scholarly journals The Bacteriophage Pf-10—A Component of the Biopesticide “Multiphage” Used to Control Agricultural Crop Diseases Caused by Pseudomonas syringae

Viruses ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 42
Author(s):  
Olesya A. Kazantseva ◽  
Rustam M. Buzikov ◽  
Tatsiana A. Pilipchuk ◽  
Leonid N. Valentovich ◽  
Andrey N. Kazantsev ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Gc Content ◽  
Microscopic Analysis ◽  
Plant Diseases ◽  
Host Cells ◽  
Agricultural Crop ◽  
Electron Microscopic ◽  
Bacterial Diseases ◽  
Dsdna Molecule ◽  
Wide Range

Phytopathogenic pseudomonads are widespread in the world and cause a wide range of plant diseases. In this work, we describe the Pseudomonas phage Pf-10, which is a part of the biopesticide “Multiphage” used for bacterial diseases of agricultural crops caused by Pseudomonas syringae. The Pf-10 chromosome is a dsDNA molecule with two direct terminal repeats (DTRs). The phage genomic DNA is 39,424 bp long with a GC-content of 56.5%. The Pf-10 phage uses a packaging mechanism based on T7-like short DTRs, and the length of each terminal repeat is 257 bp. Electron microscopic analysis has shown that phage Pf-10 has the podovirus morphotype. Phage Pf-10 is highly stable at pH values from 5 to 10 and temperatures from 4 to 60 °C and has a lytic activity against Pseudomonas strains. Phage Pf-10 is characterized by fast adsorption rate (80% of virions attach to the host cells in 10 min), but has a relatively small number of progeny (37 ± 8.5 phage particles per infected cell). According to the phylogenetic analysis, phage Pf-10 can be classified as a new phage species belonging to the genus Pifdecavirus, subfamily Studiervirinae, family Autographiviridae, order Caudovirales.

scholarly journals Unusual Kinetic and Structural Properties Control Rapid Assembly and Turnover of Actin in the Parasite Toxoplasma gondii

2006 ◽  
Vol 17 (2) ◽  
pp. 895-906 ◽  
Author(s):  
Nivedita Sahoo ◽  
Wandy Beatty ◽  
John Heuser ◽  
David Sept ◽  
L. David Sibley
Keyword(s):  
Critical Concentration ◽  
Microscopic Analysis ◽  
Protozoan Parasite ◽  
Gliding Motility ◽  
Host Cells ◽  
Filamentous Actin ◽  
Unusual Behavior ◽  
Electron Microscopic ◽  
Unusual Form ◽  
Kinetics Of

Toxoplasma is a protozoan parasite in the phylum Apicomplexa, which contains a number of medically important parasites that rely on a highly unusual form of motility termed gliding to actively penetrate their host cells. Parasite actin filaments regulate gliding motility, yet paradoxically filamentous actin is rarely detected in these parasites. To investigate the kinetics of this unusual parasite actin, we expressed TgACT1 in baculovirus and purified it to homogeneity. Biochemical analysis showed that Toxoplasma actin (TgACT1) rapidly polymerized into filaments at a critical concentration that was 3-4-fold lower than conventional actins, yet it failed to copolymerize with mammalian actin. Electron microscopic analysis revealed that TgACT1 filaments were 10 times shorter and less stable than rabbit actin. Phylogenetic comparison of actins revealed a limited number of apicomplexan-specific residues that likely govern the unusual behavior of parasite actin. Molecular modeling identified several key alterations that affect interactions between monomers and that are predicted to destabilize filaments. Our findings suggest that conserved molecular differences in parasite actin favor rapid cycles of assembly and disassembly that govern the unusual form of gliding motility utilized by apicomplexans.

scholarly journals Stimulating and toxic effects of copper and cobalt nanopowders on rice seedlings

2020 ◽  
pp. 42-52
Author(s):  
I. V. Obidina ◽  
G. I. Churilov ◽  
S. D. Polischuk ◽  
A. Yu. Tarara ◽  
S. S. Gomozova ◽  
...  
Keyword(s):  
Chemical Nature ◽  
Microscopic Analysis ◽  
Rice Seedlings ◽  
Electron Microscopic ◽  
Regional Center ◽  
Scientific Equipment ◽  
Wide Range ◽  
Object Of Study ◽  
Positive Effect

