scholarly journals The Lag Period in Auxin-Induced Expansion of Storage Tissue and Coleoptiles

1957 ◽  
Vol 10 (4) ◽  
pp. 435 ◽  
Author(s):  
Heather Adamson ◽  
D Adamson
Keyword(s):  
Cell Wall ◽  
Storage Tissue ◽  
Lag Period ◽  
Rapid Shift

Auxin caused a rapid shift in the point of incipient plasmolysis of a number: of tissues which showed auxin-induced expansion. The plasmolysis shift was not caused by dilution of the cell sap and might be due to an effect of auxin on the adhesion between cytoplasm and cell wall.

Biological and molecular correlates between induced dedifferentiation and spore germination in Dictyostelium

Development ◽  
1992 ◽  
Vol 116 (2) ◽  
pp. 417-425
Author(s):  
A. Chandrasekhar ◽  
H.L. Ennis ◽  
D.R. Soll
Keyword(s):  
Cell Wall ◽  
Spore Germination ◽  
Vegetative State ◽  
Cell Wall Formation ◽  
Original Sequence ◽  
Defective Mutant ◽  
Lag Period ◽  
Original Time ◽  
First Time ◽  
Do So

When developing cultures of Dictyostelium discoideum are disaggregated at any time prior to cell wall formation and challenged to reinitiate development, amoebae will progress through the original sequence of morphogenetic stages, but the second time through they will do so in roughly one-tenth the original time, a process known as ‘rapid recapitulation’. However, if disaggregated cells are suspended in nutrient medium, they enter a program of dedifferentiation during which they lose the capacity to rapidly recapitulate after an 80 minute lag period in a process known as ‘erasure’. Here we show that cells that have completed the morphogenetic program and emerge from spore coats in the process of germination have also erased. In addition, the germination-specific 270 gene family is expressed during induced dedifferentiation in a unique fashion, and a germination-defective mutant exhibits a dramatic delay in erasure without concomitant defects in the program of gene regulation accompanying induced dedifferentiation. These results suggest for the first time that induced dedifferentiation and spore germination share some common processes in converting cells from a developmental to vegetative state.

scholarly journals Escape of Candida from Caspofungin Inhibition at Concentrations above the MIC (Paradoxical Effect) Accomplished by Increased Cell Wall Chitin; Evidence for β-1,6-Glucan Synthesis Inhibition by Caspofungin

2006 ◽  
Vol 50 (9) ◽  
pp. 3160-3161 ◽  
Author(s):  
David A. Stevens ◽  
Masayuki Ichinomiya ◽  
Yukako Koshi ◽  
Hiroyuki Horiuchi
Keyword(s):  
Cell Wall ◽  
Paradoxical Effect ◽  
Synthesis Inhibition ◽  
Paradoxical Growth ◽  
Presence And Absence ◽  
Glucan Synthesis ◽  
Rapid Shift

ABSTRACT Concentrations above the MIC of caspofungin allow growth of some Candida isolates. A strain demonstrating paradoxical growth was grown in the presence and absence of caspofungin, and the cell wall content was analyzed. β-1,3-Glucan declined 81% in the presence of caspofungin, as expected. β-1,6-Glucan declined 73%. Chitin increased 898%, demonstrating a mechanism for paradoxical growth—a rapid shift in the key polymer.

scholarly journals Studies on the Effects of L-Prolinamide, 5-OXO-L-Prolyl-L-Phenylanyl-4-Hydroxy Compound Produced by Pseudomonas Fluorescence against Cell Wall Protein (3GNU Receptor) of Pythium SPP MTCC 10247

2016 ◽  
Vol 3 (3) ◽  
Author(s):  
E. E. Jenisha ◽  
C. Elizabeth Rani Juneius ◽  
Vinoth Vinoth
Keyword(s):  
Cell Wall ◽  
Secondary Metabolites ◽  
Ethyl Acetate Extract ◽  
Docking Study ◽  
Cell Wall Protein ◽  
Plant Diseases ◽  
Growth Reduction ◽  
Molecular Docking Study ◽  
Sds Page ◽  
Lag Period

<div><p><em>The present study was carried out inorder to assess the biocontrol efficiency of </em><em>Pseudomonas fluorescence against Pythium spp MTCC 10247.  The earlier studies have revealed its antifungal properties but the previous reports lack the details about the compounds and the target for the fungi. Hence we have designed our work plan to reveal the compounds present in the secondary metabolites of Pseudomonas fluorescence and the target on the phytopathogens </em>Pythium spp MTCC 10247 which causes plant diseases. <em>Production of secondary metabolites of     Pseudomonas fluorescence was carried out and the compounds were characterized by TLC, SDS-PAGE, and GC-MS. There were 7 peak compounds found out,  they are 1,4-diaza-2,5-dioxobicyclo[4.3.0] nonane (13,69%) , 3-isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione(10.11%), Pyrrolo[1,2-a] pyrazine 1,4dione,hexahydro-3-(2-methylpropyl(17.79%) l-Leucine,N-cyclopylcarbonyl-pentadecyl ester(7.09%), 3,6diisobutyl-2,5-piperazinedione (37.62%), 3-benzylhexahydropyrrolo[1,2-A]pyrazine-1,4-dione(8.52%), L-prolinamide, 5-oxo-l-prolyl-l-phenylanyl-4-hydroxy(5.19%). Antifungal activity of the ethyl acetate extract of the secondary metabolites were examined against Pythium spp MTCC 10247 and result revealed that the lag period of  the fungi was double fold higher than the control and the compounds were fungi static because there was a 57% of growth reduction after 7<sup>th</sup> day of incubation period.    All the seven compounds were used for molecular docking study and result showed higher score value with L-prolinamide, 5-oxo-l-prolyl-l-phenylanyl-4-hydroxy against cell wall protein (3GNU receptor) Pythium spp MTCC 10247.</em><em></em></p></div>

