Cell wall differentiation during early somatic embryogenesis in plants. II. Ultrastructural study and pectin immunolocalization on chicory embryos

2000 ◽  
Vol 78 (6) ◽  
pp. 824-831 ◽  
Author(s):  
Audrey Chapman ◽  
Anne-Sophie Blervacq ◽  
Théo Hendriks ◽  
Christian Slomianny ◽  
Jacques Vasseur ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Somatic Embryogenesis ◽  
Cell Walls ◽  
Ultrastructural Changes ◽  
Outer Cell ◽  
Embryogenic Cell ◽  
Transmission Electron ◽  
Outer Cell Wall

In Cichorium hybrid clone 474 (C. intybus L. var. sativum × C. endivia L. var. latifolia), direct somatic embryogenesis was induced from roots. Using transmission electron microscopy, we followed the ultrastructural changes of the outer cell wall in relation to embryo developmental stage. During the transition from an embryogenic cell to a somatic embryo, the differentiation of the outer cell wall involved both deposition and rearrangement processes. During the first divisions, the cell wall of few-celled embryos still enclosed in the root tissue appeared as a large amorphous layer of cellulose, thicker than the cell walls of the root cortex cells. When the proembryo emerged from the root cells, the outer wall surface exhibited a fibrillar material designated as the supraembryonic network. As this network disappeared, the outer cell wall changed organization, and two domains were distinguished. At the torpedo stage, the outer cell wall was more compact without any gaps and the protoderm was differentiated. Immunolocalization of an epitope recognised by JIM5 antibody revealed the unesterified nature of the supraembryonic network. Such pectins were also located at the outer third of the outer cell wall of protodermal cells as well as in the intercellular spaces. Highly methylesterified pectins recognized by JIM7 antibodies were slightly present in the cell walls during the embryogenesis process. The different stages of the outer cell wall differentiation as well as the development of the transient supraembryonic network are described, and its possible roles in somatic embryogenesis are proposed.Key words: cell differentiation, cell wall, Cichorium (chicory), pectin, somatic embryogenesis, transmission electron microscopy.

Ultrastructure of hyperparasitism of Coniothyrium minitans on sclerotia of Sclerotinia sclerotiorum

1987 ◽  
Vol 65 (12) ◽  
pp. 2483-2489 ◽  
Author(s):  
H. C. Huang ◽  
E. G. Kokko
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Sclerotinia Sclerotiorum ◽  
Cell Walls ◽  
Chemical Activity ◽  
Coniothyrium Minitans ◽  
Medullary Tissue ◽  
Transmission Electron

Transmission electron microscopy revealed that hyphae of the hyperparasite Coniothyrium minitans invade sclerotia of Sclerotinia sclerotiorum, resulting in the destruction and disintegration of the sclerotium tissues. The dark-pigmented rind tissue is more resistant to invasion by the hyperparasite than the unpigmented cortical and medullary tissues. Evidence from cell wall etching at the penetration site suggests that chemical activity is required for hyphae of C. minitans to penetrate the thick, melanized rind walls. The medullary tissue infected by C. minitans shows signs of plasmolysis, aggregation, and vacuolization of cytoplasm and dissolution of the cell walls. While most of the hyphal cells of C. minitans in the infected sclerotium tissue are normal, some younger hyphal cells in the rind tissue were lysed and devoid of normal contents.

Ultrastructural changes in Staphylococcus aureus treated with pulsed electric fields / Cambios ultraestructurales en Staphylococcus aureus sometida a campos eléctricos pulsantes

1997 ◽  
Vol 3 (2) ◽  
pp. 113-121 ◽  
Author(s):  
U.R. Pothakamury ◽  
G.V. Barbosa-Cánovas ◽  
B.G. Swanson ◽  
K.D. Spence
Keyword(s):  
Electron Microscopy ◽  
Staphylococcus Aureus ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Electric Field ◽  
Electric Fields ◽  
Untreated Control ◽  
Ultrastructural Changes ◽  
Transmission Electron ◽  
Treat Ment

