THE PHYSIOLOGY OF HOST–PARASITE RELATIONS: I. THE ACCUMULATION OF RADIOACTIVE SUBSTANCES AT INFECTIONS OF FACULTATIVE AND OBLIGATE PARASITES INCLUDING TOBACCO MOSAIC VIRUS

1956 ◽  
Vol 34 (3) ◽  
pp. 389-405 ◽  
Author(s):  
Michael Shaw ◽  
D. J. Samborski
Keyword(s):  
Carbon Dioxide ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
High Rate ◽  
Fungal Mycelium ◽  
Obligate Parasites ◽  
Tracer Techniques ◽  
Metabolic Products ◽  
Carbon Compounds ◽  
Host Parasite

Excised, parasitized leaves were placed with their bases in radioactive solutions or exposed to radioactive carbon dioxide and the uptake and distribution of the tracers followed by autoradiography. Carbon dioxide and 20 other carbon compounds, including sugars, amino and organic acids, phenols, and indoleacetic acid, and/or their metabolic products, as well as phosphate and calcium, accumulated strongly at uredial and conidial colonies of the obligate parasites Puccinia and Erysiphe, respectively. Accumulation of glucose occurred in the host tissue at the sites of mildew colonies on leaves from which the ectoparasitic fungal mycelium had been removed, paralleled the respiration, rate, increased progressively with the development of the parasites, and was most marked at type 4 infections. It was inhibited by sulphur dust (with mildew), sodium azide, 2,4-dinitrophenol and, reversibly, by anaerobiosis and was, therefore, dependent on aerobic respiration. On the other hand the tracers did not accumulate within senescent rust and mildew colonies or within the necrotic lesions produced by bacterial and fungal parasites which kill the tissues of their hosts. Radioactive glucose did not, but calcium and phosphate did, accumulate within young local lesions of tobacco mosaic virus on Nicotiana. The tracers did not enter dead areas on mechanically-wounded leaves and only accumulated at fresh wounds under conditions conducive to a high rate of water loss from the damaged surface. In conjunction with more conventional methods, tracer techniques provide a powerful method of attack on the problems of host–parasite relationships.

Leeuwenhoek Lecture: Virus-host cell interactions

1958 ◽  
Vol 148 (932) ◽  
pp. 370-384 ◽  
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Cellular Level ◽  
Fundamental Characteristic ◽  
Host Parasite Interactions ◽  
Intimate Association ◽  
Host Cell Interactions ◽  
Virus Research ◽  
Host Parasite ◽  
Microbiological Research

To-day’s lecture is the eighth of the series founded to honour the memory of Anthony van Leeuwenhoek who is rightly regarded as the ‘father of microbiology'. More than a century and a half had to elapse after Leeuwenhoek’s death in 1723 before a virus was isolated. Many more years passed before virology became established as a legitimate branch of microbiology. Yet, for a third time, the Leeuwenhoek lecture is to be devoted to a consideration of the viruses. To some this may seem inappropriate but there are three reasons which seem to me to justify the choice of subject. First, virology is, today, probably the most rapidly expanding field of microbiological research; secondly, Leeuwenhoek’s insatiable curiosity about creatures infinitely small would undoubtedly lead him into virus research were he still alive; thirdly, my own chief research interests lie in certain aspects of virology. The question ‘What is a virus?’ has often been asked without so far being satisfactorily answered. I shall make no attempt at a definition. For the purposes of present discussion the term ‘virus’ will be used in the widest possible sense to embrace all those agents of transmissible diseases which, for valid reasons, cannot be included in the various categories of unicellular disease incitants, irrespective of whether they are highly organized like vaccinia virus or consist of crystallizable protein like tobacco mosaic virus. Whether any stricter limitation of the term is either desirable or possible may perhaps emerge in the course of the lecture. The most fundamental characteristic of the viruses is their obligate cell parasitism. Those of the three main types, animal, plant and bacterial, differ in several very important respects but they share, in common, this necessity of entering into intimate association with the cells of higher organisms in order to multiply and survive. Clearly, therefore, elucidation of the host-parasite interactions at the cellular level must be achieved before we can understand fully the diverse phenomena resulting from virus activities.

