field random band matrices with bandwidth W >> N^(1/2). To extract the universal properties of random matrix spectra and eigenvectors, we obtain concentration estimates for their resolvent, the local laws, which generalize the celebrated Wigner semicircle law for a broad class of random matrices to much finer spectral scales. The local laws hold for both a single resolvent as well as for products of multiple resolvents, known as resolvent chains, and express the remarkable approximately-deterministic behavior of these objects down to the microscopic scale. Our primary tool for establishing the local laws is the dynamical Zigzag strategy, which we develop in the setting of spatially-inhomogeneous random matrices. Our proof method systematically addresses the challenges arising from non-trivial spatial structures and is robust to all types of singularities in the spectrum, as we demonstrate in the correlated setting. Furthermore, we incorporate the analysis of the deterministic resolvent chain approximations into the dynamical framework of the Zigzag strategy, synthesizing a unified toolkit for establishing multi-resolvent local laws. Using these methods, we prove complete eigenvector delocalization, the Eigenstate Thermalization Hypothesis, and Wigner-Dyson universality in the bulk for random band matrices down to the optimal bandwidth W >> N^(1/2). For mean-field ensembles, we establish universality of local eigenvalue statistics at the cups for random matrices with correlated entries, and the Eigenstate Thermalization Hypothesis for Wigner-type matrices in the bulk of the spectrum. Finally, this thesis also contains other applications of the multi-resolvent local laws to spatially-inhomogeneous random matrices, obtained prior to the development of the Zigzag strategy. In particular, we provide a complete analysis of mesoscopic linear-eigenvalue statistics of Wigner-type matrices in all spectral regimes, including the novel cusps, and rigorously establish the prethermalization phenomenon for deformed Wigner matrices. The main body of this thesis consists of seven research papers (listed on page xi), each presented in a separate chapter with its own introduction and all relevant context, suitable to be read independently. We ask the reader’s indulgence for the repetitions in the historical overviews and other minor redundancies that remain among the chapters as a result. The overall Introduction, preceding the chapters, provides a condensed, informal summary of the main ideas and concepts at the core of these works. }, author = {Riabov, Volodymyr}, isbn = {978-3-99078-064-0}, issn = {2663-337X}, pages = {436}, publisher = {Institute of Science and Technology Austria}, title = {{Universality in random matrices with spatial structure}}, doi = {10.15479/AT-ISTA-20575}, year = {2025}, } @phdthesis{19540, abstract = {This thesis deals with several different models for complex quantum mechanical systems and is structured in three main parts. In Part I, we study mean field random matrices as models for quantum Hamiltonians. Our focus lies on proving concentration estimates for resolvents of random matrices, so-called local laws, mostly in the setting of multiple resolvents. These estimates have profound consequences for eigenvector overlaps and thermalization problems. More concretely, we obtain, e.g., the optimal eigenstate thermalization hypothesis (ETH) uniformly in the spectrum for Wigner matrices, an optimal lower bound on non-Hermitian eigenvector overlaps, and prethermalization for deformed Wigner matrices. In order to prove our novel multi-resolvent local laws, we develop and devise two main methods, the static Psi-method and the dynamical Zigzag strategy. In Part II, we study Bardeen-Cooper-Schrieffer (BCS) theory, the standard mean field microscopic theory of superconductivity. We focus on asymptotic formulas for the characteristic critical temperature and energy gap of a superconductor and prove universality of their ratio in various physical regimes. Additionally, we investigate multi-band superconductors and show that inter-band coupling effects can only enhance the critical temperature. In Part III, we study quantum lattice systems. On the one hand, we show a strong version of the local-perturbations-perturb-locally (LPPL) principle for the ground state of weakly interacting quantum