Ultrastructure of a palmelloid-forming strain of Chlamydomonas eugametos

1978 ◽  
Vol 56 (19) ◽  
pp. 2348-2356 ◽  
Author(s):  
Kazuo Nakamura ◽  
Douglas F. Bray ◽  
Emile B. Wagenaar
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Transitional Region ◽  
Chloroplatinic Acid ◽  
Cell Wall Formation ◽  
Body Structure ◽  
Wild Type ◽  
Adhesive Properties ◽  
Chlamydomonas Eugametos ◽  
Unicellular Green Alga

A palmelloid-forming mutant of the unicellular green alga Chlamydomonas eugametos has been studied ultrastructurally. The repetition, within the palmelloid envelope, of four-celled groups surrounded by wall layers suggests that normal asexual cytokinesis occurs but successive cell generations are unable to separate. Individual palmelloid cells are smaller than wild-type cells and possess flagella which are short (1–2 μm) and occasionally bulbous at the tip but appear normal with regard to internal microtubular, transitional region, and basal body structure. The association of granules with the outer surface of the palmelloid envelope and the tendency of palmelloids to form large aggregates in culture indicate a change in the adhesive properties of the cell walls of this mutant. A comparison of the ultrastructure of mutant palmelloids with previously described chloroplatinic-acid-induced palmelloids shows that the two types differ in both flagellar development and in the extent of cell wall formation.

Controlled lysis of bacterial cells utilizing mutants with defective synthesis of D-alanine

1988 ◽  
Vol 34 (3) ◽  
pp. 256-261 ◽  
Author(s):  
Michael P. Heaton ◽  
Robert B. Johnston ◽  
Thomas L. Thompson
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Cell Walls ◽  
Alanine Racemase ◽  
Growth Media ◽  
Bacterial Cells ◽  
Cell Wall Formation ◽  
Fermentation Processes ◽  
Intracellular Enzymes ◽  
Dense Cell

An alanine racemase (EC 5.1.1.1) mutant (Dal−) of Bacillus subtilis required small amounts of D-alanine to synthesize an osmotically stable cell wall in certain growth media. Investigation of the conditions which caused lysis in hypotonic media revealed that in addition to complex media, such as nutrient broth and acid-hydrolyzed casein, glycine inhibited stable cell wall formation. D-Alanine prevented the glycine inhibition. Up to 99% lysis occurred in both dilute and dense cell suspensions (optical densities up to 110) within 2.5 h after adding 1% glycine to late log phase cultures. Intracellular enzymes recovered from the lysate were as active as those from lysozyme-disrupted cells. No amino acid tested other than glycine induced lysis. Dal− mutants can be used for controlled lysis of bacterial cells to facilitate the isolation of normal intracellular constituents and bioengineered products from fermentation processes. Cell walls of most bacteria contain D-alanine; thus, this strategy should be applicable to a wide variety of microorganisms.

Sequential Changes Associated with Cell Wall Formation and Fusion in the Vascular Cambium

IAWA Journal ◽  
1981 ◽  
Vol 2 (4) ◽  
pp. 151-162 ◽  
Author(s):  
A.M. Catesson ◽  
J.C. Roland
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Cell Walls ◽  
Microscope Level ◽  
Cell Wall Formation ◽  
Characteristic Sequence ◽  
Electron Microscope Level ◽  
Starting Point ◽  
Cell Wall Development ◽  
Cambial Zone

Cytochemical techniques and mild extractions were used at the electron microscope level for the study of the cambial zone of several hardwoods and one softwood. The maturation processes of the primary radial and tangential cell walls involve a progressive disappearance of their initial heterogeneity. The buttress-like zone joining these walls appears to be the starting point for a characteristic sequence of changes and intra-wall rearrangement. Topochemical results have suggested an alternative to the 'emboxing concept' of cell wall development.

scholarly journals The unusual cell wall of the Lyme disease spirochaete Borrelia burgdorferi is shaped by a tick sugar

