Quantification of microtubule dynamics in living plant cells using fluorescence redistribution after photobleaching

1994 ◽  
Vol 107 (4) ◽  
pp. 775-784 ◽  
Author(s):  
J.M. Hush ◽  
P. Wadsworth ◽  
D.A. Callaham ◽  
P.K. Hepler
Keyword(s):  
Mammalian Cells ◽  
Laser Scanning ◽  
Dynamic Instability ◽  
Animal Cell ◽  
Plant Cells ◽  
Preprophase Band ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Turnover Rates ◽  
Living Plant

Microtubule (MT) turnover within the four principal MT arrays, the cortical array, the preprophase band, the mitotic spindle and the phragmoplast, has been measured in living stamen hair cells of Tradescantia that have been injected with fluorescent neurotubulin. Using the combined techniques of confocal laser scanning microscopy and fluorescence redistribution after photobleaching (FRAP), we report that the half-time of turnover in spindle MTs is t 1/2 = 31 +/- 6 seconds, which is in excellent agreement with previous measurements of turnover in animal cell spindles. Tradescantia interphase MTs, however, exhibit turnover rates (t 1/2 = 67 +/- seconds) that are some 3.4-fold faster than those measured in interphase mammalian cells, and thus are revealed as being highly dynamic. Preprophase band and phragmoplast MTs have turnover rates similar to those of interphase MTs in Tradescantia. The spatial and temporal aspects of the fluorescence redistribution after photobleaching in all four MT arrays are more consistent with subunit exchange by the mechanism of dynamic instability than treadmilling. This is the first quantification of MT dynamics in plant cells.

Vacuoles Induced in Mammalian Cells by Helicobacter Cytotoxin are Acidic Organelles

1990 ◽  
Vol 48 (3) ◽  
pp. 168-169
Author(s):  
M. H. Chestnut ◽  
C. E. Catrenich
Keyword(s):  
Acridine Orange ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Ulcer Disease ◽  
Gastroduodenal Disease ◽  
H Pylori

Helicobacter pylori is a non-invasive, Gram-negative spiral bacterium first identified in 1983, and subsequently implicated in the pathogenesis of gastroduodenal disease including gastritis and peptic ulcer disease. Cytotoxic activity, manifested by intracytoplasmic vacuolation of mammalian cells in vitro, was identified in 55% of H. pylori strains examined. The vacuoles increase in number and size during extended incubation, resulting in vacuolar and cellular degeneration after 24 h to 48 h. Vacuolation of gastric epithelial cells is also observed in vivo during infection by H. pylori. A high molecular weight, heat labile protein is believed to be responsible for vacuolation and to significantly contribute to the development of gastroduodenal disease in humans. The mechanism by which the cytotoxin exerts its effect is unknown, as is the intracellular origin of the vacuolar membrane and contents. Acridine orange is a membrane-permeant weak base that initially accumulates in low-pH compartments. We have used acridine orange accumulation in conjunction with confocal laser scanning microscopy of toxin-treated cells to begin probing the nature and origin of these vacuoles.

scholarly journals Fig mosaic emaravirus p4 protein is involved in cell-to-cell movement

2013 ◽  
Vol 94 (3) ◽  
pp. 682-686 ◽  
Author(s):  
Kazuya Ishikawa ◽  
Kensaku Maejima ◽  
Ken Komatsu ◽  
Osamu Netsu ◽  
Takuya Keima ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Laser Scanning ◽  
Movement Protein ◽  
Rna Virus ◽  
Cell Movement ◽  
Plant Cells ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Series Of Experiments ◽  
Fig Mosaic Virus

Fig mosaic virus (FMV), a member of the newly formed genus Emaravirus, is a segmented negative-strand RNA virus. Each of the six genomic FMV segments contains a single ORF: that of RNA4 encodes the protein p4. FMV-p4 is presumed to be the movement protein (MP) of the virus; however, direct experimental evidence for this is lacking. We assessed the intercellular distribution of FMV-p4 in plant cells by confocal laser scanning microscopy and we found that FMV-p4 was localized to plasmodesmata and to the plasma membrane accompanied by tubule-like structures. A series of experiments designed to examine the movement functions revealed that FMV-p4 has the capacity to complement viral cell-to-cell movement, prompt GFP diffusion between cells, and spread by itself to neighbouring cells. Altogether, our findings demonstrated that FMV-p4 shares several properties with other viral MPs and plays an important role in cell-to-cell movement.

