scholarly journals Aggregations of organelles in meiotic cells of higher plants

2014 ◽  
Vol 57 (4) ◽  
pp. 637-654 ◽  
Author(s):  
Bohdan Rodkiewicz ◽  
Ewa Duda
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Higher Plants ◽  
Early Prophase ◽  
Equatorial Plate ◽  
Prophase I

During early prophase I in microsporocytes and sporocytes of various plants all mitochondria and plastids aggregate in a group, where some plastids seem to undergo division. This group desintegrates by middle prophase I. Further aggregations of plastids and mitochondria occur in microsporogenesis and sporogenesis is of a simultaneous type. Organelles aggregate the second time at the end of prophase 1 and during or after telophase I they form a dense equatorial plate which lasts until telophase IL Since the phragmoplast is dismantled after telophase I and there is no cytokinesis, organelles aggregated in the plate apparently prevent merging of the nuclei and spindles of meiosis II, thus taking over a role of a phragmoplast and cell wall. In some plants after telophase II organelle aggregation changes shape and occupies the planes where cell walls will be built in simultaneous cytokinesis. Positioning of plastids and mitochondria along these planes may facilitate their equal apportionment among the postmeiotic cells.

LYSOZYME SENSITIVITY OF THE CELL WALL OF PSEUDO-MONAS AERUGINOSA: FURTHER EVIDENCE FOR THE ROLE OF THE NON-PEPTIDOGLYCAN COMPONENTS IN CELL WALL RIGIDITY

1966 ◽  
Vol 12 (1) ◽  
pp. 105-108 ◽  
Author(s):  
K. Jane Carson ◽  
R. G. Eagon
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Wall ◽  
Electron Micrographs ◽  
Cell Walls ◽  
Gram Negative Bacteria ◽  
Normal Cells ◽  
Thin Sections ◽  
Gram Negative ◽  
Cell Wall Rigidity

Electron micrographs of thin sections of normal cells of Pseudomonas aeruginosa showed the cell walls to be convoluted and to be composed of two distinct layers. Electron micrographs of thin sections of lysozyme-treated cells of P. aeruginosa showed (a) that the cell walls lost much of their convoluted nature; (b) that the layers of the cell walls became diffuse and less distinct; and (c) that the cell walls became separated from the protoplasts over extensive cellular areas. These results suggest that the peptidoglycan component of the unaltered cell walls of P. aeruginosa is sensitive to lysozyme. Furthermore, it appears that the peptidoglycan component is not solely responsible for the rigidity of the cell walls of Gram-negative bacteria.

scholarly journals The presence of ribonucleic acid in the cell walls of higher plants

1968 ◽  
Vol 108 (1) ◽  
pp. 25-31 ◽  
Author(s):  
P. D. Phethean ◽  
L. Jervis ◽  
Mary Hallaway
Keyword(s):  
Cell Wall ◽  
Ion Exchange ◽  
Ribosomal Rna ◽  
Cell Walls ◽  
Potassium Hydroxide ◽  
Base Composition ◽  
Higher Plants ◽  
Nuclear Material ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography

A method for isolating extensively purified cell walls from higher plants is described; the preparations contain no detectable chloroplast or nuclear material and the protein content (2–5% of the dry wt. of walls) indicates that there is little contamination with cytoplasm. Incubation of purified cell walls with 0·3n-potassium hydroxide for 17hr. at 37° liberates ribonucleotides, which can be purified by adsorption on charcoal and by ion-exchange chromatography. Ribonucleotides are also liberated by incubating the walls with ribonuclease, but not with deoxyribonuclease. The RNA content varies from 0·5 to 6mg./g. dry wt. of walls, depending on the nature and age of the tissue, and at 3mg./g. dry wt. of walls accounts for about 7% of the total RNA of the tissue. Less than 0·2% of the RNA of the walls is due to the presence of bacteria in the preparation. The base composition of the cell-wall RNA is identical with that of ribosomal RNA.

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.