Influence of Cell Wall Composition on the Fossilisation of Bacteria and the Implications for the Search for Early Life Forms

1997 ◽  
Vol 161 ◽  
pp. 491-504 ◽  
Author(s):  
Frances Westall
Keyword(s):  
Cell Wall ◽  
Life Forms ◽  
Cation Binding ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Transmission Electron ◽  
Hydrothermal Sediments ◽  
Identification Of Bacteria ◽  
The Difference

AbstractThe oldest cell-like structures on Earth are preserved in silicified lagoonal, shallow sea or hydrothermal sediments, such as some Archean formations in Western Australia and South Africa. Previous studies concentrated on the search for organic fossils in Archean rocks. Observations of silicified bacteria (as silica minerals) are scarce for both the Precambrian and the Phanerozoic, but reports of mineral bacteria finds, in general, are increasing. The problems associated with the identification of authentic fossil bacteria and, if possible, closer identification of bacteria type can, in part, be overcome by experimental fossilisation studies. These have shown that not all bacteria fossilise in the same way and, indeed, some seem to be very resistent to fossilisation. This paper deals with a transmission electron microscope investigation of the silicification of four species of bacteria commonly found in the environment. The Gram positiveBacillus laterosporusand its spore produced a robust, durable crust upon silicification, whereas the Gram negativePseudomonas fluorescens, Ps. vesicularis, andPs. acidovoranspresented delicately preserved walls. The greater amount of peptidoglycan, containing abundant metal cation binding sites, in the cell wall of the Gram positive bacterium, probably accounts for the difference in the mode of fossilisation. The Gram positive bacteria are, therefore, probably most likely to be preserved in the terrestrial and extraterrestrial rock record.

Influence of Calcium Ions on the Plant Cell Surface: Membrane Fusions and Conformational Changes

1974 ◽  
Vol 32 ◽  
pp. 154-155
Author(s):  
D. James Morré ◽  
Charles E. Bracker ◽  
William J. VanDerWoude
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Conformational Changes ◽  
Calcium Ions ◽  
Surface Membrane ◽  
Carboxyl Groups ◽  
Cross Linking ◽  
Ultrastructural Evidence ◽  
Glycine Max L ◽  
Wall Extensibility

Calcium ions in the concentration range 5-100 mM inhibit auxin-induced cell elongation and wall extensibility of plant stems. Inhibition of wall extensibility requires that the tissue be living; growth inhibition cannot be explained on the basis of cross-linking of carboxyl groups of cell wall uronides by calcium ions. In this study, ultrastructural evidence was sought for an interaction of calcium ions with some component other than the wall at the cell surface of soybean (Glycine max (L.) Merr.) hypocotyls.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Microanatomy of the Periplasm of Bacillus Licheniformis

1971 ◽  
Vol 29 ◽  
pp. 262-263
Author(s):  
B.K. Ghosh
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Bacillus Licheniformis ◽  
External Environment ◽  
Permeability Barrier ◽  
Periplasmic Space ◽  
Modified Technique ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Periplasm of bacteria is the space outside the permeability barrier of plasma membrane but enclosed by the cell wall. The contents of this special milieu exterior could be regulated by the plasma membrane from the internal, and by the cell wall from the external environment of the cell. Unlike the gram-negative organism, the presence of this space in gram-positive bacteria is still controversial because it cannot be clearly demonstrated. We have shown the importance of some periplasmic bodies in the secretion of penicillinase from Bacillus licheniformis.In negatively stained specimens prepared by a modified technique (Figs. 1 and 2), periplasmic space (PS) contained two kinds of structures: (i) fibrils (F, 100 Å) running perpendicular to the cell wall from the protoplast and (ii) an array of vesicles of various sizes (V), which seem to have evaginated from the protoplast.

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.

Cell Wall Ultrastructure in Three Strains of a Cariogenic Streptococcus

1971 ◽  
Vol 29 ◽  
pp. 338-339
Author(s):  
M. J. Kramer ◽  
Alan L. Coykendall
Keyword(s):  
Cell Wall ◽  
Dental Caries ◽  
Streptococcus Mutans ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Genetic Heterogeneity ◽  
Morphological Characteristics ◽  
Electron Microscopic ◽  
Dna Reassociation ◽  
Wall Ultrastructure

During the almost 50 years since Streptococcus mutans was first suggested as a factor in the etiology of dental caries, a multitude of studies have confirmed the cariogenic potential of this organism. Streptococci have been isolated from human and animal caries on numerous occasions and, with few exceptions, they are not typable by the Lancefield technique but are relatively homogeneous in their biochemical reactions. An analysis of the guanine-cytosine (G-C) composition of the DNA from strains K-1-R, NCTC 10449, and FA-1 by one of us (ALC) revealed significant differences and DNA-DNA reassociation experiments indicated that genetic heterogeneity existed among the three strains. The present electron microscopic study had as its objective the elucidation of any distinguishing morphological characteristics which might further characterize the respective strains.

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