Early stationary phase cells of Staphylococcus aureus were inoculated into a model food, simulated milk ultrafiltrate (SMUF) and subjected to 16, 32, and 64 pulses at electric field intensities of 20, 40 and 60 kV/cm at 13 °C. In addition temperatures of 20, 25 and 30 °C were also tested with 32 pulses and an electric field of 60 kV/cm. The temperature of the SMUF increased by 1-2 ° C at the end of the 64 pulses. Cells subjected to 64 pulses at 20, 40 and 60 kV/cm were observed for ultrastructural changes using scanning and transmission electron microscopy techniques. The cell surface was rough after treatment with electric field when observed by scanning electron microscopy (SEM). The cell wall was broken, and the cytoplasmic contents were leaking out of the cell after exposure to 64 pulses at 60 kV/cm when observed by transmission electron microscopy (TEM). The breaking of the cell wall is an indication of electro-mechanical breakdown of the cell. The increase in inactivation with an increase in the electric field strength can be related to the increase in the damage to the cells. Cells subjected to 32 pulses at 60 kV/cm and 13, 20 or 25 °C were compared microscopically with the untreated control cells. Cells subjected to heat treat ment (10 min, at 66 °C) were compared with electric field-treated and untreated control cells. Although important changes were observed in the protoplast, no cell wall breakdown was observed in heat-treated cells when compared to the electric field-treated cells. This result indi cates a different mechanism of inactivation of cells with heat treatment.

Weight Loss and Cell Wall Degradation in Rubberwood Caused by Sapstain Fungus Botryodiplodia theobromae

Holzforschung ◽  
2002 ◽  
Vol 56 (3) ◽  
pp. 225-228 ◽  
Author(s):  
E. J. M. Florence ◽  
R. Gnanaharan ◽  
P. Adya Singh ◽  
J. K. Sharma
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Weight Loss ◽  
Cell Wall ◽  
Cell Walls ◽  
Cell Wall Degradation ◽  
Botryodiplodia Theobromae ◽  
Percent Weight Loss ◽  
Transmission Electron

Summary Botryodiplodia theobromae is the predominant fungus causing sapstain in rubberwood in Kerala, India. The fungus causes up to 12.2 percent weight loss in rubberwood over a period of sixteen weeks. Transmission Electron Microscopy (TEM) of sapstained rubberwood provided evidence on hyphal invasion of cells by B. theobromae through the pit region, facilitated by its ability to degrade pit membranes. The study also revealed that B. theobromae caused degradation of lignified cell walls by erosion of the cell wall surfaces of wood elements.

Use of immunogold cytochemistry to detect Mn(II)-dependent and lignin peroxidases in wood degraded by the white rot fungi Phanerochaete chrysosporium and Lentinula edodes

1990 ◽  
Vol 68 (4) ◽  
pp. 920-933 ◽  
Author(s):  
G. Daniel ◽  
B. Pettersson ◽  
T. Nllsson ◽  
J. Volc
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Phanerochaete Chrysosporium ◽  
Cell Walls ◽  
Lentinula Edodes ◽  
White Rot ◽  
Transmission Electron ◽  
Lignin Peroxidases ◽  
Immunogold Cytochemistry

Using antibodies raised against Mn(II)-dependent peroxidase and transmission electron microscopy immunogold cytochemistry, the spatial distribution of Mn(II)-dependent peroxidase during degradation of wood and wood fragments by Phanerochaete chrysosporium and Lentinula edodes was studied. In P. chrysosporium, the enzyme was localized in peripheral regions of the fungal hyphae on the cell membrane, on membranes of vesicule-like structures, and on the cell wall. The cytoplasmic distribution of Mn(II)-dependent peroxidase appeared similar to that of lignin peroxidase, as determined by double immunogold labeling procedures and antibodies raised against lignin peroxidase. In wood blocks of Betula verrucosa degraded by P. chrysosporium and L. edodes, Mn(II)-dependent peroxidase was detected on all wood cell wall layers showing signs of decay, whether at early or advanced stages of attack. In particular, the enzyme was localized in zones of degradation produced within the S2 wood cell walls. These regions displayed a looser, more open fibrillar structure than unattacked wood cell walls and were readily penetrated by purified preparations of Mn(II)-dependent and lignin peroxidases. With L. edodes, Mn(II)-dependent peroxidase was found to accumulate in middle lamellar regions selectively degraded by the fungus. Mn(II)-dependent peroxidase diffusion into undecayed wood cell walls was not observed. Key words: Mn(II)-dependent peroxidase, Phanerochaete chrysosporium, Lentinula edodes, immunogold cytochemistry, white rot decay, transmission electron microscopy.

