Ultrastructural Characterization of 18-24 Hr. Neurospora Crassa Hyphae by Freeze-Fracture Techniques

1977 ◽  
Vol 35 ◽  
pp. 604-605
Author(s):  
K. S. Howard ◽  
M. D. Socolofsky ◽  
H. D. Braymer ◽  
P. R. Clisham
Keyword(s):  
Neurospora Crassa ◽  
Phosphate Buffer ◽  
Original Work ◽  
Freeze Fracture ◽  
Glutaraldehyde Fixation ◽  
Thin Sections ◽  
Section Technique ◽  
Ultrastructural Characterization

The ultrastructure of Neurospora crassa hyphae has been characterized primarily by the thin section technique. Since the original work of Shatkin and Tatum1, however, the quality of thin sections has been hindered by difficulty in fixing, embedding, and staining. A recent study of N. crassa ascospores compared the ultrastructure as revealed by freeze-etch to that revealed by thin sections, demonstrating the utility of the freeze-etch method when applied to organisms that have been difficult to prepare for EM observation2. The present study applies freeze-fracture to II. crassa in an attempt to confirm and increase the ultrastructural information presently available.Neurospora crassa strains 73a and 74A were grown in Vogel's minimal citrate medium for 18 to 24 hours. The resultant hyphae were treated with 3% glutaraldehyde in 0.1 M phosphate buffer for 2 hours followed by immersion in 30% glycerol for 1 hour or transferred directly to 30% glycerol from growth medium without glutaraldehyde fixation.

scholarly journals Isolation and ultrastructural characterization of secretory mutants of Tetrahymena thermophila

1983 ◽  
Vol 64 (1) ◽  
pp. 49-67 ◽  
Author(s):  
E. Orias ◽  
M. Flacks ◽  
B.H. Satir
Keyword(s):  
Electron Microscopy ◽  
Tetrahymena Thermophila ◽  
Freeze Fracture ◽  
Regulatory Mechanisms ◽  
Genetic Dissection ◽  
Intramembrane Particle ◽  
Particle Array ◽  
Normal Number ◽  
Ultrastructural Characterization

Isolation of 14-secretory mutants (exo-) of Tetrahymena thermophila and ultrastructural characterization (freeze-fracture and thin-section) of two of these (SB255 and SB258) are described. The site of secretion is marked by an intramembrane particle array, the rosette, beneath which the secretory organelle rests. Using Alcian Blue (8GS) as a secretagogue, a screening procedure for exo- cells was developed. Of the resulting 14 clones isolated, 10 are stable and have a tight mutant phenotype. Two of these, SB255 and SB258, lack assembled rosettes. Electron microscopy shows that SB255 has a reduced total number of mucocysts, whereas SB258 appears to have the normal number. This study demonstrates a useful eukaryotic model with which to study by genetic dissection the regulatory mechanisms involved in membrane events in secretion.

scholarly journals Histochemical and ultrastructural characterization of serotonin-containing cells in rabbit tracheal epithelium.

1983 ◽  
Vol 31 (4) ◽  
pp. 501-508 ◽  
Author(s):  
R D Dey ◽  
W A Shannon ◽  
H K Hagler ◽  
S I Said
Keyword(s):  
Endocrine Cells ◽  
Tracheal Epithelium ◽  
Separate Experiment ◽  
Staining Reaction ◽  
Cell Type ◽  
Thin Sections ◽  
X Ray ◽  
Ultrastructural Characterization ◽  
A Cell

Tracheal endocrine cells (TECs) that contain serotonin have been characterized previously by staining with ferric ferricyanide. In the present article, the ferric ferricyanide staining reaction has been used to locate the TECs in deplasticized thick sections of Epon-embedded rabbit tracheas. Adjacent thin sections of the same cell were subsequently observed by electron microscopy. The TECs were filled with dense-core vesicles (DCVs) located in the cytoplasm between the nucleus and the lumen and also lateral to the nucleus. In a separate experiment, pieces of rabbit trachea were treated with a solution of glutaraldehyde-dichromate to demonstrate the presence of amines. High levels of chromium were detected in the DCVs by energy-dispersive X-ray analysis. The results from these studies have correlated the ultrastructure of a serotonin-containing endocrine cell present in rabbit tracheal epithelium with a cell type previously characterized only by light and fluorescence histochemical methods. The results also indicate that serotonin in these cells is stored in the DCVs.

scholarly journals Lithological models of reservoir rocks for upper cretaceous deposits in East Caucasian Region

