Main Features of Basal Cytoxicity: Sites of Toxic Action and Interaction in the Pollen Tube Cell

1996 ◽  
Vol 24 (3) ◽  
pp. 429-434
Author(s):  
Udo Kristen
Keyword(s):  
Intracellular Transport ◽  
Chemical Compounds ◽  
Cell Types ◽  
Pollen Tubes ◽  
Eukaryotic Cell ◽  
Toxic Action ◽  
Membrane Flow ◽  
Cytotoxic Compounds ◽  
Tube Cell ◽  
Basal Cytotoxicity

Pollen tubes have frequently been used to determine the cytotoxic potentials of various chemical compounds and to study the effects of toxic action in the tube cell. In this paper, the main results of these studies are used to develop a model for understanding basal cytotoxicity. The following eight intracellular sites or functions, which are known to play a significant role as targets for toxic action, are considered: mitochondria, intracellular transport, membrane flow, the endoplasmic reticulum and Golgi apparatus, lipid and protein synthesis, carbohydrate synthesis, the cytoskeleton, and the plasma membrane. The reactions of these targets to certain representative cytotoxic compounds frequently applied to pollen tubes are reviewed. These reactions, most of which were observed by using electron microscopy and immunofluorescence microscopy, are discussed in relation to cell growth inhibition. In addition, interactions between the target sites are described and schematically presented. The set of targets mentioned above is representative of what is found in the majority of eukaryotic cell types. Therefore, it is not surprising that many of the cell types which are used in cytotoxicology produce values within the same logarithmic range.

Pronounced cytoplasmic pH gradients are not required for tip growth in plant and fungal cells

1997 ◽  
Vol 110 (10) ◽  
pp. 1187-1198 ◽  
Author(s):  
R.M. Parton ◽  
S. Fischer ◽  
R. Malho ◽  
O. Papasouliotis ◽  
T.C. Jelitto ◽  
...  
Keyword(s):  
Tip Growth ◽  
Cell Types ◽  
Pollen Tubes ◽  
Fine Tuning ◽  
Cytoplasmic Ph ◽  
Dual Emission ◽  
Ph Gradients ◽  
Longitudinal Gradients ◽  
External Ph

The existence of pronounced cytoplasmic pH gradients within the apices of tip-growing cells, and the role of cytoplasmic pH in regulating tip growth, were investigated in three different cell types: vegetative hyphae of Neurospora crassa; pollen tubes of Agapanthus umbellatus; and rhizoids of Dryopteris affinis gametophytes. Examination of cytoplasmic pH in growing cells was performed by simultaneous, dual emission confocal ratio imaging of the pH-sensitive probe carboxy SNARF-1. Considerable attention was paid to the fine tuning of dye loading and imaging parameters to minimise cellular perturbation and assess the extent of dye partitioning into organelles. With optimal conditions, cytoplasmic pH was measured routinely with a precision of between +/−0.03 and +/−0.06 of a pH unit and a spatial resolution of 2.3 microm2. Based on in vitro calibration, estimated values of mean cytoplasmic pH for cells loaded with dye-ester were between 7.15 and 7.25 for the three cell types. After pressure injecting Neurospora hyphae with dextran-conjugated dye, however, the mean cytoplasmic pH was estimated to be 7.57. Dextran dyes are believed to give a better estimate of cytoplasmic pH because of their superior localisation and retention within the cytosol. No significant cytoplasmic pH gradient (delta pH of >0.1 unit) was observed within the apical 50 microm in growing cells of any of the three cell types. Acidification or alkalinisation of the cytoplasm in Neurospora hyphae, using a cell permeant weak acid (propionic acid at pH 7.0) or weak base (trimethylamine at pH 8.0), slowed down but did not abolish growth. However, similar manipulation of the cytoplasmic pH of Agapanthus pollen tubes and Dryopteris rhizoids completely inhibited growth. Modification of external pH affected the growth pattern of all cell types. In hyphae and pollen tubes, changes in external pH were found to have a small transient effect on cytoplasmic pH but the cells rapidly readjusted towards their original pH. Our results suggest that pronounced longitudinal gradients in cytoplasmic pH are not essential for the regulation of tip growth.