scholarly journals PGC-1-Related Coactivator, a Novel, Serum-Inducible Coactivator of Nuclear Respiratory Factor 1-Dependent Transcription in Mammalian Cells

2001 ◽  
Vol 21 (11) ◽  
pp. 3738-3749 ◽  
Author(s):  
Ulf Andersson ◽  
Richard C. Scarpulla
Keyword(s):  
Transcriptional Activation ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Peroxisome Proliferator ◽  
Nuclear Respiratory Factor ◽  
Nuclear Respiratory Factor 1 ◽  
Cell Extracts

ABSTRACT The thermogenic peroxisome proliferator-activated receptor γ (PPAR-γ) coactivator 1 (PGC-1) has previously been shown to activate mitochondrial biogenesis in part through a direct interaction with nuclear respiratory factor 1 (NRF-1). In order to identify related coactivators that act through NRF-1, we searched the databases for sequences with similarities to PGC-1. Here, we describe the first characterization of a 177-kDa transcriptional coactivator, designated PGC-1-related coactivator (PRC). PRC is ubiquitously expressed in murine and human tissues and cell lines; but unlike PGC-1, PRC was not dramatically up-regulated during thermogenesis in brown fat. However, its expression was down-regulated in quiescent BALB/3T3 cells and was rapidly induced by reintroduction of serum, conditions where PGC-1 was not detected. PRC activated NRF-1-dependent promoters in a manner similar to that observed for PGC-1. Moreover, NRF-1 was immunoprecipitated from cell extracts by antibodies directed against PRC, and both proteins were colocalized to the nucleoplasm by confocal laser scanning microscopy. PRC interacts in vitro with the NRF-1 DNA binding domain through two distinct recognition motifs that are separated by an unstructured proline-rich region. PRC also contains a potent transcriptional activation domain in its amino terminus adjacent to an LXXLL motif. The spatial arrangement of these functional domains coincides with those found in PGC-1, supporting the conclusion that PRC and PGC-1 are structurally and functionally related. We conclude that PRC is a functional relative of PGC-1 that operates through NRF-1 and possibly other activators in response to proliferative signals.

Cytokinesis arrest and redistribution of actin-cytoskeleton regulatory components in cells expressing the Rho GTPase CDC42Hs

1996 ◽  
Vol 109 (2) ◽  
pp. 367-377 ◽  
Author(s):  
H. Dutartre ◽  
J. Davoust ◽  
J.P. Gorvel ◽  
P. Chavrier
Keyword(s):  
Actin Cytoskeleton ◽  
Rho Gtpases ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Rho Gtpase ◽  
Laser Scanning Microscopy ◽  
Regulatory Subunit ◽  
Confocal Laser ◽  
Complex Architectures ◽  
Immunofluorescence Labelling

In mammalian cells, Rho GTPases control the reorganisation of the actin cytoskeleton in response to growth factors. In the cytoplasm, the polymerisation of actin filaments and their organisation into complex architectures is orchestrated by numerous proteins which act either directly, by interacting with actin, or by producing secondary messengers which serve as mediators between signal transduction pathways and the microfilament organisation. We sought to determine whether the intracellular distribution of some of these regulatory components may be controlled by the Rho GTPase CDC42Hs. With this aim, we have established HeLa-derived human cell lines in which expression of a constitutively activated mutant of CDC42Hs is inducible. Morphological analysis by immunofluorescence labelling and confocal laser scanning microscopy revealed a massive reorganisation of F-actin in cortical microspikes as well as podosome-like structures located at the ventral face of the cells. Concomitantly, the cells became giant and multinucleate indicating that cytokinesis was impaired. The actin bundling protein T-plastin, the vasodilatator-stimulated phosphoprotein (VASP), a profilin ligand, as well as the 85 kDa regulatory subunit of the phosphoinosite 3-kinase redistributed with F-actin into the CDC42Hs-induced structures.