Georesursy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 83-89
Author(s):  
Оlga V. Sivalneva ◽  
Aysylu S. Rakhmatullina ◽  
Аlexander V. Postnikov ◽  
Olga V. Postnikova ◽  
Оlga А. Zueva ◽  
...  
Keyword(s):  
Upper Cretaceous ◽  
Thin Sections ◽  
Reservoir Rocks ◽  
Depositional Settings ◽  
Fracture Intensity ◽  
Main Factors ◽  
Late Diagenesis ◽  
Cretaceous Deposits

The article describes the results of lithological and petrophysical investigations that would be a base for characterization of reservoir rocks in Upper Cretaceous deposits. These investigations include thin sections description, SEM and NMR analysis. As found that three main factors have constrained final quality of reservoir rocks: 1) depositional settings favorable for coccoliths and chalk sedimentation; 2) late diagenesis changes – compaction and recrystallization degree; 3) fracture intensity.

scholarly journals FACTORS INFLUENCING THE FREQUENCY OF MESOSOMES OBSERVED IN FIXED AND UNFIXED CELLS OF STREPTOCOCCUS FAECALIS

1974 ◽  
Vol 61 (2) ◽  
pp. 288-300 ◽  
Author(s):  
Michael L. Higgins ◽  
Lolita Daneo-Moore
Keyword(s):  
Osmium Tetroxide ◽  
Freeze Fracture ◽  
Culture Collection ◽  
Chemical Fixation ◽  
Macromolecular Synthesis ◽  
Glutaraldehyde Fixation ◽  
Streptococcus Faecalis ◽  
Thin Sections ◽  
Factors Influencing ◽  
Rna And Protein Synthesis

Mesosomes of Streptococcus faecalis (American Type Culture Collection 9790) were seen about 92% less frequently in freeze fractures of unfixed cells than in freeze fractures and sections of fixed cells. This difference in frequency was not related to any period of unbalanced macromolecular synthesis induced by chemical fixation. All measured synthetic processes (DNA, RNA, and protein synthesis, and glycerol incorporation) were halted with either osmium tetroxide (OS) or glutaraldehyde fixation. That fewer mesosomes were seen in freeze fractures of unfixed cells was probably due to the difficulty of observing cross-fractured mesosomes in this organism in the unfixed state. Unfortunately, mesosomes probably preferentially cross fracture in the unfixed state and therefore are usually only observed, infrequently, in those cases where the freeze fracture follows the surface layer of a mesosomal membrane. However, the addition of glycerol to unfixed cells, especially in the chilled state, greatly increased the frequency of observation of cytoplasmic mesosomes in freeze fractures. It is thought that glycerol, like chemical fixation, increases the number of surface-fractured mesosomes, which in turn increases the frequency of mesosome observation. It was also observed that cellular autolysis occurring during OS fixation seemingly reduced the number of mesosomes observed in thin sections and freeze fractures of OS-fixed cells.

scholarly journals Structural and ultrastructural characterization of the floral lip in Gongora bufonia (Orchidaceae): understanding the slip-and-fall pollination mechanism

Botany ◽  
2015 ◽  
Vol 93 (11) ◽  
pp. 759-768 ◽  
Author(s):  
Sérgio Akira Adachi ◽  
Silvia Rodrigues Machado ◽  
Elza Guimarães
Keyword(s):  
Tropical Forest ◽  
Epidermal Cells ◽  
Field Observations ◽  
Pollination Mechanism ◽  
Rear Edge ◽  
Ultrastructural Characterization ◽  
Wax Deposits ◽  
Wax Production

In this study, we investigated the pollination ecology and floral lip morphology of Gongora bufonia Lindl., an epiphytic orchid from tropical forest, to better understand the peculiarities of its unusual pollination mechanism. Field observations on pollination were performed and floral lip samples were prepared for anatomical, histochemical, and ultrastructural analyses. Male Eufriesea violacea (Blanchard) bees use the second and third pairs of legs to hold on the epichile and collect the fragrance in the hypochile region. During this process, the bee slips and falls on the column and receives the pollinarium, which is attached to the rear edge of the bee’s scutellum. A subsequent visit (usually to another flower) and fall through the flower may result in insertion of a pollinium into the stigmatic slit at the apex of the column. The fragrance production occurs in the hypochile region, specifically in the papillose epidermal cells and in the subepidermal parenchyma layers. The wax production occurs in the epichile region, exclusively in the epidermal cells. The cells of both regions, hypochile and epichile, have ultrastructural features of lipophilic secretion. The slippery quality of the epichile epidermis is due to wax deposits; this is probably essential to the pollination mechanism of G. bufonia.

