scholarly journals Fluorescence of yeast vitally stained with ethidium bromide and propidium iodide.

1981 ◽  
Vol 29 (1) ◽  
pp. 45-48 ◽  
Author(s):  
D A Corliss ◽  
W E White
Keyword(s):  
Cell Wall ◽  
Mitochondrial Dna ◽  
Ethidium Bromide ◽  
Propidium Iodide ◽  
Cell Types ◽  
Wild Type ◽  
Cytoplasmic Granules ◽  
Wild Type Yeast

Both ethidium bromide and propidium iodide stain growing yeast. As visualized in the fluorescence microscope, ethidium stains the nucleus and cytoplasm in wild type yeast and in those grown in 10% dextrose, with brightly fluorescent cytoplasmic granules being present in both. Under the latter conditions, the mitochondria are repressed but not absent. In rho 0 cells, in which the mitochondrial DNA is absent, ethidium appears to bind to the cell wall or membrane preferentially with no cytoplasmic granules being visible. In all cell types, propidium appears to bind the cell wall or membrane with no cytoplasmic granules being visible in any cell. The staining patterns thus suggest greater differences in the binding of these two types to mitochondrial DNA in situ than is suggested by their in vitro behavior. These differences in binding could explain their different mutagenic capacities..

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

scholarly journals Putative Surface Proteins Encoded within a Novel Transferable Locus Confer a High-Biofilm Phenotype to Enterococcus faecalis

2006 ◽  
Vol 188 (6) ◽  
pp. 2063-2072 ◽  
Author(s):  
Preeti M. Tendolkar ◽  
Arto S. Baghdayan ◽  
Nathan Shankar
Keyword(s):  
Cell Wall ◽  
Enterococcus Faecalis ◽  
Insertional Mutagenesis ◽  
Surface Proteins ◽  
Conjugative Plasmid ◽  
Sequence Information ◽  
Wild Type ◽  
Abiotic Surfaces ◽  
Mutant Bank

ABSTRACT Enterococci are opportunistic pathogens and among the leading causes of nosocomial infections. Enterococcus faecalis, the dominant species among infection-derived isolates, has recently been recognized as capable of forming biofilms on abiotic surfaces in vitro as well as on indwelling medical devices. A few bacterial factors known to contribute to biofilm formation in E. faecalis have been characterized. To identify additional factors which may be important to this process, we utilized a Tn917-based insertional mutagenesis strategy to generate a mutant bank in a high-biofilm-forming E. faecalis strain, E99. The resulting mutant bank was screened for mutants exhibiting a significantly reduced ability to form biofilms. One mutant, P101D12, which showed greater than 70% reduction in its ability to form biofilms compared to the wild-type parent, was further characterized. The single Tn917 insertion in P101D12 was mapped to a gene, bee-2, encoding a probable cell wall-anchored protein. Sequence information for the region flanking bee-2 revealed that this gene was a member of a locus (termed the bee locus for biofilm enhancer in enterococcus) comprised of five genes encoding three putative cell wall-anchored proteins and two probable sortases. Contour-clamped homogeneous electric field gel and Southern hybridization analyses suggested that the bee locus is likely harbored on a large conjugative plasmid. Filter mating assays using wild-type E99 or mutant P101D12 as a donor confirmed that the bee locus could transfer conjugally at high frequency to recipient E. faecalis strains. This represents the first instance of the identification of a mobile genetic element conferring biofilm-forming property in E. faecalis.

scholarly journals Toll-Like Receptor 2 Controls the Gamma Interferon Response to Francisella tularensis by Mouse Liver Lymphocytes

2007 ◽  
Vol 75 (11) ◽  
pp. 5338-5345 ◽  
Author(s):  
Kee-Jong Hong ◽  
Jason R. Wickstrum ◽  
Hung-Wen Yeh ◽  
Michael J. Parmely
Keyword(s):  
Francisella Tularensis ◽  
Cell Types ◽  
Gamma Interferon ◽  
Interferon Response ◽  
Interleukin 12 ◽  
Toll Like Receptor ◽  
Wild Type ◽  
Ifn Γ ◽  
Deficient Mice

