Cinétique de l'infection de plants d'Heveabrasiliensis (Willd. ex Adr. de Juss) Mull. Arg. par Rigidoporuslignosus (Kl.) Imazeki

1983 ◽  
Vol 13 (3) ◽  
pp. 359-364 ◽  
Author(s):  
M. Nicole ◽  
D. Nandris ◽  
J.-P. Geiger
Keyword(s):  
Reaction Mechanisms ◽  
Cellular Level ◽  
Infection Process ◽  
Artificial Inoculation ◽  
Inoculation Technique ◽  
Tissue Invasion ◽  
Disease Progress ◽  
Entire Plant ◽  
Stage Infection ◽  
Infection Study

Using an artificial inoculation technique, a kinetic infection study of Heveabrasiliensis (Willd. ex Adr. de Juss) Mull. Arg. by Rigidoporuslignosus (Kl.) Imazeki has shown the existence of a three-stage infection process: (i) a particularly fast contamination stage. After 15 days of exposure, all plants showed rhizomorphs to be present on taproots; (ii) the spread of epiphytic mycelium all over taproots is associated with numerous punctual penetrations allowing tissue invasion and infection. Beginning at the apex, a rot develops and progresses upward; in less than 3 months, it affects nearly 40% of the invaded plants' taproot. In response to this, the host develops reaction mechanisms which become evident at the cellular level and on the entire plant; and (iii) at this time, a state of equilibrium is reached between the host and the parasite which is shown through a stagnant disease progress. The efficiency of the various host reactions observed in the plants is discussed. [Journal translation]

scholarly journals PirABVP Toxin Binds to Epithelial Cells of the Digestive Tract and Produce Pathognomonic AHPND Lesions in Germ-Free Brine Shrimp

Toxins ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 717 ◽  
Author(s):  
Vikash Kumar ◽  
Lobke De Bels ◽  
Liesbeth Couck ◽  
Kartik Baruah ◽  
Peter Bossier ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Digestive Tract ◽  
Brine Shrimp ◽  
Penaeid Shrimp ◽  
Cellular Level ◽  
Infection Process ◽  
Intestinal Lumen ◽  
Bacterial Disease ◽  
Germ Free ◽  
Acute Hepatopancreatic Necrosis Disease

Acute hepatopancreatic necrosis disease (AHPND), a newly emergent farmed penaeid shrimp bacterial disease originally known as early mortality syndrome (EMS), is causing havoc in the shrimp industry. The causative agent of AHPND was found to be a specific strain of bacteria, e.g., Vibrio and Shewanella sps., that contains pVA1 plasmid (63–70 kb) encoding the binary PirAVP and PirBVP toxins. The PirABVP and toxins are the primary virulence factors of AHPND-causing bacteria that mediates AHPND and mortality in shrimp. Hence, in this study using a germ-free brine shrimp model system, we evaluated the PirABVP toxin-mediated infection process at cellular level, including toxin attachment and subsequent toxin-induced damage to the digestive tract. The results showed that, PirABVP toxin binds to epithelial cells of the digestive tract of brine shrimp larvae and produces characteristic symptoms of AHPND. In the PirABVP-challenged brine shrimp larvae, shedding or sloughing of enterocytes in the midgut and hindgut regions was regularly visualized, and the intestinal lumen was filled with moderately electron-dense cells of variable shapes and sizes. In addition, the observed cellular debris in the intestinal lumen of the digestive tract was found to be of epithelial cell origin. The detailed morphology of the digestive tract demonstrates further that the PirABVP toxin challenge produces focal to extensive necrosis and damages epithelial cells in the midgut and hindgut regions, resulting in pyknosis, cell vacuolisation, and mitochondrial and rough endoplasmic reticulum (RER) damage to different degrees. Taken together, our study provides substantial evidence that PirABVP toxins bind to the digestive tract of brine shrimp larvae and seem to be responsible for generating characteristic AHPND lesions and damaging enterocytes in the midgut and hindgut regions.

