Cytochemical and subcellular organization of root apical meristems of dry and germinating jack pine embryos

1977 ◽  
Vol 7 (2) ◽  
pp. 263-276 ◽  
Author(s):  
A. J. Mia ◽  
D. J. Durzan
Keyword(s):  
Significant Extent ◽  
Electron Microscopic ◽  
Cytoplasmic Staining ◽  
Nitrogenous Compounds ◽  
Linear Arrays ◽  
Subcellular Organelles ◽  
Daughter Cells ◽  
High Lipid ◽  
Acidic Proteins ◽  
Food Reserves

By cytochemical and electron microscopic methods, the emerging radicle of Pinusbanksiana Lamb. was shown to contain an abundance of food reserves largely proteins, lipids, and starch grains. After 4 days of imbibition, the food reserves were dispersed to the daughter cells that tended to form through a sequence of divisions, linear arrays of adhering cells. The main cytochemical changes were associated with the later stages of imbibition and the consumption of carbohydrates and nitrogenous compounds for the synthesis of newly dispersed macromolecules. Peroxidase (EC 1.11.1.7) not found to any significant extent in the dry embryo, appeared by day 4 in the root cap and epidermal cells. As for DNA synthesis, cells of the quiescent zone were shown by autoradiography to incorporate very little [methyl-3H]thymidine. By contrast, most cells in the radicle incorporated thymidine in advance of the first wave of cell division between 3 to 4 days.The initial tight packing of subcellular organelles and the high lipid content of dry cells made the evaluation of subcellular changes difficult. In the nucleus and cytoplasm, the increase of ribosomes and polysomes was supported by the increased cytoplasmic staining for total RNA and acidic proteins. In emerging radicles, the overall redistribution of organic reserves and the associated subcellular reorganization related to the tactical displacement of cells and to new channels for the initial uptake of water and nutrients from the soil.

Fine Structural Classification of Chromophobe Adenomas of the Human Pituitary Gland

1975 ◽  
Vol 33 ◽  
pp. 378-379
Author(s):  
K. Kovacs ◽  
E. Horvath
Keyword(s):  
Pituitary Adenomas ◽  
Secretory Activity ◽  
Microscopic Investigation ◽  
Uranyl Acetate ◽  
Electron Microscopic Investigation ◽  
Electron Microscopic ◽  
Human Pituitary ◽  
Cytoplasmic Staining ◽  
Human Pituitary Gland ◽  
Microscopic Features

Chromophobe pituitary adenomas arise from adenohypophysial cells and fail to exhibit cytoplasmic staining with conventional acid or basic dyes by light microscopy. The aim of the present work was to study the electron microscopic features of these tumors, to separate them into distinct entities and to correlate their fine structural appearances with secretory activity.Among 48 surgically removed various pituitary adenomas 30 tumors were found which, based on the tinctorial characteristics of the cytoplasm, corresponded to chromophobe adenomas. For electron microscopic investigation pieces of these tumors were fixed in 2.5 per cent glutaraldehyde in Sorensen's buffer, post fixed in 1 per cent osmium tetroxide in Millonig's buffer, dehydrated in graded ethanol and embedded in Epon 812. Ultrathin sections were stained with uranyl acetate and lead citrate.By electron microscopy it was possible to separate chromophobe adenomas into 3 distinct entities: 1) adenomas consisting of sparsely granulated growth hormone cells (7 cases).

Light and Electron Microscopic Examination of the Parasitic Dinoflagellate Haplozoon

2000 ◽  
Vol 6 (S2) ◽  
pp. 884-885
Author(s):  
Stephen C. Landers
Keyword(s):  
Gulf Coast ◽  
Light And Electron Microscopy ◽  
Electron Microscopic Examination ◽  
The United States ◽  
Intestinal Wall ◽  
State University ◽  
University Campus ◽  
Electron Microscopic ◽  
Daughter Cells ◽  
A Chain

The parasitic dinoflagellate Haplozoon is found in the intestine of marine polychaetes. It is composed of a chain of cells that hang from the intestinal wall into the lumen, and releases daughter cells from the posterior end of the chain which leave the host and reinfect other polychaetes. Few studies exist in the recent literature regarding Haplozoon and it has not been reported from the Gulf Coast of the United States. This study reports the genus Haplozoon from the maldanid polychaete Axiothella mucosa in St. Andrew Bay, Florida, and examines the structure of the organism by light and electron microscopy.Axiothella mucosa was collected in St. Andrew Bay, Florida and maintained in seawater at the Troy State University campus. Haplozoon spp. was prepared for whole mounts by smearing minced setigers of the worms onto a slide with a drop of seawater.