spin systems with a uniform on-site gap. On the other hand, we introduce a notion of a local gap and rigorously justify response theory and the Kubo formula under the weakened assumption of a local gap. Additionally, we discuss two classes of problems which do not fit into the three main parts of the thesis. These are deformational rigidity of Liouville metrics on the torus and relativistic toy models of particle creation via interior-boundary-conditions (IBCs). }, author = {Henheik, Sven Joscha}, isbn = {978-3-99078-057-2}, issn = {2663-337X}, pages = {720}, publisher = {Institute of Science and Technology Austria}, title = {{Modeling complex quantum systems: Random matrices, BCS theory, and quantum lattice systems}}, doi = {10.15479/AT-ISTA-19540}, year = {2025}, } @article{18764, abstract = {We prove that a class of weakly perturbed Hamiltonians of the form H_λ= H_0 + λW, with W being a Wigner matrix, exhibits prethermalization. That is, the time evolution generated by H_λ relaxes to its ultimate thermal state via an intermediate prethermal state with a lifetime of order λ^{-2}. Moreover, we obtain a general relaxation formula, expressing the perturbed dynamics via the unperturbed dynamics and the ultimate thermal state. The proof relies on a two-resolvent law for the deformed Wigner matrix H_λ.}, author = {Erdös, László and Henheik, Sven Joscha and Reker, Jana and Riabov, Volodymyr}, issn = {1424-0637}, journal = {Annales Henri Poincare}, pages = {1991--2033}, publisher = {Springer Nature}, title = {{Prethermalization for deformed Wigner matrices}}, doi = {10.1007/s00023-024-01518-y}, volume = {26}, year = {2025}, } @article{18707, abstract = {Lead Sulfide (PbS) has garnered attention as a promising thermoelectric (TE) material due to its natural abundance and cost-effectiveness. However, its practical application is hindered by inherently high lattice thermal conductivity and low electrical conductivity. In this study, we address these challenges by surface functionalization of PbS nanocrystals using Cu2S molecular complexes-based ligand displacement. The molecular complexes facilitate the incorporation of Cu into the PbS matrix and leads to the formation of nanoscale defects, dislocations, and strain fields while optimizing the charge carrier transport. The structural modulations enhance the phonon scattering and lead to a significant reduction in lattice thermal conductivity of 0.60 W m−1K−1 at 867 K in the PbS-Cu2S system. Simultaneously, the Cu incorporation improves electrical conductivity by increasing both carrier concentration and mobility with carefully optimized the content of Cu2S molecular complexes. These synergistic modifications yield a peak figure-of-merit (zT) of 1.05 at 867 K for the PbS-1.0 %Cu2S sample, representing an almost twofold enhancement in TE performance compared to pristine PbS. This work highlights the effectiveness of surface treatment in overcoming the intrinsic limitations of PbS-based materials and presents a promising strategy for the development of high-efficiency TE systems.}, author = {Shu, Haibo and Zhao, Mingjun and Lu, Shaoqing and Wan, Shanhong and Genç, Aziz and Huang, Lulu and Ibáñez, Maria and Lim, Khak Ho and Hong, Min and Liu, Yu}, issn = {1095-7103}, journal = {Journal of Colloid and Interface Science}, pages = {703--712}, publisher = {Elsevier}, title = {{Influence of surface engineering on the transport properties of lead sulfide nanomaterials}}, doi = {10.1016/j.jcis.2024.12.067}, volume = {683}, year = {2025}, } @article{18558, abstract = {The current investigation presents a facile and cost-effective sol-gel approach for the synthesis of phase-pure multiferroic bismuth ferrite (BiFeO3) nanoparticles (BFO NPs) by using propylene glycol as a complexing agent, intended for use as a photocatalyst to efficiently degrade organic dyes in aqueous solutions under natural sunlight. Characterization techniques, including thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD), elucidated a plausible reaction pathway for the formation of phase-pure BFO NPs. Rietveld refinement of the XRD data, in conjunction with transmission electron microscopy (TEM) and Raman spectroscopy, confirmed the synthesis of single-phase BFO NPs at 400 °C, displaying a space group of R3c and an average crystallite size of 25 nm. UV–visible diffuse reflectance spectroscopy revealed an absorption cut-off wavelength near 590 nm, corresponding to a band gap of 2.08 eV, indicating the capability of BFO NPs to absorb visible light within the 400–590 nm range. BFO NPs have shown efficient and rapid photocatalytic degradation of methylene blue (MB) in acidic, neutral, and basic pH conditions under natural sunlight. This is attributed to the intrinsic ferroelectric and ferromagnetic ordering present in synthesized BFO NPs which facilitates the separation and migration of photoinduced charges through band bending phenomena at the interface.