Endonuclear lipids in liver cellsThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 459-468 ◽  
Author(s):  
Sabina M. Maté ◽  
Rodolfo R. Brenner ◽  
Ana Ves-Losada
Keyword(s):  
Fatty Acid ◽  
Rat Liver ◽  
Molecular Species ◽  
Special Functions ◽  
Total Lipids ◽  
Special Issue ◽  
A Cell ◽  
Liver Nuclei ◽  
Triton X ◽  
Selection Of

Lipids are not only components of cell nucleus membranes, but are also found in the membrane-depleted nuclei where they fulfill special functions. We have investigated the lipid composition of membrane-depleted rat liver nuclei obtained by incubation with low Triton X-100 concentrations of 0.04% and 0.08%, which rendered them unaltered or hardly altered. Under these conditions, 26% of proteins and 22% of phospholipids were recovered. The main phospholipids were phosphatidylcholine > phosphatidylethanolamine > phosphatidylinositol ≥ phosphatidylserine and sphingomyelin (in decreasing concentrations). The fatty acid components of total lipids and phosphatidylcholine were mainly unsaturated. Over 40% belonged to the n–6 series (arachidonic ≥25% and linoleic 15%); approximately 40% corresponded to saturated acids and <10% were monoenoic. Endonuclear phosphatidylcholine was built up by 16 molecular species, the most abundant being 18:0–20:4 (32%), 16:0–20:4 (19%), 16:0–18:2 (13%), and 18:0–18:2 (11%). The fatty acid composition and phosphatidylcholine molecular species distribution in the membrane-depleted nucleus of rat liver showed patterns similar to the whole nucleus, mitochondria, microsomes, and homogenate of the parent liver cells, suggesting that endonuclear lipid pool composition is mainly determined by a liver organ profile.

Nuclear import of spliceosomal snRNPsThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 367-376 ◽  
Author(s):  
Christiane Rollenhagen ◽  
Nelly Panté
Keyword(s):  
Cell Nucleus ◽  
Nuclear Import ◽  
Current Knowledge ◽  
Protein Complexes ◽  
Special Issue ◽  
A Cell ◽  
Rna Maturation ◽  
Small Nuclear Ribonucleoproteins ◽  
Selection Of

Uridine-rich small nuclear ribonucleoproteins (U snRNPs) are the building units of the spliceosome. These RNA and protein complexes assemble in the cytoplasm. After proper assembly and RNA maturation, mature U snRNPs are imported into the cell nucleus, where they take part in the splicing process. In this paper we review the current knowledge of how U snRNPs enter the nucleus.

Somatic DNA recombination in the brainThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 319-324
Author(s):  
Toyoki Maeda ◽  
Saburo Sakoda ◽  
Tomokazu Suzuki ◽  
Naoki Makino
Keyword(s):  
Dna Recombination ◽  
Biological Significance ◽  
Indirect Evidence ◽  
Dna Rearrangement ◽  
Special Issue ◽  
Recombination Activity ◽  
A Cell ◽  
The Brain ◽  
Oriented Approach ◽  
Selection Of

Possible somatic DNA recombination in the brain has been investigated by attempting to capture direct or indirect evidence of it. Until recently, the biological significance of the DNA event, the genes is involved in the recombination, or even whether the event actually occurs in the brain has remained unclear. The DNA-rearranged locus-oriented approach and the recombination activity-oriented approach have mutually contributed to the elucidation of the biological features of extra-immune system somatic DNA recombination. There have been only 2 loci proposed for the candidate, one is a repetitive sequence and the other DNA recombination is nonrepetitive locus. This review states conventional concepts and discussions chronologically and finally to the newest aspects of DNA rearrangement in the brain.

