Rod-shaped and spherical viruslike particles in cowpea rust fungus

1978 ◽  
Vol 56 (8) ◽  
pp. 963-975 ◽  
Author(s):  
John G. McDonald ◽  
Michèle C. Heath
Keyword(s):  
Phosphotungstic Acid ◽  
Rust Fungus ◽  
Ammonium Molybdate ◽  
Size Distributions ◽  
Wide Diameter ◽  
Thin Sectioning ◽  
Rigid Rod ◽  
Viruslike Particles ◽  
The Stability ◽  
Germ Tubes

Three types of rod-shaped viruslike particles (VLPs) (a short rigid rod (RR), 260 × 12 nm. a long narrow-diameter flexuous rod (NFR), 660 × 10 nm, and a long wide-diameter flexuous rod (WFR), 740 × 16 nm) and a spherical VLP (35 nm in diameter) were found in extracts of uredospores, germ tubes, and pustules of cowpea rust, negatively stained with ammonium molybdate. Both the size distributions and the stability of these VLPs was affected by the choice of stain since when phosphotungstic acid was used, two additional length classes of the RR (150 nm and 90 nm) were noted, and this stain tended to disassemble the WFR by unwinding the helix of this particle. The WFR also disassembled at pHs 4and5 in 10 mM acetate but only at pH 4 in the presence of 0.2 M NaCl. Examination of cowpea rust by thin sectioning revealed the presence of four types of VLPs. Morphologies of these particle types were consistent with the data obtained by negative staining.

The preparation and ultrastructure of avian erythrocyte nuclear envelope enclosed by the plasma membrane

1978 ◽  
Vol 34 (1) ◽  
pp. 81-90
Author(s):  
J.R. Harris
Keyword(s):  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Ammonium Molybdate ◽  
Negative Staining ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Thin Sectioning ◽  
Avian Erythrocyte ◽  
Pore Complexes ◽  
Low Ionic Strength

A procedure is described for the preparation of avian erythrocyte nuclear envelope ghosts which remain enclosed by the ellipsoid plasma membrane. Haemoglobin-free nucleated chicken erythrocyte ghosts are treated in a low ionic strength buffer plus heparin which brings about decondensation of the chromatin. This is followed by solubilization of the chromatin by digestion with pancreatic deoxyribonuclease-1. When studied by light microscopy using either phase-contrast or Nomarski interference optics, the ellipsoid plasma membrane is clearly seen to remain with the collapsed nuclear envelope trapped inside. This interpretation is supported by negative-staining electron microscopy using ammonium molybdate, which in addition reveals the presence of the nuclear pore complexes. The suggestion is advanced that structural protection is provided for the fragile nuclear envelope system by the surrounding plasma membrane, which might account for the final nuclear envelope being in the form of relatively intact ghosts with well defined nuclear pore complexes. The nuclear envelope is highly fragmented when the plasma membrane is absent, the nuclear pore complexes showing appreciable breakdown. Thin sectioning supports the results of negative staining and in addition shows the nuclear envelope retained within the plasma membrane to be composed of both inner and outer nuclear membranes, but the nuclear pore complexes are not clearly defined.

scholarly journals Experimental Investigation of Water Based Colloidal Gas Aphron Fluid Stability

2019 ◽  
Vol 3 (1) ◽  
pp. 31 ◽  
Author(s):  
Seyed Hosseini-Kaldozakh ◽  
Ehsan Khamehchi ◽  
Bahram Dabir ◽  
Ali Alizadeh ◽  
Zohreh Mansoori
Keyword(s):  
Xanthan Gum ◽  
Drilling Fluid ◽  
Sodium Dodecyl ◽  
Ammonium Bromide ◽  
Drilling Fluids ◽  
Size Distributions ◽  
Electrolyte System ◽  
Colloidal Gas Aphron ◽  
The Stability ◽  
Filtration Properties

