scholarly journals Ultrastructural and cytochemical changes in Pelargonium leaves due to aphid (Acyrthosiphon pelargonii (Kalt.) infestation

2012 ◽  
Vol 59 (2) ◽  
pp. 59-67
Author(s):  
Joanna Ślusarczyk
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Phenolic Compounds ◽  
Intercellular Spaces ◽  
Membrane Degradation

Infestation of aphid <i>Acyrthosiphon pelargonii</i> (Kalt.) caused increased deposition of phenolic compounds in the leaves of <i>Pelargonium sp</i>. Most deposits were located in the vacuole and in the area between the plasma membrane and cell wall, as well as some in the intercellular spaces. In cytoplasm damages were observed involving tonoplast and numerous vesicle deposits in the vicinity of the plasma membrane. Endoplasmic reticulum and myelin structures increased in number, as well as mitochondria whose cristae were longer and larger. Thus, we observed both the increase of organelle activity in such cells and the segregation of damaged areas in the form of membrane degradation.

THE ORGANIZATION OF CYTOPLASMIC COMPONENTS DURING THE PHASE OF CELL WALL THICKENING IN DIFFERENTIATING CAMBIAL DERIVATIVES OF ACER RUBRUM

1965 ◽  
Vol 43 (11) ◽  
pp. 1401-1407 ◽  
Author(s):  
James Cronshaw
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Osmium Tetroxide ◽  
Acer Rubrum ◽  
Middle Layer ◽  
Wall Thickening ◽  
Cytoplasmic Microtubules ◽  
Derivatives Of ◽  
Peripheral Cytoplasm

Cambial derivatives of Acer rubrum have been examined at stages of their differentiation following fixation in 3% or 6% glutaraldehyde with a post fixation in osmium tetroxide. At early stages of development numerous free ribosomes are present in the cytoplasm, and elements of the endoplasmic reticulum tend to align themselves parallel to the cell surfaces. The plasma membrane is closely applied to the cell walls. During differentiation a complex system of cytoplasmic microtubules develops in the peripheral cytoplasm. These microtubules are oriented, mirroring the orientation of the most recently deposited microfibrils of the cell wall. The microtubules form a steep helix in the peripheral cytoplasm at the time of deposition of the middle layer of the secondary wall. During differentiation the free ribosomes disappear from the cytoplasm and numerous elements of rough endoplasmic reticulum with associated polyribosomes become more evident. In many cases the endoplasmic reticulum is associated with the cell surface. During the later stages of differentiation there are numerous inclusions between the cell wall and the plasma membrane.

scholarly journals Four distinct secretory pathways serve protein secretion, cell surface growth, and peroxisome biogenesis in the yeast Yarrowia lipolytica.

1997 ◽  
Vol 17 (9) ◽  
pp. 5210-5226 ◽  
Author(s):  
V I Titorenko ◽  
D M Ogrydziak ◽  
R A Rachubinski
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Protein Secretion ◽  
Peroxisome Biogenesis ◽  
Peroxisomal Membrane ◽  
Mycelial Form ◽  
Secretory Pathways ◽  
Associated Proteins ◽  
Yeast Yarrowia Lipolytica

We have identified and characterized mutants of the yeast Yarrowia lipolytica that are deficient in protein secretion, in the ability to undergo dimorphic transition from the yeast to the mycelial form, and in peroxisome biogenesis. Mutations in the SEC238, SRP54, PEX1, PEX2, PEX6, and PEX9 genes affect protein secretion, prevent the exit of the precursor form of alkaline extracellular protease from the endoplasmic reticulum, and compromise peroxisome biogenesis. The mutants sec238A, srp54KO, pex2KO, pex6KO, and pex9KO are also deficient in the dimorphic transition from the yeast to the mycelial form and are affected in the export of only plasma membrane and cell wall-associated proteins specific for the mycelial form. Mutations in the SEC238, SRP54, PEX1, and PEX6 genes prevent or significantly delay the exit of two peroxisomal membrane proteins, Pex2p and Pex16p, from the endoplasmic reticulum en route to the peroxisomal membrane. Mutations in the PEX5, PEX16, and PEX17 genes, which have previously been shown to be essential for peroxisome biogenesis, affect the export of plasma membrane and cell wall-associated proteins specific for the mycelial form but do not impair exit from the endoplasmic reticulum of either Pex2p and Pex16p or of proteins destined for secretion. Biochemical analyses of these mutants provide evidence for the existence of four distinct secretory pathways that serve to deliver proteins for secretion, plasma membrane and cell wall synthesis during yeast and mycelial modes of growth, and peroxisome biogenesis. At least two of these secretory pathways, which are involved in the export of proteins to the external medium and in the delivery of proteins for assembly of the peroxisomal membrane, diverge at the level of the endoplasmic reticulum.

scholarly journals Intercellular trafficking via plasmodesmata: molecular layers of complexity

