The positioning of the nucleus is achieved by two interconnected processes, anchoring and migration, both of which are controlled by cytoskeleton structures. Rotation is a special type of nuclear motility in many cell types, but its significance remains unclear. We used a vimentin-null cell line, MFT-16, which shows extensive nuclear rotation to study the phenomenon in detail. By selective disruption of cytoskeletal structures and video-microscopic analysis, nuclear rotation was a microtubule-dependent process that F-actin partially impedes. The dynein-dynactin complex is responsible and inhibiting this motor by expression of a dominant negative mutant of its component P-150 completely stops it. Nuclear rotation is powered by dynein associated with the nuclear envelope along stationary microtubules, centrosomes remaining immobile. We confirmed that vimentin IFs inhibit nuclear rotation, and variant proteins of the mutated wild type gene for vimentin that lacked considerable fragments of the N- and C-terminal domains restored nuclear anchoring. Immunochemical analysis showed that these mutated IFs also bound plectin, arguing for a key role of this cytolinker protein in nuclear anchoring. It is proposed that this versatile machinery guarantees not only rotation and the correct location of a nucleus, but also its orientation in a cell.
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http://dx.doi.org/10.1016/j.cellbi.2009.06.020 | DOI Listing |
Sci Rep
December 2024
Nuclear Safeguards and Physical Protection Department, Egyptian Atomic Energy Authority (EAEA), Cairo, Egypt.
The effective implementation of domestic and international safeguards necessitates verification techniques for Nuclear Materials (NM). Even in the case of very small quantities of NMs, accounting for and analyzing such traces can provide insights into the mass balance of NMs and/or state activities, ensuring consistency in state declarations. This paper proposes and benchmarks an absolute calibration methodology for estimating the uranium-mass content in large-volume barrels (200 L).
View Article and Find Full Text PDFJ Phys Chem A
December 2024
Departamento de Química Física y Química Inorgánica, Facultad de Ciencias─I.U. CINQUIMA, Paseo de Belén, 7, 47011 Valladolid, Spain.
The conformational space of 3-chloropropionic acid has been studied under the isolated conditions of a supersonic expansion using Stark-modulated free-jet absorption millimeter-wave and centimeter-wave chirped-pulse Fourier transform microwave spectroscopy techniques. The rotational spectra originating from the three most stable conformers including Cl and Cl isotopologues were observed in both experiments using helium expansion while a partial conformational relaxation involving skeletal rearrangements takes place in an argon expansion. The rotational parameters, geometries, and energy order were determined from the experiment, allowing a comparison with quantum chemical predictions.
View Article and Find Full Text PDFElife
December 2024
Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
Parkinson's disease (PD) is a multifactorial disease caused by irreversible progressive loss of dopaminergic neurons (DANs). Recent studies have reported the successful conversion of astrocytes into DANs by repressing polypyrimidine tract binding protein 1 (PTBP1), which led to the rescue of motor symptoms in a chemically-induced mouse model of PD. However, follow-up studies have questioned the validity of this astrocyte-to-DAN conversion model.
View Article and Find Full Text PDFJ Chem Phys
December 2024
Department of Chemistry, Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
A simplified theoretical description of multiple-quantum excitation and mixing for nuclear magnetic resonance of half-integer quadrupolar nuclei is presented. The approach recasts the multiple-quantum nutation behavior in terms of reduced excitation and mixing curves through a scaling of the first-order offset frequency by the quadrupolar coupling constant. The two-dimensional correlation of the static first-order anisotropic line shape to the second-order anisotropic magic-angle-spinning (MAS) line shape is utilized to transform the three-dimensional integral over the three Euler angles into a single integral over the dimensionless first-order offset parameter.
View Article and Find Full Text PDFJ Chem Phys
December 2024
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
We demonstrate that working with a correct phase-space electronic Hamiltonian captures electronic inertial effects. In particular, we show that phase space surface hopping dynamics do not suffer (at least to very high order) from non-physical non-adiabatic transitions between electronic eigenstates during the course of pure nuclear translational and rotational motion. This work opens up many new avenues for quantitatively investigating complex phenomena, including angular momentum transfer between chiral phonons and electrons as well as chiral-induced spin selectivity effects.
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