Prestalk cells in monolayer cultures exhibit two distinct modes of cellulose synthesis during stalk cell differentiation in Dictyostelium

Development ◽  
1993 ◽  
Vol 119 (3) ◽  
pp. 703-710
Author(s):  
L. Blanton R
Keyword(s):  
Cell Walls ◽  
Cell Formation ◽  
Tube Formation ◽  
Stalk Cell ◽  
Cellulose Synthesis ◽  
Cell Wall Formation ◽  
Monolayer Cultures ◽  
Major Structural Component ◽  
The Individual ◽  
Tinopal Lpw

Stalk formation in Dictyostelium discoideum involves the synthesis of a stalk tube by the prestalk cell population and stalk cell walls by the individual prestalk cells. Cellulose is a major structural component of the stalk tube and stalk cell walls. The DIF-deficient strain HM44 was used to study the events of stalk formation in monolayer cultures. The induction of cellulose synthase activity was shown to require both DIF and cAMP. Microscopical observations of monolayer cultures using the cellulose-indicating fluorochrome Tinopal LPW demonstrated the presence in these cultures of two cellulose-containing materials: the stalk cell walls and an intercellular material found between cells and around cell clumps. The synthesis of intercellular material precedes that of stalk cell walls in induced cultures. Cells committed to stalk cell formation were delayed in doing so if they were switched to medium containing cAMP but no DIF. During this delay the cells synthesized large quantities of the intercellular material. The intercellular material was shown to be microfibrillar, was sensitive to cellulase, and labelled with a colloidal gold-conjugated cellulase. The intercellular material may have the same mode of cellulose synthesis as that involved in stalk tube formation. If so, that mode would be favored by DIF and cAMP in combination, whereas the cellulose synthesis involved in stalk cell wall formation would be DIF-dependent but delayed or repressed by cAMP.

Regulation of stalk and spore antigen expression in monolayer cultures of Dictyostelium discoideum by pH

Development ◽  
1986 ◽  
Vol 96 (1) ◽  
pp. 131-150
Author(s):  
Janice A. Dominov ◽  
Christopher D. Town
Keyword(s):  
Dictyostelium Discoideum ◽  
Phenotypic Expression ◽  
Cell Formation ◽  
Antigen Expression ◽  
Low Ph ◽  
Stalk Cell ◽  
Protein Antigens ◽  
High Ph ◽  
Monolayer Cultures ◽  
Effects Of Ph

The terminal differentiation of Dictyostelium discoideum cells plated as monolayers with cyclic AMP is dramatically affected by developmental buffer conditions. High pH and addition of weak bases induces spore differentiation while low pH and weak acids favour stalk cell formation. In order to analyse the timing and nature of this regulation we have raised and characterized an anti-stalk serum which we have used together with an anti-spore serum to monitor developmental progression in the monolayer system and to detect the phenotypic effects of pH at earlier stages of development. The stalk serum detects both polysaccharide and protein antigens expressed during the terminal stages of normal development. In monolayer culture, the stalk-specific protein antigen appears precociously, while the timing of prespore vacuole appearance is unaffected. Expression of stalk polysaccharide antigens in monolayer cultures occurs as early as 12 h and is localized in a single subset of cells or region of extracellular space within the small cell clumps that form. The effects of pH (and acid/base) on these phenotype-specific antigens can be detected early in development, shortly after their first appearance. In monolayers of wild-type V12 M2 cells, the low pH regimes appear to act more by suppressing the spore than enhancing the stalk pathway, while the high pH regimes both suppress stalk and enhance spore antigen expression. In monolayers of the sporogenous mutant HM29, low pH regimes both enhance stalk antigen and suppress spore antigen expression. These results show that extracellular pH regulates phenotypic expression during a large part of the differentiation process and is not simply restricted to terminal cytodifferentiation.

scholarly journals Ancient origin of fucosylated xyloglucan in charophycean green algae

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Maria Dalgaard Mikkelsen ◽  
Jesper Harholt ◽  
Bjørge Westereng ◽  
David Domozych ◽  
Stephen C. Fry ◽  
...  
Keyword(s):  
Green Algae ◽  
Structural Component ◽  
Cell Walls ◽  
Uronic Acid ◽  
Structural Elucidation ◽  
Land Plants ◽  
Evolutionary Significance ◽  
Biosynthetic Enzymes ◽  
Major Structural Component ◽  
Mesotaenium Caldariorum

AbstractThe charophycean green algae (CGA or basal streptophytes) are of particular evolutionary significance because their ancestors gave rise to land plants. One outstanding feature of these algae is that their cell walls exhibit remarkable similarities to those of land plants. Xyloglucan (XyG) is a major structural component of the cell walls of most land plants and was originally thought to be absent in CGA. This study presents evidence that XyG evolved in the CGA. This is based on a) the identification of orthologs of the genetic machinery to produce XyG, b) the identification of XyG in a range of CGA and, c) the structural elucidation of XyG, including uronic acid-containing XyG, in selected CGA. Most notably, XyG fucosylation, a feature considered as a late evolutionary elaboration of the basic XyG structure and orthologs to the corresponding biosynthetic enzymes are shown to be present in Mesotaenium caldariorum.

