Biomedical subjects

J Beaudouin

Publications and source records attributed to J Beaudouin.

4 recordsLinked to original sources

PubMed2001

An evolutionarily conserved NPC subcomplex, which redistributes in part to kinetochores in mammalian cells.

The nuclear pore complexes (NPCs) are evolutionarily conserved assemblies that allow traffic between the cytoplasm and the nucleus. In this study, we have identified and characterized a novel human nuclear pore protein, hNup133, through its homology with the Saccharomyces cerevisiae nucleoporin scNup133. Two-hybrid screens and immunoprecipitation experiments revealed a direct and evolutionarily conserved interaction between Nup133 and Nup84/Nup107 and indicated that hNup133 and hNup107 are part of a NPC subcomplex that contains two other nucleoporins (the previously characterized hNup96 and a novel nucleoporin designated as hNup120) homologous to constituents of the scNup84 subcomplex. We further demonstrate that hNup133 and hNup107 are localized on both sides of the NPC to which they are stably associated at interphase, remain associated as part of a NPC subcomplex during mitosis, and are targeted at early stages to the reforming nuclear envelope. Throughout mitosis, a fraction of hNup133 and hNup107 localizes to the kinetochores, thus revealing an unexpected connection between structural NPCs constituents and kinetochores. Photobleaching experiments further showed that the mitotic cytoplasm contains kinetochore-binding competent hNup133 molecules and that in contrast to its stable association with the NPCs the interaction of this nucleoporin with kinetochores is dynamic.

Evolution, Molecular↗

PubMed2001

Nuclear pore complexes form immobile networks and have a very low turnover in live mammalian cells.

The nuclear pore complex (NPC) and its relationship to the nuclear envelope (NE) was characterized in living cells using POM121-green fluorescent protein (GFP) and GFP-Nup153, and GFP-lamin B1. No independent movement of single pore complexes was found within the plane of the NE in interphase. Only large arrays of NPCs moved slowly and synchronously during global changes in nuclear shape, strongly suggesting mechanical connections which form an NPC network. The nuclear lamina exhibited identical movements. NPC turnover measured by fluorescence recovery after photobleaching of POM121 was less than once per cell cycle. Nup153 association with NPCs was dynamic and turnover of this nucleoporin was three orders of magnitude faster. Overexpression of both nucleoporins induced the formation of annulate lamellae (AL) in the endoplasmic reticulum (ER). Turnover of AL pore complexes was much higher than in the NE (once every 2.5 min). During mitosis, POM121 and Nup153 were completely dispersed and mobile in the ER (POM121) or cytosol (Nup153) in metaphase, and rapidly redistributed to an immobilized pool around chromatin in late anaphase. Assembly and immobilization of both nucleoporins occurred before detectable recruitment of lamin B1, which is thus unlikely to mediate initiation of NPC assembly at the end of mitosis.

Animals↗

PubMed2001

Four-dimensional imaging and quantitative reconstruction to analyse complex spatiotemporal processes in live cells.

Live-cell imaging technology using fluorescent proteins (green fluorescent protein and its homologues) has revolutionized the study of cellular dynamics. But tools that can quantitatively analyse complex spatiotemporal processes in live cells remain lacking. Here we describe a new technique--fast multi-colour four-dimensional imaging combined with automated and quantitative time-space reconstruction--to fill this gap. As a proof of principle, we apply this method to study the re-formation of the nuclear envelope in live cells. Four-dimensional imaging of three spectrally distinct fluorescent proteins is used to simultaneously visualize three different cellular compartments at high speed and with high spatial resolution. The highly complex data, comprising several thousand images from a single cell, were quantitatively reconstructed in time-space by software developed in-house. This analysis reveals quantitative and qualitative insights into the highly ordered topology of nuclear envelope formation, in correlation with chromatin expansion - results that would have been impossible to achieve by manual inspection alone. Our new technique will greatly facilitate study of the highly ordered dynamic architecture of eukaryotic cells.

Animals↗

PubMed1980

Effect of sewage sludge diets fed swine on nutrient digestibility, reproduction, growth and minerals in tissues.

Twelve female swine were fed in a 3 X 4 crossover design metabolism trial corn-soybean grower diets that contained 0, 10 or 20% sewage sludge over three 19-day periods. The mean values for total digestible nutrients were 79.4, 73.7 and 55.0%; those for metabolizable energy were 3.36, 2.25 and 1.15 Mcal/kg diet; and those for nitrogen retained were 42.8, 44.0 and 25.3%, respectively. Sewage sludge (0, 10, 20%) diets were fed to 31 sows approximately equally divided into the dietary groups during their first two pregnancies, and to their offspring from weaning until market weight. More live pigs were farrowed and weaned per litter from sows fed 20% sludge diets than from the control group. However, 21-day weaning weights of pigs were lower from sows fed the sludge-containing diets. Offspring of both first and second litters fed growing and finishing diets containing sludge from weaning until market weight had decreased daily weight gains and feed efficiency. There were no increases in nine elements (Pb, Cd, Ni, Zn, Cr, Cu, Mn, Fe and Al) in sow's milk or blood. Offspring of sows fed sludge diets showed increases of several elements in selected tissues at weaning and after consuming sludge diets until market weight.

Animals↗