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 STRUCTURAL FEATURES OF MESOSOMES (CHONDRIOIDS) OF BACILLUS SUBTILIS AFTER FREEZE-ETCHING

1968 ◽  
Vol 39 (2) ◽  
pp. 251-263 ◽  
Author(s):  
N. Nanninga
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Plasma Membrane ◽  
Outer Surface ◽  
Osmium Tetroxide ◽  
Close Association ◽  
Membrane Surface ◽  
Bacterial Membranes ◽  
Inner Surface ◽  
Freeze Etching

Freeze-etched cells of Bacillus subtilis have been studied with the electron microscope. The outer surface of the plasma membrane, i.e. the side facing the cell wall, is covered with numerous granules and short strands, each measuring approximately 50 A in diameter. These strands are occasionally seen to enter the cell wall. The inner surface of the plasma membrane, i.e. the side facing the cytoplasm, appears to be sparsely dotted with small particles measuring about 50 A. The envelope of mesosomes differs from the plasma membrane. Blunt protrusions arise from its outer surface; the inner surface appears smooth. Stalked particles, as described by other investigators after negative staining with phosphotungstic acid, were not observed on any membrane surface in our material. Preparations were also made of specimens prefixed in osmium tetroxide prior to freeze-etching. Under these conditions the bacterial membranes appeared to be surprisingly well preserved. In contrast to directly frozen, unfixed cells, some osmium tetroxide-fixed preparations showed a differentiation in cytoplasm and nucleoplasm, which made it possible to observe the close association of the mesosome with the latter.

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.

Ultrastructure and development of urediospore ornamentation in Melampsora lini

1971 ◽  
Vol 49 (12) ◽  
pp. 2067-2073 ◽  
Author(s):  
L. J. Littlefield ◽  
C. E. Bracker
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Outer Surface ◽  
Spore Wall ◽  
Wall Material ◽  
Wild Type ◽  
Melampsora Lini ◽  
Inner Surface ◽  
External Position ◽  
Basal Portion

The urediospores of Melampsora lini (Ehrenb.) Lev. are echinulate, with spines ca. 1 μ long over their surface. The spines are electron-transparent, conical projections, with their basal portion embedded in the electron-dense spore wall. The entire spore, including the spines, is covered by a wrinkled pellicle ca. 150–200 Å thick. The spore wall consists of three recognizable layers in addition to the pellicle. Spines form initially as small deposits at the inner surface of the spore wall adjacent to the plasma membrane. Endoplasmic reticulum occurs close to the plasma membrane in localized areas near the base of spines. During development, the spore wall thickens, and the spines increase in size. Centripetal growth of the wall encases the spines in the wall material. The spines progressively assume a more external position in the spore wall and finally reside at the outer surface of the wall. A mutant strain with finely verrucose spores was compared to the wild type. The warts on the surface of the mutant spores are rounded, electron-dense structures ca. 0.2–0.4 μ high, in contrast to spines of the wild type. Their initiation near the inner surface of the spore wall and their eventual placement on the outer surface of the spore are similar to that of spines. The wall is thinner in mutant spores than in wild-type spores.

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.

Electron Microscopic Observations on Virus-Like Particles of a Catfish Papilloma

1977 ◽  
Vol 35 ◽  
pp. 394-395
Author(s):  
M. R. Edwards ◽  
W. A. Samsonoff
Keyword(s):  
Endoplasmic Reticulum ◽  
Major Part ◽  
Osmium Tetroxide ◽  
Electron Microscopic ◽  
Brown Bullhead ◽  
Thin Sections ◽  
Lower Lip ◽  
Virus Like Particles ◽  
Tumor Tissues ◽  
Microscopic Techniques

Papillomas in catfishes have been described (1) but the presence of viruses in these tumors has not (2). This report is concerned with the study of a papilloma found on the lower lip of a brown bullhead (letalurus nebulosus) which had been frozen prior to arrival at our laboratory.Tumor tissues were thawed in 2.5% glutaraldehyde and postfixed in 1$ osmium tetroxide. Both fixatives were prepared in Millonig's buffer. Fixation, washing, dehydration, and Epon embedding were accomplished according to conventional electron microscopic techniques.Examination of thin sections revealed virus-like particles in epidermal cells which constituted the major part of the neoplasm (Fig. 1). No particles were found in the connective tissue surrounding the epidermal papillae. The cells containing particles were usually isolated from one another, had a spindle or fusiform shape, and exhibited many cytoplasmic extensions in random directions. Their nuclei were pleomorphic and displayed irregular nuclear envelopes with relatively large lacunae. Vesiculation of the cytoplasm was extensive, apparently caused by dilations of the endoplasmic reticulum.