The influence of acetylsalicylic acid on oxylipin migration in Cryptococcus neoformans var.neoformansUOFS Y-1378

2008 ◽  
Vol 54 (2) ◽  
pp. 91-96 ◽  
Author(s):  
Olihile M. Sebolai ◽  
Carolina H. Pohl ◽  
Piet J. Botes ◽  
Pieter W.J. van Wyk ◽  
Johan L.F. Kock
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Acetylsalicylic Acid ◽  
Cryptococcus Neoformans ◽  
Cell Walls ◽  
Bone Lesion ◽  
Acid Synthesis ◽  
Immunogold Labeling ◽  
Transmission Electron

In this paper we report the influence of acetylsalicylic acid on oxylipin migration in Cryptococcus neoformans var. neoformans UOFS Y-1378, previously isolated from human bone lesion. Transmission electron microscopy suggests that osmiophilic material originates in mitochondria and is deposited inside the yeast cell wall, from which it is excreted into the environment, along capsule protuberances, or through capsule detachments. Previous studies using immunogold labeling indicate that these osmiophilic layers contain 3-hydroxy oxylipins. In this study, the addition of acetylsalicylic acid (an inhibitor of mitochondrial function) in increasing amounts to the cells abrogated the migration of osmiophilic material, as well as capsule detachment from cell walls, and hence, oxylipin excretion. Consequently, we hypothesize that 3-hydroxy oxylipins are produced in mitochondria, probably via incomplete β-oxidation or fatty acid synthesis, from which they are deposited inside the cell wall and excreted through tubular protuberances attached to the surrounding capsules and (or) through detachment of these oxylipin-containing capsules.

Ultrastructural analysis of basidiosporogenesis in Panellus stypticus

1992 ◽  
Vol 70 (10) ◽  
pp. 2017-2027 ◽  
Author(s):  
Wilma L. Lingle ◽  
Ronald P. Clay ◽  
David Porter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Wheat Germ Agglutinin ◽  
Cell Walls ◽  
Wheat Germ ◽  
Freeze Substitution ◽  
Rapid Freezing ◽  
Transmission Electron ◽  
Meiosis I

The ultrastructure of events in basidiosporogenesis in Panellus stypticus was examined using conventional, aqueous-based fixation procedures and freeze substitution fixation following plunge freezing in liquid propane. Freeze substitution was superior in preserving cytological features and in retaining cell wall and extracellular materials. Synapsis, all stages of meiosis I (including prophase, metaphase, anaphase, and telophase), and prophase of meiosis II were observed. The nuclear envelope breaks down during meiosis I, temporarily reforms during interphase, and is at least partially broken down during meiosis II. Many stages of spore development, including sterigma initiation, sterigma elongation, organelle translocation, and nuclear migration, were observed. Spindle pole bodies with microtubule arrays were associated with nuclear migration into developing spores. Analysis of hymenial cells with gold-tagged lectins and enzymes revealed an α-amylase positive outer cell wall layer specific to basidiospores. Only after basidiospore release were surfaces of sterigmata and basidia similarly labeled. All cell walls observed were positive for wheat germ agglutinin, indicating the presence of chitin. Septa-delimiting basidiospores from sterigmata were heavily labeled with wheat germ agglutinin. This is the first investigation of basidiosporogenesis in a homobasidiomycete preserved for transmission electron microscopy by rapid freezing and freeze substitution. Key words: fungal cell walls, lectins, gold labeling, meiosis, rapid freezing, transmission electron microscopy.