scholarly journals Listeria monocytogenes Possesses Adhesins for Fibronectin

1999 ◽  
Vol 67 (12) ◽  
pp. 6698-6701 ◽  
Author(s):  
Philippe Gilot ◽  
Paul André ◽  
Jean Content
Keyword(s):  
Extracellular Matrix ◽  
Listeria Monocytogenes ◽  
Cell Surface ◽  
Bacterial Cell ◽  
Cell Types ◽  
Eukaryotic Cell ◽  
Eukaryotic Cells ◽  
Food Borne ◽  
Human Fibronectin ◽  
Fibronectin Binding

ABSTRACT Listeria monocytogenes is a gram-positive, nonsporulating, food-borne pathogen of humans and animals that is able to invade many eukaryotic cells. Several listerial surface components have been reported to interact with eukaryotic cell receptors, but the complete mechanism by which the bacteria interact with all of these cell types remains largely unknown. In this work, we found thatL. monocytogenes binds to human fibronectin, a 450,000-Da dimeric glycoprotein found in body fluids, on the surface of cells and in an insoluble component of the extracellular matrix. The binding of fibronectin to L. monocytogenes was found to be saturable and dependent on proteinaceous receptors. Five fibronectin-binding proteins of 55.3, 48.6, 46.7, 42.4, and 26.8 kDa were identified. The 55.3-kDa protein was proved to be present at the bacterial cell surface. The binding of L. monocytogenes to fibronectin adds to the number of molecules to which the bacterium is able to adhere and emphasizes the complexity of host-pathogen interactions.

scholarly journals Punctuated Aneuploidization of the Budding Yeast Genome

Genetics ◽  
2020 ◽  
Vol 216 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Lydia R. Heasley ◽  
Ruth A. Watson ◽  
Juan Lucas Argueso
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Tumor Cells ◽  
Genomic Instability ◽  
High Frequency ◽  
Budding Yeast ◽  
Cell Types ◽  
Eukaryotic Cell ◽  
Yeast Genome ◽  
Single Chromosome ◽  
Brewing Yeasts

Remarkably complex patterns of aneuploidy have been observed in the genomes of many eukaryotic cell types, ranging from brewing yeasts to tumor cells. Such aberrant karyotypes are generally thought to take shape progressively over many generations, but evidence also suggests that genomes may undergo faster modes of evolution. Here, we used diploid Saccharomyces cerevisiae cells to investigate the dynamics with which aneuploidies arise. We found that cells selected for the loss of a single chromosome often acquired additional unselected aneuploidies concomitantly. The degrees to which these genomes were altered fell along a spectrum, ranging from simple events affecting just a single chromosome, to systemic events involving many. The striking complexity of karyotypes arising from systemic events, combined with the high frequency at which we detected them, demonstrates that cells can rapidly achieve highly altered genomic configurations during temporally restricted episodes of genomic instability.

scholarly journals Paralemmin, a Prenyl-Palmitoyl–anchored Phosphoprotein Abundant in Neurons and Implicated in Plasma Membrane Dynamics and Cell Process Formation

1998 ◽  
Vol 143 (3) ◽  
pp. 795-813 ◽  
Author(s):  
Christian Kutzleb ◽  
Gabriele Sanders ◽  
Raina Yamamoto ◽  
Xiaolu Wang ◽  
Beate Lichte ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Species Conservation ◽  
Cell Types ◽  
Membrane Dynamics ◽  
Morphological Properties ◽  
Developmentally Regulated ◽  
Membrane Flow ◽  
Western Blots ◽  
Process Formation

We report the identification and initial characterization of paralemmin, a putative new morphoregulatory protein associated with the plasma membrane. Paralemmin is highly expressed in the brain but also less abundantly in many other tissues and cell types. cDNAs from chicken, human, and mouse predict acidic proteins of 42 kD that display a pattern of sequence cassettes with high inter-species conservation separated by poorly conserved linker sequences. Prenylation and palmitoylation of a COOH-terminal cluster of three cysteine residues confers hydrophobicity and membrane association to paralemmin. Paralemmin is also phosphorylated, and its mRNA is differentially spliced in a tissue-specific and developmentally regulated manner. Differential splicing, lipidation, and phosphorylation contribute to electrophoretic heterogeneity that results in an array of multiple bands on Western blots, most notably in brain. Paralemmin is associated with the cytoplasmic face of the plasma membranes of postsynaptic specializations, axonal and dendritic processes and perikarya, and also appears to be associated with an intracellular vesicle pool. It does not line the neuronal plasmalemma continuously but in clusters and patches. Its molecular and morphological properties are reminiscent of GAP-43, CAP-23, and MARCKS, proteins implicated in plasma membrane dynamics. Overexpression in several cell lines shows that paralemmin concentrates at sites of plasma membrane activity such as filopodia and microspikes, and induces cell expansion and process formation. The lipidation motif is essential for this morphogenic activity. We propose a function for paralemmin in the control of cell shape, e.g., through an involvement in membrane flow or in membrane–cytoskeleton interaction.

