Étude cytologique de l'effet de l'éthéphon sur la texture des cerises Bigarreau-Napoléon

1998 ◽  
Vol 76 (3) ◽  
pp. 547-551
Author(s):  
Cyrille Batisse ◽  
Claude Coulomb ◽  
Philippe Jean Coulomb ◽  
Michel Buret
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
A Cell

This study presents a comparison between tissues of treated and nontreated Bigarreau-Napoléon cherries using physiochemical and cytological tests. Ethephon provokes a cell wall destructuration greater in the mesocarp tissue than in the under-peduncular area. It consists of breakage or an enlargement of some cell walls with the formation of a hydrated pectin network. Ethephon induces a cell wall catabolism characteristic of a fast cell wall senescence.Key words: Ethephon, ethylene, Bigarreau-Napoléon cherries, cell wall alterations, mechanical harvest.

scholarly journals Organismal view of a plant and a plant cell.

2001 ◽  
Vol 48 (2) ◽  
pp. 443-451 ◽  
Author(s):  
P Wojtaszek
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Cell Walls ◽  
Growth Time ◽  
Dead Cell ◽  
Plant Body ◽  
The Status ◽  
A Cell ◽  
Plant Form ◽  
Biological Organisation

Cell walls are at the basis of a structural, four-dimensional framework of plant form and growth time. Recent rapid progress of cell wall research has led to the situation where the old, long-lasting juxtaposition: "living" protoplast--"dead" cell wall, had to be dropped. Various attempts of re-interpretation cast, however, some doubts over the very nature of plant cell and the status of the walls within such a cell. Following a comparison of exocellular matrices of plants and animals, their position in relation to cells and organisms is analysed. A multitude of perspectives of the biological organisation of living beings is presented with particular attention paid to the cellular and organismal theories. Basic tenets and resulting corollaries of both theories are compared, and evolutionary and developmental implications are considered. Based on these data, "The Plant Body"--an organismal concept of plants and plant cells is described.

scholarly journals Secretion of Cryparin, a Fungal Hydrophobin

1999 ◽  
Vol 65 (12) ◽  
pp. 5431-5435 ◽  
Author(s):  
Patricia M. McCabe ◽  
Neal K. Van Alfen
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Submerged Culture ◽  
Secretory Pathway ◽  
Culture Medium ◽  
Secretory Vesicle ◽  
Cryphonectria Parasitica ◽  
Secreted Protein ◽  
Filamentous Ascomycete ◽  
A Cell

ABSTRACT Cryparin is a cell-surface-associated hydrophobin of the filamentous ascomycete Cryphonectria parasitica. This protein contains a signal peptide that directs it to the vesicle-mediated secretory pathway. We detected a glycosylated form of cryparin in a secretory vesicle fraction, but secreted forms of this protein are not glycosylated. This glycosylation occurred in the proprotein region, which is cleaved during maturation by a Kex2-like serine protease, leaving a mature form of cryparin that could be isolated from both the cell wall and culture medium. Pulse-chase labeling experiments showed that cryparin was secreted through the cell wall, without being bound, into the culture medium. The secreted protein then binds to the cell walls ofC. parasitica, where it remains. Binding of cryparin to the cell wall occurred in submerged culture, presumably because of the lectin-like properties unique to this hydrophobin. Thus, the binding of this hydrophobin to the cell wall is different from that of other hydrophobins which are reported to require a hydrophobic-hydrophilic interface for assembly.

THE EFFECT OF PENICILLIN ON THE STRUCTURE OF STAPHYLOCOCCAL CELL WALLS

1959 ◽  
Vol 5 (6) ◽  
pp. 641-648 ◽  
Author(s):  
R. G. E. Murray ◽  
W. H. Francombe ◽  
B. H. Mayall
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Untreated Control ◽  
Osmium Tetroxide ◽  
Wall Material ◽  
Cell Wall Material ◽  
Cell Wall Synthesis ◽  
Cell Wall Component ◽  
A Cell ◽  
Resistant Strains

Cultures of sensitive stains of Staphylococcus aureus were fixed with osmium tetroxide after 1–5 hours' exposure to various does of pencillin and were embedded in methacrylate for sectioning and electron microscopy. They were compared with untreated, control cultures. The contrast of the cell wall material was untreated, control cultures. The contrast of the cell wall material was increased, by cutting the section of lanthanum nitrate.The cells increased in size and the surrounding cell wall was thinner than normal. The main lesions appeared in the developing cell wall septa, which showed a loss in density and gross irregularity of shape. Some questionable inclusions were seen in the cytoplasm. Lysis was prevented in a medium containing 0.3 M sucrose and the stable spheroplasts retained a recognizable cell wall after 24 hours' exposure to penicillin. However, the septa could not be demonstrated in the cells treated in sucrose medium.Two resistant strains were exposed to penicillin. In one, the cells showed no morphological effects; in the other, there was temporary damage to the cell septa with complete recovery.The observations support the hypothesis that penicillin interferes with the synthesis of a cell wall component and indicate that the main point of cell wall synthesis is at the site of septum formation.

