Organisation of Glycoproteins into Plasma Membrane Domains on Fucus Serratus Eggs

1992 ◽  
Vol 101 (2) ◽  
pp. 437-448
Author(s):  
C. J. STAFFORD ◽  
J. R. GREEN ◽  
J. A. CALLOW
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Egg Cell ◽  
Double Labelling ◽  
Membrane Glycoproteins ◽  
Western Blots ◽  
Fucus Serratus

Fertilisation in the brown alga Fucus involves the interaction of motile, biflagellate sperm with spherical eggs. The eggs differ from those of animals in not having the equivalent of a vitelline layer, jelly coat or zona pellucida outside the plasma membrane, and in addition they are not surrounded by a cell wall. Previous studies on Fucus eggs have shown that the lectin Concanavalin A (ConA) binds in patches on the egg surface, suggesting that there is a non-uniform distribution of plasma membrane glycoproteins. In this paper we have further investigated the occurrence of domains on the Fucus egg plasma membrane using monoclonal antibodies (mAbs) and the lectins ConA and Fucose Binding Protein (FBP). Confocal laser scanning microscopy (CLSM) has been used to observe the binding of probes to the Fucus egg cell surface. Four mAbs (FS2, FS4, FS5 and FS9) raised to Fucus serratus sperm have previously been shown to cross-react with crude egg membrane vesicles. Three of these mAbs (FS2, FS4 and FS5) have now been shown to bind to the egg cell surface and they recognise glycoproteins which are organised into domains. mAb FS4 labels large areas of the egg surface, whereas mAbs FS2 and FS5 bind to smaller patches. The lectins ConA and FBP also bind to smaller, discrete domains. Western blotting results and competition binding assays have shown that mAbs FS2 and FS5 compete for binding to the same set of glycoproteins, and FS5 is used in subsequent experiments; FS4 also binds to several glycoproteins but produces a different pattern of labelling on Western blots compared to FS5, though there may be some common components. ConA labels a subset of the glycoproteins recognised by mAb FS5, and FBP recognises one major glycoprotein which is also recognised by ConA and FS5. Double labelling experiments using the CLSM, with FITC- and Au-labelled probes, have shown that the regions on the egg surface labelled by FS4 and FS5 are mainly exclusive, with small areas of overlap. There are also areas which are not labelled by either of these antibodies. The domains recognised by mAb FS5 contain smaller areas which are labelled by ConA. Overall the results show that the Fucus egg surface is heterogeneous with different sets of glycoproteins being organised into domains. With the probes used it is possible to distinguish between FS4+ FS5−, FS4− FS5+, FS4+ FS5+ and FS4− FS5− regions. Within the FS5+ domains smaller sets of glycoproteins are recognised by ConA and within these latter regions there are glycoproteins recognised by FBP.

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 Vacuolar-type H+-ATPase regulates cytoplasmic pH in Toxoplasma gondii tachyzoites

1998 ◽  
Vol 330 (2) ◽  
pp. 853-860 ◽  
Author(s):  
N. J. Silvia MORENO ◽  
Li ZHONG ◽  
Hong-Gang LU ◽  
Wanderley DE SOUZA ◽  
Marlene BENCHIMOL
Keyword(s):  
Plasma Membrane ◽  
Toxoplasma Gondii ◽  
Laser Scanning ◽  
Membrane Surface ◽  
Surface Proteins ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Dependent Manner ◽  
Cytoplasmic Ph ◽  
Bafilomycin A1

Cytoplasmic pH (pHi) regulation was studied in Toxoplasma gondii tachyzoites by using the fluorescent dye 2ʹ,7ʹ-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein. Their mean baseline pHi (7.07±0.06; n = 5) was not significantly affected in the absence of extracellular Na+, K+ or HCO3- but was significantly decreased in a dose-dependent manner by low concentrations of N,Nʹ-dicyclohexylcarbodi-imide (DCCD), N-ethylmaleimide (NEM) or bafilomycin A1. Bafilomycin A1 also inhibited the recovery of tachyzoite pHi after an acid load with sodium propionate. Similar concentrations of DCCD, NEM and bafilomycin A1 produced depolarization of the plasma membrane potential as measured with bis-(1,3-diethylthiobarbituric)trimethineoxonol (bisoxonol), and DCCD prevented the hyperpolarization that accompanies acid extrusion after the addition of propionate, in agreement with the electrogenic nature of this pump. Confocal laser scanning microscopy indicated that, in addition to being located in cytoplasmic vacuoles, the vacuolar (V)-H+-ATPase of T. gondii tachyzoites is also located in the plasma membrane. Surface localization of the V-H+-ATPase was confirmed by experiments using biotinylation of cell surface proteins and immunoprecipitation with antibodies against V-H+-ATPases. Taken together, the results are consistent with the presence of a functional V-H+-ATPase in the plasma membrane of these intracellular parasites and with an important role of this enzyme in the regulation of pHi homoeostasis in these cells.