2020 ◽  
Author(s):  
Ziqiang Patrick Li ◽  
Andrea Paterlini ◽  
Marie Glavier ◽  
Emmanuelle M. Bayer
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Plant Cells ◽  
Functional Domains ◽  
Dynamic Interactions ◽  
Intercellular Trafficking ◽  
Multiple Routes ◽  
Molecular Components ◽  
Molecular Layers

Abstract Plasmodesmata are intercellular pores connecting together most plant cells. These structures consist of a central constricted form of the endoplasmic reticulum, encircled by some cytoplasmic space, in turn delimited by the plasma membrane, itself ultimately surrounded by the cell wall. The presence and structure of plasmodesmata create multiple routes for intercellular trafficking of a large spectrum of molecules (encompassing RNAs, proteins, hormones and metabolites) and also enable local signalling events. Movement across plasmodesmata is finely controlled in order to balance processes requiring communication with those necessitating symplastic isolation. Here, we describe the identities and roles of the molecular components (specific sets of lipids, proteins and wall polysaccharides) that shape and define plasmodesmata structural and functional domains. We highlight the extensive and dynamic interactions that exist between the plasma/endoplasmic reticulum membranes, cytoplasm and cell wall domains, binding them together to effectively define plasmodesmata shapes and purposes.

scholarly journals Subcellular localization of cellulases in auxin-treated pea.

1976 ◽  
Vol 69 (1) ◽  
pp. 97-105 ◽  
Author(s):  
A K Bal ◽  
D P Verma ◽  
H Byrne ◽  
G A Maclachlan
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Major Part ◽  
Osmium Tetroxide ◽  
Close Association ◽  
Cellulase Activity ◽  
Cytochemical Localization ◽  
Tissue Sections ◽  
Inner Surface

Two forms of cellulase, buffer soluble (BS) and buffer insoluble (BI), are induced as a result of auxin treatment of dark-grown pea epicotyls. These two cellulases have been purified to homogeneity. Antibodies raised against the purified cellulases were conjugated with ferritin and were used to localize the two cellulases. Tissue sections were fixed in cold paraformaldehyde-glutaraldehyde and incubated for 1 h in the ferritin conjugates. The sections were washed with continuous shaking for 18 h and subsequently postfixed in osmium tetroxide. Tissue incubated in unconjugated ferritin was used as a control. A major part of BI cellulase is localized at the inner surface of the cell wall in close association with microfibrils. BS cellulase is localized mainly within the distended endoplasmic reticulum. Gogli complex and plasma membrane appear to be completely devoid of any cellulase activity. These observations are consistent with cytochemical localization and biochemical data on the distribution of these two cellulases among various cell and membrane fractions.

scholarly journals Abnormal sterol-induced cell wall glucan deficiency in yeast is due to impaired glucan synthase transport to the plasma membrane

2020 ◽  
Vol 477 (24) ◽  
pp. 4729-4744
Author(s):  
L. Roxana Gutierrez-Armijos ◽  
Rodrigo A. C. Sussmann ◽  
Ariel M. Silber ◽  
Mauro Cortez ◽  
Agustín Hernández
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Cell Walls ◽  
Bone Development ◽  
Cholesterol Biosynthesis ◽  
Cellular Functions ◽  
Fungal Cell ◽  
Glucan Synthase ◽  
Unconventional Secretion

Abnormal sterols disrupt cellular functions through yet unclear mechanisms. In Saccharomyces cerevisiae, accumulation of Δ8-sterols, the same type of sterols observed in patients of Conradi–Hünermann–Happle syndrome or in fungi after amine fungicide treatment, leads to cell wall weakness. We have studied the influence of Δ8-sterols on the activity of glucan synthase I, the protein synthetizing the main polymer in fungal cell walls, its regulation by the Cell Wall Integrity (CWI) pathway, and its transport from the endoplasmic reticulum to the plasma membrane. We ascertained that the catalytic characteristics were mostly unaffected by the presence of abnormal sterols but the enzyme was partially retained in the endoplasmic reticulum, leading to glucan deficit at the cell wall. Furthermore, we observed that glucan synthase I traveled through an unconventional exocytic route to the plasma membrane that is associated with low density intracellular membranes. Also, we found out that the CWI pathway remained inactive despite low glucan levels at the cell wall. Taken together, these data suggest that Δ8-sterols affect cell walls by inhibiting unconventional secretion of proteins leading to retention and degradation of glucan synthase I, while the compensatory CWI pathway is unable to activate. These results could be instrumental to understand defects of bone development in cholesterol biosynthesis disorders and fungicide mechanisms of action.