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.

Cellulose microfibrils, cell motility, and plasma membrane protein organization change in parallel during culmination in Dictyostelium discoideum

1996 ◽  
Vol 109 (13) ◽  
pp. 3079-3087 ◽  
Author(s):  
M.J. Grimson ◽  
C.H. Haigler ◽  
R.L. Blanton
Keyword(s):  
Cell Motility ◽  
Dictyostelium Discoideum ◽  
Plasma Membranes ◽  
Freeze Fracture ◽  
Cellulose Microfibrils ◽  
Stalk Cell ◽  
Cellulose Synthesis ◽  
Particle Aggregates ◽  
Terminal Complexes

Prestalk cells of Dictyostelium discoideum contribute cellulose to two distinct structures, the stalk tube and the stalk cell wall, during culmination. This paper demonstrates by freeze fracture electron microscopy that two distinct types of intramembrane particle aggregates, which can be characterized as cellulose microfibril terminal complexes, occur in the plasma membranes of cells synthesizing these different forms of cellulose. The same terminal complexes were observed in situ in developing culminants and in vitro in monolayer cells induced to synthesize the two types of cellulose. We propose that cessation of cell motility is associated with a change in packing and intramembrane mobility of the particle aggregates, which cause a change in the nature of the cellulose synthesized. The terminal complexes are compared to those described in other organisms and related to the previous hypothesis of two modes of cellulose synthesis in Dictyostelium.

scholarly journals MtrP, a putative methyltransferase in Corynebacteria, is required for optimal membrane transport of trehalose mycolates

2020 ◽  
Vol 295 (18) ◽  
pp. 6108-6119 ◽  
Author(s):  
Arek K. Rainczuk ◽  
Stephan Klatt ◽  
Yoshiki Yamaryo-Botté ◽  
Rajini Brammananth ◽  
Malcolm J. McConville ◽  
...  
Keyword(s):  
Cell Walls ◽  
Double Mutant ◽  
Pathogenic Bacteria ◽  
Genetic Locus ◽  
Methyltransferase Activity ◽  
Mycolic Acids ◽  
Bacterial Cell Membrane ◽  
The Individual ◽  
Cytoplasmic Side ◽  
Long Chain

Pathogenic bacteria of the genera Mycobacterium and Corynebacterium cause severe human diseases such as tuberculosis (Mycobacterium tuberculosis) and diphtheria (Corynebacterium diphtheriae). The cells of these species are surrounded by protective cell walls rich in long-chain mycolic acids. These fatty acids are conjugated to the disaccharide trehalose on the cytoplasmic side of the bacterial cell membrane. They are then transported across the membrane to the periplasm where they act as donors for other reactions. We have previously shown that transient acetylation of the glycolipid trehalose monohydroxycorynomycolate (hTMCM) enables its efficient transport to the periplasm in Corynebacterium glutamicum and that acetylation is mediated by the membrane protein TmaT. Here, we show that a putative methyltransferase, encoded at the same genetic locus as TmaT, is also required for optimal hTMCM transport. Deletion of the C. glutamicum gene NCgl2764 (Rv0224c in M. tuberculosis) abolished acetyltrehalose monocorynomycolate (AcTMCM) synthesis, leading to accumulation of hTMCM in the inner membrane and delaying its conversion to trehalose dihydroxycorynomycolate (h2TDCM). Complementation with NCgl2764 normalized turnover of hTMCM to h2TDCM. In contrast, complementation with NCgl2764 derivatives mutated at residues essential for methyltransferase activity failed to rectify the defect, suggesting that NCgl2764/Rv0224c encodes a methyltransferase, designated here as MtrP. Comprehensive analyses of the individual mtrP and tmaT mutants and of a double mutant revealed strikingly similar changes across several lipid classes compared with WT bacteria. These findings indicate that both MtrP and TmaT have nonredundant roles in regulating AcTMCM synthesis, revealing additional complexity in the regulation of trehalose mycolate transport in the Corynebacterineae.

scholarly journals Key events during the transition from rapid growth to quiescence in budding yeast require posttranscriptional regulators

2013 ◽  
Vol 24 (23) ◽  
pp. 3697-3709 ◽  
Author(s):  
Lihong Li ◽  
Shawna Miles ◽  
Zephan Melville ◽  
Amalthiya Prasad ◽  
Graham Bradley ◽  
...  
Keyword(s):  
Cell Walls ◽  
Posttranscriptional Regulation ◽  
Cell Formation ◽  
Cell Types ◽  
G1 Arrest ◽  
Quiescent State ◽  
Diauxic Shift ◽  
Cell Wall Assembly ◽  
Daughter Cells ◽  
Mother Cells