The nuclear tubular invaginations are dynamic structures inside the nucleus of HeLa cellsThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 477-486 ◽  
Author(s):  
Rebecca K.Y. Lee ◽  
Pauline P.Y. Lui ◽  
Erika K.S. Ngan ◽  
Julian C.K. Lui ◽  
Y.K. Suen ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Fluorescent Protein ◽  
Red Fluorescent Protein ◽  
Membrane Protrusion ◽  
Special Issue ◽  
A Cell ◽  
Dynamic Structures ◽  
Protein Transfection ◽  
Confocal And Electron Microscopy ◽  
Selection Of

Nuclear tubules (NTs) were found in the nucleus of HeLa cells. Although no function has been ascribed to these structures, our previous data has shown that they are the sites of Ca2+ release with mitochondria shuttled around. In the present study, we further characterized these NTs through different fluorescent dye-labeling and red fluorescent protein transfection experiments. We found that doxorubicin (Dox) is a good indicator to demonstrate the NTs since Dox is fluorescent and DNA is able to quench its fluorescence. By using confocal and electron microscopy, we show that the number and nature of the NTs in HeLa vary from cell to cell, ranging from tubular to intricately branched structures. Additionally, these NTs are double-membrane invaginations of the nuclear envelope and usually lie close to nucleolus. At rest, NTs appeared to be stable and their mouths are always closed. Upon Ca2+ ionomycin stimulation, various forms of dynamism, including membrane protrusion to the nucleus, enlargement and shrinkage of the NTs, and distortion of the nuclear envelope and NTs were observed over a time scale of minutes. These observations suggest that the NT represents a specialized and dynamic compartment inside the nucleus under the control of Ca2+.

scholarly journals ISOLATION OF TWO DISTINCT CLASSES OF POLYSOMES FROM A NUCLEAR FRACTION OF RAT LIVER

1968 ◽  
Vol 37 (1) ◽  
pp. 163-181 ◽  
Author(s):  
Paul D. Sadowski ◽  
Janet Alcock Howden
Keyword(s):  
Outer Membrane ◽  
Rat Liver ◽  
Orotic Acid ◽  
Specific Activity ◽  
Nuclear Fraction ◽  
Differential Centrifugation ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Triton X

Isolated rat liver nuclei were washed with Triton-X-100 in the presence of liver cell sap. This treatment liberated a fraction of polysomes which were isolated by differential centrifugation and were designated "outer membrane polysomes." The outer membrane polysomes synthesized protein in vivo. Shortly after injection of orotic acid-14C, the RNA of outer membrane polysomes had a higher specific activity than that of cytoplasmic polysomes. It was postulated that outer membrane polysomes may be an intermediate in the transfer of newly synthesized RNA from the nucleus to the cytoplasm. In other experiments, Triton-washed rat liver nuclei were lysed in the presence of deoxycholate and deoxyribonuclease. A ribonucleoprotein fraction was isolated from the lysate by differential centrifugation. This fraction contained "intranuclear ribosomes," which sedimented like partially degraded polysomes in sucrose gradients. This degradation could be partially prevented if intranuclear ribosomes were purified by sedimentation through heavy sucrose. The resulting pellets were termed "intranuclear polysomes" because they contained some undergraded polysomes. Intranuclear polysomes were highly radioactive after a brief pulse with orotic acid-14C, but did not appear to synthesize protein rapidly in vivo. Intranuclear polysomes may represent the initial stage of assembly of polyribosomes in the nucleus.

Getting across the nuclear pore complex: new insights into nucleocytoplasmic transportThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 499-507 ◽  
Author(s):  
Daniel Stoffler ◽  
Kyrill Schwarz-Herion ◽  
Ueli Aebi ◽  
Birthe Fahrenkrog
Keyword(s):  
Nuclear Pore Complex ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Special Issue ◽  
The Past ◽  
Transport Receptors ◽  
A Cell ◽  
New Evidence ◽  
Retention Signal ◽  
Selection Of

Small ions and molecules can traverse the nuclear pore complex (NPC) simply by diffusion, whereas larger proteins and RNAs require specific signals and factors that facilitate their passage through the NPC. Our understanding of the factors that participate and regulate nucleocytoplasmic transport has increased tremendously over the past years, whereas the actual translocation step through the NPC has remained largely unclear. Here, we present and discuss recent findings on the interaction between the NPC and transport receptors and provide new evidence that the NPC acts as a constrained diffusion pore for molecules and particles without retention signal and as an affinity gate for signal-bearing cargos.

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