}, author = {Verma, Madhu and Kumar, Ajay and Thakur, Vijay Kumar and Maurya, Akanksha and Kumar, Sachin and Singh, Saurabh and Srivastav, Simant Kumar}, issn = {1573-4846}, journal = {Journal of Sol-Gel Science and Technology}, pages = {356--373}, publisher = {Springer Nature}, title = {{Efficient and rapid sunlight-driven photocatalytic degradation of methylene blue dye using multiferroic BiFeO3 nanoparticles}}, doi = {10.1007/s10971-024-06607-2}, volume = {113}, year = {2025}, } @article{18701, abstract = {We developed in-situ engineered polycrystalline polythiophene (PTh) and its composite with reduced graphene oxide (PTh-rGO) via a simple chemical synthesis. The PTh-rGO-based electrodes in a symmetrical device with xanthan gum in 1 M aq. Na2SO4 as an electrolyte, delivers a specific capacitance (Csp) of 114.7 F g–1 (electrode) and 28.7 F g–1 (cell) at an applied current density of 0.2 A g−1. The maximum energy and power densities recorded from the device were 588.0 mWh kg−1 and 1.1 kW kg−1 at 1.5 A g−1. The device exhibited a remarkable retention of Csp of 98.9 % over 10,000 continuous galvanostatic charge–discharge cycles highlighting an excellent performance. Electrochemical impedance spectroscopy analysis emphasizes material’s excellent structural integrity. This is attributed to the crystalline phases present in the matrix.}, author = {Mahato, Neelima and Singh, Saurabh and Sreekanth, T. V.M. and Yoo, Kisoo and Kim, Jonghoon}, issn = {1873-4979}, journal = {Materials Letters}, publisher = {Elsevier}, title = {{In-situ engineered highly-crystalline Polythiophene empowered electrochemical capacitor-II: Anomalous electrochemical charge storage behavior of Polythiophene-rGO composite}}, doi = {10.1016/j.matlet.2024.137869}, volume = {382}, year = {2025}, } @article{18753, abstract = {We continue a line of research which studies which hereditary families of digraphs have bounded dichromatic number. For a class of digraphs C, a hero in C is any digraph H such that H -free digraphs in C have bounded dichromatic number. We show that if F is an oriented star of degree at least five, the only heroes for the class of F -free digraphs are transitive tournaments. For oriented stars F of degree exactly four, we show the only heroes in F -free digraphs are transitive tournaments, or possibly special joins of transitive tournaments. Aboulker et al. characterized the set of heroes of {H,K1+P2→} -free digraphs almost completely, and we show the same characterization for the class of {H,rK1+P3→} -free digraphs. Lastly, we show that if we forbid two "valid" orientations of brooms, then every transitive tournament is a hero for this class of digraphs.}, author = {Carbonero, Alvaro and Koerts, Hidde and Moore, Benjamin and Spirkl, Sophie}, issn = {0195-6698}, journal = {European Journal of Combinatorics}, publisher = {Elsevier}, title = {{On heroes in digraphs with forbidden induced forests}}, doi = {10.1016/j.ejc.2024.104104}, volume = {125}, year = {2025}, } @article{19603, abstract = {MaxCut is a classical NP-complete problem and a crucial building block in many combinatorial algorithms. The famousEdwards-Erdös bound states that any connected graph on n vertices with m edges contains a cut of size at least m/2 + n−1/4 . Crowston, Jones and Mnich [Algorithmica, 2015] showed that the MaxCut problem on simple connected graphs admits an FPT algorithm, where the parameter k is the difference between the desired cut size c and the lower bound given by the Edwards-Erdös bound. This was later improved by Etscheid and Mnich [Algorithmica, 2017] to run in parameterized linear time, i.e., f (k) · O(m). We improve upon this result in two ways: Firstly, we extend the algorithm to work also for multigraphs (alternatively, graphs with positive integer weights). Secondly, we change the parameter; instead of the difference to the Edwards-Erdös bound, we use the difference to the Poljak-Turzík bound. The Poljak-Turzík bound states that any weighted graph G has a cut of weight at least w(G)/2 + wMSF (G)/4 , where w(G) denotes the total weight of G, and wMSF (G) denotes the weight of its minimum spanning forest. In connected simple graphs the two bounds are equivalent, but for multigraphs the Poljak-Turzík bound can be larger and thus yield a smaller parameter k. Our algorithm also runs in parameterized linear time, i.e., f (k) · O(m + n).