Yeast that naturally exhaust the glucose from their environment differentiate into three distinct cell types distinguishable by flow cytometry. Among these is a quiescent (Q) population, which is so named because of its uniform but readily reversed G1 arrest, its fortified cell walls, heat tolerance, and longevity. Daughter cells predominate in Q-cell populations and are the longest lived. The events that differentiate Q cells from nonquiescent (nonQ) cells are initiated within hours of the diauxic shift, when cells have scavenged all the glucose from the media. These include highly asymmetric cell divisions, which give rise to very small daughter cells. These daughters modify their cell walls by Sed1- and Ecm33-dependent and dithiothreitol-sensitive mechanisms that enhance Q-cell thermotolerance. Ssd1 speeds Q-cell wall assembly and enables mother cells to enter this state. Ssd1 and the related mRNA-binding protein Mpt5 play critical overlapping roles in Q-cell formation and longevity. These proteins deliver mRNAs to P-bodies, and at least one P-body component, Lsm1, also plays a unique role in Q-cell longevity. Cells lacking Lsm1 and Ssd1 or Mpt5 lose viability under these conditions and fail to enter the quiescent state. We conclude that posttranscriptional regulation of mRNAs plays a crucial role in the transition in and out of quiescence.

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.

Synthesis of cell wall glucan, chitin, and protein by regenerating protoplasts and mycelia of Trichoderma reesei

1990 ◽  
Vol 36 (3) ◽  
pp. 211-217 ◽  
Author(s):  
Robert Messner ◽  
Christian P. Kubicek
Keyword(s):  
Cell Wall ◽  
Trichoderma Reesei ◽  
Cell Walls ◽  
Cell Wall Protein ◽  
Protoplast Regeneration ◽  
Secretory Proteins ◽  
Soluble Cell ◽  
Cell Wall Biogenesis ◽  
The Individual ◽  
Specific Labelling

The synthesis of constituent polymers of the cell wall by either growing mycelia or regenerating protoplasts of Trichoderma reesei QM 9414 was investigated by following the incorporation of radioactive precursors of the individual polymers (i.e., N[14C] acetyl-glucosamine, [3H] and [14C]glucose, [14C]mannose, and [35S]methionine) into individual fractions. N-Acetyl-glucosamine and glucose were found to become specifically incorporated into cell wall chitin and glucan by both mycelia and regenerating protoplasts, indicating the activity of chitin and glucan synthases in both systems. Cell wall glucan from regenerating protoplasts, however, consisted only of α-glucan and specifically lacked β-glucan which is found in mycelial cell walls. Mannose became metabolized to glucose before its label appeared in the cell wall, and was thus unsuitable for specific labelling. [35S]Methionine was found in a small (< 21 kDa) polypeptide from the first alkali-soluble cell wall fraction, but also in cell wall bound secretory proteins, i. e., β-glucosidase. These results indicate that cell wall biogenesis in T. reesei, in contrast to a report by other authors, is similar to that of other filamentous fungi. Key words: Trichoderma reesei, protoplast regeneration, cell wall polymer, β-glucan, cell wall protein.

Effect of supplementary energy and protein feeding on the true digestion of grass-silage organic matter, cell walls and nitrogen estimated by the combined synthetic-fibre-bag method in cows

1992 ◽  
Vol 72 (3) ◽  
pp. 671-678 ◽  
Author(s):  
Tuomo Varvikko ◽  
Aila Vanhatalo
Keyword(s):  
Organic Matter ◽  
Cell Walls ◽  
Latin Square ◽  
Rapeseed Meal ◽  
Concentrate Supplementation ◽  
Rumen Degradation ◽  
Grass Silage ◽  
Intestinal Digestion ◽  
Ruminal Degradation ◽  
The Individual

Four ruminally and duodenally cannulated non-lactating Finnish Ayrshire cows were used in a balanced 4 × 4 Latin square to study the effect of different concentrate supplements on the true partial and total-tract digestion (TTD) of grass silage, estimated by using the combined rumen-bag-intestinal-bag method. The cows were fed, at maintenance level, grass silage alone or supplemented with good-quality ground barley, ground barley and rapeseed meal, or ground barley and soybean meal. The determination of the proportion of grass silage degraded in the rumen (RD) was based on disappearance of feeds from nylon bags during the rumen incubation as a function of time, using the outflow rate of k = 0.0625. The intestinal digestion (ID) was estimated by the mobile-bag method with the residues that resisted degradation during the 16-h rumen incubation. Combination of these two was calculated to provide the TTD. Concentrate supplementation always caused a clear and consistent decline in rumen degradation and TTD of organic matter (OM), neutral detergent fibre (NDF) and Kjeldahl-N of grass silage but had no real influence on its ID. The type of concentrate, however, had only little effect. The average TTD of NDF was 16% lower than that of OM, but TTD of N was always very much higher than the respective value for OM. The results indicate that concentrate supplementation decreases the total-tract digestion of OM, cell walls and nitrogen of grass silage owing to impaired ruminal degradation. The combined bag method appears a convenient tool to provide digestion coefficients close to the true feed digestion of the individual feeds. Key words: Grass silage, nylon bag, mobile bag, combined bag, ruminal degradation, intestinal digestion, true digestion

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.

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