2021 ◽  
Vol 6 (12) ◽  
pp. 1583-1592
Author(s):  
Tanner G. DeHart ◽  
Mara R. Kushelman ◽  
Sherry B. Hildreth ◽  
Richard F. Helm ◽  
Brandon L. Jutras
Keyword(s):  
Cell Wall ◽  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Cell Walls ◽  
Structural Strength ◽  
Cell Envelope ◽  
Wild Type ◽  
Tick Vector ◽  
Cell Wall Alteration ◽  
Main Component

AbstractPeptidoglycan—a mesh sac of glycans that are linked by peptides—is the main component of bacterial cell walls. Peptidoglycan provides structural strength, protects cells from osmotic pressure and contributes to shape. All bacterial glycans are repeating disaccharides of N-acetylglucosamine (GlcNAc) β-(1–4)-linked to N-acetylmuramic acid (MurNAc). Borrelia burgdorferi, the tick-borne Lyme disease pathogen, produces glycan chains in which MurNAc is occasionally replaced with an unknown sugar. Nuclear magnetic resonance, liquid chromatography–mass spectroscopy and genetic analyses show that B. burgdorferi produces glycans that contain GlcNAc–GlcNAc. This unusual disaccharide is chitobiose, a component of its chitinous tick vector. Mutant bacteria that are auxotrophic for chitobiose have altered morphology, reduced motility and cell envelope defects that probably result from producing peptidoglycan that is stiffer than that in wild-type bacteria. We propose that the peptidoglycan of B. burgdorferi probably evolved by adaptation to obligate parasitization of a tick vector, resulting in a biophysical cell-wall alteration to withstand the atypical torque associated with twisting motility.

scholarly journals Exocytosis of the silicified cell wall of diatoms involves extensive membrane disintegration

2021 ◽  
Author(s):  
Diede de Haan ◽  
Hadas Peled-Zehavi ◽  
Yoseph Addadi ◽  
Oz Ben Joseph ◽  
Lior Aram ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Membrane Dynamics ◽  
Cell Wall Formation ◽  
Mineral Phase ◽  
Wall Formation ◽  
Unicellular Algae ◽  
Silica Cell ◽  
Membrane Bound ◽  
Organelle Membrane

Diatoms are unicellular algae that are characterized by their silica cell walls. The silica elements form intracellularly in a membrane-bound organelle, and are exocytosed after completion. How diatoms maintain membrane homeostasis during the exocytosis of these large and rigid silica elements is a long-standing enigma. We studied membrane dynamics during cell wall formation and exocytosis in the diatom Stephanopyxis turris, using live-cell confocal microscopy and advanced electron microscopy. Our results provide detailed information on the ultrastructure and dynamics of the silicification process, showing that during cell wall formation, the organelle membranes tightly enclose the mineral phase, creating a precise mold of the delicate geometrical patterns. Surprisingly, during exocytosis of the mature silica elements, the proximal organelle membrane becomes the new plasma membrane, and the distal membranes gradually disintegrate into the extracellular space without any noticeable endocytic retrieval or extracellular repurposing. These observations suggest that diatoms evolved an extraordinary exocytosis mechanism in order to secrete their cell wall elements.

scholarly journals Cytokinesis in fra2 Arabidopsis thaliana p60-katanin Mutant: Defects in Cell Plate/Daughter Wall Formation

2021 ◽  
Author(s):  
Emmanuel Panteris ◽  
Anna Kouskouveli ◽  
Dimitris Pappas ◽  
Ioannis-Dimosthenis S. Adamakis
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Walls ◽  
Higher Plants ◽  
Cell Plate ◽  
Wild Type ◽  
Microtubule Organization ◽  
Root Cells ◽  
Wall Formation ◽  
In The Wild

Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate, to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), while deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy, in root cells of the fra2 Arabidopsis thaliana mutant. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls appeared also faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild-type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild-type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.