scholarly journals Developing an artificial inoculation technique for screening chickpea genotypes against a Syrian isolate of Chickpea chlorotic stunt virus

2020 ◽  
Vol 38 (2) ◽  
pp. 103-114
Author(s):  
Nader Asaad ◽  
◽  
Safaa Kumari ◽  
Amin Hajj Kassem ◽  
Atiya Arab ◽  
...  
Keyword(s):  
Artificial Inoculation ◽  
Inoculation Technique

scholarly journals Potyvirus Genome-Linked Protein (VPg) Determines Pea Seed-Borne Mosaic Virus Pathotype-Specific Virulence in Pisum sativum

1998 ◽  
Vol 11 (2) ◽  
pp. 124-130 ◽  
Author(s):  
Karen E. Keller ◽  
Elisabeth Johansen ◽  
Robert R. Martin ◽  
R. O. Hampton
Keyword(s):  
Coat Protein ◽  
Pisum Sativum ◽  
Cellular Level ◽  
Infection Process ◽  
Post Inoculation ◽  
Coding Region ◽  
Viral Coat Protein ◽  
Viral Coat ◽  
Polymerase Chain ◽  
Pea Seed

The mechanism of Pisum sativum pathotype-specific resistance to pea seed-borne mosaic potyvirus (PSbMV) was investigated and the coding region determinant of PSbMV virulence was defined. Homozygous recessive sbm-1 peas are unable to support replication of PSbMV pathotype 1 (P-1), whereas biochemically and serologically related pathotype 4 (P-4) is fully infectious in the sbm-1/sbm-1 genotype. We were unable to detect viral coat protein or RNA with double antibody sandwich-enzyme-linked im-munosorbent assay and reverse transcription-polymerase chain reaction in sbm-1/sbm-1 P-1-inoculated protoplasts and plants. Lack of viral coat protein or RNA in P-1 trans-fected sbm-1/sbm-1 protoplasts suggests that sbm-1 resistance is occurring at the cellular level and that inhibition of cell-to-cell virus movement is not the operating form of resistance. In addition, because virus products were not detected at any time post-inoculation, resistance must either be constitutive or expressed very early in the virus infection process. P-1-resistant peas challenged with full-length, infectious P-1/P-4 recombinant clones demonstrated that a specific P-4 coding region, the 21-kDa, genome-linked protein (VPg), was capable of overcoming sbm-1 resistance, whereas clones containing the P-1 VPg coding region were noninfectious to sbm-1/sbm-1 peas. VPg is believed to be involved in potyvirus replication and its identification as the PSbMV determinant of infectivity in sbm-1/sbm-1 peas is consistent with disruption of an early P-1 replication event.

Establishment of an Artificial Inoculation Method of Ustilaginoidea virens without Damaging the Rice Panicle Sheaths

Plant Disease ◽  
2021 ◽  
Author(s):  
Xianfeng Hu ◽  
Jian Wang ◽  
Rongyu Li ◽  
Xiaomao Wu ◽  
Xiubing Gao ◽  
...  
Keyword(s):  
Natural Infection ◽  
Infection Process ◽  
Artificial Inoculation ◽  
Flowering Stage ◽  
Ustilaginoidea Virens ◽  
Inoculation Method ◽  
Young Panicle ◽  
False Smut ◽  
The Mean ◽  
Sheath Structure

Rice false smut (RFS) is a destructive disease of rice worldwide caused by Ustilaginoidea virens. There is a lack of efficient and stable artificial inoculation method to simulate the natural infection of U. virens, which is an important factor limiting further research on the disease. The purpose of this study was to establish an artificial inoculation method, which can simulate the natural infection process of U. virens without destroying the panicle sheath structure of rice. In this research, rice plants were inoculated by soaking roots at the seedling stage, spraying at the tillering stage, injecting at the booting stage, and again spraying at the flowering stage to determine the appropriate artificial inoculation time. The panicle sheath instillation method and injection inoculation method were compared. The results show that stages 6 to 8 of young panicle differentiation are an important period for U. virens infection. There were no significant differences in the mean rates of infected panicles, mean rates of infected grains, and maximum infected grains per panicle between the two inoculation methods. However, the frequency of RFS ball occurrence at the upper part of the panicles was significantly higher on the spikelets inoculated by the injection method than that of spikelets inoculated by natural infection and panicle sheath instillation. Therefore, panicle sheath instillation method was more similar to the natural infection of U. virens in the field. This research exhibited an innovative artificial inoculation method for identification of U. virens pathogenicity and evaluation of rice resistance against RFS.