scholarly journals Myxobacteria-Derived Outer Membrane Vesicles: Potential Applicability Against Intracellular Infections

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 194 ◽  
Author(s):  
Adriely Goes ◽  
Philipp Lapuhs ◽  
Thomas Kuhn ◽  
Eilien Schulz ◽  
Robert Richter ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Respiratory Infections ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Potential Applicability ◽  
Intracellular Infections

In 2019, it was estimated that 2.5 million people die from lower tract respiratory infections annually. One of the main causes of these infections is Staphylococcus aureus, a bacterium that can invade and survive within mammalian cells. S. aureus intracellular infections are difficult to treat because several classes of antibiotics are unable to permeate through the cell wall and reach the pathogen. This condition increases the need for new therapeutic avenues, able to deliver antibiotics efficiently. In this work, we obtained outer membrane vesicles (OMVs) derived from the myxobacteria Cystobacter velatus strain Cbv34 and Cystobacter ferrugineus strain Cbfe23, that are naturally antimicrobial, to target intracellular infections, and investigated how they can affect the viability of epithelial and macrophage cell lines. We evaluated by cytometric bead array whether they induce the expression of proinflammatory cytokines in blood immune cells. Using confocal laser scanning microscopy and flow cytometry, we also investigated their interaction and uptake into mammalian cells. Finally, we studied the effect of OMVs on planktonic and intracellular S. aureus. We found that while Cbv34 OMVs were not cytotoxic to cells at any concentration tested, Cbfe23 OMVs affected the viability of macrophages, leading to a 50% decrease at a concentration of 125,000 OMVs/cell. We observed only little to moderate stimulation of release of TNF-alpha, IL-8, IL-6 and IL-1beta by both OMVs. Cbfe23 OMVs have better interaction with the cells than Cbv34 OMVs, being taken up faster by them, but both seem to remain mostly on the cell surface after 24 h of incubation. This, however, did not impair their bacteriostatic activity against intracellular S. aureus. In this study, we provide an important basis for implementing OMVs in the treatment of intracellular infections.

scholarly journals Visualization of the Peroxisomal Compartment in Living Mammalian Cells: Dynamic Behavior and Association with Microtubules

1997 ◽  
Vol 136 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Erik A.C. Wiemer ◽  
Thibaut Wenzel ◽  
Thomas J. Deerinck ◽  
Mark H. Ellisman ◽  
Suresh Subramani
Keyword(s):  
Mammalian Cells ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Time Lapse ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Small Subset ◽  
Subcellular Compartment ◽  
Directional Movement ◽  
Green Fluorescent

Peroxisomes in living CV1 cells were visualized by targeting the green fluorescent protein (GFP) to this subcellular compartment through the addition of a COOH-terminal peroxisomal targeting signal 1 (GFP–PTS1). The organelle dynamics were examined and analyzed using time-lapse confocal laser scanning microscopy. Two types of movement could be distinguished: a relatively slow, random, vibration-like movement displayed by the majority (∼95%) of the peroxisomes, and a saltatory, fast directional movement displayed by a small subset (∼5%) of the peroxisomes. In the latter instance, peak velocities up to 0.75 μm/s and sustained directional velocities up to 0.45 μm/s over 11.5 μm were recorded. Only the directional type of motion appeared to be energy dependent, whereas the vibrational movement continued even after the cells were depleted of energy. Treatment of cells, transiently expressing GFP–PTS1, with microtubule-destabilizing agents such as nocodazole, vinblastine, and demecolcine clearly altered peroxisome morphology and subcellular distribution and blocked the directional movement. In contrast, the microtubule-stabilizing compound paclitaxel, or the microfilament-destabilizing drugs cytochalasin B or D, did not exert these effects. High resolution confocal analysis of cells expressing GFP–PTS1 and stained with anti-tubulin antibodies revealed that many peroxisomes were associated with microtubules. The GFP–PTS1–labeled peroxisomes were found to distribute themselves in a stochastic, rather than ordered, manner to daughter cells at the time of mitosis.