Role of Golgi Apparatus in the Formation of Plant Slimes, Cuticles and Extraneous Wall Material

1974 ◽  
Vol 32 ◽  
pp. 86-87
Author(s):  
Hilton H. Mollenhauer
Keyword(s):  
Cell Wall ◽  
Golgi Apparatus ◽  
Cell Walls ◽  
Growth And Development ◽  
Characteristic Property ◽  
Plant Cells ◽  
Plant Biology ◽  
Wall Material ◽  
Wall Properties

Cell walls are fundamentally involved in many aspects of plant biology including the morphology, growth, and development of plant cells and the interactions between plant hosts and their pathogens. Intuitively, one can recognize that these wall properties result from the sum total of the various components of which the wall is composed and that there are classes of substances each of which impart a characteristic property to the cell wall.

scholarly journals ELECTRON-OPAQUE FIBRILS AND GRANULES IN AND BETWEEN THE CELL WALLS OF HIGHER PLANTS

1972 ◽  
Vol 53 (3) ◽  
pp. 695-703 ◽  
Author(s):  
Gary G. Leppard ◽  
J. Ross Colvin
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Cultured Cells ◽  
Higher Plants ◽  
Middle Lamella ◽  
Woody Species ◽  
Morning Glory ◽  
Plant Cell Walls ◽  
Higher Plant ◽  
Cell Wall Matrix

The components of higher-plant cell walls which become electron-opaque after staining with ruthenium-osmium were studied by electron microscopy. A fibrillar material which absorbs this stain is a major wall constituent in the root epidermal cells of carrot and morning glory. In both form and size, these fibrils resemble those found on the surface of suspension-cultured cells of the same species Some cells of woody species show an irregular distribution of electron-opaque material in the cell wall matrix and middle lamella. This material, which has an amorphous appearance with many electron stains, is shown by ruthenium-osmium staining to be an aggregate of discrete granules, 150–220 A in diameter. These observations are not consistent with the concept of the cell wall matrix and middle lamella as an amorphous, uniform gel

Cell Walls of the Phycobionts Trebouxia and Pseudotrebouxia: Constituents and Their Localization

1984 ◽  
Vol 16 (2) ◽  
pp. 129-144 ◽  
Author(s):  
J. König ◽  
E. Peveling
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Cell Wall Composition ◽  
Recognition Mechanism ◽  
Absorption Spectrophotometry ◽  
Species Specific ◽  
Layer Chromatography ◽  
Polysaccharide Layer ◽  
Wall Components

AbstractThe cell wall composition of several species of the lichen phycobionts Trebouxia and Pseudotrebouxia has been investigated using gas chromatography, thin layer chromatography and infrared absorption spectrophotometry. In addition cell wall components (cellulose, non-cellulosic polysaccharides, sporopollenin, protein) were localized with cytochemical methods at the EM- level. The cell walls of Trebouxia and Pseudotrebouxia consist of several layers. In Trebouxia the inner layer (Si) consists mainly of cellulose, then followed by a non-cellulosic polysaccharide layer (S2), a sporopollenin-layer (S3) and an outer layer consisting again of a non-cellulosic polysaccharide (S4). In addition Trebouxia is surrounded by a sheath (a polysaccharide with species-specific terminal residues). In Pseudotrebouxia the cell wall is similarly constructed compared to Trebouxia, however, the sheath is lacking and the S4 layer contains a polysaccharide with species-specific terminal sugar residues. The role of the different cell wall constituents for the recognition mechanism between the lichen symbionts is discussed.

scholarly journals The role of plant cell wall encapsulation and porosity in regulating lipolysis during the digestion of almond seeds

2016 ◽  
Vol 7 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Myriam M. L. Grundy ◽  
Frédéric Carrière ◽  
Alan R. Mackie ◽  
David A. Gray ◽  
Peter J. Butterworth ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Cell Walls ◽  
Plant Cell Wall ◽  
Intact Cell ◽  
Lipid Digestion

Intact cell walls of almond prevent lipase penetration thus hindering lipid digestion.

scholarly journals UDP-GLYCOSYLTRANSFERASE 72E3 Plays a Role in Lignification of Secondary Cell Walls in Arabidopsis