}, author = {Lill, Jonas and Petrova, Kalina H and Weber, Simon}, issn = {1432-0541}, journal = {Algorithmica}, pages = {983--1007}, publisher = {Springer Nature}, title = {{Linear-time MaxCut in multigraphs parameterized above the Poljak-Turzík bound}}, doi = {10.1007/s00453-025-01306-y}, volume = {87}, year = {2025}, } @phdthesis{20741, abstract = {Life on Earth emerged when biomacromolecules were membrane-enclosed in a confined space where many essential chemical reactions were more likely to happen and thereby accelerate evolution. These kinds of membranes separated internal reactions from the outside chaos while staying flexible so that those primordial cells can move, adopt their shape and, most importantly, propagate. Such membrane plasticity still remains a defining feature of all modern cell types. This remarkable ability to change their shape is most prominently observed during their propagation (i.e., cell division). Throughout division, a cell undergoes drastic change in its shape, usually at the middle of the cell, pulling the two opposite membrane sides inward, closer to each other, and, finally, culminating in pinching off to separate the cell into two daughter cells. To achieve this, a cell needs to employ a protein machinery, usually termed divisome, that can coordinate all necessary intracellular processes with membrane remodelling and synthesis of other extracellular structures that decorate a cell. The focus of this dissertation is a membrane-remodelling FtsZ system that is present across all domains of life. FtsZ forms filaments that further self-organize into ring-like structures at the cell septum and together with other division proteins perform cell envelope synthesis and constriction. However, there are still knowledge gaps in our mechanistic understanding of division in both archaea and bacteria. My work presented in this dissertation centres around a simple yet not well understood question: How is the divisome positioned correctly at the mid-cell? To achieve the proper positioning, the divisome needs to (i) be recruited to the mid-cell and (ii) localized orthogonally to the long cell axis. I tackle these processes in two different systems by applying an in vitro biochemical bottom-up reconstitution approach. I use purified components of Haloferax volcanii and Escherichia coli divisome to explore how divisome is recruited to the mid-cell in archaea and how the Z-ring positions orthogonally to the long cell axis in bacteria, respectively. Firstly, I collaborate with archaeal cell and structural biologists to explore the assembly of early division proteins in two FtsZ-containing archaeon H. volcanii, a standard model system for understudied archaeal organisms. I particularly address the hierarchy of interactions that allow a tripartite complex formation (SepF-CdpB1-CdpB2) and how the hierarchy of interactions ultimately leads to the recruitment of FtsZ filaments to the septum. This part of work has been published in (Nußbaum et al., 2024). In collaboration with evolutionary biologists, I shed light on ancient features that archaeal divisome has retained to this day and also speculate on a property that it might have lost during the course of evolution. Next, I switch my attention to E. coli divisome. Particularly, I address the FtsZ’s intrinsic biophysical property that drives the Z-ring diameter, and thereby the perpendicular orientation of the Z-ring to the long cell axis based on suggested membrane curvature sensing mechanism (Vanhille-Campos et al., 2024). This property allows formation of different Z-ring diameters that match the variety of cell diameters present in prokaryotes. The results showcase that the distribution of charged amino acids in the intrinsically