Quantitative Measurements on the Ion Etching of TMV

1973 ◽  
Vol 31 ◽  
pp. 336-337
Author(s):  
Irwin Bendet ◽  
Nabil Rizk
Keyword(s):  
Electron Microscope ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Ion Current ◽  
Beam Diameter ◽  
Ion Etching ◽  
Preliminary Results ◽  
Quantitative Measurements ◽  
Monitoring Devices

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.

Tobacco Mosaic Virus-Infected Tissue

1985 ◽  
Vol 43 ◽  
pp. 510-511
Author(s):  
Egbert W. Henry
Keyword(s):  
Nicotiana Tabacum ◽  
Tobacco Mosaic Virus ◽  
Chlorogenic Acid ◽  
Mosaic Virus ◽  
Host Resistance ◽  
Oxidative Metabolism ◽  
Leaf Tissue ◽  
Vein Clearing ◽  
Basal Septum ◽  
Concentration Levels

Tobacco mosaic virus (TMV) infection has been studied in several investigations of Nicotiana tabacum leaf tissue. Earlier studies have suggested that TMV infection does not have precise infective selectivity vs. specific types of tissues. Also, such tissue conditions as vein banding, vein clearing, liquification and suberization may result from causes other than direct TMV infection. At the present time, it is thought that the plasmodesmata, ectodesmata and perhaps the plasmodesmata of the basal septum may represent the actual or more precise sites of TMV infection.TMV infection has been implicated in elevated levels of oxidative metabolism; also, TMV infection may have a major role in host resistance vs. concentration levels of phenolic-type enzymes. Therefore, enzymes such as polyphenol oxidase, peroxidase and phenylalamine ammonia-lyase may show an increase in activity in response to TMV infection. It has been reported that TMV infection may cause a decrease in o-dihydric phenols (chlorogenic acid) in some tissues.

Nitroxyl Modified Tobacco Mosaic Virus as a Metal-Free High-Relaxivity MRI and EPR Active Superoxide Sensor

2018 ◽  
Author(s):  
Madushani Dharmarwardana ◽  
André F. Martins ◽  
Zhuo Chen ◽  
Philip M. Palacios ◽  
Chance M. Nowak ◽  
...  
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Single Molecule ◽  
Biological Fluids ◽  
Cellular Respiration ◽  
Organic Radical ◽  
Paramagnetic Resonance ◽  
Metal Free ◽  
Disease States

Superoxide overproduction is known to occur in multiple disease states requiring critical care yet non-invasive detection of superoxide in deep tissue remains a challenge. Herein, we report a metal-free magnetic resonance imaging (MRI) and electron paramagnetic resonance (EPR) active contrast agent prepared by “click conjugating” paramagnetic organic radical contrast agents (ORCAs) to the surface of tobacco mosaic virus (TMV). While ORCAs are known to be reduced <i>in vivo</i> to an MRI/EPR silent state, their oxidation is facilitated specifically by reactive oxygen species—in particular superoxide—and are largely unaffected by peroxides and molecular oxygen. Unfortunately, single molecule ORCAs typically offer weak MRI contrast. In contrast, our data confirm that the macromolecular ORCA-TMV conjugates show marked enhancement for <i>T<sub>1</sub></i> contrast at low field (<3.0 T), and <i>T<sub>2</sub></i> contrast at high field (9.4 T). Additionally, we demonstrated that the unique topology of TMV allows for “quenchless fluorescent” bimodal probe for concurrent fluorescence and MRI/EPR imaging, which was made possible by exploiting the unique inner and outer surface of the TMV nanoparticle. <a>Finally, we show TMV-ORCAs do not respond to normal cellular respiration, minimizing the likelihood for background, yet still respond to enzymatically produced superoxide in complicated biological fluids like serum.</a>

Sign in / Sign up

Export Citation Format

Share Document