Pulmonary Endothelial Cell Modifications after Storage in Solid-Organ Preservation Solutions

1995 ◽  
Vol 23 (3) ◽  
pp. 200-206 ◽  
Author(s):  
P Carbognani ◽  
L Spaggiari ◽  
M Rusca ◽  
L Cattelani ◽  
P Solli ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Organ Preservation ◽  
Ultrastructural Changes ◽  
Osmic Acid ◽  
Solid Organ ◽  
Ringer Lactate ◽  
University Of Wisconsin ◽  
Transmission Electron ◽  
Grading Scale

During lung preservation, the vascular endothelium is probably the first site of damage and these lesions are considered the main limiting factor in solid-organ preservation. In the present study, the ultrastructural changes in the endothelial cells of human pulmonary artery hypothermically stored (at 4 °C) for 6 and 12 h in Euro-Collins, University of Wisconsin and Ringer-lactate solutions were compared. The arteries obtained from three patients who underwent pneumonectomy were divided into 20 segments and preserved in the three solutions mentioned. The specimens, which were fixed in osmic acid, were examined using transmission electron microscopy. Transmission electron microscopy indicated that the cells stored in the University of Wisconsin solution either for 6 or 12 h were the best preserved, while the most severely damaged cells were those stored in Euro-Collins solution, even after just 6 h. The cells stored in Ringer-lactate showed an intermediate level of damage. The data from an ultrastructural grading scale, which quantified the damage to the cytoplasm, mitochondria and nucleus, were in broad agreement with the general transmission electron microscopy observations. Analysis of variance of the grading scale data showed that there were statistically significant differences between the groups after both 6 and 12 h storage ( P < 0.05).

scholarly journals Pollen, Tapetum, and Orbicule Development inColletia paradoxaandDiscaria americana(Rhamnaceae)

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
M. Gotelli ◽  
B. Galati ◽  
D. Medan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Ultrastructural Changes ◽  
Transmission Electron ◽  
The Family ◽  
Tapetal Cells ◽  
Grain Formation

Tapetum, orbicule, and pollen grain ontogeny inColletia paradoxaandDiscaria americanawere studied with transmission electron microscopy (TEM). The ultrastructural changes observed during the different stages of development in the tapetal cells and related to orbicule and pollen grain formation are described. The proorbicules have the appearance of lipid globule, and their formation is related to the endoplasmic reticulum of rough type (ERr). This is the first report on the presence of orbicules in the family Rhamnaceae. Pollen grains are shed at the bicellular stage.

A freeze-etch study of plant cell walls for ectodesmata

1974 ◽  
Vol 52 (9) ◽  
pp. 2033-2036 ◽  
Author(s):  
N. C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Leaf Tissue ◽  
Physicochemical Characteristics ◽  
Outer Cell ◽  
Plantago Major ◽  
Plant Cell Walls ◽  
Phaseolus Vulgaris L ◽  
Epidermal Cell Wall ◽  
Outer Cell Wall

Leaf tissue of Phaseolus vulgaris L. and Plantago major L. was prepared by the freeze-etch technique and examined in the electron microscope for the presence of ectodesmata. No structures analagous to ectodesmata observed with light microscopy could be found in freeze-etched preparations of chemically unfixed material or in material fixed only in glutaraldehyde. Objects appearing as broad, shallow, granular areas in the epidermal cell wall beneath the cuticle were observed in leaf replicas after fixation in complete sublimate fixative, the acid components of the sublimate fixative, or mercuric chloride alone. Because of their distribution and location, these objects can be considered analagous to ectodesmata observed by light microscopists. Because these areas occur only in chemically fixed walls and are localized within the walls in discrete areas, their presence supports the contention that ectodesmata are sites in the outer cell wall with defined physicochemical characteristics.

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