Spatial organization of nuclear pores in Xaenopus laevis oocytes

The structure of nuclear pores has been the object of considerable investigation, but how nuclear pores are arranged on the nuclear surface is still less studied. Here, we analyze super-resolution images of the surface of Xenopus laevis oocytes nuclei during development and characterize the arrangement of nuclear pore using tools commonly used to study atomic structural and topological features of ordinary matter. To interpret the experimental results, we perform numerical simulations of octagonal clusters mimicking typical pore shapes and find structures that are in excellence agreement with experiments. The statistical features of the geometrical arrangement does not depend on the type of interaction between the pores, attractive or repulsive, but only on their octagonal geometry. We conclude that the observed arrangement of the pores is mainly is dominated by their octagonal symmetry.

The Phage Nucleus and PhuZ Spindle: Defining Features of the Subcellular Organization and Speciation of Nucleus-Forming Jumbo Phages

Bacteriophages and their bacterial hosts are ancient organisms that have been co-evolving for billions of years. Some jumbo phages, those with a genome size larger than 200 kilobases, have recently been discovered to establish complex subcellular organization during replication. Here, we review our current understanding of jumbo phages that form a nucleus-like structure, or “Phage Nucleus,” during replication. The phage nucleus is made of a proteinaceous shell that surrounds replicating phage DNA and imparts a unique subcellular organization that is temporally and spatially controlled within bacterial host cells by a phage-encoded tubulin (PhuZ)-based spindle. This subcellular architecture serves as a replication factory for jumbo Pseudomonas phages and provides a selective advantage when these replicate in some host strains. Throughout the lytic cycle, the phage nucleus compartmentalizes proteins according to function and protects the phage genome from host defense mechanisms. Early during infection, the PhuZ spindle positions the newly formed phage nucleus at midcell and, later in the infection cycle, the spindle rotates the nucleus while delivering capsids and distributing them uniformly on the nuclear surface, where they dock for DNA packaging. During the co-infection of two different nucleus-forming jumbo phages in a bacterial cell, the phage nucleus establishes Subcellular Genetic Isolation that limits the potential for viral genetic exchange by physically separating co-infection genomes, and the PhuZ spindle causes Virogenesis Incompatibility, whereby interacting components from two diverging phages negatively affect phage reproduction. Thus, the phage nucleus and PhuZ spindle are defining cell biological structures that serve roles in both the life cycle of nucleus-forming jumbo phages and phage speciation.

Exergy: Mechanical Nuclear Physics Measures Pressure, Viscosity and X-Ray Resonance in K-Shell in a Classical Way

First, the liquid drop model assumes a priori; to the atomic nucleus composed of protons and neutrons, as an incompressible nuclear fluid that should comply with the Navier–Stokes 3D equations (N-S3D). Conjecture, not yet proven, however, this model has successfully predicted the binding energy of the nuclei. Second, the calculation of nuclear pressure p0∈1.42,1.94]1032Pa and average viscosity η=1.71×1024fm2/s, as a function of the nuclear decay constant k=p02η=1T1/2, not only complements the information from the National Nuclear Data Center, but also presents an analytical solution of (N- S3D). Third, the solution of (N-S3D) is a Fermi Dirac generalized probability function Pxyzt=11+ep02ηt−μx2+y2+z21/2, Fourth, the parameter μ has a correspondence with the Yukawa potential coefficient μ=αm=1/r, Fifth, using low energy X-rays we visualize and measure parameters of the nuclear surface (proton radio) giving rise to the femtoscope. Finally, we obtain that the pressure of the proton is 8.14 times greater than the pressure of the neutron, and 1000 times greater than the pressure of the atomic nucleus. Analyzed data were isotopes: 9≤Z≤92 and 9≤N≤200.