Today, the drilling operators use the Colloidal Gas Aphron (CGA) fluids as a part of drilling fluids in their operations to reduce formation damages in low-pressure, mature or depleted reservoirs. In this paper, a Taguchi design of experiment (DOE) has been designed to analyse the effect of salinity, polymer and surfactant types and concentration on the stability of CGA fluids. Poly Anionic Cellulose (PacR) and Xanthan Gum (XG) polymers are employed as viscosifier; Hexadecyl Trimethyl Ammonium Bromide (HTAB) and Sodium Dodecyl Benzene Sulphonate (SDBS) have been also utilized as aphronizer. Moreover, bubble size distributions, rheological and filtration properties of aphronized fluids are investigated. According to the results, the polymer type has the highest effect, whereas the surfactant type has the lowest effect on the stability of CGA drilling fluid. It was also observed that increasing salinity in CGA fluid reduces the stability. Finally, it should be noted that the micro-bubbles generated with HTAB surfactant in an electrolyte system, are more stable than SDBS surfactant.

Biomechanical Evaluation of a Wide-Diameter Short Dental Implant for Use in Compromised Bone Quality Regions by Finite Element Method

2006 ◽  
Author(s):  
Hsuan-Yu Chou ◽  
Sinan Mu¨ftu¨ ◽  
Dinc¸er Bozkaya
Keyword(s):  
Finite Element ◽  
Dental Implant ◽  
Bone Quality ◽  
Biomechanical Properties ◽  
Good Alternative ◽  
Mandibular Canal ◽  
Success Rates ◽  
Wide Diameter ◽  
Clinical Scenarios ◽  
The Stability

The success rates of dental implant treatments in posterior mandible and maxilla could be compromised due to the increased masticatory forces and poor bone quality. In addition, the length of the implant is limited by maxillary sinus and mandibular canal in these regions. Wide-diameter short (WDS) implants provide a good alternative to increase the stability and the reliability of the implants in such conditions. The objective of this study is to evaluate the biomechanical properties of a wide implant by performing finite element analyses (FEA). Comparison of the strain distribution induced in the bone by a WDS implant and by a narrow-diameter long (NDL) implant, in clinical scenarios exhibiting different amounts of crestal bone, and under varying insertion depths demonstrated that WDS implant can be used safely and should perform as well as its NDL counterpart.

scholarly journals Transfer of label from 3H-glucose in Digitaria eriantha leaves to the rust fungus Puccinia digitariae Pole Evans.

1985 ◽  
Vol 33 (8) ◽  
pp. 809-812 ◽  
Author(s):  
M E Rey ◽  
H M Garnett
Keyword(s):  
Primary Infection ◽  
Secondary Infection ◽  
Rust Fungus ◽  
Infection Process ◽  
Bremia Lactucae ◽  
Infection Structures ◽  
Obligate Parasites ◽  
Digitaria Eriantha ◽  
Germ Tubes

Digitaria eriantha pentzii was fed 3H-glucose prior to inoculation with uredospores of Puccinia digitariae Pole Evans. Twenty-one hours after inoculation, uptake of label from 3H-glucose by the primary infection structures of P. digitariae was demonstrated employing autoradiography. These results indicate that an exchange of nutrients between host and pathogen occurs very early on in the infection process, during the formation of the primary infection structures. Despite contrary reports that obligate parasites receive no nutrition before establishment of haustoria, this study supports the work of Andrews (Can J Bot 53:1103, 1975), who demonstrated uptake of 3H-glucose label from lettuce cotyledons into the primary and secondary infection vesicles, appressoria, and germ tubes of Bremia lactucae.

