Methods for preparation of cribellate spider silk fibrils for Transmission Electron Microscopy

1995 ◽  
Vol 53 ◽  
pp. 1076-1077
Author(s):  
B. Cutler
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Osmium Tetroxide ◽  
Spider Silk ◽  
Significant Component ◽  
Fixation Methods ◽  
Transmission Electron ◽  
Sputter Coating ◽  
Formaldehyde Exposure

Spider silk has been examined by transmission electron microscopy (TEM) for over 50 years. A later, more detailed study produced higher resolution images and included a discussion of fixation with osmium tetroxide (OSO4) vapor. The fixation resulted in only minor effects compared to unfixed specimens. Cribellate spiders produce a nonviscous adhesive silk that has as a significant component very fine fibrils produced by a structure called a cribellum. An opportunity to study cribellate silk in a spider family not previously investigated also led to a study of different fixation methods. Immature specimens of Titanoeca nigrella (Chamberlin) (Araneae, Titanoecidae) were collected under rocks at the Cimarron National Grasslands, Morton Co., Kansas. Spiders were kept in the laboratory and spun normal appearing webs. Copper and gold (for OSO4 treatments) 200 m grids were dragged through the webs. All combinations of treatments were used, but formaldehyde exposure always preceded OSO4 exposure which preceded sputter coating. Grids were examined with a JEOL 1200 EXII TEM. An accelerating voltage of 60kv and 100 um objective aperture were used for imaging.

Transmission Electron Microscopy of Lipid Vesicles for Drug Delivery: Comparison between Positive and Negative Staining

2010 ◽  
Vol 16 (4) ◽  
pp. 456-461 ◽  
Author(s):  
Valentina Bello ◽  
Giovanni Mattei ◽  
Paolo Mazzoldi ◽  
Nicoletta Vivenza ◽  
Paolo Gasco ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Drug Delivery ◽  
Transmission Electron Microscopy ◽  
Iron Oxide ◽  
Osmium Tetroxide ◽  
Lipid Vesicles ◽  
Negative Staining ◽  
Transmission Electron ◽  
Compositional Characterization

AbstractLipid-containing nanostructures, in the form of solid lipid nanoparticles or iron oxide nanoparticles (NPs) coated with a lipid shell, were used as case studies for assessing and optimizing staining for transmission electron microscopy structural and compositional characterization. These systems are of paramount importance as drug delivery systems or as bio-compatible contrast agents. In particular, we have treated the systems with a negative (phospshotungstic acid) or with a positive (osmium tetroxide) staining agent. For iron-oxide NPs coated with the lipid shell, negative staining was more efficient with respect to the positive one. Nevertheless, in particular cases the combination of the two staining procedures provided more complete morphological and compositional characterization of the particles.

scholarly journals Improved contrast in cytochemistry of dehydrogenases by scanning transmission electron microscopy.

1981 ◽  
Vol 29 (5) ◽  
pp. 678-681 ◽  
Author(s):  
W Deimann ◽  
R Freeman ◽  
H D Fahimi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Osmium Tetroxide ◽  
Lactic Dehydrogenase ◽  
Scanning Transmission Electron Microscope ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Tissue Contrast ◽  
Stem Image

A scanning transmission electron microscope (STEM) was used to examine ultrathin sections of rabbit white skeletal muscle. Lactic dehydrogenase (LDH) activity was localized in the tissue using the tetra-nitro blue tetrazolium (TNBT) method. For most specimens postfixation was omitted in order to avoid reoxidation and solubilization of the formazan by osmium tetroxide. The STEM image revealed sufficient contrast of the intracellular structures and apparently electron-dense reaction product in the sarcoplasmic reticulum and mitochondria. Substantially less contrast was obtained when the same areas were observed by conventional transmission electron microscopy (CTEM). In material postfixed with osmium tetroxide, although the tissue contrast was improved, the TNBT reaction product was focally leached out, exhibiting lower contrast than in unosmicated sections. These results indicate that the fine structural visualization of dehydrogenases with TNBT, the STEM technique as used in the present study is superior to that obtained by CTEM.