scholarly journals Coordination Between Fission Yeast Glucan Formation and Growth Requires a Sphingolipase Activity

Genetics ◽  
2001 ◽  
Vol 158 (4) ◽  
pp. 1397-1411 ◽  
Author(s):  
Anna Feoktistova ◽  
Paula Magnelli ◽  
Claudia Abeijon ◽  
Pilar Perez ◽  
Robert L Lester ◽  
...  
Keyword(s):  
Cell Wall ◽  
Secretory Pathway ◽  
Temperature Sensitive ◽  
Cell Wall Formation ◽  
Wild Type ◽  
Wall Formation ◽  
Biochemical Analyses ◽  
Membrane Spanning ◽  
Mutant Cells ◽  
Large Deposits

Abstractcss1 mutants display a novel defect in Schizosaccharomyces pombe cell wall formation. The mutant cells are temperature-sensitive and accumulate large deposits of material that stain with calcofluor and aniline blue in their periplasmic space. Biochemical analyses of this material indicate that it consists of α- and β-glucans in the same ratio as found in cell walls of wild-type S. pombe. Strikingly, the glucan deposits in css1 mutant cells do not affect their overall morphology. The cells remain rod shaped, and the thickness of their walls is unaltered. Css1p is an essential protein related to mammalian neutral sphingomyelinase and is responsible for the inositolphosphosphingolipid-phospholipase C activity observed in S. pombe membranes. Furthermore, expression of css1+ can compensate for loss of ISC1, the enzyme responsible for this activity in Saccharomyces cerevisiae membranes. Css1p localizes to the entire plasma membrane and secretory pathway; a C-terminal fragment of Css1p, predicted to encode a single membrane-spanning segment, is sufficient to direct membrane localization of the heterologous protein, GFP. Our results predict the existence of an enzyme(s) or process(es) essential for the coordination of S. pombe cell wall formation and division that is, in turn, regulated by a sphingolipid metabolite.

scholarly journals Arabidopsis cell wall composition determines disease resistance specificity and fitness

2021 ◽  
Vol 118 (5) ◽  
pp. e2010243118 ◽  
Author(s):  
Antonio Molina ◽  
Eva Miedes ◽  
Laura Bacete ◽  
Tinguaro Rodríguez ◽  
Hugo Mélida ◽  
...  
Keyword(s):  
Cell Wall ◽  
Disease Resistance ◽  
Plant Cell ◽  
Cell Walls ◽  
Plant Cell Walls ◽  
Wild Type ◽  
Glycome Profiling ◽  
Enhanced Resistance ◽  
Trade Offs ◽  
Resistance Specificity

Plant cell walls are complex structures subject to dynamic remodeling in response to developmental and environmental cues and play essential functions in disease resistance responses. We tested the specific contribution of plant cell walls to immunity by determining the susceptibility of a set of Arabidopsis cell wall mutants (cwm) to pathogens with different parasitic styles: a vascular bacterium, a necrotrophic fungus, and a biotrophic oomycete. Remarkably, most cwm mutants tested (29/34; 85.3%) showed alterations in their resistance responses to at least one of these pathogens in comparison to wild-type plants, illustrating the relevance of wall composition in determining disease-resistance phenotypes. We found that the enhanced resistance of cwm plants to the necrotrophic and vascular pathogens negatively impacted cwm fitness traits, such as biomass and seed yield. Enhanced resistance of cwm plants is not only mediated by canonical immune pathways, like those modulated by phytohormones or microbe-associated molecular patterns, which are not deregulated in the cwm tested. Pectin-enriched wall fractions isolated from cwm plants triggered immune responses in wild-type plants, suggesting that wall-mediated defensive pathways might contribute to cwm resistance. Cell walls of cwm plants show a high diversity of composition alterations as revealed by glycome profiling that detect specific wall carbohydrate moieties. Mathematical analysis of glycome profiling data identified correlations between the amounts of specific wall carbohydrate moieties and disease resistance phenotypes of cwm plants. These data support the relevant and specific function of plant wall composition in plant immune response modulation and in balancing disease resistance/development trade-offs.

