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+.

Illuminating subcellular structures and dynamics in plants: a fluorescent protein toolboxThis review is one of a selection of papers published in the Special Issue on Plant Cell Biology.

2006 ◽  
Vol 84 (4) ◽  
pp. 515-522 ◽  
Author(s):  
Preetinder K. Dhanoa ◽  
Alison M. Sinclair ◽  
Robert T. Mullen ◽  
Jaideep Mathur
Keyword(s):  
Plant Cell ◽  
Cell Biology ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Live Imaging ◽  
Living Cells ◽  
Special Issue ◽  
Exciting Possibility ◽  
Selection Of

The discovery and development of multicoloured fluorescent proteins has led to the exciting possibility of observing a remarkable array of subcellular structures and dynamics in living cells. This minireview highlights a number of the more common fluorescent protein probes in plants and is a testimonial to the fact that the plant cell has not lagged behind during the live-imaging revolution and is ready for even more in-depth exploration.

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.

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.

NPY, ET-1, and Ang II nuclear receptors in human endocardial endothelial 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. 299-307 ◽  
Author(s):  
Danielle Jacques ◽  
Sawsan Sader ◽  
Claudine Perreault ◽  
Dima Abdel-Samad ◽  
Farah Jules ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
Membrane Receptors ◽  
Ang Ii ◽  
Special Issue ◽  
A Cell ◽  
Endocardial Endothelial Cells ◽  
Plasma Membrane Receptors ◽  
G Protein Coupled ◽  
Selection Of

Neuropeptide Y (NPY), endothelin-1 (ET-1), and angiotensin II (Ang II) are peptides that are known to play many important roles in cardiovascular homeostasis. The physiological actions of these peptides are thought to be primarily mediated by plasma membrane receptors that belong to the G-protein-coupled receptor superfamily. However, there is increasing evidence that suggests the existence of functional G-protein-coupled receptors at the level of the nucleus and that the nucleus could be a cell within a cell. Here, we review our work showing the presence in the nucleus of the NPY Y1 receptor, the ETA and ETB receptors, as well as the AT1 and AT2 receptors and their respective ligands. This work was carried out in 20-week-old fetal human endocardial endothelial cells. Our results demonstrate that nuclear Y1, AT1, and ETA receptors modulate nuclear calcium in these cells.

GM1 ganglioside: another nuclear lipid that modulates nuclear calcium. GM1 potentiates the nuclear sodium–calcium exchangerThis 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. 393-402 ◽  
Author(s):  
Robert W. Ledeen ◽  
Gusheng Wu
Keyword(s):  
Plasma Membrane ◽  
Neuroblastoma Cells ◽  
Genetically Engineered ◽  
Neural Cells ◽  
Special Issue ◽  
Sodium Calcium ◽  
A Cell ◽  
Induced Apoptosis ◽  
Selection Of ◽  
Exchange Activity

The nuclear envelope (NE) enclosing the cell nucleus, although morphologically and chemically distinct from the plasma membrane, has certain features in common with the latter including the presence of GM1 as an important modulatory molecule. This ganglioside influences Ca2+ flux across both membranes, but by quite different mechanisms. GM1 in the NE contributes to regulation of nuclear Ca2+ through potentiation of a Na+/Ca2+ exchanger in the inner nuclear membrane, whereas in the cell membrane, it regulates cytosolic Ca2+ through modulation of a nonvoltage-gated Ca2+ channel. Studies with neuroblastoma cells suggest GM1 concentration becomes elevated in the NE with onset of axonogenesis. However, the nuclear GM1/exchanger complex is not limited to neuronal cells but also occurs in NE of astrocytes, C6 cells, and certain non-neural cells. Immunoprecipitation and immunoblot experiments have shown high affinity association of the nuclear Na+/Ca2+ exchanger with GM1, in contrast to Na+/Ca2+ exchangers of the plasma membrane, which bind GM1 less avidly or not at all. This is believed to be due to different isoforms of the exchanger and a difference in topology of GM1 relative to the large inner loop of the exchanger in the 2 membranes. Cultured neurons from mice genetically engineered to lack GM1 suffered Ca2+ dysregulation as seen in their high vulnerability to Ca2+-induced apoptosis. They were rescued by GM1 and more effectively by LIGA20, a membrane-permeant derivative of GM1. The mutant animals were highly susceptible to kainate-induced seizures, which are also a reflection of Ca2+ dysregulation. The seizures were effectively attenuated by LIGA20 in parallel with the ability of this agent to enter brain cells, insert into the NE, and potentiate Na+/Ca2+ exchange activity in the nucleus. The Na+/Ca2+ exchanger of the NE, in association with nuclear GM1, is thus seen contributing to independent regulation of Ca2+ by the nucleus in a manner that provides cytoprotection against Ca2+-induced apoptosis.