scholarly journals Stay in Touch—The Cortical ER of Moss Protonemata in Osmotic Stress Situations

Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 421 ◽  
Author(s):  
Dominik Harant ◽  
Ingeborg Lang
Keyword(s):  
Plasma Membrane ◽  
Cell Biology ◽  
Laser Scanning ◽  
Structural Changes ◽  
Physcomitrella Patens ◽  
Dynamic Network ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Natural State ◽  
Cell Cortex

Plasmolysis is usually introduced to cell biology students as a tool to illustrate the plasma membrane: hypertonic solutions cause the living protoplast to shrink by osmotic water loss; hence, it detaches from the surrounding cell wall. What happens, however, with the subcellular structures in the cell cortex during this process of turgor loss? Here, we investigated the cortical endoplasmic reticulum (ER) in moss protonema cells of Physcomitrella patens in a cell line carrying a transgenic ER marker (GFP-HDEL). The plasma membrane was labelled simultaneously with the fluorescent dye FM4-64 to achieve structural separation. By placing the protonemata in a hypertonic mannitol solution (0.8 M), we were able to follow the behaviour of the cortical ER and the protoplast during plasmolysis by confocal laser scanning microscopy (CLSM). The protoplast shape and structural changes of the ER were further examined after depolymerisation of actin microfilaments with latrunculin B (1 µM). In its natural state, the cortical ER is a dynamic network of fine tubes and cisternae underneath the plasma membrane. Under acute and long-term plasmolysis (up to 45 min), changes in the protoplast form and the cortical ER, as well as the formation of Hechtian strands and Hechtian reticula, were observed. The processing of the high-resolution z-scans allowed the creation of 3D models and gave detailed insight into the ER of living protonema cells before, during and after plasmolysis.

Human cytomegalovirus UL37 immediate-early regulatory proteins traffic through the secretory apparatus and to mitochondria

Microbiology ◽  
2000 ◽  
Vol 81 (7) ◽  
pp. 1779-1789 ◽  
Author(s):  
Anamaris M. Colberg-Poley ◽  
Mital B. Patel ◽  
Darwin P. P. Erezo ◽  
Jay E. Slater
Keyword(s):  
Plasma Membrane ◽  
Human Cytomegalovirus ◽  
Laser Scanning ◽  
Human Cells ◽  
Laser Scanning Microscopy ◽  
Regulatory Proteins ◽  
Immediate Early ◽  
Confocal Laser ◽  
Amino Terminal ◽  
Secretory Apparatus

The human cytomegalovirus (HCMV) UL36–38 immediate-early (IE) locus encodes the UL37 exon 1 (pUL37x1) and UL37 (gpUL37) regulatory proteins, which have anti-apoptotic activities. pUL37x1 shares its entire sequence, including a hydrophobic leader and an acidic domain, with the exception of one residue, with the amino terminus of gpUL37. gpUL37 has, in addition, unique N-linked glycosylation, transmembrane and cytosolic domains. A rabbit polyvalent antiserum was generated against residues 27–40 in the shared amino-terminal domain and a mouse polyvalent antiserum was generated against the full-length protein to study trafficking of individual UL37 proteins in human cells that transiently expressed gpUL37 or pUL37x1. Co-localization studies by confocal laser scanning microscopy detected trafficking of gpUL37 and pUL37x1 from the endoplasmic reticulum to the Golgi apparatus in permissive U373 cells and in human diploid fibroblasts (HFF). Trafficking of gpUL37 to the cellular plasma membrane was detected in unfixed HFF cells. FLAG-tagged gpUL37 trafficked similarly through the secretory apparatus to the plasma membrane. By using confocal microscopy and immunoblotting of fractionated cells, gpUL37 and pUL37x1 were found to co-localize with mitochondria in human cells. This unconventional dual trafficking pattern through the secretory apparatus and to mitochondria is novel for herpesvirus IE regulatory proteins.