Metal nanopowders have a stimulating effect on the growth and development of plants. The biological activity of nanoparticles depends on size, concentration, and chemical composition. Nanoparticles require further study because they have a wide range of applications in medicine and agriculture. Being biocompatible, copper and cobalt can play the role of growth stimulant, are not toxic and can be used for contact with living systems. The object of study was rice, as an economically important culture. The study addressed the effect of cobalt and copper nanoparticles on the germination and development of rice seedlings. The optimal concentration of ultrafine solutions of these nanopowders for pre-sowing treatment of seeds was determined. Although copper and cobalt have different chemical nature, the nanoparticles show similar impact and doze-dependent effect. Minimum concentrations of the nanoparticles had a positive effect on the morphological and biometric indicators of sprouts. The activity of oxidase enzymes was measured and it showed a reversible nature of oxidative stress. An increase in superoxide dismutase activity and a decrease in catalase activity by less than 30% indicates the stress resistance of rice sprouts and the absence of phytotoxic effects of the nanopowders. The presence of these metals in the seedling homogenate was determined to define the toxic effect. The electron microscopic analysis of the partition of metals in the tissues of experimental plants did not reveal significant deviations from control values. The experiments were performed using scientific equipment of Regional Center for Collective Use of Probe Microscopy in Ryazan State Radio Engineering University.

scholarly journals Self-assembly of the general membrane-remodeling protein PVAP into sevenfold virus-associated pyramids

2014 ◽  
Vol 111 (10) ◽  
pp. 3829-3834 ◽  
Author(s):  
Bertram Daum ◽  
Tessa E. F. Quax ◽  
Martin Sachse ◽  
Deryck J. Mills ◽  
Julia Reimann ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Self Assembly ◽  
Morphological Changes ◽  
Biological Membrane ◽  
Rotational Symmetry ◽  
Host Cells ◽  
Membrane Remodeling ◽  
Electron Microscopic ◽  
Host Cell Membrane ◽  
Wide Range

Viruses have developed a wide range of strategies to escape from the host cells in which they replicate. For egress some archaeal viruses use a pyramidal structure with sevenfold rotational symmetry. Virus-associated pyramids (VAPs) assemble in the host cell membrane from the virus-encoded protein PVAP and open at the end of the infection cycle. We characterize this unusual supramolecular assembly using a combination of genetic, biochemical, and electron microscopic techniques. By whole-cell electron cryotomography, we monitored morphological changes in virus-infected host cells. Subtomogram averaging reveals the VAP structure. By heterologous expression of PVAP in cells from all three domains of life, we demonstrate that the protein integrates indiscriminately into virtually any biological membrane, where it forms sevenfold pyramids. We identify the protein domains essential for VAP formation in PVAP truncation mutants by their ability to remodel the cell membrane. Self-assembly of PVAP into pyramids requires at least two different, in-plane and out-of-plane, protein interactions. Our findings allow us to propose a model describing how PVAP arranges to form sevenfold pyramids and suggest how this small, robust protein may be used as a general membrane-remodeling system.

Pin-Point Transmission Electron Microscopic Analysis Applied to Off-Leakage Failures of a Bipolar Transistor in 0.5μm BiCMOS Devices

1996 ◽  
Author(s):  
M. Okihara ◽  
H. Tanaka ◽  
N. Hirashita ◽  
T. Nakamura ◽  
H. Okada ◽  
...  
Keyword(s):  
Large Scale ◽  
Ion Beam ◽  
Microscopic Analysis ◽  
Bipolar Transistor ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Electron Microscopic ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Wide Range

Abstract Pin-point (specific area) planar transmission electron microscopy (TEM) analysis has been improved to study process-induced defects in recent very large scale integrated (VLSI) devices. The specimens are prepared by a combination of marking failure sites with focused ion beam (FTB) equipment and planar TEM specimen preparation technique. This method provides not only planar observation of localized failures with an accurate observation with high positioning accuracy but also wide range of observable area which is feasible to carry out some application techniques associated with TEM. In particular, it is found to be a powerful method to identify the nature of crystalline defects which cause the failures. This work presents the detailed procedure and demonstrates its successful applicability via studying a leaky bipolar transistor in 0.5μm BiCMOS devices (one failure of more than 4500 transistors). The results clarify the presence of stacking faults, formed during epitaxial growth, between collector and emitter regions in the specific transistor with resistive collector-emitter leakage current.

scholarly journals Direction of force generated by the inner row of dynein arms on flagellar microtubules.