Ultrastructure features of the tertiary envelope in the cyst of the brine shrimp Artemia franciscana (Anostraca)

1994 ◽  
Vol 52 ◽  
pp. 362-363
Author(s):  
Kit W. Lee ◽  
Mark A. Gouthro ◽  
Denton Belk ◽  
James R. Rosowski
Keyword(s):  
Electron Microscopy ◽  
Critical Point ◽  
Brine Shrimp ◽  
Osmium Tetroxide ◽  
Larval Food ◽  
Biochemical Processes ◽  
Transmission Electron ◽  
Sputter Coating ◽  
Experimental Organism ◽  
Ethanol Series

The brine shrimp is an important experimental organism in developmental biology and a key larval food in aquaculture. Morris and Afzelius established the basic ultrastructure of cyst and embryo membranes of Artemia and a subsequent report provided some additional features. A better understanding of the cyst shell structure and composition are prerequisites to elucidating the physical and biochemical processes of the hatching events. In the present study, scanning and transmission electron microscopy were used to visualize the internal features of the maternally produced pigmented tertiary envelope (TE) of the hatched brine shrimp cyst shell. This combined SEM and TEM approach revealed several previously unrecognized features.Utah biotype cysts, from Sanders Brine Shrimp Company Inc., Ogden, Utah, U.S.A., were hatched over 24 hrs in saltwater. Hydrated cysts were fixed in 3% glutaraldehyde, post-fixed in 1% osmium tetroxide, dehydrated in an ethanol series, and critical-point dried or embedded in Epon. In some cases, the critical-point dried cyst shell was fractured before sputter-coating with gold/palladium for SEM.

Sample preparation utilizing sputter coating increases contrast of cellulose nanocrystals in the transmission electron microscope

Microscopy ◽  
2019 ◽  
Author(s):  
Marina R Mulenos ◽  
Bernd Zechmann ◽  
Christie M Sayes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cellulose Nanocrystals ◽  
Particle Aggregation ◽  
Crystalline Cellulose ◽  
Metal Atoms ◽  
Transmission Electron ◽  
Final Layer ◽  
Sputter Coating ◽  
Cellulose Materials

Abstract Cellulose nanocrystals (CNCs) are prepared for transmission electron microscopy (TEM) using positive or negative stains in an effort to increase the contrast between the specimen and background. When imaging CNCs, conventional stains have been shown to induce particle aggregation and produce artifacts. In this study, we report on methods used to image CNCs. To increase contrast and decrease artifacts and aggregation, sputter coating was used to coat the samples. CNCs were loaded onto copper grids and sputter coated with one of four different metals: iridium, carbon, gold, and titanium. The final layer was deposited at 5 nm to ensure surface homogeneity. The thin layer of conductive metal atoms deposited onto the specimen surface significantly increased contrast and improved image quality. The results presented here demonstrate the advantages of using sputter coating for imaging of highly crystalline cellulose materials with TEM.

The role of endoplasmic reticulum during gametogenesis in the aquatic fungus Allomyces macrogynus

1991 ◽  
Vol 69 (2) ◽  
pp. 336-341 ◽  
Author(s):  
Tommy C. Sewall ◽  
Jeffrey C. Pommerville
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Osmium Tetroxide ◽  
Cleavage Furrow ◽  
Aquatic Fungus ◽  
Transmission Electron ◽  
Allomyces Macrogynus ◽  
Zinc Iodide

The Chytridiomycete Allomyces macrogynus generates new membranes for cleavage furrow and nuclear-cap formation during gametogenesis and zoosporogenesis. Transmission electron microscopy after impregnation with a mixture of zinc iodide and osmium tetroxide clearly demonstrated changes in the endoplasmic reticulum. Endoplasmic reticulum was intensely stained but did not appear to contribute to the formation of the unstained flagellar membranes or cleavage furrows. However, the relative cytoplasmic volume of endoplasmic reticulum decreased as positively stained nuclear-cap membrane formed. These observations are consistent with the hypothesis that flagellar membranes and cleavage furrows are derived from trans-Golgi equivalents, whereas the nuclear-cap membrane is derived from the endoplasmic reticulum. Key words: Allomyces macrogynus, Chytridiomycetes, endoplasmic reticulum, gametogenesis, zoosporogenesis.