Confocal microscopy analysis of native, full length and B-domain deleted coagulation factor VIII trafficking in mammalian cells

2004 ◽  
Vol 92 (07) ◽  
pp. 23-35 ◽  
Author(s):  
Sven Becker ◽  
Jeremy Simpson ◽  
Rainer Pepperkok ◽  
Stefan Heinz ◽  
Christian Herder ◽  
...  
Keyword(s):  
Factor Viii ◽  
Golgi Complex ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Coagulation Factor ◽  
Full Length ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Microscopy Analysis ◽  
Recombinant Fviii

SummaryIn mammalian cells, factor VIII (FVIII) secretion depends upon its interaction with chaperones of the endoplasmic reticulum (ER) and requires a unique ATP-dependent step to dissociate aggregates formed within the ER. To further elucidate mechanisms which might account for the inefficient secretion of recombinant FVIII (rFVIII), we have analyzed the pathways of recombinant full length (rFVIII-FL) and B-domain deleted (rFVIIIΔB) FVIII and compared these to the secretion route of native FVIII in primary hepatocytes. Using confocal laser scanning microscopy in combination with a pulse chase of a known secretion marker, we describe the trafficking route of FVIII, which upon release from the ER – where it colocalizes with calnexin – is transported to the Golgi complex in vesiculartubular transport complexes (VTCs) which could be further identified as being COP I coated. However, a large portion of rFVIII is retained in the ER and additionally in structures which could not be assigned to the ER, Golgi complex or intermediate compartment. Moderate BiP transcription levels indicate that this observed retention of FVIII does not reflect cellular stress due to an overexpression of FVIII-protein in transduced cells. Moreover, a pulse of newly synthesized rFVIII protein is released within 4 hrs, indicating that once rFVIII is released from the ER there is no further limitation to its secretion. Our data provide new details about the secretory route of FVIII, which may ultimately help to identify factors currently limiting the efficient and physiological expression of FVIII in gene therapy and manufacture.

Relocation of nucleolar proteins around chromosomes at mitosis. A study by confocal laser scanning microscopy

1992 ◽  
Vol 102 (4) ◽  
pp. 729-737 ◽  
Author(s):  
T. Gautier ◽  
M. Robert-Nicoud ◽  
M.N. Guilly ◽  
D. Hernandez-Verdun
Keyword(s):  
Confocal Laser Scanning Microscopy ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Scanning Microscopy ◽  
Confocal Laser ◽  
Early Prophase ◽  
Late Prophase ◽  
Nucleolar Proteins

The behaviour of nucleolar antigens known to associate with chromosomes at mitosis was investigated in mammalian cells (HeLa, HEp-2, PtK1, CHO) by immunofluorescence and confocal laser scanning microscopy. Serial optical sections through mitotic cells, from prophase to telophase, were used to generate three-dimensional images of the antigen distribution. Our results indicate that, at the onset of mitosis, these antigens leave the nucleoli in a highly ordered manner to form a network extending from the nucleoli towards the nuclear envelope. The migration begins at very early prophase, when the condensation of the chromosomes is not yet visible. After completion of the migration at late prophase, the labelling is found at the chromosome periphery. The antigens remain distributed as a sheath surrounding the chromosomes from prophase to telophase. Therefore, the proteins involved in the formation of this perichromosomal layer have different behaviour than those of the prenucleolar bodies. The antigens appear to interact strongly with chromosomes, since they are not lost during chromosome isolation in hypotonic buffer. Each chromosome is entirely covered from one telomere to the other, except in the centromeric region. Thus the relocation of these nucleolar proteins does not appear to be the result of a passive accumulation at the chromosome periphery, but seems rather to be due to an active targeting to specific sites. Consequently, these proteins may have a determining function in the progression of the cells through mitosis, possibly by participating in the protection and stabilization of the chromosomes.

scholarly journals Morphometric studies of the localization of the glucocorticoid receptor in mammalian cells and of glucocorticoid hormone-induced effects.