Colocalization of MCT1, CD147, and LDH in mitochondrial inner membrane of L6 muscle cells: evidence of a mitochondrial lactate oxidation complex

2006 ◽  
Vol 290 (6) ◽  
pp. E1237-E1244 ◽  
Author(s):  
Takeshi Hashimoto ◽  
Rajaa Hussien ◽  
George A. Brooks
Keyword(s):  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Lactate Oxidation ◽  
Western Blots ◽  
Lactate Shuttle ◽  
Mitochondrial Inner Membrane ◽  
Transport Chain ◽  
Mitochondrial Fractions ◽  
L6 Muscle Cells

Results of previous studies suggested a role of mitochondria in intracellular and cell-cell lactate shuttles. Therefore, by using a rat-derived L6 skeletal muscle cell line and confocal laser-scanning microscopy (CLSM), we examined the cellular locations of mitochondria, lactate dehydrogenase (LDH), the lactate-pyruvate transporter MCT1, and CD147, a purported chaperone protein for MCT1. CLSM showed that LDH, MCT1, and CD147 are colocalized with the mitochondrial reticulum. Western blots showed that cytochrome oxidase (COX), NADH dehydrogenase, LDH, MCT1, and CD147 are abundant in mitochondrial fractions of L6 cells. Interactions among COX, MCT1, and CD147 in mitochondria were confirmed by immunoblotting after immunoprecipitation. These findings support the presence of a mitochondrial lactate oxidation complex associated with the COX end of the electron transport chain that might explain the oxidative catabolism of lactate and, hence, mechanism of the intracellular lactate shuttle.

Determination of Dynamics of Plant Plasma Membrane Proteins with Fluorescence Recovery and Raster Image Correlation Spectroscopy

2016 ◽  
Vol 22 (2) ◽  
pp. 290-299 ◽  
Author(s):  
Martina Laňková ◽  
Jana Humpolíčková ◽  
Stanislav Vosolsobě ◽  
Zdeněk Cit ◽  
Jozef Lacek ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Laser Scanning ◽  
Correlation Spectroscopy ◽  
Laser Scanning Microscopy ◽  
Image Correlation ◽  
Fluorescence Recovery ◽  
Confocal Laser ◽  
Raster Image ◽  
Image Correlation Spectroscopy ◽  
Plant Plasma Membrane

AbstractA number of fluorescence microscopy techniques are described to study dynamics of fluorescently labeled proteins, lipids, nucleic acids, and whole organelles. However, for studies of plant plasma membrane (PM) proteins, the number of these techniques is still limited because of the high complexity of processes that determine the dynamics of PM proteins and the existence of cell wall. Here, we report on the usage of raster image correlation spectroscopy (RICS) for studies of integral PM proteins in suspension-cultured tobacco cells and show its potential in comparison with the more widely used fluorescence recovery after photobleaching method. For RICS, a set of microscopy images is obtained by single-photon confocal laser scanning microscopy (CLSM). Fluorescence fluctuations are subsequently correlated between individual pixels and the information on protein mobility are extracted using a model that considers processes generating the fluctuations such as diffusion and chemical binding reactions. As we show here using an example of two integral PM transporters of the plant hormone auxin, RICS uncovered their distinct short-distance lateral mobility within the PM that is dependent on cytoskeleton and sterol composition of the PM. RICS, which is routinely accessible on modern CLSM instruments, thus represents a valuable approach for studies of dynamics of PM proteins in plants.

FAP-1 in pancreatic cancer cells

2001 ◽  
Vol 114 (15) ◽  
pp. 2735-2746
Author(s):  
Hendrik Ungefroren ◽  
Marie-Luise Kruse ◽  
Anna Trauzold ◽  
Stefanie Roeschmann ◽  
Christian Roeder ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cell Surface ◽  
Pancreatic Carcinoma ◽  
Cancer Cells ◽  
Golgi Complex ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Pancreatic Cancer Cells ◽  
Induced Apoptosis

In this study we investigated the functional role of FAP-1 as a potential inhibitor of CD95 (Fas, APO-1)-mediated apoptosis in pancreatic cancer cells. Stable transfection of the CD95-sensitive, FAP-1-negative cell line Capan-1 with an FAP-1 cDNA resulted in a strongly decreased sensitivity to CD95-induced apoptosis, as measured by DNA fragmentation and caspase-3 activity. Inhibition of cellular protein tyrosine phosphatases with orthovanadate dose-dependently increased CD95-induced apoptosis in CD95-resistant FAP-1-positive Panc89 and Capan-1-FAP-1 cells almost to the level seen in wild-type Capan-1 cells. Blocking the CD95/FAP-1 interaction in Panc89 cells by cytoplasmic microinjection of a synthetic tripeptide mimicking the C terminus of CD95 resulted in a mean 5.5-fold increase in apoptosis compared to cells that received a control peptide. Using confocal laser scanning microscopy we show that in Panc89 cells FAP-1 is mainly associated with the Golgi complex and with peripheral vesicles. FAP-1 displayed enhanced colocalization with CD95 upon CD95 stimulation in the Golgi complex but not in surface-associated vesicles. This correlated with a decrease in plasma membrane staining for CD95 as determined by FACS analysis. Inhibition of Golgi anterograde transport by brefeldin A abolished the anti-CD95-induced colocalization of FAP-1 and CD95 as well as the decrease in cell-surface-associated CD95. Finally, we demonstrate by immunohistochemistry that FAP-1 is strongly expressed in tumor cells from pancreatic carcinoma tissues. Taken together, these results show that FAP-1 can protect pancreatic carcinoma cells from CD95-mediated apoptosis, probably by preventing anti-CD95-induced translocation of CD95 from intracellular stores to the cell surface.