Scanning and Transmission Electron Microscopy of Isolated Cells of Hydra littoralis

1972 ◽  
Vol 30 ◽  
pp. 160-161 ◽  
Author(s):  
Jane A. Westfall ◽  
Paul D. Enos
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Osmium Tetroxide ◽  
Culture Medium ◽  
Sensory Cells ◽  
Isolated Cells ◽  
Sem And Tem ◽  
Transmission Electron ◽  
Cacodylate Buffer ◽  
Calcium And Magnesium Ions

Using scanning and transmission electron microscopy (SEM and TEM), we observed batteries of 20-30 nematocytes, cnidoblasts, sensory cells, and other neurons invaginated within epitheliomuscular cells of Hydra. In an attempt to determine how the cells were structurally interrelated, we isolated cells of Hydra littoralis for further study by SEM and TEM.To isolate cells, 30 Hydra littoralis were placed for 30 minutes in a P19 culture medium modified by omitting calcium and magnesium ions, adding 20% sucrose and stabilizing at pH 7.2 with sodium phosphate, then pipetted gently to free the epithelial cells from the mesoglea. Glutaraldehyde was added to make a 5% solution and the cells were fixed 1 hour at 0-4°C, centrifuged 10 minutes at 1000 X g, resuspended in cacodylate buffer twice, and placed 2 hours in 4% osmium tetroxide at 0-4°C.

Concurrent Annealing Of Vacancy-Type And Interstitial-Type Damage In Neutron Irradiated Stainless Steel

2000 ◽  
Vol 650 ◽  
Author(s):  
E. P. Simonen ◽  
D. J. Edwards ◽  
S. M. Bruemmer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Microstructural Characterization ◽  
Size Distributions ◽  
Significant Component ◽  
Frank Loop ◽  
Transmission Electron ◽  
Model Predictions

ABSTRACTAnalysis of the effect of annealing on change in void and loop size distributions provided insights that complement microstructural characterization using transmission electron microscopy (TEM). The predictions of concurrent vacancy-type and interstitial-type damage annealing are applied to measurements in neutron-irradiated austenitic stainless steels. Irradiation at 330°C produces void and loop microstructures for which the measured annealing response is in accord with predictions. Irradiation at 275° produces only Frank loop microstructure for which the annealing response cannot be predicted from measured microstructures. The model predictions are based on an assumed vacancy source not detected using TEM. The measured loop microstructure is typically reported to be interstitial in character but this analysis suggests that a significant component of the loop population is vacancy-type damage based on defect inventory and kinetic arguments.

Ultrastructural & image analysis of mitochondrial changes in myocardium of copper-deficient rats administered a toxic dose of cocaine

1989 ◽  
Vol 47 ◽  
pp. 1094-1095
Author(s):  
U. Bielenberg ◽  
W. Burns ◽  
J.C. Smith
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Image Analysis ◽  
Single Dose ◽  
Osmium Tetroxide ◽  
Heart Tissue ◽  
Giant Mitochondria ◽  
Toxic Dose ◽  
Apparent Increase ◽  
Transmission Electron

We examined the effects of a single dose of cocaine (Coc) on the myocardium of rats fed copper sufficient (CuS) compared to copper deficient (CuD) diets. Weanling males were fed either CuS (n=13) or CuD (n=12) for 7 weeks. Ten in each group, (paired for Cu status), were injected (ip) with Coc-HCL (80-90mg/kg bw), 5 served as controlsRats which survived for 15 minutes were killed and heart tissue was obtained for light and transmission electron microscopy as well as Cu analysis. Tissue for ultrastruetural study was fixed in Carson’s fixative and post fixed in osmium tetroxide.Myocardial foci showed necrosis, fibrosis, and inflammation in all rats given cocaine but were more severe in the CuD group. CuS controls (no Coc) showed no similar lesions. Ultrastructurally the myocardium confirmed the light microscopy findings and showed apparent increase in the number of mitochondria which were of variable sizes and shapes. Giant mitochondria, clumping and foci of molding were observed. Crystalline configurations of cristae were also seen.

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