ABSTRACT The production of gamma interferon (IFN-γ) is a key step in the protective innate immune response to Francisella tularensis. Natural killer cells and T cells in the liver are important sources of this cytokine during primary F. tularensis infections, and interleukin-12 (IL-12) appears to be an essential coactivating cytokine for hepatic IFN-γ expression. The present study was undertaken to determine whether or not macrophages (Mφ) or dendritic cells (DC) provide coactivating signals for the liver IFN-γ response in vitro, whether IL-12 mediates these effects, and whether Toll-like receptor (TLR) signaling is essential to induce this costimulatory activity. Both bone marrow-derived Mφ and DC significantly augmented the IFN-γ response of F. tularensis-challenged liver lymphocytes in vitro. While both cell types produced IL-12p40 in response to F. tularensis challenge, only DC secreted large quantities of IL-12p70. DC from both IL-12p35-deficient and TLR2-deficient mice failed to produce IL-12p70 and did not costimulate liver lymphocytes for IFN-γ production in response to viable F. tularensis organisms. Conversely, liver lymphocytes from TLR2-deficient mice cocultured with wild-type accessory cells produced IFN-γ at levels comparable to those for wild-type hepatic lymphocytes. These findings indicate that TLR2 controls hepatic lymphocyte IFN-γ responses to F. tularensis by regulating DC IL-12 production. While Mφ also coinduced hepatic IFN-γ production in response to F. tularensis, they did so in a fashion less dependent on TLR2.

scholarly journals Prohormone convertases 1/3 and 2 together orchestrate the site-specific cleavages of progastrin to release gastrin-34 and gastrin-17

2008 ◽  
Vol 415 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Jens F. Rehfeld ◽  
Xiaorong Zhu ◽  
Christina Norrbom ◽  
Jens R. Bundgaard ◽  
Anders H. Johnsen ◽  
...  
Keyword(s):  
Structural Factors ◽  
Cleavage Sites ◽  
Wild Type ◽  
Prohormone Convertases ◽  
Site Specific ◽  
G Cells ◽  
Processing Site ◽  
Vitro Effect

Cellular synthesis of peptide hormones requires PCs (prohormone convertases) for the endoproteolysis of prohormones. Antral G-cells synthesize the most gastrin and express PC1/3, 2 and 5/6 in the rat and human. But the cleavage sites in progastrin for each PC have not been determined. Therefore, in the present study, we measured the concentrations of progastrin, processing intermediates and α-amidated gastrins in antral extracts from PC1/3-null mice and compared the results with those in mice lacking PC2 and wild-type controls. The expression of PCs was examined by immunocytochemistry and in situ hybridization of mouse G-cells. Finally, the in vitro effect of recombinant PC5/6 on progastrin and progastrin fragments containing the relevant dibasic cleavage sites was also examined. The results showed that mouse G-cells express PC1/3, 2 and 5/6. The concentration of progastrin in PC1/3-null mice was elevated 3-fold. Chromatography showed that cleavage of the Arg36Arg37 and Arg73Arg74 sites were grossly decreased. Accordingly, the concentrations of progastrin products were markedly reduced, α-amidated gastrins (-34 and -17) being 25% of normal. Lack of PC1/3 was without effect on the third dibasic site (Lys53Lys54), which is the only processing site for PC2. Recombinant PC5/6 did not cleave any of the dibasic processing sites in progastrin and fragments containing the relevant dibasic processing sites. The complementary cleavages of PC1/3 and 2, however, suffice to explain most of the normal endoproteolysis of progastrin. Moreover, the results show that PCs react differently to the same dibasic sequences, suggesting that additional structural factors modulate the substrate specificity.

scholarly journals Absence of the Macrophage Mannose Receptor in Mice Does Not Increase Susceptibility to Pneumocystis carinii Infection In Vivo

2003 ◽  
Vol 71 (11) ◽  
pp. 6213-6221 ◽  
Author(s):  
Steve D. Swain ◽  
Sena J. Lee ◽  
Michel C. Nussenzweig ◽  
Allen G. Harmsen
Keyword(s):  
Pneumocystis Carinii ◽  
Hydrolytic Enzymes ◽  
Mannose Receptor ◽  
Opportunistic Pathogen ◽  
Cell Types ◽  
Surface Expression ◽  
Wild Type ◽  
Macrophage Mannose Receptor

ABSTRACT Host defense against the opportunistic pathogen Pneumocystis carinii requires functional interactions of many cell types. Alveolar macrophages are presumed to be a vital host cell in the clearance of P. carinii, and the mechanisms of this interaction have come under scrutiny. The macrophage mannose receptor is believed to play an important role as a receptor involved in the binding and phagocytosis of P. carinii. Although there is in vitro evidence for this interaction, the in vivo role of this receptor in P. carinii clearance in unclear. Using a mouse model in which the mannose receptor has been deleted, we found that the absence of this receptor is not sufficient to allow infection by P. carinii in otherwise immunocompetent mice. Furthermore, when mice were rendered susceptible to P. carinii by CD4+ depletion, mannose receptor knockout mice (MR-KO) had pathogen loads equal to those of wild-type mice. However, the MR-KO mice exhibited a greater influx of phagocytes into the alveoli during infection. This was accompanied by increased pulmonary pathology in the MR-KO mice, as well as greater accumulation of glycoproteins in the alveoli (glycoproteins, including harmful hydrolytic enzymes, are normally cleared by the mannose receptor). We also found that the surface expression of the mannose receptor is not downregulated during P. carinii infection in wild-type mice. Our findings suggest that while the macrophage mannose receptor may be important in the recognition of P. carinii, in vivo, this mechanism may be redundant, and the absence of this receptor may be compensated for.