scholarly journals RESULTS OF EXPERIMENTAL INFECTION OF TURKEYS WITH A/DUCK/ALTAI/469/14 H5N1 STRAIN OF AVIAN INFLUENZA VIRUS

2018 ◽  
pp. 46-51
Author(s):  
V. Yu. Sosipatorova ◽  
D. A. Altunin ◽  
I. A. Chvala ◽  
N. S. Mudrak ◽  
D. B. Andreychuk
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Experimental Infection ◽  
Polyclonal Antibodies ◽  
Immunohistochemical Analysis ◽  
Virus Antigen ◽  
Cellular Level ◽  
Infection Process ◽  
Immunohistochemical Studies

The data on experimental infection of 6-week-old Big-6 cross turkeys with an epidemic A/duck/Altai/469/14 H5N1 clade 2.3.2.1c strain of avian influenza virus are presented. The characteristics of the infection process in birds inoculated intranasally at a dose of 5.0 lg EID50/0.5 cm3 are described with an indication of the incubation period and the mean time of death. The pathomorphological changes at the tissue and cellular level are shown based on histological and immunohistochemical studies of fragments of respiratory, digestive, cardiovascular, nervous, excretory, lymphoid and muscular systems of experimental birds. The testing was carried out using paired preparations of paraffin-embedded tissue sections from experimentally infected and healthy turkeys. One sample was subjected to histological staining using hematoxylin and eosin dyes, and its duplicate was subjected to immunohistochemical assay using a preparation of polyclonal antibodies as primary antibodies against the ribonucleoprotein of avian influenza virus. The results of histological and immunohistochemical studies are photodocumented and presented in the paper. Inflammatory and necrotic lesions of varying severity are detected in the preparations of the trachea, lung, muscular stomach, glandular stomach, small intestine, large intestine, pancreas, brain, cerebellum, heart, kidneys, liver and spleen of turkeys. Immunohistochemical analysis showed the greatest distribution of the influenza virus antigen in the cerebral endothelium, cerebellar Purkinje neurons, acinar cells of the pancreas and in myocardiocytes of the heart. In the course of the experiment it was established that A/duck/Altai/469/14 H5N1 caused a generalized form of infection in turkeys with clinical and pathologic lesions characteristic of highly pathogenic avian influenza.

Infection of Escherichia coli with bacteriophages

1969 ◽  
Vol 27 ◽  
pp. 370-371
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Nucleic Acid ◽  
Cell Surface ◽  
Virus Type ◽  
Infection Process ◽  
Adsorption Site ◽  
The Other ◽  
Specific Receptors ◽  
Bacterial Receptors

The first step in the infection of a bacterium by a virus consists of a collision between cell and bacteriophage. The presence of virus-specific receptors on the cell surface will trigger a number of events leading eventually to release of the phage nucleic acid. The execution of the various "steps" in the infection process varies from one virus-type to the other, depending on the anatomy of the virus. Small viruses like ØX 174 and MS2 adsorb directly with their capsid to the bacterial receptors, while other phages possess attachment organelles of varying complexity. In bacteriophages T3 (Fig. 1) and T7 the small conical processes of their heads point toward the adsorption site; a welldefined baseplate is attached to the head of P22; heads without baseplates are not infective.