Visualization, adhesiveness, and cytochemistry of the extracellular matrix produced by urediniospore germ tubes of Puccinia sorghi

1991 ◽  
Vol 69 (9) ◽  
pp. 2044-2054 ◽  
Author(s):  
Rajendra Chaubal ◽  
V. A. Wilmot ◽  
Willard K. Wynn
Keyword(s):  
Electron Microscopy ◽  
Extracellular Matrix ◽  
Rust Fungus ◽  
Cetylpyridinium Chloride ◽  
Freeze Substitution ◽  
Ruthenium Red ◽  
Puccinia Sorghi ◽  
Temperature Scanning ◽  
Germ Tubes ◽  
Scanning Electron

Adherence of germinating urediniospores of the common maize rust fungus (Puccinia sorghi Schw.) to substrata was studied by ultrastructural and cytochemical examination of extracellular matrix produced by germ tubes in conjunction with measurements of adhesion to plastic and glass surfaces. Copious amounts of extracellular matrix on germ tubes could consistently be visualized by scanning and transmission electron microscopy only when (i) a cationic detergent (cetylpyridinium chloride, polydiallyldimethylammonium chloride) or a cationic stain (ruthenium red, alcian blue, cuprolinic blue) was added to the fixation solutions, (ii) germ tubes were fixed by rapid-freezing and freeze-substitution and observed with a scanning electron microscope, or when (iii) germ tubes were observed in a frozen-hydrated state by low-temperature scanning electron microscopy. Incubation of germinated spores with dilute alkalies (NaOH, KOH), pronase E (nonspecific protease), and laminarinase (β-1,3 (1,3; 1,4-glucanase) removed the extracellular matrix and detached germ tubes from surfaces. Treatments with water, dilute acids, ionic and neutral detergents, organic solvents, hydrocarbons, and several polysaccharide-degrading enzymes did not remove the extracellular matrix and also did not detach germ tubes. These results, together with staining patterns obtained with lectins and other polysaccharide-specific reagents, indicate that the extracellular matrix is composed mainly of glycoproteins rich in acidic amino acids and β-1,3-glucan polymers, and that it is probably responsible for the adhesion of the rust germ tubes to the host leaf surfaces. Key words: Puccinia sorghi, germ tube adhesion, extracellular matrix, cytochemistry.

scholarly journals Fusion Body Formation, Germ Tube Anastomosis, and Nuclear Migration During the Germination of Urediniospores of the Wheat Leaf Rust Fungus, Puccinia triticina

2009 ◽  
Vol 99 (12) ◽  
pp. 1355-1364 ◽  
Author(s):  
Xiben Wang ◽  
Brent McCallum
Keyword(s):  
Leaf Rust ◽  
Germ Tube ◽  
Rust Fungus ◽  
Puccinia Triticina ◽  
Rust Fungi ◽  
Wheat Leaf Rust ◽  
Virulence Phenotype ◽  
Close Proximity ◽  
Wheat Leaf ◽  
Germ Tubes

Vegetative or parasexual recombination is thought to be a key mechanism for the genetic diversity of cereal rust fungi. The process of germ tube fusion leading to hyphal anastomosis and nuclear recombination was analyzed in wheat leaf rust fungus, Puccinia triticina. Germ tube anastomosis was observed in 27 P. triticina isolates, each representing a different virulence phenotype. Germ tube fusion bodies (GFBs), which appeared as viscid globules formed at tips of germ tubes, were essential for germ tube anastomosis. The formation of GFBs was affected by the urediniospore density and the length of illumination during germination. GFBs were formed at the highest frequency when urediniospores were spread to a concentration of 1 × 106 urediniospores/ml and incubated in dark for 12 to 24 h during germination. GFB attached to either the side of another germ tube (“tip to side”) or to another GFB formed at the tip of a second germ tube (“tip to tip”). In “tip to side” anastomosis, two nuclei in the germ tube bearing the GFB migrated into the second germ tube through the GFB which resulted in four nuclei within this germ tube. In “tip to tip” anastomosis, nuclei in both germ tubes migrated into the fused GFB and all four nuclei came into close proximity. Urediniospores of isolates MBDS-3-115 and TBBJ-5-11 were stained with DAPI (4′,6′diamine-2-phenylindole) and Nuclear Yellow (Hoechst S769121), respectively, and then mixed and germinated on water agar. Some fused GFBs contained nuclei stained with DAPI and nuclei stained with Nuclear Yellow in close proximity, demonstrating the fusion between genetically different P. triticina isolates. In some fused GFBs, “bridge-like” structures connecting different nuclei were observed.