An immunocytochemical, cytosol, and ultrastructural study of tissue ferritin in breast carcinoma

1994 ◽  
Vol 52 ◽  
pp. 298-299
Author(s):  
Robert L. Elliott ◽  
Fen Wang ◽  
Mary C. Elliott ◽  
Jonathan F. Head
Keyword(s):  
Breast Carcinoma ◽  
Malignant Tissue ◽  
Electron Microscopic ◽  
Major Site ◽  
Intense Staining ◽  
Cytoplasmic Staining ◽  
Ferritin Concentration ◽  
Benign Tissue ◽  
Microscopic Findings

Increased levels of serum ferritin in breast carcinoma is well known, however, its exact source has been disputed. Weinstein et al found six times the ferritin concentration in malignant tissue as compared to benign tissue. The anaplastic tumors had the highest ferritin concentrations, suggesting that the major site of the increased ferritin was the malignant epithelium. We found in a previous cytosolic and electron microscopic study of tissue ferritin in breast carcinoma that the malignant epithelium is almost certainly the source of the increased ferritin.To better define and expand this study and increase our knowledge of the role of transferrin receptors and iron metabolism in breast cancer, we began an immunocytochemical study of tissue ferritin to compliment our cytosol and ultrastructural observations. This was done with a mouse antihuman ferritin monoclonal antibody. To date 92 specimens have been examined by all three techniques. Immunocytochemical tissue slides showed intense staining of the cytoplasm with immunoperoxidase, and the intensity of the cytoplasmic staining correlated with the cytosolic concentrations and the electron microscopic findings.

Dissociation and re-assembly of the endoplasmic reticulum in live cells

1988 ◽  
Vol 91 (4) ◽  
pp. 511-522 ◽  
Author(s):  
G.L. Koch ◽  
C. Booth ◽  
F.B. Wooding
Keyword(s):  
Endoplasmic Reticulum ◽  
Channel Blocker ◽  
External Medium ◽  
Calcium Ionophore ◽  
Live Cells ◽  
3T3 Cells ◽  
Normal Medium ◽  
Linear Arrays ◽  
Daughter Cells ◽  
Rough Er

The endoplasmic reticulum (ER) of a typical interphase 3T3 fibroblast consists of a compact perinuclear arrangement of cisternae and lamellae which can be observed by immunofluorescence with anti-endoplasmin. During mitosis the reticulum dissociates into small fragments from which it appears to re-assemble in the daughter cells. When interphase 3T3 cells are exposed to calcium ionophores, but not other ionophores, there is a similar dissociation of the ER into small uniform fragments, which are dispersed throughout the cytoplasm. Electron microscopy shows that the fragments consist of small vesicular structures and that essentially all of the rough ER except the nuclear envelope is dissociated. The dissociation of the ER by calcium ionophore is a relatively specific process since other organelles and supramolecular assemblies remain unaffected. When cells with dissociated ER are returned to normal medium, there is a rapid reassembly of the fragments into the continuous reticulum. In a proportion of the cells it is possible to observe linear arrays of the fragments, which probably represent intermediates in the re-assembly process. These observations demonstrate that the ER in interphase 3T3 cells can be dissociated into, and re-assembled from, small fragments. Re-assembly of the ER from the fragments is dependent on the presence of millimolar levels of calcium in the external medium. In the presence of calcium, re-assembly is inhibited by the calcium channel blocker, verapamil. Thus calcium ions appear to play an important role in ER structure and assembly.

Lipid absorption, transport and hepatic assimilation studied with electron microscopy

1960 ◽  
Vol 198 (6) ◽  
pp. 1326-1328 ◽  
Author(s):  
C. T. Ashworth ◽  
V. A. Stembridge ◽  
E. Sanders
Keyword(s):  
Cell Membrane ◽  
Lipid Droplets ◽  
Corn Oil ◽  
Parenchymal Cell ◽  
The Body ◽  
Lipid Absorption ◽  
Direct Transfer ◽  
Electron Microscopic ◽  
High Lipid ◽  
Space Of Disse

An electron microscopic study of intestine and liver in rats ingesting a high-lipid diet or receiving corn oil by stomach tube was carried out. Studies of the intestinal phase of lipid absorption in rats showed what appears to be the direct transfer of particles across the cell membrane confirming the postulate that some of the process of lipid absorption involves triglyceride particles. Lipid droplets, representing chylomicrons were identified in hepatic sinusoids. They were traced into the pericellular space of Disse, which they had entered through the wide pore spaces in the sinusoidal endothelial cytoplasm. Lipid particles were also observed in different stages of direct transfer across the hepatic parenchymal cell membrane, and their formation of larger cytoplasmic lipid droplets within the cytoplasm of liver cells. This mechanism is proposed as a major device of the body in dispersing the lipemia which occurs after the ingestion of a fat meal.