Experimental study on in-plane compressive response of irregular honeycombs

2017 ◽  
Vol 52 (8) ◽  
pp. 1121-1135
Author(s):  
Youming Chen ◽  
Raj Das ◽  
Mark Battley
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Mechanical Performance ◽  
Three Dimensional ◽  
Compressive Load ◽  
Neighbouring Cell ◽  
Deformation And Failure ◽  
Compressive Response ◽  
A Cell ◽  
Foam Mechanics

Compared with regular honeycombs, irregular honeycombs are more representative of real foams, and thus more suitable for the study of foam mechanics. In this paper, the deformation and failure progression in the irregular honeycombs are investigated by analysing the images captured in order to gain an improved understanding on foam failure. Irregular honeycombs with varying cell wall thickness, cell size and cell shape were manufactured using a three-dimensional printer and tested under compression. The behaviour of irregular honeycombs is found to be different from that of regular honeycombs. In irregular honeycombs, cell walls start to fracture at some point, initially at a low speed from multiple locations. The global stress reaches its maximum value shortly after the first fracture of cell walls. Only a few cell walls buckle in the specimens with cells of irregular shape. Fracture is more likely to occur to thin and long cell walls aligned within a medium angle (around 30 to 60°) to the compressive load. However, the susceptibility of a cell wall is to fracture is also affected by its neighbouring cell walls. Strong and stiff neighbouring cell walls could shield load away and protect it from breaking. Because of this, it is better to think of a weak spot as a region, rather than an individual cell or cell wall. Overall, the more uniform cell wall size and thickness are, the better the mechanical performance of cellular solids is.

Silicification of 'cell walls’ of certain protistan flagellates

1984 ◽  
Vol 304 (1121) ◽  
pp. 529-536 ◽  
Keyword(s):  
Cell Cycle ◽  
Cell Wall ◽  
Cell Walls ◽  
Silica Deposition ◽  
Early Stages ◽  
A Cell ◽  
Stephanoeca Diplocostata

Silica deposition is described for two protistan flagellates, Synura petersenii (Chrysophyceae, algae) and Stephanoeca diplocostata (Choanoflagellida, Protozoa). Both taxa produce silica units intracellularly and subsequently assemble them outside the protoplast to form a ‘cell wall’. In Synura the cell wall consists of a scale case to which scales are added throughout the cell cycle. In Stephanoeca individual siliceous, costal strips are accumulated outside the protoplast and assembled into a lorica once sufficient strips have been produced. In both taxa silica is laid down within silica deposition vesicles (s.d.vs) of uncertain origin. Microtubules are involved in the orientation and support of s.d.vs during early stages of silica unit biogenesis. Detailed comparisons of silica deposition are made between Synura and Stephanoeca and between these and other silica-depositing protistans.

The outer layer of the cell envelope of Halobacterium halobium

1969 ◽  
Vol 47 (1) ◽  
pp. 71-74 ◽  
Author(s):  
Carolyn L. Marshall ◽  
A. J. Wicken ◽  
A. D. Brown
Keyword(s):  
Cell Wall ◽  
Chemical Analysis ◽  
Outer Layer ◽  
Bacterial Cell ◽  
Cell Walls ◽  
Cell Envelope ◽  
Halobacterium Halobium ◽  
A Cell ◽  
Bacterial Cell Walls

The outer layer of the cell envelope of Halobacterium halobium was isolated after suspending the envelope in either 1 M NaCl or 0.02 M MgCl2. Chemical analysis of the isolated, solubilized outer layer showed it to consist of protein or glycoprotein with about 3% RNA. No free or bound lipid was detected. No cytochromes were present in the outer layer. Components commonly associated with bacterial cell walls were absent.Chemical composition together with the marked instability of the outer layer in a slight ion deficit are not consistent with a function of this layer as a "cell wall" of the organism.