1987 ◽  
Vol 105 (4) ◽  
pp. 1781-1787 ◽  
Author(s):  
L A Fox ◽  
W S Sale
Keyword(s):  
Beat Frequency ◽  
Microscopic Analysis ◽  
Force Generation ◽  
Electron Microscopic Analysis ◽  
Electron Microscopic ◽  
Sperm Tail ◽  
Relative Direction ◽  
Wide Range ◽  
Dynein Arms ◽  
Definition Of

Our goal was to determine the direction of force generation of the inner dynein arms in flagellar axonemes. We developed an efficient means of extracting the outer row of dynein arms in demembranated sperm tail axonemes, leaving the inner row of dynein arms structurally and functionally intact. Sperm tail axonemes depleted of outer arms beat at half the beat frequency of sperm tails with intact arms over a wide range of ATP concentrations. The isolated, outer arm-depleted axonemes were induced to undergo microtubule sliding in the presence of ATP and trypsin. Electron microscopic analysis of the relative direction of microtubule sliding (see Sale, W. S. and P. Satir, 1977, Proc. Natl. Acad. Sci. USA, 74:2045-2049) revealed that the doublet microtubule with the row of inner dynein arms, doublet N, always moved by sliding toward the proximal end of the axoneme relative to doublet N + 1. Therefore, the inner arms generate force such that doublet N pushes doublet N + 1 tipward. This is the same direction of microtubule sliding induced by ATP and trypsin in axonemes having both inner and outer dynein arms. The implications of this result for the mechanism of ciliary bending and utility in functional definition of cytoplasmic dyneins are discussed.

scholarly journals Isolation and characterization of a new type of chlorovirus that infects an endosymbiotic Chlorella strain of the heliozoon Acanthocystis turfacea

2005 ◽  
Vol 86 (10) ◽  
pp. 2871-2877 ◽  
Author(s):  
Julia A. Bubeck ◽  
Artur J. P. Pfitzner
Keyword(s):  
Genome Structure ◽  
Microscopic Analysis ◽  
Host Cells ◽  
Natural Environments ◽  
Electron Microscopic ◽  
Chlorella Virus ◽  
Isolation And Characterization ◽  
The Family ◽  
New Type

A novel virus, named Acanthocystis turfacea Chlorella virus (ATCV), that infects endosymbiotic Chlorella algae of the heliozoon Acanthocystis turfacea was isolated from freshwater samples. Electron microscopic analysis of ATCV revealed that the viral capsid has a distinct icosahedral shape with a diameter of 140–190 nm. Filamentous structures extending from some of the virus vertices, which may aid attachment of the virus to host cells, were also observed. The capsid is made up of one major coat protein of about 50 kDa and contains a large dsDNA genome. ATCV is a member of the genus Chlorovirus, which belongs to the family Phycodnaviridae, a group of large, icosahedral, dsDNA-containing viruses that infect algae and are ubiquitous in natural environments. However, ATCV is clearly distinct from the prototype Chlorovirus, Paramecium bursaria Chlorella virus (PBCV-1), in some aspects of its genome structure and gene content and therefore must be regarded as a member of a new group of Chlorella viruses.

scholarly journals Inhibition of Fungal and Bacterial Plant Pathogens In Vitro and In Planta with Ultrashort Cationic Lipopeptides

2007 ◽  
Vol 73 (20) ◽  
pp. 6629-6636 ◽  
Author(s):  
Arik Makovitzki ◽  
Ada Viterbo ◽  
Yariv Brotman ◽  
Ilan Chet ◽  
Yechiel Shai
Keyword(s):  
Pseudomonas Syringae ◽  
Pathogenic Bacteria ◽  
Plant Pathogens ◽  
Antimicrobial Agents ◽  
Plant Protection ◽  
Microscopic Analysis ◽  
Plant Diseases ◽  
In Planta ◽  
Global Food Security

ABSTRACT Plant diseases constitute an emerging threat to global food security. Many of the currently available antimicrobial agents for agriculture are highly toxic and nonbiodegradable and cause extended environmental pollution. Moreover, an increasing number of phytopathogens develop resistance to them. Recently, we have reported on a new family of ultrashort antimicrobial lipopeptides which are composed of only four amino acids linked to fatty acids (A. Makovitzki, D. Avrahami, and Y. Shai, Proc. Natl. Acad. Sci. USA 103:15997-16002, 2006). Here, we investigated the activities in vitro and in planta and the modes of action of these short lipopeptides against plant-pathogenic bacteria and fungi. They act rapidly, at low micromolar concentrations, on the membranes of the microorganisms via a lytic mechanism. In vitro microscopic analysis revealed wide-scale damage to the microorganism's membrane, in addition to inhibition of pathogen growth. In planta potent antifungal activity was demonstrated on cucumber fruits and leaves infected with the pathogen Botrytis cinerea as well as on corn leaves infected with Cochliobolus heterostrophus. Similarly, treatment with the lipopeptides of Arabidopsis leaves infected with the bacterial leaf pathogen Pseudomonas syringae efficiently and rapidly reduced the number of bacteria. Importantly, in contrast to what occurred with many native lipopeptides, no toxicity was observed on the plant tissues. These data suggest that the ultrashort lipopeptides could serve as native-like antimicrobial agents economically feasible for use in plant protection.