scholarly journals Cytokinesis in fra2 Arabidopsis thaliana p60-Katanin Mutant: Defects in Cell Plate/Daughter Wall Formation

2021 ◽  
Vol 22 (3) ◽  
pp. 1405
Author(s):  
Emmanuel Panteris ◽  
Anna Kouskouveli ◽  
Dimitris Pappas ◽  
Ioannis-Dimosthenis S. Adamakis
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Walls ◽  
Higher Plants ◽  
Cell Plate ◽  
Wild Type ◽  
Microtubule Organization ◽  
Root Cells ◽  
Wall Formation ◽  
In The Wild

Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast have been reported to occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), in root cells of the fra2 Arabidopsis thaliana loss-of-function mutant. In addition, deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls also appeared faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.

Carbon source dependent differences in the composition of the cell walls of the basidiomycete Picnoporus cinnabarinus

1977 ◽  
Vol 23 (9) ◽  
pp. 1313-1317 ◽  
Author(s):  
J. A. Cury ◽  
Déa Amaral
Keyword(s):  
Cell Wall ◽  
Carbon Source ◽  
Cell Walls ◽  
Amino Sugars ◽  
Enzymatic Analysis ◽  
Wild Type ◽  
Monokaryotic Strain ◽  
Morphological Differences ◽  
Isolated Cell

A wild-type monokaryotic strain of Picnoporus cinnabarinus grown on glucose produced shorter and thicker hyphae than cultures grown on acetate. Colonies from glucose media were smaller and more compact than acetate-grown colonies. Chemical and enzymatic analysis of the isolated cell wall of both morphological types showed that the amount of amino sugars and the ratio glucosamine:galactosamine were higher in the acetate-grown cells. This may be the cause of morphological differences observed.

Xylem Anatomy and Cell Wall Ultrastructure of Nicotiana Tabacum After Lignin Genetic Modification Through Transcriptional Activator EgMYB2

IAWA Journal ◽  
2012 ◽  
Vol 33 (3) ◽  
pp. 269-286 ◽  
Author(s):  
Veronica De Micco ◽  
Katia Ruel ◽  
Jean-Paul Joseleau ◽  
Jacqueline Grima-Pettenati ◽  
Giovanna Aronne
Keyword(s):  
Cell Wall ◽  
Genetic Modification ◽  
Cell Walls ◽  
Lignin Content ◽  
Transcriptional Activator ◽  
Myb Transcription Factor ◽  
Wild Type ◽  
Reduced Frequency ◽  
Light Fluorescence ◽  
R2r3 Myb

The transcriptional activator EgMYB2, which belongs to the large R2R3 MYB transcription factor family, plays a major role in the coordinated control of genes in the lignin biosynthetic pathway. Given that lignin genetic modification can lead to xylem alterations compromising vascular functionality, we characterised wood anatomical properties of two transgenic tobacco lines over-expressing EgMYB2, using light, fluorescence, confocal, transmission electron microscopy, immunocytochemical labelling and digital image analysis. Transgenic wood, compared with wild type, was characterised by both reduced frequency of larger vessels and lower vessel grouping; these traits are known to have physiological implications in terms of water transport efficiency and safety against embolism. Transgenic wood also appeared denser due to the occurrence of thicker cell walls and higher incidence of fibres than wild type. Increased lignin content was accompanied by a concomitant increase in cellulose and xylan, but no alterations in the usual distribution of guaiacyl and syringyl units in secondary cell walls were observed. Altogether, these results show that EgMYB2 is a master regulator controlling the synthesis of the three major polymers of the secondary cell wall and that its overexpression has significant influence on quantitative anatomical traits of wood which affect its functional properties.

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