1994 ◽  
Vol 42 (5) ◽  
pp. 645-657 ◽  
Author(s):  
G Akner ◽  
A C Wikström ◽  
K Mossberg ◽  
K G Sundqvist ◽  
J A Gustafsson
Keyword(s):  
Glucocorticoid Receptor ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Nuclear Translocation ◽  
Cell Types ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Mitotic Apparatus ◽  
Glucocorticoid Treatment ◽  
Cytoplasmic Microtubules

We studied the subcellular distribution of the glucocorticoid receptor (GR) by light microscopy (LM) and confocal laser scanning microscopy (CLSM) in different mammalian cell types. The effect of added glucocorticoid hormones on GR distribution was investigated by photometric quantitation on optical sections obtained by CLSM followed by statistical analysis. In the control interphase cytoplasm, the distribution of GR was fibrillar in some and diffuse in other cell types. Fibrillar GR was distributed along cytoplasmic microtubules (MTs) with predilection for a subset of MTs. GR was also observed in the centrosomes. Nuclear GR was both diffuse and granular in distribution. During cell division, GR appeared in the mitotic apparatus at all stages of mitosis. These findings were not fixation-dependent. Glucocorticoid treatment increased both the nuclear and cytoplasmic GR signal. However, this was detectable only after precipitating but not cross-linking fixation. There was both intra- and intercellular GR heterogeneity in the absence and presence of hormone but no indication of a hormone-induced nuclear translocation of GR. We present a hypothetical model of two independent GR populations in the nucleus and cytoplasm, respectively, without any discernible ligand-induced nuclear translocation of GR. The extranuclear GR population may exert effect(s) on site in the cytoplasm without involving nuclear genomic transcription.

scholarly journals Essential Role for the Legionella pneumophila Rep Helicase Homologue in Intracellular Infection of Mammalian Cells

2000 ◽  
Vol 68 (12) ◽  
pp. 6970-6978 ◽  
Author(s):  
Omar S. Harb ◽  
Yousef Abu Kwaik
Keyword(s):  
Legionella Pneumophila ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Alveolar Epithelial Cells ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Wild Type ◽  
Intracellular Replication ◽  
Simultaneous Exposure ◽  
U937 Macrophage

ABSTRACT We have previously isolated 32 mutants of Legionella pneumophila that are defective in the infection of mammalian cells but not protozoa. The mutated loci have been designated macrophage-specific infectivity (mil) loci. In this study we characterized the mil mutant GK11. This mutant was incapable of growth within U937 macrophage-like cells and WI-26 alveolar epithelial cells. This defect in intracellular replication correlated with a defect in cytopathogenicity to these cells. Sequence analysis of the GK11 locus revealed it to be highly similar torep helicase genes of other bacteria. Since helicase mutants of Escherichia coli are hypersensitive to thymine starvation, we examined the sensitivity of GK11 to thymineless death (TLD). In the absence of thymine and thymidine, mutant GK11 did not undergo TLD but was defective for in vitro growth, and the defect was partially restored when these compounds were added to the growth medium. In addition, supplementation with thymidine or thymine partially restored the ability of GK11 to grow within and kill U937 macrophage-like cells. The data suggested that the low levels of thymine or thymidine in the L. pneumophila phagosome contributed to the defect of GK11 within macrophages. Using confocal laser scanning microscopy, we determined the effect of the mutation in the Rep helicase homologue on the intracellular trafficking of GK11 within macrophages. In contrast to the wild-type strain, phagosomes harboring GK11 colocalized with several late endosomal/lysosomal markers, including LAMP-1, LAMP-2, and cathepsin D. In addition, only 50% of the GK11 phagosomes colocalized with the endoplasmic reticulum marker BiP 4 h postinfection. Colocalization of BiP with GK11 phagosomes was absent 6 h postinfection, while 90% of the wild-type phagosomes colocalized with this marker at both time points. We propose that the low level of thymine within the L. pneumophila phagosome in combination with simultaneous exposure to multiple stress stimuli results in deleterious mutations that cannot be repaired in therep helicase homologue mutant, rendering it defective in intracellular replication.

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