scholarly journals Chemical compound-based direct reprogramming for future clinical applications

2018 ◽  
Vol 38 (3) ◽  
Author(s):  
Yukimasa Takeda ◽  
Yoshinori Harada ◽  
Toshikazu Yoshikawa ◽  
Ping Dai
Keyword(s):  
Stem Cells ◽  
Transcription Factors ◽  
Chemical Compound ◽  
Chemical Compounds ◽  
Cell Types ◽  
Direct Reprogramming ◽  
Cell Type ◽  
Promising Alternative ◽  
Cell Functions ◽  
Transplantation Therapy

Recent studies have revealed that a combination of chemical compounds enables direct reprogramming from one somatic cell type into another without the use of transgenes by regulating cellular signaling pathways and epigenetic modifications. The generation of induced pluripotent stem (iPS) cells generally requires virus vector-mediated expression of multiple transcription factors, which might disrupt genomic integrity and proper cell functions. The direct reprogramming is a promising alternative to rapidly prepare different cell types by bypassing the pluripotent state. Because the strategy also depends on forced expression of exogenous lineage-specific transcription factors, the direct reprogramming in a chemical compound-based manner is an ideal approach to further reduce the risk for tumorigenesis. So far, a number of reported research efforts have revealed that combinations of chemical compounds and cell-type specific medium transdifferentiate somatic cells into desired cell types including neuronal cells, glial cells, neural stem cells, brown adipocytes, cardiomyocytes, somatic progenitor cells, and pluripotent stem cells. These desired cells rapidly converted from patient-derived autologous fibroblasts can be applied for their own transplantation therapy to avoid immune rejection. However, complete chemical compound-induced conversions remain challenging particularly in adult human-derived fibroblasts compared with mouse embryonic fibroblasts (MEFs). This review summarizes up-to-date progress in each specific cell type and discusses prospects for future clinical application toward cell transplantation therapy.

scholarly journals Cortactin: A Major Cellular Target of the Gastric Carcinogen Helicobacter pylori

Cancers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 159 ◽  
Author(s):  
Irshad Sharafutdinov ◽  
Steffen Backert ◽  
Nicole Tegtmeyer
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Cell Movement ◽  
Cell Types ◽  
Eukaryotic Cell ◽  
Actin Binding ◽  
Gastric Diseases ◽  
Cell Functions ◽  
H Pylori ◽  
Cytoskeletal Rearrangements

Cortactin is an actin binding protein and actin nucleation promoting factor regulating cytoskeletal rearrangements in nearly all eukaryotic cell types. From this perspective, cortactin poses an attractive target for pathogens to manipulate a given host cell to their own benefit. One of the pathogens following this strategy is Helicobacter pylori, which can cause a variety of gastric diseases and has been shown to be the major risk factor for the onset of gastric cancer. During infection of gastric epithelial cells, H. pylori hijacks the cellular kinase signaling pathways, leading to the disruption of key cell functions. Specifically, by overruling the phosphorylation status of cortactin, H. pylori alternates the activity of molecular interaction partners of this important protein, thereby manipulating the performance of actin-cytoskeletal rearrangements and cell movement. In addition, H. pylori utilizes a unique mechanism to activate focal adhesion kinase, which subsequently prevents host epithelial cells from extensive lifting from the extracellular matrix in order to achieve chronic infection in the human stomach.

scholarly journals Interaction of mammalian neprilysin with binding protein and calnexin in Schizosaccharomyces pombe

1999 ◽  
Vol 340 (3) ◽  
pp. 813-819 ◽  
Author(s):  
Hugues BEAULIEU ◽  
Aram ELAGÖZ ◽  
Philippe CRINE ◽  
Luis A. ROKEACH
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Binding Protein ◽  
Cell Types ◽  
Neutral Endopeptidase ◽  
Integral Membrane Protein ◽  
Eukaryotic Cell ◽  
Unfolded Proteins ◽  
Folding Intermediates ◽  
Bona Fide ◽  
The Brain