scholarly journals The Occurrence of Intercellular Bridges in Groups of Cells Exhibiting Synchronous Differentiation

1959 ◽  
Vol 5 (3) ◽  
pp. 453-460 ◽  
Author(s):  
Don W. Fawcett ◽  
Susumu Ito ◽  
David Slautterback
Keyword(s):  
Phase Contrast ◽  
Fruit Fly ◽  
Giant Cells ◽  
Electron Microscopic ◽  
Free Communication ◽  
Intercellular Bridges ◽  
Daughter Cells ◽  
Contrast Microscopy ◽  
Undifferentiated Cells ◽  
Multinucleate Giant Cells

A previous electron microscopic study of the cat testis revealed that spermatids derived from the same spermatogonium are joined together by intercellular bridges. The present paper records the observation of similar connections between spermatocytes and between spermatids in Hydra, fruit-fly, opossum, pigeon, rat, hamster, guinea pig, rabbit, monkey, and man. In view of these findings, it is considered likely that a syncytial relationship within groups of developing male germ cells is of general occurrence and is probably responsible for their synchronous differentiation. When clusters of spermatids, freshly isolated from the germinal epithelium are observed by phase contrast microscopy, the constrictions between the cellular units of the syncytium disappear and the whole group coalesces into a spherical multinucleate mass. The significance of this observation in relation to the occurrence of abnormal spermatozoa in semen and the prevalence of multinucleate giant cells in pathological testes is discussed. In the ectoderm of Hydra, the clusters of cnidoblasts that arise from proliferation of interstitial cells are also connected by intercellular bridges. The development of nematocysts within these groups of conjoined cells is precisely synchronized. Both in the testis of vertebrates and the ectoderm of Hydra, a syncytium results from incomplete cytokinesis in the proliferation of relatively undifferentiated cells. The intercellular bridges between daughter cells are formed when the cleavage furrow encounters the spindle remnant and is arrested by it. The subsequent dissolution of the spindle filaments establishes free communication between the cells. The discovery of intercellular bridges in the two unrelated tissues discussed here suggests that a similar syncytial relationship may be found elsewhere in nature where groups of cells of common origin differentiate synchronously.

scholarly journals AN ELECTRON MICROSCOPIC STUDY OF THE DEVELOPMENT OF THE CLEAVAGE FURROW IN MAMMALIAN CELLS

1962 ◽  
Vol 13 (1) ◽  
pp. 117-125 ◽  
Author(s):  
Robert C. Buck ◽  
James M. Tisdale
Keyword(s):  
Equatorial Plane ◽  
Mammalian Cells ◽  
Cleavage Plane ◽  
Intimate Relationship ◽  
Cleavage Furrow ◽  
Intercellular Bridge ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Daughter Cells ◽  
Cytoplasmic Cleavage

The process of cytoplasmic cleavage has been studied in thin sections of rat erythroblasts and the cells of mouse leukemia and Walker 256 carcinoma of the rat. The development of the cleavage furrow begins in relation to the mid-body, which, earlier, appears on the equatorial plane in association with the continuous fibers of the spindle. The earliest evidence of a cleavage furrow is the presence of a vesicle or vesicles close to the mid-body. Subsequently, many smaller vesicles are seen in the equatorial plane. The cleavage furrow probably develops by the fusion of these vesicles so that a new plasma membrane is formed between the daughter cells, and extends from the telophase intercellular bridge to the cell margin. During the stage of formation of the vesicles, cisternae, believed to be part of the endoplasmic reticulum, assume an intimate relationship with the cleavage plane, and they may perhaps be involved in the formation of the vesicles.

Electron Microscopic Analysis of active and Repressed Chromatin within Normal and Neoplastic Human Cells

1980 ◽  
Vol 38 ◽  
pp. 542-543
Author(s):  
J. H. Frenster
Keyword(s):  
Rna Synthesis ◽  
Molecular Conformation ◽  
Intact Cell ◽  
Microscopic Analysis ◽  
Dna Molecules ◽  
Cell Nuclei ◽  
Animal Cells ◽  
Electron Microscopic ◽  
Acidic Proteins ◽  
Dna Template

Chromatin within the nuclei of animal cells consists of DNA molecules in non-covalent association with such intra-nuclear macromolecules as histones, acidic proteins, lipoproteins, and RNA species (1). These associated ligands and counter-ligands direct the molecular conformation and biological activity of DNA molecules within intact cell nuclei and within the intact chromatin complexes that can be isolated from such cell nuclei (2). Two major phase states of chromatin are recognized by ultrastructural, bio-synthetic, and biophysical criteria, and these two states of chromatin contain DNA template molecules that are either active in or repressed for RNA synthesis (3). DNA template molecules active in RNA synthesis are found within extended euchromatin microfibrils (Chart 1) which contain increased amounts and kinds of acidic proteins, lipoproteins, and RNA species. Each of these molecular species Is capable of activating for RNA synthesis the DNA molecules within repressed heterochromatin (Chart 1). By contrast, the DNA molecules within condensed heterochromatin are found to be repressed for RNA synthesis (3), and such repressed heterochromatin is relatively devoid of acidic proteins, lipoproteins, and RNA species.