disordered linker at the C-terminus (CTL) of FtsZ is the major determining factor of Z-ring diameter with inter-CTL interactions as an underlying mechanism. Finally, I thoroughly explain the methodology I used to address the abovementioned projects, and I finish with a discussion on how early archaeal divisome assembly and curvature sensing mechanism in bacteria, at first sight unrelated topics, are interconnected and important groundwork for both fundamental and translational research. }, author = {Kojic, Marko}, isbn = {978-3-99078-073-2}, issn = {2663-337X}, publisher = {Institute of Science and Technology Austria}, title = {{Towards understanding the assembly mechanisms of the Z-ring in Archaea and Bacteria}}, doi = {10.15479/AT-ISTA-20741}, year = {2025}, } @phdthesis{19393, abstract = {Rotations constitute one of the fundamental symmetries in physics, characterized by their intricate group structure and infinite dimensional representations. In contrast to classical rotations, quantum mechanics unveils the SO(3) symmetry group structure, manifesting in phenomena without classical counterparts, from angular momentum quantization to non-trivial addition of angular momenta. While most studies of topological physics have focused on two-band systems, the SO(3) symmetry group of quantum rotors offers an inherently more complex platform with unprecedented possibilities for exploring topological phenomena. Despite their ubiquity in nature– from molecules to nanorotors– their potential for hosting topological phases has remained largely unexamined. In this thesis, we mainly focus on periodically driven linear molecules as a prototype for studying topological phenomena in quantum rotors. Recent technological advances in coherent control of molecules, particularly through precisely shaped laser pulses, have made it possible to investigate linear rotors in the context of topology. While planar rotors have received some attention in recent years, threedimensional rotors–particularly linear molecules–harbor substantially richer topological phenomena due to their non-abelian nature and their additional angular degrees of freedom. We demonstrate that these systems can host novel edge states and topological features fundamentally impossible in planar systems. We begin by establishing a theoretical bridge between periodically kicked rotors and "crystalline" lattices in angular momentum space. Using non-interacting linear molecules as our primary example, we show how quantum interference and revival patterns lead to the possibility to simulate band models with arbitrary number of bands N. While our framework applies to various quantum rotors, including nanorotors and kicked Bose-Einstein condensates, linear molecules provide an ideal experimental platform due to their abovementioned precise controllability. The core of this work examines adiabatic dynamics of 3D quantum rotors, establishing a geometric framework based on the Euler class to characterize its non-abelian topology. The non-Hermitian nature of the system enables novel braiding behaviors and topological transitions impossible in static systems, leading to an anomalous Dirac string phase with edge states in each gap, even though the Berry phases are all zero. These features can be directly observed through molecular alignment and rotational level populations. These findings establish quantum rotors as an alternative platform for studying multi-band topological physics, while suggesting practical implementations for quantum computation where topological protection could offer natural resilience against decoherence. The rich structure of three-dimensional rotation groups, combined with the tunability of topological features through driving parameters, makes this platform particularly valuable for exploring fundamental physics and developing quantum technologies.