Some Effects of Oxidant Air Pollutants (Ozone and Peroxyacetyl Nitrate) on the Ultrastructure of Leaf Tissues

1972 ◽  
Vol 30 ◽  
pp. 360-361
Author(s):  
William W. Thomson ◽  
Elizabeth S. Swanson
Keyword(s):  
Air Pollutants ◽  
Electron Microscopic Examination ◽  
Peroxyacetyl Nitrate ◽  
Electron Microscopic ◽  
Growth Physiology ◽  
Physiology And Biochemistry ◽  
Entire Plant ◽  
Leaf Tissues ◽  
Gaseous Hydrocarbons ◽  
The Individual

The oxidant air pollutants, ozone and peroxyacetyl nitrate, are produced in the atmosphere through the interaction of light with nitrogen oxides and gaseous hydrocarbons. These oxidants are phytotoxicants and are known to deleteriously affect plant growth, physiology, and biochemistry. In many instances they induce changes which lead to the death of cells, tissues, organs, and frequently the entire plant. The most obvious damage and biochemical changes are generally observed with leaves.Electron microscopic examination of leaves from bean (Phaseolus vulgaris L.) tobacco (Nicotiana tabacum L.) and cotton (Gossipyum hirsutum L.) fumigated for .5 to 2 hours with 0.3 -1 ppm of the individual oxidants revealed that changes in the ultrastructure of the cells occurred in a sequential fashion with time following the fumigation period. Although occasional cells showed severe damage immediately after fumigation, the most obvious change was an enhanced clarity of the cell membranes.

Analyzing reactions of single mechanoenzyme molecules by light microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 426-427
Author(s):  
Jeff Gelles
Keyword(s):  
Image Processing ◽  
Reaction Mechanisms ◽  
Transient State ◽  
Nanometer Scale ◽  
Reaction Intermediates ◽  
Enzyme Molecule ◽  
Directed Movement ◽  
Enzyme Molecules ◽  
Individual Enzyme ◽  
Single Reaction

Mechanoenzymes are enzymes which use a chemical reaction to power directed movement along biological polymer. Such enzymes include the cytoskeletal motors (e.g., myosins, dyneins, and kinesins) as well as nucleic acid polymerases and helicases. A single catalytic turnover of a mechanoenzyme moves the enzyme molecule along the polymer a distance on the order of 10−9 m We have developed light microscope and digital image processing methods to detect and measure nanometer-scale motions driven by single mechanoenzyme molecules. These techniques enable one to monitor the occurrence of single reaction steps and to measure the lifetimes of reaction intermediates in individual enzyme molecules. This information can be used to elucidate reaction mechanisms and determine microscopic rate constants. Such an approach circumvents difficulties encountered in the use of traditional transient-state kinetics techniques to examine mechanoenzyme reaction mechanisms.

Multimode light microscopy and fluorescence-based reagents as tools for the study of chemical and molecular dynamics of living cells and tissues

1992 ◽  
Vol 50 (1) ◽  
pp. 418-419
Author(s):  
D. L. Taylor
Keyword(s):  
Living Cells ◽  
Cellular Level ◽  
Molecular Techniques ◽  
Cellular Functions ◽  
Macromolecular Assemblies ◽  
Cell Functions ◽  
Molecular Events ◽  
Yield Information ◽  
Full Knowledge ◽  
Structural Methods

Cells function through the complex temporal and spatial interplay of ions, metabolites, macromolecules and macromolecular assemblies. Biochemical approaches allow the investigator to define the components and the solution chemical reactions that might be involved in cellular functions. Static structural methods can yield information concerning the 2- and 3-D organization of known and unknown cellular constituents. Genetic and molecular techniques are powerful approaches that can alter specific functions through the manipulation of gene products and thus identify necessary components and sequences of molecular events. However, full knowledge of the mechanism of particular cell functions will require direct measurement of the interplay of cellular constituents. Therefore, there has been a need to develop methods that can yield chemical and molecular information in time and space in living cells, while allowing the integration of information from biochemical, molecular and genetic approaches at the cellular level.

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