arXiv subjects

Christian Hanauer

Publications and source records attributed to Christian Hanauer.

3 recordsLinked to original sources

arXiv2026

Control of morphology and topology in a lattice model of branching morphogenesis

We present a lattice model for morphogen-controlled branching morphogenesis which combines ideas and concepts from non-equilibrium physics and developmental biology. In this model, the stochastic occupation dynamics of cells is coupled with signaling molecules (morphogens) produced by the cells. We investigate growth patterns governed by morphogen concentration gradients, spanning regimes ranging from the diffusion-limited aggregation limit to the stochastic surface growth (Eden model) limit. Moreover, we introduce control over topology by a local operator and study growth, degrowth, and steady-state dynamics of branched patterns. The topology-preserving steady-state clusters exhibit a power-law scaling of radius of gyration with cluster size, yielding the exponents $0.68\pm0.01$ in square lattice and $0.67\pm 0.01$ in hexagonal lattice.

cond-mat.stat-mech↗

arXiv2025

A Model for Self-Organized Growth, Branching, and Allometric Scaling of the Planarian Gut

The growth and scaling of organs is a fundamental aspect of animal development. However, how organs grow to the right size and shape required by physiological demands, remains largely unknown. Here, we provide a framework combining theory and experiment to study the scaling of branched organs. As a biological model, we focus on the branching morphogenesis of the planarian gut, which is a highly branched organ responsible for the delivery of nutrients. Planarians undergo massive body size changes requiring gut morphology to adapt to these size variations. Our experimental analysis shows that various gut properties scale with organism size according to power laws. We introduce a theoretical framework to understand the growth and scaling of branched organs. Our theory considers the dynamics of the interface between organ and surrounding tissue to be controlled by a morphogen and illustrates how a shape instability of this interface can give rise to the self-organized formation and growth of complex branched patterns. Considering the reaction-diffusion dynamics in a growing domain representative of organismal growth, we show that a wide range of scaling behaviors of the branching pattern emerges from the interplay between interface dynamics and organism growth. Our model can recapitulate the scaling laws of planarian gut morphology that we quantified and also opens new directions for understanding allometric scaling laws in various other branching systems in organisms.

physics.bio-ph↗

arXiv2021

Theory of Active Intracellular Transport by DNA-relaying

The spatiotemporal organization of bacterial cells is crucial for the active segregation of replicating chromosomes. In several species, including Caulobacter crescentus, the ATPase ParA binds to DNA and forms a gradient along the long cell axis. The ParB partitioning complex on the newly replicated chromosome translocates up this ParA gradient, thereby contributing to chromosome segregation. A DNA-relay mechanism - deriving from the elasticity of the fluctuating chromosome - has been proposed as the driving force for this cargo translocation, but a mechanistic theoretical description remains elusive. Here, we propose a minimal model to describe force generation by the DNA-relay mechanism over a broad range of operational conditions. Conceptually, we identify four distinct force-generation regimes characterized by their dependence on chromosome fluctuations. These relay force regimes arise from an interplay of the imposed ParA gradient, chromosome fluctuations, and an emergent friction force due chromosome-cargo interactions.

physics.bio-ph↗