}, author = {Karle, Volker}, issn = {2663-337X}, pages = {192}, publisher = {Institute of Science and Technology Austria}, title = {{Non-equilibrium topological phases with periodically driven molecules and quantum rotors}}, doi = {10.15479/AT-ISTA-19393}, year = {2025}, } @article{18879, abstract = {Our brain has remarkable computational power, generating sophisticated behaviors, storing memories over an individual’s lifetime, and producing higher cognitive functions. However, little of our neuroscience knowledge covers the human brain. Is this organ truly unique, or is it a scaled version of the extensively studied rodent brain? Combining multicellular patch-clamp recording with expansion-based superresolution microscopy and full-scale modeling, we determined the cellular and microcircuit properties of the human hippocampal CA3 region, a fundamental circuit for memory storage. In contrast to neocortical networks, human hippocampal CA3 displayed sparse connectivity, providing a circuit architecture that maximizes associational power. Human synapses showed unique reliability, high precision, and long integration times, exhibiting both species- and circuit-specific properties. Together with expanded neuronal numbers, these circuit characteristics greatly enhanced the memory storage capacity of CA3. Our results reveal distinct microcircuit properties of the human hippocampus and begin to unravel the inner workings of our most complex organ. }, author = {Watson, Jake and Vargas Barroso, Victor M and Morse, Rebecca and Navas Olivé, Andrea C and Tavakoli, Mojtaba and Danzl, Johann G and Tomschik, Matthias and Rössler, Karl and Jonas, Peter M}, issn = {1097-4172}, journal = {Cell}, number = {2}, pages = {501--514.e18}, publisher = {Cell Press}, title = {{Human hippocampal CA3 uses specific functional connectivity rules for efficient associative memory}}, doi = {10.1016/j.cell.2024.11.022}, volume = {188}, year = {2025}, } @article{19404, abstract = {Cell migration is a fundamental process during embryonic development. Most studies in vivo have focused on the migration of cells using the extracellular matrix (ECM) as their substrate for migration. In contrast, much less is known about how cells migrate on other cells, as found in early embryos when the ECM has not yet formed. Here, we show that lateral mesendoderm (LME) cells in the early zebrafish gastrula use the ectoderm as their substrate for migration. We show that the lateral ectoderm is permissive for the animal-pole-directed migration of LME cells, while the ectoderm at the animal pole halts it. These differences in permissiveness depend on the lateral ectoderm being more cohesive than the animal ectoderm, a property controlled by bone morphogenetic protein (BMP) signaling within the ectoderm. Collectively, these findings identify ectoderm tissue cohesion as one critical factor in regulating LME migration during zebrafish gastrulation.}, author = {Tavano, Ste and Brückner, David and Tasciyan, Saren and Tong, Xin and Kardos, Roland and Schauer, Alexandra and Hauschild, Robert and Heisenberg, Carl-Philipp J}, issn = {2211-1247}, journal = {Cell Reports}, number = {3}, publisher = {Cell Press}, title = {{BMP-dependent patterning of ectoderm tissue material properties modulates lateral mesendoderm cell migration during early zebrafish gastrulation}}, doi = {10.1016/j.celrep.2025.115387}, volume = {44}, year = {2025}, } @article{19602, abstract = {N4-methylcytosine (4mC) is an important DNA modification in prokaryotes, but its relevance and even its presence in eukaryotes have been mysterious. Here we show that spermatogenesis in the liverwort Marchantia polymorpha involves two waves of extensive DNA methylation reprogramming. First, 5-methylcytosine (5mC) expands from transposons to the entire genome. Notably, the second wave installs 4mC throughout genic regions, covering over 50% of CG sites in sperm. 4mC requires a methyltransferase (MpDN4MT1a) that is specifically expressed during late spermiogenesis. Deletion of MpDN4MT1a alters the sperm transcriptome, causes sperm swimming and fertility defects, and impairs post-fertilization development. Our results reveal extensive 4mC in a eukaryote, identify a family of eukaryotic methyltransferases, and elucidate the biological functions of 4mC in reproductive development, thereby expanding the repertoire of functional eukaryotic DNA modifications.