Unique geometry of actin-membrane anchorage sites in avian gizzard smooth muscle cells

1989 ◽  
Vol 94 (4) ◽  
pp. 703-711
Author(s):  
A. Draeger ◽  
E.H. Stelzer ◽  
M. Herzog ◽  
J.V. Small
Keyword(s):  
Smooth Muscle ◽  
Cell Surface ◽  
Smooth Muscle Cells ◽  
Laser Scanning ◽  
Smooth Muscles ◽  
Muscle Cells ◽  
Laser Scanning Microscopy ◽  
Surface Pattern ◽  
Confocal Laser ◽  
Dense Bodies

Adherens junctions in isolated avian gizzard smooth muscle cells appear as short longitudinal streaks or chevrons that are arranged in periodic, mainly transverse bands along the cell surface. This barrel-like geometry, revealed by antibodies to either vinculin or talin, was seen also in teased gizzard strips by confocal laser-scanning microscopy and contrasted with the rib-like surface pattern observed here and previously in other avian and mammalian smooth muscles. There were on average 67 transverse bands per gizzard cell and an estimated total of around 800 vinculin/talin sites. The longitudinal spacing between the transverse bands of vinculin streaks in the gizzard cells changed from 4–5 microns in extended cells to around 1 micron in shortened cells and the bands remained essentially transverse at all cell lengths, inconsistent with a screw-like mode of cell shortening as has been invoked for smooth muscle cells by others. The absence of rotation on shortening was confirmed by observations on isolated and bead-decorated skinned cells that were induced to contract with ATP. Counterlabelling of cells with alpha-actinin antibodies produced more or less exclusive staining of the cytoplasmic dense bodies, and little surface label: the total number of dense bodies per cell, estimated from confocal microscope through focal series was in the range of 3000. The data are consistent with a periodic anchorage of actin filaments to the cell surface and, in turn, with the existence of regularly spaced contractile assemblies.

scholarly journals Charged residues in the M2 region of α-hENaC play a role in channel conductance

2000 ◽  
Vol 278 (2) ◽  
pp. C277-C291 ◽  
Author(s):  
Anne Lynn B. Langloh ◽  
Bakhrom Berdiev ◽  
Hong-Long Ji ◽  
Kent Keyser ◽  
Bruce A. Stanton ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Transmembrane Domain ◽  
Single Channel ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Channel Conductance ◽  
Α Subunit ◽  
Whole Cell

The epithelial Na+channel (ENaC) is a low-conductance channel that is highly selective for Na+ and Li+ over K+ and impermeable to anions. The molecular basis underlying these conduction properties is not well known. Previous studies with the ENaC subunits demonstrated that the M2 region of α-ENaC is critical to channel function. Here we examine the effects of reversing the negative charges of highly conserved amino acids in α-subunit human ENaC (α-hENaC) M1 and M2 domains. Whole cell and single-channel current measurements indicated that the M2 mutations E568R, E571R, and D575R significantly decreased channel conductance but did not affect Na+:K+permeability. We observed no functional perturbations from the M1 mutation E108R. Whole cell amiloride-sensitive current recorded from oocytes injected with the M2 α-hENaC mutants along with wild-type (wt) β- and γ-hENaC was low (46–93 nA) compared with the wt channel (1–3 μA). To determine whether this reduced macroscopic current resulted from a decreased number of mutant channels at the plasma membrane, we coexpressed mutant α-hENaC subunits with green fluorescent protein-tagged β- and γ-subunits. Confocal laser scanning microscopy of oocytes demonstrated that plasma membrane localization of the mutant channels was the same as that of wt. These experiments demonstrate that acidic residues in the second transmembrane domain of α-hENaC affect ion permeation and are thus critical components of the conductive pore of ENaC.

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