2020 ◽  
Vol 21 (17) ◽  
pp. 6094
Author(s):  
Fabien Baldacci-Cresp ◽  
Julien Le Roy ◽  
Brigitte Huss ◽  
Cédric Lion ◽  
Anne Créach ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Lignin Content ◽  
Mutant Cell ◽  
Subsequent Investigation ◽  
Secondary Cell Walls ◽  
Chemical Determination ◽  
Safranin O

Lignin is present in plant secondary cell walls and is among the most abundant biological polymers on Earth. In this work we investigated the potential role of the UGT72E gene family in regulating lignification in Arabidopsis. Chemical determination of floral stem lignin contents in ugt72e1, ugt72e2, and ugt72e3 mutants revealed no significant differences compared to WT plants. In contrast, the use of a novel safranin O ratiometric imaging technique indicated a significant increase in the cell wall lignin content of both interfascicular fibers and xylem from young regions of ugt72e3 mutant floral stems. These results were globally confirmed in interfascicular fibers by Raman microspectroscopy. Subsequent investigation using a bioorthogonal triple labelling strategy suggested that the augmentation in lignification was associated with an increased capacity of mutant cell walls to incorporate H-, G-, and S-monolignol reporters. Expression analysis showed that this increase was associated with an up-regulation of LAC17 and PRX71, which play a key role in lignin polymerization. Altogether, these results suggest that UGT72E3 can influence the kinetics of lignin deposition by regulating monolignol flow to the cell wall as well as the potential of this compartment to incorporate monomers into the growing lignin polymer.

scholarly journals RAD51C deficiency in mice results in early prophase I arrest in males and sister chromatid separation at metaphase II in females

2007 ◽  
Vol 176 (5) ◽  
pp. 581-592 ◽  
Author(s):  
Sergey Kuznetsov ◽  
Manuela Pellegrini ◽  
Kristy Shuda ◽  
Oscar Fernandez-Capetillo ◽  
Yilun Liu ◽  
...  
Keyword(s):  
Meiotic Recombination ◽  
Early Prophase ◽  
Null Mouse ◽  
Sexually Dimorphic ◽  
Rad51 Protein ◽  
Hypomorphic Allele ◽  
Prophase I ◽  
Early Stages ◽  
Sister Chromatids

RAD51C is a member of the RecA/RAD51 protein family, which is known to play an important role in DNA repair by homologous recombination. In mice, it is essential for viability. Therefore, we have generated a hypomorphic allele of Rad51c in addition to a null allele. A subset of mice expressing the hypomorphic allele is infertile. This infertility is caused by sexually dimorphic defects in meiotic recombination, revealing its two distinct functions. Spermatocytes undergo a developmental arrest during the early stages of meiotic prophase I, providing evidence for the role of RAD51C in early stages of RAD51-mediated recombination. In contrast, oocytes can progress normally to metaphase I after superovulation but display precocious separation of sister chromatids, aneuploidy, and broken chromosomes at metaphase II. These defects suggest a possible late role of RAD51C in meiotic recombination. Based on the marked reduction in Holliday junction (HJ) resolution activity in Rad51c-null mouse embryonic fibroblasts, we propose that this late function may be associated with HJ resolution.

Comparing Mechanical Properties of Normal and Compression Wood in Norway Spruce: The Role of Lignin in Compression Parallel to the Grain

Holzforschung ◽  
2002 ◽  
Vol 56 (4) ◽  
pp. 395-401 ◽  
Author(s):  
W. Gindl
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cell Wall ◽  
Mechanical Testing ◽  
Cell Walls ◽  
Compression Wood ◽  
Lignin Content ◽  
Microfibril Angle ◽  
Compression Failure

Summary Cell-wall lignin content and composition, as well as microfibril angle of normal and compression wood samples were determined prior to mechanical testing in compression parallel to the grain. No effect of increased lignin content on the Young's modulus in compression wood was discernible because of the dominating influence of microfibril angle. In contrast, compressive strength of compression wood was not negatively affected by the high microfibril angle. It is proposed that the observed high lignification in compression wood increases the resistance of the cell walls to compression failure. An increased percentage of p-hydroxyphenylpropane units observed in compression wood lignin may also contribute to the comparably high compressive strength of compression wood.

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