Biology subjects

Fallesen, T.

Publications and source records attributed to Fallesen, T..

4 recordsLinked to original sources

bioRxiv2026

Stage-specific checkpoint signalling by ATM, ATR and DNA-PK safeguards oocyte genome integrity

In somatic cells, DNA double-strand breaks (DSBs) are potentially catastrophic lesions that activate phosphatidylinositol 3-kinase-related kinase (PIKK) signalling to promote DNA repair or eliminate damaged cells. During meiosis, however, DSBs are deliberately generated as essential intermediates in homologous recombination, raising the question of how DNA damage signalling distinguishes programmed recombination from genome instability. To define how PIKK signalling is adapted to these distinct contexts, we resolved the function of the three PIKKs ATM, ATR and DNA-PK in physiological meiotic recombination and the response to postnatal DNA damage in mouse oocytes. Following postnatal irradiation, ATM functions as the dominant response kinase, with ATR and DNA-PK acting redundantly to eliminate damaged oocytes. In contrast, meiotic surveillance is mediated by ATR, with ATR removal rescuing oocyte loss in response to asynapsis and, independently, to persistent meiotic DSBs. Our findings demonstrate that DNA damage signalling is developmentally reconfigured during oogenesis and highlight distinct pathways of oocyte elimination that may ultimately inform strategies to maintain the ovarian reserve in mammals.

molecular biology↗

bioRxiv2025

Investigations into fission yeast chromosome size determinants

Mitotic chromosome dimensions differ between organisms, and they differ within a species between developmental stages. The physiological determinants of chromosome size remain poorly understood. Here, we investigate chromosome size determinants in the fission yeast Schizosaccharomyces pombe. Super-resolution microscopy and semi-automated measurements reveal that cell or nuclear volume in interphase, or the time spent in mitosis (both previously proposed chromosome size determinants), have little influence on resultant chromosome dimensions. Instead, levels of the chromosomal condensin complex affect chromosome size, with increasing condensin levels resulting in more compact, shorter and thinner, chromosomes. These observations inform our understanding of how chromosome dimensions are controlled in an organism. They suggest that a chromosome-intrinsic mechanism sets chromosome size, more so than the environment in which chromosomes find themselves in.

cell biology↗

bioRxiv2023

Intermittent cell division dynamics in regenerating Arabidopsis roots reveals complex long-range interactions

In this work, we present a quantitative comparison of the cell division dynamics between populations of intact and regenerating root tips in the plant model system Arabidopsis thaliana. To achieve the required temporal resolution and to sustain it for the duration of the regeneration process, we adopted a live imaging system based on light-sheet fluorescence microscopy, previously developed in the laboratory. We offer a straightforward quantitative analysis of the temporal and spatial patterns of cell division events showing a statistically significant difference in the frequency of mitotic events and spatial separation of mitotic event clusters between intact and regenerating roots.

plant biology↗

bioRxiv2018

Tracking transient fluorescent events in structured point clouds

BackgroundParticle-tracking in 3D is an indispensable computational tool to extract critical information on dynamical processes from raw time-lapse imaging. This is particularly true with in vivo time-lapse fluorescence imaging in cell and developmental biology, where complex dynamics are observed at high temporal resolution. Common tracking algorithms used with time-lapse data in fluorescence microscopy typically assume a continuous signal where background, recognisable keypoints and independently moving objects of interest are permanently visible. Under these conditions, simple registration and identity management algorithms can track the objects of interest over time. In contrast, here we consider the case of transient signals and objects whose movements are constrained within a tissue, where standard algorithms fail to provide robust tracking. ResultsTo optimize 3D tracking in these conditions, we propose the merging of registration and tracking tasks into a fuzzy registration algorithm to solve the identity management problem. We describe the design and application of such an algorithm, illustrated in the domain of plant biology, and make it available as an open-source software implementation. The algorithm is tested on mitotic events in 4D data-sets obtained with light-sheet fluorescence microscopy on growing Arabidopsis thaliana roots expressing CYCB::GFP. We validate the method by comparing the algorithm performance against both surrogate data and manual tracking. ConclusionThis method fills a gap in existing tracking techniques, following mitotic events in challenging data-sets using transient fluorescent markers in unregistered images.

bioinformatics↗