Escape of mitochondrial DNA to the nucleus in yme1 yeast is mediated by vacuolar-dependent turnover of abnormal mitochondrial compartments

1998 ◽  
Vol 111 (16) ◽  
pp. 2455-2464 ◽  
Author(s):  
C.L. Campbell ◽  
P.E. Thorsness
Keyword(s):  
Alkaline Phosphatase ◽  
Mitochondrial Dna ◽  
High Rate ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mitochondrial Defects ◽  
Proteinase A ◽  
Abnormal Mitochondria ◽  
Wild Type Yeast

Inactivation of Yme1p, a mitochondrially-localized ATP-dependent metallo-protease in the yeast Saccharomyces cerevisiae, causes a high rate of DNA escape from mitochondria to the nucleus as well as pleiotropic functional and morphological mitochondrial defects. The evidence presented here suggests that the abnormal mitochondria of a yme1 strain are degraded by the vacuole. First, electron microscopy of Yme1p-deficient strains revealed mitochondria physically associated with the vacuole via electron dense structures. Second, disruption of vacuolar function affected the frequency of mitochondrial DNA escape from yme1 and wild-type strains. Both PEP4 or PRC1 gene disruptions resulted in a lower frequency of mitochondrial DNA escape. Third, an in vivo assay that monitors vacuole-dependent turnover of the mitochondrial compartment demonstrated an increased rate of mitochondrial turnover in yme1 yeast when compared to the rate found in wild-type yeast. In this assay, vacuolar alkaline phosphatase, encoded by PHO8, was targeted to mitochondria in a strain bearing disruption to the genomic PHO8 locus. Maturation of the mitochondrially localized alkaline phosphatase pro-enzyme requires proteinase A, which is localized in the vacuole. Therefore, alkaline phosphatase activity reflects vacuole-dependent turnover of mitochondria. This assay reveals that mitochondria of a yme1 strain are taken up by the vacuole more frequently than mitochondria of an isogenic wild-type strain when these yeast are cultured in medium necessitating respiratory growth. Degradation of abnormal mitochondria is one pathway by which mitochondrial DNA escapes and migrates to the nucleus.

Temporal changes in the expression of the insulin-like growth factor II gene associated with tissue maturation in the human fetus

Development ◽  
1989 ◽  
Vol 106 (3) ◽  
pp. 543-554 ◽  
Author(s):  
A.L. Brice ◽  
J.E. Cheetham ◽  
V.N. Bolton ◽  
N.C. Hill ◽  
P.N. Schofield
Keyword(s):  
Growth Factor ◽  
Cell Types ◽  
Specific Cell ◽  
Insulin Like Growth Factor ◽  
Vitro Fertilization ◽  
Age Related ◽  
Factor Ii ◽  
Metanephric Blastema

The insulin-like growth factors are broadly distributed in the human conceptus and are thought to play a role in the growth and differentiation of tissues during development. Using in situ hybridization we have shown that a wide variety of specific cell types within tissues express the gene for insulin-like growth factor II at times of development from 18 days to 14 weeks of gestation. Examination of blastocysts produced by in vitro fertilization showed no expression, thus bracketing the time of first accumulation of IGF-II mRNA to between 5 and 18 days postfertilization. The pattern of IGF-II expression shows specific age-related differences in different tissues. In the kidney, for example, expression is found in the cells of the metanephric blastema which is dramatically reduced as the blastema differentiates. The reverse is also seen, and we have noted an increase in expression of IGF-II in the cytotrophoblast layer of the placenta with gestational age. The sites of expression do not correlate with areas of either high mitotic activity or specific types of differentiation, but the observed pattern of expression in the kidney, adrenal glands and liver suggests an explanation for the abnormally high IGF-II mRNA expression in developmental tumours such as Wilms' tumour.

