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.

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.

Lignification of spruce tracheid secondary cell walls related to longitudinal hardness and modulus of elasticity using nano-indentation

2002 ◽  
Vol 80 (10) ◽  
pp. 1029-1033 ◽  
Author(s):  
W Gindl ◽  
H S Gupta ◽  
C Grünwald
Keyword(s):  
Cell Wall ◽  
Modulus Of Elasticity ◽  
Cell Walls ◽  
Secondary Cell Wall ◽  
Lignin Content ◽  
Wood Formation ◽  
Nano Indentation ◽  
Secondary Cell Walls ◽  
Cell Wall Development ◽  
The One

The lignin content and the mechanical properties of lignifying and fully lignified spruce tracheid secondary cell walls were determined using UV microscopy and nano-indentation, respectively. The average lignin content of developing tracheids was 0.10 g·g–1, as compared with 0.21 g·g–1 in mature tracheids. The modulus of elasticity of developing cells was on average 22% lower than the one measured in mature, fully lignified cells. For the longitudinal hardness, a larger difference of 26% was observed. As lignifying cells in the cambial zone are undergoing cell wall development, spaces in the cellulose–hemicellulose structure are filled with lignin and the density of the cell wall is believed to increase. It is therefore suggested that the observed difference in modulus of elasticity between developing and fully lignified cell walls is due to the filling of spaces with lignin and an increase of the packing density of the cell wall during lignification. Although remarkably less stiff than the composite polysaccharide structure in the secondary cell wall, lignin may be considered equally hard. Therefore, the observed increase in lignin content may contribute directly to the measured increase of hardness.Key words: secondary cell wall, hardness, lignin, modulus of elasticity, wood formation.

scholarly journals CYTOCHEMISTRY OF 5-HYDROXYTRYPTAMINE AT THE ELECTRON MICROSCOPE LEVEL I. STUDY OF THE SPECIFICITY OF THE REACTION IN ISOLATED BLOOD PLATELETS

1968 ◽  
Vol 16 (3) ◽  
pp. 162-171 ◽  
Author(s):  
GUILLERMO JAIM ETCHEVERRY ◽  
LUIS MARIA ZIEHER
Keyword(s):  
Electron Microscope ◽  
Blood Platelets ◽  
Microscope Level ◽  
Storage Site ◽  
Electron Microscope Level ◽  
Dense Granules ◽  
Amine Content ◽  
Level I ◽  
Previous Assumption

Blood platelets obtained from normal rabbits and those isolated from reserpine-treated animals and subsequently incubated in vitro with 5-hydroxytryptamine, norepinephrine and histamine were assayed for amine content or processed for examination under the electron microscope. With the glutaraldehyde-dichromate reaction for unsubstituted catechol- and indoleamines, reactive granules were observed in normal platelets. Formaldehyde fixation prior to the glutaraldehyde-dichromate reaction resulted in a similar image under the electron microscope. In platelets obtained from animals treated with reserpine a decrease of the amine content with a corresponding reduction in the number of dense granules was observed. Following incubation with 5-hydroxytryptamine the concentration of the amine increased markedly and the number of dense granules that reacted with both techniques became practically normal. In norepinephrine-incubated platelets dense granules were demonstrated with the glutaraldehyde-dichromate reaction, but no reactive products were observed using prefixation with formaldehyde. Histamine was also incorporated into depleted platelets but gave no reaction. It is concluded that prefixation with formaldehyde renders negative the reaction with catecholamines, leaving unaffected indoleamine-reactive sites. The previous assumption that the dense granules contain 5-hydroxytryptamine has been confirmed by such a cytochemical approach. The possibility that these organelles constitute a common storage site for different amines is discussed.

Osmium Staining Fails to Detect Early Cell Wall Damage in Brown Rot Wood Decay

IAWA Journal ◽  
1994 ◽  
Vol 15 (2) ◽  
pp. 133-136
Author(s):  
W. Wayne Wilcox
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Cell Walls ◽  
Osmium Tetroxide ◽  
Wood Decay ◽  
Brown Rot ◽  
X Ray ◽  
Polarised Light ◽  
Early Manifestation ◽  
Scanning Electron

Loss of cell wall birefringence under polarised light in the light microscope is an important diagnostic characteristic for early stages of brown rot wood decay not available with the scanning electron microscope (SEM). Osmium tetroxide staining was explored as a means of visualising this early manifestation of decay in the SEM, but proved unsuccessful as X-ray spectroscopy indicated that osmium was evenly distributed across both distorted and non-distorted cell walls.

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.

Infundibulomyces: a new genus of coelomycetes from Thailand

2003 ◽  
Vol 81 (7) ◽  
pp. 732-737 ◽  
Author(s):  
Narumol Plaingam ◽  
Sayanh Somrithipol ◽  
E B. Gareth Jones
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Light Microscope ◽  
Type Species ◽  
New Genus ◽  
Anamorphic Fungi ◽  
Microscope Level ◽  
Electron Microscope Level ◽  
Fallen Leaves ◽  
Scanning Electron

The genus Infundibulomyces is proposed for coelomycetous fungi with nidulariaceous-like conidiomata and bipolar appendaged conidia. Infundibulomyces cupulata sp. nov., collected from fallen leaves of Lagerstroemia sp. from Thailand, is described as the type species of the genus. This fungus is illustrated at the light microscope and scanning electron microscope level and compared with other morphologically related taxa. Cupulate conidiomata are uncommon and Infundibulomyces is compared with these.Key words: anamorphic fungi, coelomycete, Infundibulomyces, Thailand, tropical.

Sign in / Sign up

Export Citation Format

Share Document