Lomasome biogenesis and function in armillaria mellea

1978 ◽  
Vol 36 (2) ◽  
pp. 402-403
Author(s):  
B. Ch. Behboodi
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Osmium Tetroxide ◽  
Higher Plants ◽  
Cell Wall Formation ◽  
Extensive Investigation ◽  
Sodium Cacodylate ◽  
Armillaria Mellea ◽  
Synthetic Media ◽  
And Function

IntroductionBorder bodies or lomasomes are the aggregation of membranes and vesicles located between the plasma membrane and the cell wall of many fungi, algae, and higher plants. Despite extensive investigation, the biogenesis as well as function of these structures is not yet known. The purpose of this investigation was to describe the biogenesis of lomasomes in Armillaria mellea and to provide some observations on their function related to cell wall formation.Materials and MethodsVarious thalli of fungi as non-aggregated hyphae, pseudosclerotes, rhizomorphs and carpophores were grown either on orange or synthetic media as described previously. The thalli were fixed in 4% glutaraldehyde buffered with 0.1 M sodium cacodylate (pH 7.4), and 0.15 M sucrose for 4 h at 4°. They were postfixed with 1% osmium tetroxide in the same buffer for 2 h at 4° and embedded in Epon according to the Luft procedure. Cytochemical studies using thiocarbohydrazide-silver proteinate were performed according the Thiéry.

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.

The behavior of ATPase in cotyledon tissue during germination

1972 ◽  
Vol 50 (2) ◽  
pp. 327-332 ◽  
Author(s):  
Y. F. Lai ◽  
J. E. Thompson
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Phaseolus Vulgaris ◽  
Atpase Activity ◽  
Major Part ◽  
Protein Body ◽  
Transport Processes ◽  
Assay Mixture ◽  
Storage Cells ◽  
Soluble Fractions

The behavior of ATPase in cotyledon tissue of Phaseolus vulgaris during germination has been examined with a view to assessing the feasibility of its involvement in transport processes. Both basal ATPase activity (no cations added to the assay mixture) and Na+–K+ stimulated activity were routinely present in homogenates of the tissue but decreased during germination in a manner that corresponded very closely with the pattern of protein attenuation for the same period. Since the decreased levels of protein primarily reflect protein body digestion, this parallel behavior suggests that as the need for transport of metabolites out of the storage cells becomes less, there is a corresponding decrease in the levels of basal and cation-stimulated ATPases.Fractionation of the tissue revealed that ATPase activity is present in isolated soluble fractions, but throughout the germination period the major proportions of both basal and Na+–K+ stimulated activities proved to be particulate and were distributed among nuclear, mitochondrial, and microsomal fractions. Since both types of ATPase are present in purified cell wall and plasma membrane from this tissue, this distribution is thought to reflect in large part fragmentation of cell wall and plasma membrane incurred during homogenization. Thus the subcellular distributions of the enzymes as well as their patterns of change during germination are consistent with the involvement of a major part of the cotyledon ATPase activity in transport phenomena.

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.

scholarly journals Trafficking Processes and Secretion Pathways Underlying the Formation of Plant Cuticles

2022 ◽  
Vol 12 ◽  
Author(s):  
Glenn Philippe ◽  
Damien De Bellis ◽  
Jocelyn K. C. Rose ◽  
Christiane Nawrath
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Close Association ◽  
Tubular Structures ◽  
Complex Matrix ◽  
Acyl Lipid ◽  
Wall Structures ◽  
Plant Cuticles ◽  
Secretion Pathways ◽  
Macromolecular Architecture

Cuticles are specialized cell wall structures that form at the surface of terrestrial plant organs. They are largely comprised lipidic compounds and are deposited in the apoplast, external to the polysaccharide-rich primary wall, creating a barrier to diffusion of water and solutes, as well as to environmental factors. The predominant cuticle component is cutin, a polyester that is assembled as a complex matrix, within and on the surface of which aliphatic and aromatic wax molecules accumulate, further modifying its properties. To reach the point of cuticle assembly the different acyl lipid-containing components are first exported from the cell across the plasma membrane and then traffic across the polysaccharide wall. The export of cutin precursors and waxes from the cell is known to involve plasma membrane-localized ATP-binding cassette (ABC) transporters; however, other secretion mechanisms may also contribute. Indeed, extracellular vesiculo-tubular structures have recently been reported in Arabidopsis thaliana (Arabidopsis) to be associated with the deposition of suberin, a polyester that is structurally closely related to cutin. Intriguingly, similar membranous structures have been observed in leaves and petals of Arabidopsis, although in lower numbers, but no close association with cutin formation has been identified. The possibility of multiple export mechanisms for cuticular components acting in parallel will be discussed, together with proposals for how cuticle precursors may traverse the polysaccharide cell wall before their assimilation into the cuticle macromolecular architecture.

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