}, author = {Walker, James and Zhang, Jingyi and Liu, Yalin and Xu, Shujuan and Yu, Yiming and Vickers, Martin and Ouyang, Weizhi and Tálas, Judit and Dolan, Liam and Nakajima, Keiji and Feng, Xiaoqi}, issn = {1097-4172}, journal = {Cell}, number = {11}, pages = {2890--2906.e14}, publisher = {Cell Press}, title = {{Extensive N4 cytosine methylation is essential for Marchantia sperm function}}, doi = {10.1016/j.cell.2025.03.014}, volume = {188}, year = {2025}, } @article{19703, abstract = {An enlarged brain underlies the complex central nervous system of vertebrates. The dramatic expansion of the brain that diverges its shape from the spinal cord follows neural tube closure during embryonic development. Here, we show that this differential deformation is encoded by a pre-pattern of tissue material properties in chicken embryos. Using magnetic droplets and atomic force microscopy, we demonstrate that the dorsal hindbrain is more fluid than the dorsal spinal cord, resulting in a thinning versus a resisting response to increasing lumen pressure, respectively. The dorsal hindbrain exhibits reduced apical actin and a disorganized laminin matrix consistent with tissue fluidization. Blocking the activity of neural-crest-associated matrix metalloproteinases inhibits hindbrain expansion. Transplanting dorsal hindbrain cells to the spinal cord can locally create an expanded brain-like morphology in some cases. Our findings raise questions in vertebrate head evolution and suggest a general role of mechanical pre-patterning in sculpting epithelial tubes.}, author = {Mclaren, Susannah B.P. and Xue, Shi-lei and Ding, Siyuan and Winkel, Alexander K. and Baldwin, Oscar and Dwarakacherla, Shreya and Franze, Kristian and Hannezo, Edouard B and Xiong, Fengzhu}, issn = {1878-1551}, journal = {Developmental Cell}, number = {17}, pages = {2237--2247.e4}, publisher = {Cell Press}, title = {{Differential tissue deformability underlies fluid pressure-driven shape divergence of the avian embryonic brain and spinal cord}}, doi = {10.1016/j.devcel.2025.04.010}, volume = {60}, year = {2025}, } @article{20143, abstract = {Bacteria and archaea deploy diverse antiviral defense systems, many of which remain mechanistically uncharacterized. Here, we characterize Kiwa, a widespread two-component system composed of the transmembrane sensor KwaA and the DNA-binding effector KwaB. Cryogenic electron microscopy (cryo-EM) analysis reveals that KwaA and KwaB assemble into a large, membrane-associated supercomplex. Upon phage binding, KwaA senses infection at the membrane, leading to KwaB binding of ejected phage DNA and inhibition of replication and late transcription, without inducing host cell death. Although KwaB can bind DNA independently, its antiviral activity requires association with KwaA, suggesting spatial or conformational regulation. We show that the phage-encoded DNA-mimic protein Gam directly binds and inhibits KwaB but that co-expression with the Gam-targeted RecBCD system restores protection by Kiwa. Our findings support a model in which Kiwa coordinates membrane-associated detection of phage infection with downstream DNA binding by its effector, forming a spatially coordinated antiviral mechanism.}, author = {Zhang, Zhiying and Todeschini, Thomas C. and Wu, Yi and Kogay, Roman and Naji, Ameena and Cardenas Rodriguez, Joaquin and Mondi, Rupavidhya and Kaganovich, Daniel and Taylor, David W. and Bravo, Jack Peter Kelly and Teplova, Marianna and Amen, Triana and Koonin, Eugene and Patel, Dinshaw J. and Nobrega, Franklin L.}, issn = {1097-4172}, journal = {Cell}, number = {21}, pages = {5862--5877.e23}, publisher = {Cell Press}, title = {{Kiwa is a membrane-embedded defense supercomplex activated at phage attachment sites}}, doi = {10.1016/j.cell.2025.07.002}, volume = {188}, year = {2025}, } @article{19846, abstract = {The Ca2+-release-activated Ca2+ (CRAC) channel Orai1 is activated by interaction with the Ca2+ sensor Stromal Interaction Molecule 1 (STIM1). Owing to the lack of structurally resolved Orai1/STIM1 complexes, the impact of their coupling on individual Orai1 transmembrane domain (TM) movements is unclear. This study investigates STIM1-independent and STIM1-dependent Orai1-TM dynamics using photocrosslinking unnatural amino acids (UAAs) at each individual TM position. We primarily identify CRAC-channel-like currents directly after UAA incorporation or additional UV-light irradiation at TM3 sites that interface with non-pore-lining TMs. Using UAAs combined with conventional site-directed mutagenesis and molecular dynamics simulations, we discover that pore opening involves a widening of interfaces formed by TM3 with non-pore-lining TMs. Orai1 mutants with a UAA in TM3 exhibit weaker STIM1-induced activation after UV exposure, possibly caused by a restricted widening of non-pore-lining TM interfaces. We demonstrate that photocrosslinking UAAs are excellent tools for improving our understanding of key determinants and ion channel dynamics modulating pore opening.