Kolar-Znika, L. | bioRxiv Science

bioRxiv2026

Rearrangement of chromosome spatial organization in mouse zygotes using optical tweezers does not affect preimplantation development

The spatial arrangement of chromosomes is thought to influence key processes such as gene expression or chromosome segregation. However, the contribution of chromosome spatial organization in physiological contexts remains disputed. Here, we use optical tweezers to displace nucleoli and physically rearrange the nuclear contents of mouse zygotes. Monitoring the preimplantation development of zygotes with physically shuffled nuclei reveals that cell dynamics, gene expression and overall blastocyst formation are not affected. This suggests that in mouse zygotes, the spatial organisation of chromosomes is not critical for blastocyst development.

developmental biology↗

bioRxiv2021

Live-cell micromanipulation of a genomic locus reveals interphase chromatin mechanics

Our understanding of the physical principles organizing the genome in the nucleus is limited by the lack of tools to directly exert and measure forces on interphase chromosomes in vivo and probe their material nature. Here, we present a novel approach to actively manipulate a genomic locus using controlled magnetic forces inside the nucleus of a living human cell. We observe viscoelastic displacements over microns within minutes in response to near-picoNewton forces, which are well captured by a Rouse polymer model. Our results highlight the fluidity of chromatin, with a moderate contribution of the surrounding material, revealing the minor role of crosslinks and topological effects and challenging the view that interphase chromatin is a gel-like material. Our new technology opens avenues for future research, from chromosome mechanics to genome functions.

biophysics↗