SV40-transformed hamster cells resistant to 100–250 microgram/ml of ethidium bromide

1978 ◽  
Vol 33 (1) ◽  
pp. 157-169
Author(s):  
G. Wolf ◽  
L. Tejmar ◽  
S. Borell ◽  
W. Klietman
Keyword(s):  
Mitochondrial Dna ◽  
Cell Lines ◽  
Ethidium Bromide ◽  
Gel Electrophoresis ◽  
Mitochondrial Proteins ◽  
Wild Type ◽  
Mitochondrial Ultrastructure ◽  
Gold Hamsters ◽  
Resistant Cells

SV40-transformed hamster cells were selected for resistance to ethidium bromide (EB). Several cell lines were established, which grew in the presence of up to 250 microgram/ml EB. The EB resistance is genetically stable. The cloned resistant cells show no difference in morphology, with the exception of the mitochondrial ultrastructure, which exhibits condensed cristae formation. The tumorigenicity of these cells in Syrian gold hamsters is considerably reduced. Incorporation of radioactive labelled thymidine into mitochondrial DNA is not influenced by the presence of the drug. Gel electrophoresis with mitochondrial proteins from wild-type and resistant cells reveals significantly different patterns. The mechanism of EB resistance is discussed.

scholarly journals Loss of a Protein Phosphatase 2A Regulatory Subunit (Cdc55p) Elicits Improper Regulation of Swe1p Degradation

2000 ◽  
Vol 20 (21) ◽  
pp. 8143-8156 ◽  
Author(s):  
Haifeng Yang ◽  
Wei Jiang ◽  
Matthew Gentry ◽  
Richard L. Hallberg
Keyword(s):  
Phosphatase Activity ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Cell Types ◽  
Regulatory Subunit ◽  
Cyclin Dependent Kinase ◽  
Wild Type ◽  
Phosphatase 2A

ABSTRACT CDC55 encodes a Saccharomyces cerevisiaeprotein phosphatase 2A (PP2A) regulatory subunit.cdc55-null cells growing at low temperature exhibit a failure of cytokinesis and produce abnormally elongated buds, butcdc55-null cells producing the cyclin-dependent kinase Cdc28-Y19F, which is unable to be inhibited by Y19 phosphorylation, show a loss of the abnormal morphology. Furthermore,cdc55-null cells exhibit a hyperphosphorylation of Y19. For these reasons, we have examined in wild-type and cdc55-null cells the levels and activities of the kinase (Swe1p) and phosphatase (Mih1p) that normally regulate the extent of Cdc28 Y19 phosphorylation. We find that Mih1p levels are comparable in the two strains, and an estimate of the in vivo and in vitro phosphatase activity of this enzyme in the two cell types indicates no marked differences. By contrast, while Swe1p levels are similar in unsynchronized and S-phase-arrested wild-type and cdc55-null cells, Swe1 kinase is found at elevated levels in mitosis-arrestedcdc55-null cells. This excess Swe1p incdc55-null cells is the result of ectopic stabilization of this protein during G2 and M, thereby accounting for the accumulation of Swe1p in mitosis-arrested cells. We also present evidence indicating that, in cdc55-null cells, misregulated PP2A phosphatase activity is the cause of both the ectopic stabilization of Swe1p and the production of the morphologically abnormal phenotype.

scholarly journals Distinct purinergic signaling pathways in prepubescent mouse spermatogonia

2016 ◽  
Vol 148 (3) ◽  
pp. 253-271 ◽  
Author(s):  
David Fleck ◽  
Nadine Mundt ◽  
Felicitas Bruentgens ◽  
Petra Geilenkirchen ◽  
Patricia A. Machado ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Purinergic Signaling ◽  
Cell Communication ◽  
Atp Release ◽  
Cell Types ◽  
Control Male ◽  
Electrophysiological Recordings ◽  
Unique Approach

Spermatogenesis ranks among the most complex, yet least understood, developmental processes. The physiological principles that control male germ cell development in mammals are notoriously difficult to unravel, given the intricate anatomy and complex endo- and paracrinology of the testis. Accordingly, we lack a conceptual understanding of the basic signaling mechanisms within the testis, which control the seminiferous epithelial cycle and thus govern spermatogenesis. Here, we address paracrine signal transduction in undifferentiated male germ cells from an electrophysiological perspective. We identify distinct purinergic signaling pathways in prepubescent mouse spermatogonia, both in vitro and in situ. ATP—a dynamic, widespread, and evolutionary conserved mediator of cell to cell communication in various developmental contexts—activates at least two different spermatogonial purinoceptor isoforms. Both receptors operate within nonoverlapping stimulus concentration ranges, display distinct response kinetics and, in the juvenile seminiferous cord, are uniquely expressed in spermatogonia. We further find that spermatogonia express Ca2+-activated large-conductance K+ channels that appear to function as a safeguard against prolonged ATP-dependent depolarization. Quantitative purine measurements additionally suggest testicular ATP-induced ATP release, a mechanism that could increase the paracrine radius of initially localized signaling events. Moreover, we establish a novel seminiferous tubule slice preparation that allows targeted electrophysiological recordings from identified testicular cell types in an intact epithelial environment. This unique approach not only confirms our in vitro findings, but also supports the notion of purinergic signaling during the early stages of spermatogenesis.

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