}, author = {Najjar, Hadil and Weiß, Sarah and Horvath, Ferdinand and Hopl, Valentina and Tiffner, Adéla and Höbarth, Lorenz and Söllner, Julia and Fröhlich, Maximilian and Prantl, Magdalena and Müller, Nora and Nazarenko, Yuliia and Harant, Selina and Weissenböck, Lukas and Grabmayr, Herwig and Sallinger, Matthias and Maltan, Lena and Echefu, Linda V. and Radiskovic, Tamara and Leopold, Melanie and Lindinger, Sonja and Humer, Christina and Höglinger, Carmen and Krobath, Heinrich and Renger, Thomas and Derler, Isabella}, issn = {2666-3864}, journal = {Cell Reports Physical Science}, number = {6}, publisher = {Cell Press}, title = {{STIM1-induced widening of non-pore-lining TM interfaces is crucial for Orai1 pore opening}}, doi = {10.1016/j.xcrp.2025.102623}, volume = {6}, year = {2025}, } @article{20029, abstract = {Vacuolar acidification is crucial for the homeostasis of intracellular pH and the recycling of proteins and nutrients in cells, thereby playing important roles in various physiological processes related to vacuolar function. The key factors regulating vacuolar acidification and underlying mechanisms remain unclear. Here, we report that Arabidopsis phospholipase Dζ2 (PLDζ2) promotes the acidification of the vacuolar lumen to stimulate autophagic degradation under phosphorus deficiency. The pldζ2 mutant massively accumulates autophagic structures while exhibiting premature leaf senescence under nutrient starvation. Impaired autophagic flux, lytic vacuole morphology, and lytic degradation in pldζ2 indicate that PLDζ2 regulates autophagy by affecting the vacuolar function. PLDζ2 locates in both tonoplast and cytoplasm. Genetic, structural, and biochemical studies demonstrate that PLDζ2 directly interacts with vacuolar-type ATPase (V-ATPase) subunit D (VATD) to promote vacuolar acidification and autophagy under phosphorus starvation. These findings reveal the importance of V-ATPase and vacuolar pH in autophagic activity and provide clues in elucidating the regulatory mechanism of vacuolar acidification.}, author = {Guan, Bin and Xie, Ke Xuan and Du, Xin Qiao and Bai, Yu Xuan and Hao, Peng Chao and Lin, Wen Hui and Friml, Jiří and Xue, Hong Wei}, issn = {2211-1247}, journal = {Cell Reports}, number = {7}, publisher = {Cell Press}, title = {{Arabidopsis phospholipase Dζ2 facilitates vacuolar acidification and autophagy under phosphorus starvation by interacting with VATD}}, doi = {10.1016/j.celrep.2025.116024}, volume = {44}, year = {2025}, } @article{20116, abstract = {Auxin regulates various aspects of plant growth and development by modulating the transcription of target genes through the degradation of auxin/indole-3-acetic acid (Aux/IAA) repressors via the 26S proteasome. Proteasome regulator 1 (PTRE1), a positive regulator of proteasome activity, has been implicated in auxin-mediated proteasome suppression; however, the mechanism by which auxin modulates PTRE1 function remains unclear. Here, we demonstrate that auxin promotes the interaction between germin-like protein 1 (GLP1) and PTRE1, facilitating PTRE1 retention at the plasma membrane. The relocation of PTRE1 results in reduced nuclear 26S proteasome activity, and thus the attenuated Aux/IAA degradation and altered Aux/IAA homeostasis, ultimately resulting in suppressed auxin-mediated transcriptional regulation. Our findings uncover a previously uncharacterized regulatory axis in auxin signaling that controls Aux/IAA protein stability, functioning alongside the TIR1- and TRANSMEMBRANE KINASE 1 (TMK1)-mediated pathways, and highlight the coordination of auxin signaling from the cell surface to the nucleus via auxin-induced PTRE1 relocation, which fine-tunes Aux/IAA protein homeostasis and auxin responses.}, author = {Xu, Faqing and Yu, Yongqiang and Guan, Bin and Xu, Tongda and Xu, Zhihong and Xue, Hongwei}, issn = {2211-1247}, journal = {Cell Reports}, number = {8}, publisher = {Cell Press}, title = {{Germin-like protein 1 interacts with proteasome regulator 1 to regulate auxin signaling by controlling Aux/IAA homeostasis}}, doi = {10.1016/j.celrep.2025.116056}, volume = {44}, year = {2025}, }