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.

Fluorescent proteins for in vivo imaging, where's the biliverdin?

2020 ◽  
Vol 48 (6) ◽  
pp. 2657-2667
Author(s):  
Felipe Montecinos-Franjola ◽  
John Y. Lin ◽  
Erik A. Rodriguez
Keyword(s):  
Hydrogen Peroxide ◽  
In Vivo Imaging ◽  
Near Infrared ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescent Imaging ◽  
Infrared Light ◽  
Red Fluorescent Protein ◽  
Color Palette

Noninvasive fluorescent imaging requires far-red and near-infrared fluorescent proteins for deeper imaging. Near-infrared light penetrates biological tissue with blood vessels due to low absorbance, scattering, and reflection of light and has a greater signal-to-noise due to less autofluorescence. Far-red and near-infrared fluorescent proteins absorb light &gt;600 nm to expand the color palette for imaging multiple biosensors and noninvasive in vivo imaging. The ideal fluorescent proteins are bright, photobleach minimally, express well in the desired cells, do not oligomerize, and generate or incorporate exogenous fluorophores efficiently. Coral-derived red fluorescent proteins require oxygen for fluorophore formation and release two hydrogen peroxide molecules. New fluorescent proteins based on phytochrome and phycobiliproteins use biliverdin IXα as fluorophores, do not require oxygen for maturation to image anaerobic organisms and tumor core, and do not generate hydrogen peroxide. The small Ultra-Red Fluorescent Protein (smURFP) was evolved from a cyanobacterial phycobiliprotein to covalently attach biliverdin as an exogenous fluorophore. The small Ultra-Red Fluorescent Protein is biophysically as bright as the enhanced green fluorescent protein, is exceptionally photostable, used for biosensor development, and visible in living mice. Novel applications of smURFP include in vitro protein diagnostics with attomolar (10−18 M) sensitivity, encapsulation in viral particles, and fluorescent protein nanoparticles. However, the availability of biliverdin limits the fluorescence of biliverdin-attaching fluorescent proteins; hence, extra biliverdin is needed to enhance brightness. New methods for improved biliverdin bioavailability are necessary to develop improved bright far-red and near-infrared fluorescent proteins for noninvasive imaging in vivo.

Introduction: Affixes and bases

2011 ◽  
Vol 4 (2) ◽  
pp. 161-168
Author(s):  
Stela Manova
Keyword(s):  
Special Issue ◽  
Affix Order ◽  
Selection Of ◽  
Affix Ordering

This special issue includes a selection of papers presented at the 2nd Vienna Workshop on Affix Order held in Vienna, Austria on June 4–5, 2009. The workshop was in honor of Wolfgang U. Dressler on the occasion of his 70th birthday. However, this special issue differs from the classical Festschrift dedicated to a renowned scholar and is ‘more special’ in two respects at least: 1) not all authors are Dressler's friends and colleagues, some of them are only indirectly related to him, through his students; and 2) since the papers were presented at a topic-oriented workshop, they are thematically uniform. In other words, this special issue is a kind of scientific genealogy in terms of affix ordering. Thus, the title Affixes and bases should be understood in two ways: literally – affixes and bases as linguistic notions, and metaphorically – affixes and bases as linguists related directly and indirectly to a prominent base: Wolfgang U. Dressler.

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