Early embryonic requirement for nucleoporin Nup35/NPP-19 in nuclear assembly

11 pages, 8 figures, 3 tables.-- PMID: 19146848 [PubMed].-- Available online Dec 30, 2008.Supporting information (Suppl. figs S1-S5, movies S1-S6) available at: http://dx.doi.org/10.1016/j.ydbio.2008.12.024Nuclear pore complexes (NPCs) are gateways for transport between the nucleus and cytoplasm of eukaryotic cells and play crucial roles in regulation of gene expression. NPCs are composed of multiple copies of not, vert, similar 30 different nucleoporins (nups) that display both ubiquitous and cell type specific functions during development. Vertebrate Nup35 (also known as Nup53) was previously described to interact with Nup93, Nup155 and Nup205 and to be required for nuclear envelope (NE) assembly in vitro. Here, we report the first in vivo characterization of a Nup35 mutation, npp-19(tm2886), and its temperature-dependent effects on Caenorhabditis elegans embryogenesis. At restrictive temperature, npp-19(tm2886) embryos exhibit chromosome missegregation, nuclear morphology defects and die around mid-gastrulation. Depletion of Nup35/NPP-19 inhibits NE localization of Nup155/NPP-8, NPC assembly and nuclear lamina formation. Consequently, nuclear envelope function, including nucleo-cytoplasmic transport, is impaired. In contrast, recruitment of Nup107/NPP-5, LEM-2 and nuclear membranes to the chromatin surface is Nup35/NPP-19-independent, suggesting an uncoupling of nuclear membrane targeting and NPC assembly in the absence of Nup35/NPP-19. We propose that Nup35/NPP-19 has an evolutionary conserved role in NE formation and function, and that this role is particularly critical during the rapid cell divisions of early embryogenesis.This work was funded by grants from the Spanish Ministry of Science and Education (RYC-2003-001521, BFU-2004-01096, BFU-2007-60116) to PA. In addition, we wish to acknowledge Fundación Ramón Areces for a fellowship to ER and Junta de Andalucía for institutional support.Peer reviewe

Verification of a binary fluid solidification model using semi-analytical solution of 1D heat diffusion equation

The aim of the present work is to verify a numerical implementation of a binary fluid, heat conduction dominated solidification model with a novel semi-analytical solution to the heat diffusion equation. The semi-analytical solution put forward by Chakaraborty and Dutta (2002) is extended by taking into account variable in the mushy region solid/liquid mixture heat conduction coefficient. Subsequently, the range in which the extended semi-analytical solution can be used to verify numerical solutions is investigated and determined. It has been found that linearization introduced to analytically integrate the heat diffusion equation impairs its ability to predict solidus and liquidus line positions whenever the magnitude of latent heat of fusion exceeds a certain value

Modeling of the wave breaking with CICSAM and HRIC high resolution schemes

The paper concerns modeling of two-phase flow with the volume of fluid method (VOF) and two high-resolution advection schemes based on the normalized variable diagram (NVD). Compressive Interface Capturing Scheme for Arbitrary Meshes (CICSAM) and High Resolution Interface Capturing scheme (HRIC). Both considered schemes are used to discretize convective term in the scalar equation for the transport of the volume fraction. High-resolution schemes are employed to minimize influence of the artificial numerical dissipation and to keep the shape of the step interface profile. Original contribution of this work is a detailed comparison of the two high-resolution schemes CICSAM and HRIC in the case of the breaking wave phenomenon. It is shown that using relatively simple to apply, high-resolution schemes it is possible to obtain good agreement with an experimental evidence and other authors results. However, some difficulties connected with optimal size of the local Courant number are adressed. Additionally, since HRIC scheme is used in commercial software (e.g. Comet, Fluent) it is important to understand its capabilities and deficiencies when compared to other schemes