scholarly journals Hybrid Vesicle Stability under Sterilisation and Preservation Processes Used in the Manufacture of Medicinal Formulations

2020 ◽  
Author(s):  
Rashmi Seneviratne ◽  
Lars J.C. Jeuken ◽  
Michael Rappolt ◽  
Paul A. Beales
Keyword(s):  
Block Copolymer ◽  
Colloidal Stability ◽  
Size Distributions ◽  
Process Stability ◽  
Vesicle Size ◽  
Industry Applications ◽  
Poly Ethylene ◽  
The Stability ◽  
Future Work ◽  
Vesicle Stability

Sterilisation and preservation of vesicle formulations are an important consideration for their viable manufacture for industry applications, particular those intended for medicinal use. Here we undertake an initial investigation of the stability of hybrid lipid – block copolymer vesicles to common sterilisation and preservation processes, with particular interest in how the block copolymer component might tune vesicle stability. We investigate two sizes of polybutadiene-block-poly(ethylene oxide) polymers (PBd12-PEO11 and PBd22-PEO14) mixed with the phospholipid POPC considering the encapsulation stability of a fluorescent cargo and the colloidal stability of vesicle size distributions. We find that autoclaving and lyophilisation cause complete loss of encapsulation stability under the conditions studied here. Filtering through 200 nm pores appears to be viable for sterilisation for all vesicle compositions with comparatively low release of encapsulated cargo, even for vesicle size distributions which extend beyond the 200 nm filter pore size. Freeze-thaw of vesicles also shows promise for preservation of hybrid vesicles with high block copolymer content. We discuss the process stability of hybrid vesicles in terms of the complex mechanical interplay between bending resistance, stretching elasticity and lysis strain of these membranes and propose strategies for future work to further enhance the process stability of these vesicle formulations.

scholarly journals STABILITY OF MICROSPHERE OF SARGASSUM PLAGYOPHYLLUM (MERTENS) J. G. AGARDH EXTRACT PRODUCED BY SPRAY DRYING USING MALTODEXTRIN

2018 ◽  
Vol 10 (1) ◽  
pp. 376
Author(s):  
Effionora Anwar ◽  
Dyah Ayu Ratna Yulianti ◽  
Kurnia Sari Setio Putri
Keyword(s):  
Antioxidant Activity ◽  
Spray Drying ◽  
Brown Seaweed ◽  
Inlet Temperature ◽  
Aqueous Extracts ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Coating Agent ◽  
Polyphenol Compounds ◽  
The Stability

Objective: This study aimed to determine the stability of microspheres of Sargassum plagyophyllum (brown seaweed) after preparation using spraydrying with maltodextrin DE 10–15 and during drying and storage.Methods: Aqueous extracts of brown seaweed were formulated into microspheres using maltodextrin DE 10–15 as a coating agent. For increasing thestability of polyphenol compounds, spray drying was performed with an inlet temperature of 110°C. Four microsphere formulations were producedusing maltodextrin DE 10–15 at concentrations of 0%, 5%, 10%, and 15%. The resulting microspheres were then characterized in the assessments ofmoisture contents, particle size distributions, pH, total phlorotannin contents, and antioxidant activity, and surface morphology was analyzed usingscanning electron microscope analyses.Results: Powders that were produced with 0% and 15% maltodextrin were more stable at 4°C±2°C than at 28°C±2°C and 40°C±2°C. At the lowesttemperature, phlorotannin contents were maintained in powders that were prepared with 15% maltodextrin but were decreased by 10% in powdersthat were prepared without maltodextrin.Conclusion: Maltodextrin DE 10–15 is a suitable coating agent for dry formulations of S. plagyophyllum powder and maintained stability during spraydrying at 110°C and during storage for 2 months at 4°C±2°C.

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