Ultrastructure of tobacco mosaic virus lesions and surrounding tissue in Phaseolus vulgaris var. Pinto

1971 ◽  
Vol 49 (3) ◽  
pp. 417-421 ◽  
Author(s):  
D. F. Spencer ◽  
W. C. Kimmins

Leaves of Phaseolus vulgaris var. Pinto were inoculated with the U1 strain of tobacco mosaic virus TMV (U1) and fully expanded lesions and adjacent healthy tissue were examined in the electron microscope. Emphasis was placed on the band of healthy cells (resistant zone) surrounding the lesion, with the object of detecting the first changes in ultrastructure as healthy tissue graded into the infected area. Cells in the resistant zone were characterized by the appearance of membrane-bound vesicular bodies (paramural bodies) between the plasmalemma and cell wall. Where paramural bodies accumulated, the plasmalemma was withdrawn and intercellular cytoplasmic connections through the plasmodesmata were severed. These changes were found most frequently for a distance of about three cell diameters beyond cells visibly infected at the lesion periphery. It is suggested that these changes in ultrastructure are related to the events of localization. Spread of the virus may be inhibited because of a lack of cytoplasmic connections between cells surrounding the virus-induced lesion.

Author(s):  
Irwin Bendet ◽  
Nabil Rizk

Preliminary results reported last year on the ion etching of tobacco mosaic virus indicated that the diameter of the virus decreased more rapidly at 10KV than at 5KV, perhaps reaching a constant value before disappearing completely.In order to follow the effects of ion etching on TMV more quantitatively we have designed and built a second apparatus (Fig. 1), which incorporates monitoring devices for measuring ion current and vacuum as well as accelerating voltage. In addition, the beam diameter has been increased to approximately 1 cm., so that ten electron microscope grids can be exposed to the beam simultaneously.


RSC Advances ◽  
2021 ◽  
Vol 11 (33) ◽  
pp. 20101-20108
Author(s):  
Sourabh Shukla ◽  
Isaac Marks ◽  
Derek Church ◽  
Soo-Khim Chan ◽  
Jonathan K. Pokorski ◽  
...  

Prostate-specific membrane antigen (PSMA) is a membrane-bound protein that is preferentially expressed in the prostate gland and induced in many prostate cancers, making it an important target for new diagnostics and therapeutics.


The three-dimensional structure of the stacked-disk rod of tobacco mosaic virus protein has been reconstructed to a resolution of about 2 nm from electron microscope images. Closed rings of seventeen protein subunits (compared with 16 ⅓ in one turn of the virus helix) are stacked in polar fashion, the stacking being accompanied by an axial perturbation of periodicity 5.3 nm connecting successive pairs of rings into disks. The axial perturbation consists of a movement towards each other of the outer parts of the subunits in the two rings comprising a disk, together with a movement of the inner parts in the opposite direction. This could be explained either by a bending of parts of the subunits in the appropriate directions or by a bodily tilting of the subunits in the two rings in opposite directions.


1999 ◽  
Vol 354 (1383) ◽  
pp. 637-643 ◽  
Author(s):  
Vitaly Citovsky

Cell–to–cell movement of tobacco mosaic virus (TMV) is used to illustrate macromolecular traffic through plant intercellular connections, the plasmodesmata. This transport process is mediated by a specialized viral movement protein, P30. In the initially infected cell, P30 is produced by transcription of a subgenomic RNA derived from the invading virus. Presumably, P30 then associates with a certain proportion of the viral RNA molecules, sequestering them from replication and mediating their transport into neighbouring uninfected host cells. This nucleoprotein complex is targeted to plasmodesmata, possibly via interaction with the host cell cytoskeleton. Prior to passage through a plasmodesma, the plasmodesmal channel is dilated by the movement protein. It is proposed that targeting of P30–TMV RNA complexes to plasmodesmata involves binding to a specific cell wall–associated receptor molecule. In addition, a cell wall–associated protein kinase, phosphorylates P30 at its carboxy–terminus and minimizes P30–induced interference with plasmodesmatal permeability during viral infection.


1967 ◽  
Vol 33 (3) ◽  
pp. 665-678 ◽  
Author(s):  
Katherine Esau ◽  
James Cronshaw

The relation of tobacco mosaic virus (TMV) to host cells was studied in leaves of Nicotiana tabacum L. systemically infected with the virus. The typical TMV inclusions, striate or crystalline material and ameboid or X-bodies, which are discernible with the light microscope, and/or particles of virus, which are identifiable with the electron microscope, were observed in epidermal cells, mesophyll cells, parenchyma cells of the vascular bundles, differentiating and mature tracheary elements, and immature and mature sieve elements. Virus particles were observed in the nuclei and the chloroplasts of parenchyma cells as well as in the ground cytoplasm, the vacuole, and between the plasma membrane and the cell wall. The nature of the conformations of the particle aggregates in the chloroplasts was compatible with the concept that some virus particles may be assembled in these organelles. The virus particles in the nuclei appeared to be complete particles. Under the electron microscope the X-body constitutes a membraneless assemblage of endoplasmic reticulum, ribosomes, virus particles, and of virus-related material in the form of wide filaments indistinctly resolvable as bundles of tubules. Some parenchyma cells contained aggregates of discrete tubules in parallel arrangement. These groups of tubules were relatively free from components of host protoplasts.


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