Neutral endopeptidase (neprilysin or NEP, EC 3.4.24.11) is a zinc metallo-endopeptidase expressed in many eukaryotic cell types and displaying several important physiological roles. In the brain (and central nervous system), this enzyme is involved in the molecular mechanism of pain by its action in the degradation of enkephalin molecules. In the kidney, NEP is implicated in the degradation of regulatory factors involved in the control of arterial pressure, including atrial natriuretic peptide and bradykinin. In this study we assessed the potential of the fission yeast Schizosaccharomyces pombe to overproduce rabbit NEP and secreted NEP (sNEP, a soluble derivative of this integral membrane protein). Both recombinant NEP and sNEP were produced at high levels (5 mg/l) in this system. Enzymic studies revealed that these recombinant proteins were fully active and exhibit kinetic parameters similar to those of the bona fide enzyme. Immunofluorescence microscopy and enzymic assays demonstrated that recombinant NEP is correctly targeted to the cell membrane. Furthermore, co-immunoprecipitation studies showed that folding intermediates of NEP and sNEP, produced in S. pombe, interact in the endoplasmic reticulum (ER) with binding protein (BiP) and calnexin (Cnx1p). The amount of sNEP coprecipitated with both BiP and Cnx1p augmented when cells were subjected to various stresses causing the accumulation of unfolded proteins in the ER. The interactions of NEP with BiP and Cnx1p were, however, more refractive to the same stresses.

scholarly journals Cytosolic chaperones mediate quality control of higher-order septin assembly in budding yeast

2015 ◽  
Vol 26 (7) ◽  
pp. 1323-1344 ◽  
Author(s):  
Courtney R. Johnson ◽  
Andrew D. Weems ◽  
Jennifer M. Brewer ◽  
Jeremy Thorner ◽  
Michael A. McMurray
Keyword(s):  
Quality Control ◽  
De Novo ◽  
Cell Types ◽  
Binding Pocket ◽  
Sole Source ◽  
Eukaryotic Cell ◽  
Higher Order ◽  
Native Proteins ◽  
Wild Type Counterpart ◽  
Quality Control Mechanism

Septin hetero-oligomers polymerize into cytoskeletal filaments with essential functions in many eukaryotic cell types. Mutations within the oligomerization interface that encompasses the GTP-binding pocket of a septin (its “G interface”) cause thermoinstability of yeast septin hetero-oligomer assembly, and human disease. When coexpressed with its wild-type counterpart, a G interface mutant is excluded from septin filaments, even at moderate temperatures. We show that this quality control mechanism is specific to G interface mutants, operates during de novo septin hetero-oligomer assembly, and requires specific cytosolic chaperones. Chaperone overexpression lowers the temperature permissive for proliferation of cells expressing a G interface mutant as the sole source of a given septin. Mutations that perturb the septin G interface retard release from these chaperones, imposing a kinetic delay on the availability of nascent septin molecules for higher-order assembly. Un­expectedly, the disaggregase Hsp104 contributes to this delay in a manner that does not require its “unfoldase” activity, indicating a latent “holdase” activity toward mutant septins. These findings provide new roles for chaperone-mediated kinetic partitioning of non-native proteins and may help explain the etiology of septin-linked human diseases.

scholarly journals A conserved expression signature predicts growth rate and reveals cell & lineage-specific differences

2019 ◽  
Author(s):  
Zhisheng Jiang ◽  
Serena Francesca Generoso ◽  
Marta Badia ◽  
Bernhard Payer ◽  
Lucas B. Carey
Keyword(s):  
Cell Lineage ◽  
Gene Expression Signature ◽  
Cell Types ◽  
Eukaryotic Cell ◽  
Rna Seq ◽  
Cell Type Specificity ◽  
Expression Signature ◽  
Differentiated Cells ◽  
Different Cell Types ◽  
High Degree

By performing RNA-seq on cells FACS sorted by their proliferation rate, this study identifies a gene expression signature capable of predicting proliferation rates in diverse eukaryotic cell types and species. This signature, applied to scRNAseq data from C.elegans, reveals lineage-specific differences in proliferation during development. In contrast to the universality of the proliferation signature, mitochondria and metabolism related genes show a high degree of cell-type specificity; mouse pluripotent stem cells (mESCs) and differentiated cells (fibroblasts) exhibit opposite relations between mitochondria state and proliferation. Furthermore, we identified a slow proliferating subpopulation of mESCs with higher expression of pluripotency genes. Finally, we show that fast and slow proliferating subpopulations are differentially sensitive to mitochondria inhibitory drugs in different cell types.

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