scholarly journals Ammonia oxidation at pH 2.5 by a new gammaproteobacterial ammonia-oxidizing bacterium

2020 ◽  
Author(s):  
Nunzia Picone ◽  
Arjan Pol ◽  
Rob Mesman ◽  
Maartje A. H. J. van Kessel ◽  
Geert Cremers ◽  
...  
Keyword(s):  
Growth Rate ◽  
Doubling Time ◽  
Ammonia Oxidation ◽  
Microscopic Analysis ◽  
Ammonia Oxidizers ◽  
Electron Microscopic ◽  
Intracytoplasmic Membrane ◽  
Nitrogenous Compounds ◽  
Continuous Bioreactor ◽  
Ammonia Oxidizing Bacterium

AbstractAmmonia oxidation was considered impossible under highly acidic conditions, as the protonation of ammonia leads to decreased substrate availability and formation of toxic nitrogenous compounds. Recently, some studies described archaeal and bacterial ammonia oxidizers growing at pH as low as 4, while environmental studies observed nitrification at even lower pH values. In this work, we report on the discovery, cultivation, and physiological, genomic, and transcriptomic characterization of a novel gammaproteobacterial ammonia-oxidizing bacterium enriched via continuous bioreactor cultivation from an acidic air biofilter that was able to grow and oxidize ammonia at pH 2.5. This microorganism has a chemolithoautotrophic lifestyle, using ammonia as energy source. The observed growth rate on ammonia was 0.196 day−1, with a doubling time of 3.5 days. The strain also displayed ureolytic activity and cultivation with urea as ammonia source resulted in a growth rate of 0.104 day−1 and a doubling time of 6.7 days. A high ammonia affinity (Km(app) = 147 ± 14 nM) and high tolerance to toxic nitric oxide could represent an adaptation to acidic environments. Electron microscopic analysis showed coccoid cell morphology with a large amount of intracytoplasmic membrane stacks, typical of gammaproteobacterial ammonia oxidizers. Furthermore, genome and transcriptome analysis showed the presence and expression of diagnostic genes for nitrifiers (amoCAB, hao, nor, ure, cbbLS), but no nirK was identified. Phylogenetic analysis revealed that this strain belonged to a novel bacterial genus, for which we propose the name “Candidatus Nitrosacidococcus tergens” sp. RJ19.

scholarly journals Role of Cell Shape in Determination of the Division Plane in Schizosaccharomyces pombe: Random Orientation of Septa in Spherical Cells

2000 ◽  
Vol 182 (6) ◽  
pp. 1693-1701 ◽  
Author(s):  
M. Sipiczki ◽  
M. Yamaguchi ◽  
A. Grallert ◽  
K. Takeo ◽  
E. Zilahi ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mother Cell ◽  
Freeze Substitution ◽  
Longitudinal Axis ◽  
Electron Microscopic ◽  
Division Plane ◽  
Daughter Cells ◽  
Freeze Etching ◽  
Spherical Cells

ABSTRACT The establishment of growth polarity in Schizosaccharomyces pombe cells is a combined function of the cytoplasmic cytoskeleton and the shape of the cell wall inherited from the mother cell. The septum that divides the cylindrical cell into two siblings is formed midway between the growing poles and perpendicularly to the axis that connects them. Since the daughter cells also extend at their ends and form their septa at right angles to the longitudinal axis, their septal (division) planes lie parallel to those of the mother cell. To gain a better understanding of how this regularity is ensured, we investigated septation in spherical cells that do not inherit morphologically predetermined cell ends to establish poles for growth. We studied four mutants (defining four novel genes), over 95% of whose cells displayed a completely spherical morphology and a deficiency in mating and showed a random distribution of cytoplasmic microtubules, Tea1p, and F-actin, indicating that the cytoplasmic cytoskeleton was poorly polarized or apolar. Septum positioning was examined by visualizing septa and division scars by calcofluor staining and by the analysis of electron microscopic images. Freeze-substitution, freeze-etching, and scanning electron microscopy were used. We found that the elongated bipolar shape is not essential for the determination of a division plane that can separate the postmitotic nuclei. However, it seems to be necessary for the maintenance of the parallel orientation of septa over the generations. In the spherical cells, the division scars and septa usually lie at angles to each other on the cell surface. We hypothesize that the shape of the cell indirectly affects the positioning of the septum by directing the extension of the spindle.

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