During eukaryotic cell division, a microtubule-based structure called the spindle exerts forces on chromosomes. The best-studied spindle forces, including those responsible for the separation of sister chromatids, are directed parallel to the spindle's long axis. By contrast, little is known about forces perpendicular to the spindle axis, which determine the metaphase plate configuration and thus the location of chromosomes in the subsequent nucleus. Using live-cell microscopy, we find that metaphase chromosomes are spatially anti-correlated in mouse oocyte spindles, evidence of previously unknown long-range forces acting perpendicular to the spindle axis. We explain this observation by showing that the spindle's microtubule network behaves as a nematic liquid crystal and that deformation of the nematic field around embedded chromosomes causes long-range repulsion between them.
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http://dx.doi.org/10.1126/sciadv.adq7540 | DOI Listing |
ACS Nano
January 2025
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States.
Controlling charge transport at the interfaces of nanostructures is crucial for their successful use in optoelectronic and solar energy applications. Mixed-dimensional heterostructures based on single-walled carbon nanotubes (SWCNTs) and transition metal dichalcogenides (TMDCs) have demonstrated exceptionally long-lived charge-separated states. However, the factors that control the charge transport at these interfaces remain unclear.
View Article and Find Full Text PDFNat Commun
January 2025
Biomimetic Systems for Cell Engineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
Intestinal epithelial cells are segregated into proliferative crypts and differentiated regions. This organization relies on specific signals, including Wnt3a, which regulates cell proliferation within crypts, and Eph/Ephrin, which dictates cell positioning along the crypt-villus axis. However, studying how the spatial distributions of these signals influences crypt-villus organization is challenging both in vitro and in vivo.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
School of Physical Sciences, University of Chinese Academy of Sciences (UCAS), Beijing 100049, China.
It is well established that the long-range van der Waals or thermal Casimir interaction between two semi-infinite dielectrics separated by a distance H is screened by an intervening electrolyte. Here we show how this interaction is modified when an electric field of strength E is applied parallel to the dielectric boundaries, leading to a nonequilibrium steady state with a current. The presence of the field induces a long-range thermal repulsive interaction, scaling just like the thermal Casimir interaction between dielectrics without the intervening electrolyte, i.
View Article and Find Full Text PDFACS Nano
December 2024
Department of Chemistry, James Franck Institute, and Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.
Electrostatically stabilized nanocrystals (NCs) and, in particular, quantum dots (QDs) hold promise for forming strongly coupled superlattices due to their compact and electronically conductive surface ligands. However, studies of the colloidal dispersion and interparticle interactions of electrostatically stabilized sub-10 nm NCs have been limited, hindering the optimization of their colloidal stability and self-assembly. In this study, we employed small-angle X-ray scattering (SAXS) experiments to investigate the interparticle interactions and arrangement of PbS QDs with thiostannate ligands (PbS-SnS) in polar solvents.
View Article and Find Full Text PDFJ Chem Phys
November 2024
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA.
The electrostatic correlations between ions profoundly influence the structure and forces within electrical double layers. Here, we apply the modified Gaussian renormalized fluctuation theory to investigate the counter-intuitive phenomenon of repulsion between two oppositely charged surfaces and discuss its relationship with overcharging. By accurately accounting for the effect of spatially varying ion-ion correlations, we capture these repulsive forces for divalent, trivalent, as well as tetravalent ions, in quantitative agreement with reported simulation results.
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