Studies of the structure and chemical composition of the cell walls of Vaucheriaceae and Saprolegniaceae

1963 ◽  
Vol 158 (973) ◽  
pp. 435-445 ◽  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Insoluble Fraction ◽  
Water Soluble ◽  
Hot Water ◽  
Cellulose Microfibrils ◽  
Wall Material ◽  
Native Cellulose ◽  
A Cell ◽  
Crystalline Component

The cell walls of members of the Vaucheriaceae and Saprolegniaceae have been examined by X-ray analysis and electron microscopy, and their composition determined by hydrolysis and paper partition chromatography of the hydrolysates. Both differences and similarities between the members of these two species examined are found to supplement the comparative morphological and physiological information at present available. Saprolegnia , Achlya , Brevilegnia and Dictyuchus among the Saprolegniaceae possess hot-water soluble polysaccharides containing glucose residues only. This polysaccharide is not crystallographically identical with the polysaccharide found in Vaucheria sessilis with a similar solubility. The members of the Saprolegniaceae contain large amounts of alkali-soluble polysaccharides in contrast with the negligible amount found in V. sessilis . These polysaccharides are only weakly crystalline, but the indications are that the same polysaccharides may occur through­out the Saprolegniaceae. The alkali-insoluble wall material of Vaucheria species consists of highly crystalline native cellulose with large, apparently randomly arranged, microfibrils. The hydrolysate of this material contains ribose, xylose and arabinose in addition to glucose, presumably representing strongly bound pentosans. Native cellulose also occurs in the Saprolegniaceae but only in small proportion. The bulk of the alkali-insoluble fraction in the walls of these fungi appears amorphous in the electron microscope and is only weakly crystalline. It consists of one or m ore substances containing glucose, mannose, ribose and possibly other sugars together with traces of glucosamine. These substances presumably cover the cellulose microfibrils. The total quantity of non-cellulosic polysaccharide in the Saprolegniaceae approaches 85% of the total wall weight in contrast with the situation in Vaucheria where the cellulose alone approaches 90% of the total cell wall. Dichotomosiphon is unique among the organism s studied in this paper, in possessing a cell wall entirely soluble in alkali and composed of approximately equal quantities of glucose and xylose. The crystalline component is aβ-1,3-linked xylan, as already reported for some of the Siphonales (closely related algae) by Frei & Preston.

scholarly journals Identification of a transitional cell state in the developmental pathway to carrot somatic embryogenesis.

1992 ◽  
Vol 119 (5) ◽  
pp. 1371-1380 ◽  
Author(s):  
R I Pennell ◽  
L Janniche ◽  
G N Scofield ◽  
H Booij ◽  
S C de Vries ◽  
...  
Keyword(s):  
Cell Wall ◽  
Somatic Embryogenesis ◽  
Cell Walls ◽  
Single Cells ◽  
Transitional Cell ◽  
Cell Types ◽  
Suspension Cultures ◽  
Developmental Pathway ◽  
Reactive Cell ◽  
A Cell

We have located a novel carbohydrate epitope in the cell walls of certain single cells in embryogenic, but not in non-embryogenic, suspension cultures of carrot. Expression of this epitope, recognized by the mAb JIM8, is regulated during initiation, proliferation, and prolonged growth of suspension cultures such that changes in the abundance of JIM8-reactive cells always precede equivalent changes in embryogenic potential. Therefore, a direct correlation exists between the presence of the JIM8-reactive cell wall epitope and somatic embryo formation. The JIM8-reactive cell wall epitope is expressed in the cell walls of three types of single cells and one type of cell cluster. One of the single cell types seems able to follow one of two phytohormone-controlled developmental pathways, either a cell elongation pathway that eventually leads to cell death, or a cell division pathway that gives rise to proembryogenic masses. We demonstrate that all JIM8-reactive cell types in embryogenic carrot suspension cultures are developmentally related, and that the switch by one of them to somatic embryogenesis is accompanied by the immediate dissipation of the JIM8-reactive cell wall epitope. The cell wall carbohydrate epitope recognized by JIM8 therefore represents a cell wall marker for a very early transitional cell state in the developmental pathway to carrot somatic embryogenesis.

Cell walls of algae in the volvocales: Their sensitivity to a cell wall lytic enzyme and labeling with an anti-cell wall glycopeptide ofChlamydomonas reinhardtii

1987 ◽  
Vol 100 (4) ◽  
pp. 373-384 ◽  
Author(s):  
Yoshihiro Matsuda ◽  
Alan Musgrave ◽  
Herman Ende ◽  
Keith Roberts
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Lytic Enzyme ◽  
A Cell
Sign in / Sign up

Export Citation Format

Share Document