Freeze-fracture, freeze-etch complementary pairs of virus-infected cells reveal value of etching even when relatively high concentrations of cryoprotectants are used

1978 ◽  
Vol 36 (2) ◽  
pp. 136-137
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe
Keyword(s):  
Plant Tissue ◽  
Phosphate Buffer ◽  
Infected Plant ◽  
Freeze Fracture ◽  
Distilled Water ◽  
Virus Infected Plant ◽  
Infected Cells ◽  
High Concentrations

It has been assumed by many involved in freeze-etch or freeze-fracture studies that it would be useless to etch specimens which were cryoprotected by more than 15% glycerol. We presumed that the amount of cryoprotective material exposed at the surface would serve as a contaminating layer and prevent the visualization of fine details. Recent unexpected freeze-etch results indicated that it would be useful to compare complementary replicas in which one-half of the frozen-fractured specimen would be shadowed and replicated immediately after fracturing whereas the complement would be etched at -98°C for 1 to 10 minutes before being shadowed and replicated.Standard complementary replica holders (Steere, 1973) with hinges removed were used for this study. Specimens consisting of unfixed virus-infected plant tissue infiltrated with 0.05 M phosphate buffer or distilled water were used without cryoprotectant. Some were permitted to settle through gradients to the desired concentrations of different cryoprotectants.

Visualization of Antibody Transport in Rat Visceral Yolk-Sac Placenta

1982 ◽  
Vol 40 ◽  
pp. 246-247
Author(s):  
William P. Jollie
Keyword(s):  
Phosphate Buffer ◽  
Yolk Sac ◽  
Female Rats ◽  
Thin Sections ◽  
Visceral Yolk Sac ◽  
Antibody Complex ◽  
Cytochemical Reaction ◽  
Hind Foot ◽  
Antigen Antibody ◽  
Yolk Sac Placenta

A technique has been developed for visualizing antibody against horseradish peroxidase (HRP) in rat visceral yolk sac, the placental membrane across which passive immunity previously has been shown to be transferred from mother to young just prior to birth. Female rats were immunized by injecting both hind foot pads with 1 mg HRP emulsified in complete Freund's adjuvant. They were given a booster of 0.5mg HRP in 0.1 ml normal saline i.v. after one week, then bred and autopsied at selected stages of pregnancy, viz., 12, 1 7 and 22 days post coitum, receiving a second booster, injected as above, five days before autopsy. Yolk sacs were removed surgically and fixed immediately in 2% paraformaldehye, 1% glutaraldehye in 0.1 M phosphate buffer with 0.01% CaCl2 at pH 7.4, room temperature, for 3 hr, rinsed 3X in 0.1 M phosphate buffer plus 5% sucrose, then exposed to 1 mg HRP in 1 ml 0.1 M phosphate buffer at pH 7.4 for 1 hr. They were refixed in aldehydes, as above, for 1 5 min (to assure binding of antigen-antibody complex). Following buffer washes, the tissues were incubated in 3 mg diaminobenzidine tetrahydrochloride and 0.01% H2O2 in 0.05 M Tris-HCl buffer for 30 min. After brief buffer washes, they were postfixed in 2% OsO4. in phosphate buffer at pH 7.4, 4°C for 2 hr, dehydrated through a graded series of ethanols, and embedded in Durcupan. Thin sections were observed and photographed without contrast-enhancement with heavy metals. Cytochemical reaction product marked the site of HRP (i.e., antigen) which, in turn, was present only where it was bound with anti-HRP antibody.

The Immuno-Electron Microscopic Localization of the Mo-Fe Protein Component of Nitrogenase in Cells of Azotobacter Vinelandii

1973 ◽  
Vol 31 ◽  
pp. 574-575
Author(s):  
J. T. Stasny ◽  
R. C. Burns ◽  
R. W. F. Hardy
Keyword(s):  
Cellular Localization ◽  
Direct Evidence ◽  
Azotobacter Vinelandii ◽  
Intracellular Localization ◽  
Protein Component ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Fe Protein ◽  
Intracytoplasmic Membranes

Structure-functlon studies of biological N2-fixation have correlated the presence of the enzyme nitrogenase with increased numbers of intracytoplasmic membranes in Azotobacter. However no direct evidence has been provided for the internal cellular localization of any nitrogenase. Recent advances concerned with the crystallizatiorTand the electron microscopic characterization of the Mo-Fe protein component of Azotobacter nitrogenase, prompted the use of this purified protein to obtain antibodies (Ab) to be conjugated to electron dense markers for the intracellular localization of the protein by electron microscopy. The present study describes the use of ferritin conjugated to goat antitMo-Fe protein immunoglobulin (IgG) and the observations following its topical application to thin sections of N2-grown Azotobacter.

Sign in / Sign up

Export Citation Format

Share Document