scholarly journals Viroplasm matrix protein Pns9 from rice gall dwarf virus forms an octameric cylindrical structure

2011 ◽  
Vol 92 (9) ◽  
pp. 2214-2221 ◽  
Author(s):  
Fusamichi Akita ◽  
Naoyuki Miyazaki ◽  
Hiroyuki Hibino ◽  
Takumi Shimizu ◽  
Akifumi Higashiura ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Matrix Protein ◽  
Three Dimensional ◽  
Microscopic Analysis ◽  
Host Cells ◽  
Size Exclusion ◽  
Dwarf Virus ◽  
Electron Microscopic ◽  
The Family ◽  
Rice Gall Dwarf Virus

The non-structural Pns9 protein of rice gall dwarf virus (RGDV) accumulates in viroplasm inclusions, which are structures that appear to play an important role in viral morphogenesis and are commonly found in host cells infected by viruses in the family Reoviridae. Immunofluorescence and immunoelectron microscopy of RGDV-infected vector cells in monolayers, using antibodies against Pns9 of RGDV and expression of Pns9 in Spodoptera frugiperda cells, demonstrated that Pns9 is the minimal viral factor necessary for formation of viroplasm inclusion during infection by RGDV. When Pns9 in solution was observed under a conventional electron microscope, it appeared as ring-like aggregates of approximately 100 Å in diameter. Cryo-electron microscopic analysis of these aggregates revealed cylinders of octameric Pns9, whose dimensions were similar to those observed under the conventional electron microscope. Octamerization of Pns9 in solution was confirmed by the results of size-exclusion chromatography. Among proteins of viruses that belong to the family Reoviridae whose three-dimensional structures are available, a matrix protein of the viroplasm of rotavirus, NSP2, forms similar octamers, an observation that suggests similar roles for Pns9 and NSP2 in morphogenesis in animal-infecting and in plant-infecting reoviruses.

scholarly journals Parasitism of Rhizoctonia solani by strains of Trichoderma spp.

2000 ◽  
Vol 57 (1) ◽  
pp. 55-59 ◽  
Author(s):  
Itamar Soares de Melo ◽  
Jane L. Faull
Keyword(s):  
Rhizoctonia Solani ◽  
Mycelial Growth ◽  
Host Cells ◽  
Mechanical Activity ◽  
Electron Microscopic ◽  
Trichoderma Spp ◽  
Strong Activity ◽  
Toxic Metabolites ◽  
Wide Range

Rhizoctonia solani causes serious diseases in a wide range of plant species. The fungus Trichoderma has been shown to be particularly effective in the control of the pathogen. Thus, this research was carried out to screen fourteen Trichoderma strains against R. solani in vitro. All strains tested inhibited the growth of R. solani. Three T. koningii strains produced toxic metabolites with strong activity against R. solani, inhibiting the mycelial growth by 79%. T. harzianum, Th-9 reduced the viability of sclerotia of R. solani by 81.8% and T. koningii, TK-5 reduced by 53%. Electron microscopic observations revealed that all T. harzianum strains interacted with R. solani. Th-9 grew toward and coiled around the host cells, penetrating and destroying the hyphae. Penetration of host cells was apparently accomplished by mechanical activity.

Preparatory Procedures for Electron Microscopic Analysis at the Molecular Level of Resolution

1978 ◽  
Vol 36 (3) ◽  
pp. 516-520
Author(s):  
F.J. Sjostrand
Keyword(s):  
Electron Microscope ◽  
Molecular Level ◽  
Microscopic Analysis ◽  
Resolving Power ◽  
Cellular Structures ◽  
Electron Microscopic ◽  
Systematic Analysis ◽  
Technical Developments ◽  
Thin Sectioning ◽  
Obvious Reason

In the 1940's and 1950's electron microscopy conferences were attended with everybody interested in learning about the latest technical developments for one very obvious reason. There was the electron microscope with its outstanding performance but nobody could make very much use of it because we were lacking proper techniques to prepare biological specimens. The development of the thin sectioning technique with its perfectioning in 1952 changed the situation and systematic analysis of the structure of cells could now be pursued. Since then electron microscopists have in general become satisfied with the level of resolution at which cellular structures can be analyzed when applying this technique. There has been little interest in trying to push the limit of resolution closer to that determined by the resolving power of the electron microscope.

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