Embryology of Brassica campestris: the entrance and discharge of the pollen tube in the synergid and the formation of the zygote

1992 ◽  
Vol 70 (8) ◽  
pp. 1577-1590 ◽  
Author(s):  
M. J. Sumner
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Pollen Tube ◽  
Brassica Campestris ◽  
Periodic Acid ◽  
Outer Integument ◽  
Central Cell ◽  
Egg Cell ◽  
Intense Staining

The postanthesis synergids and zygote of Brassica campestris cv. Candle were examined using techniques of light, fluorescence, and electron microscopy. The pollen tube enters the degenerate synergid by way of the filiform apparatus. A degeneration of one of the two synergids occurs after anthesis and is independent of pollination. The first sign of synergid degeneration is a more intense staining of one of the synergids, followed by a loss of organelle membrane integrity. There is a disappearance of the plasma membrane and dictyosome cisternae; however, profiles of degenerate synergid mitochondria, plastids, and dilated endoplasmic reticulum remain along with dictyosome vesicles that contain periodic acid – thiocarbo-hydrazide – silver proteinate positive substances. The zygote, shortly after fertilization, is reduced in size and lacks the large micropylar vacuole characteristic of the mature unfertilized egg cell. Plastids and mitochondria are concentrated around the centrally located nucleus of the zygote, and dictyosomes, active in vesicle production, are located in the lateral and chalazal regions of the cell, adjacent to the cell wall. The lateral cell walls are periodic acid – Schiff's and Calcofluor positive, while the ampulliform chalazal tip of the cell is weakly periodic acid – Schiff s positive and Calcofluor negative. Microtubules, with the long axis perpendicular to the long axis of the zygote, are abundant in the ampulliform chalazal tip of the cell. Following fertilization the central cell becomes highly vacuolate. There is continuity between the zygote – central cell plasma membrane, the central cell vacuole tonoplast, and membranes of the central cell endoplasmic reticulum. Central cell wall projections, of the transfer cell type, are located in the lateral regions of the megagametophyte adjacent to the developing zygote cell and are positioned adjacent to the region of inner and outer integument starch. Key words: Brassica, ultrastructure, synergid, megagametophyte, pollen tube, zygote.

Studies in the brown alga Ectocarpus in culture: ultrastructural localization of enzymic activities

1976 ◽  
Vol 54 (9) ◽  
pp. 913-922 ◽  
Author(s):  
Luis Oliveira ◽  
Thana Bisalputra
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Brown Alga ◽  
Ultrastructural Localization ◽  
Vegetative Cells ◽  
Perinuclear Space ◽  
Catalase Peroxidase

The localization of enzymic activities (catalase. peroxidase, adenosinetriphosphatase) in vegetative cells of Ectocarpus sporophytes was carried out at the ultrastructural level.Catalase (EC 1.11.1.6) was only found in organelles recognizable as microbodies. Peroxidase (EC 1.11.1.7) was present in the cell wall, but the deposition of reaction product was also observed in the perinuclear space, endoplasmic reticulum, dictyosomes, and paramural space. Adenosinetriphosphatase (ATPase) (EC 3.6.1.3) was found associated with mitochondria, thylakoids, and the plasma membrane.

Microanatomy of the Periplasm of Bacillus Licheniformis

1971 ◽  
Vol 29 ◽  
pp. 262-263
Author(s):  
B.K. Ghosh
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Bacillus Licheniformis ◽  
External Environment ◽  
Permeability Barrier ◽  
Periplasmic Space ◽  
Modified Technique ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Periplasm of bacteria is the space outside the permeability barrier of plasma membrane but enclosed by the cell wall. The contents of this special milieu exterior could be regulated by the plasma membrane from the internal, and by the cell wall from the external environment of the cell. Unlike the gram-negative organism, the presence of this space in gram-positive bacteria is still controversial because it cannot be clearly demonstrated. We have shown the importance of some periplasmic bodies in the secretion of penicillinase from Bacillus licheniformis.In negatively stained specimens prepared by a modified technique (Figs. 1 and 2), periplasmic space (PS) contained two kinds of structures: (i) fibrils (F, 100 Å) running perpendicular to the cell wall from the protoplast and (ii) an array of vesicles of various sizes (V), which seem to have evaginated from the protoplast.

Triple Fixation For Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 90-91 ◽  
Author(s):  
M. A. Hayat
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Plasma Membrane ◽  
Myelin Sheath ◽  
Good Deal ◽  
Granular Structure ◽  
Oxidizing Agent ◽  
Fixation Technique ◽  
Large Clusters

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.

Enrichment of vitronectin- and fibronectin-like proteins in NaCI-adapted plant cells and evidence for their involvement in plasma membrane-cell wall adhesion

1993 ◽  
Vol 3 (5) ◽  
pp. 637-646 ◽  
Author(s):  
Jian-Kang Zhu ◽  
Jun Shi ◽  
Utpal Singh ◽  
Sarah E. Wyatt ◽  
Ray A. Bressan ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Plant Cells ◽  
Membrane Cell
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