Biology subjects

Pasvinter, I.

Publications and source records attributed to Pasvinter, I..

2 recordsLinked to original sources

bioRxiv2026

β-catenin Dynamics in Regenerating Hydra

Body axis specification is essential for morphogenesis, yet how axial patterning is dynamically coordinated remains unclear. In Hydra, Wnt/{beta}-catenin signaling is central to axial patterning, but its spatiotemporal dynamics are not well understood. Since nuclear {beta}-catenin mediates Wnt-dependent transcription, its localization provides a relevant readout for pathway dynamics. Here, we track {beta}-catenin abundance and nuclear localization in vivo during regeneration from bisected Hydra, tissue rings, and small tissue fragments. Following bisection, nuclear {beta}-catenin is detected exclusively at the regenerating oral end, where a broad signal appears and then declines before focusing at the future head. Tissue rings, lacking both head and foot, exhibit similar oral-aboral asymmetry. In regenerating fragments, the initial response often spans nearly the entire tissue, including the future foot region, followed by an additional peak before stabilizing at the future head. Overall, our results show that the spatial restriction of nuclear {beta}-catenin correlates with the divergence of regenerative dynamics toward head or foot formation, while the trajectories leading to these outcomes vary across different initial tissue configurations.

biophysics↗

bioRxiv2024

Mechanical strain focusing at topological defect sites in regenerating Hydra

The formation of a new head during Hydra regeneration involves the establishment of a head organizer that functions as a signaling center and contains an aster-shaped topological defect in the organization of the supracellular actomyosin fibers. Here we show that the future head region in regenerating tissue fragments undergoes multiple instances of extensive stretching and rupture events from the onset of regeneration. These recurring localized tissue deformations arise due to transient contractions of the supracellular ectodermal actomyosin fibers that focus mechanical strain at defect sites. We further show that stabilization of aster-shaped defects is disrupted by perturbations of the Wnt signaling pathway. We propose a closed-loop feedback mechanism promoting head organizer formation, and develop a biophysical model of regenerating Hydra tissues that incorporates a morphogen source activated by mechanical strain and an alignment interaction directing fibers along morphogen gradients. We suggest that this positive feedback loop leads to mechanical strain focusing at defect sites, enhancing local morphogen production and promoting robust organizer formation.

biophysics↗