Optical Diagnostics Fungal and Virus Diseases of Plants

Author(s):  
A. Michtchenko ◽  
A.V. Budagovsky ◽  
O.N. Budagovskaya
Author(s):  
O. E. Bradfute

Electron microscopy is frequently used in preliminary diagnosis of plant virus diseases by surveying negatively stained preparations of crude extracts of leaf samples. A major limitation of this method is the time required to survey grids when the concentration of virus particles (VPs) is low. A rapid survey of grids for VPs is reported here; the method employs a low magnification, out-of-focus Search Mode similar to that used for low dose electron microscopy of radiation sensitive specimens. A higher magnification, in-focus Confirm Mode is used to photograph or confirm the detection of VPs. Setting up the Search Mode by obtaining an out-of-focus image of the specimen in diffraction (K. H. Downing and W. Chiu, private communications) and pre-aligning the image in Search Mode with the image in Confirm Mode facilitates rapid switching between Modes.


1950 ◽  
Vol 34 (6) ◽  
pp. 1637-1652
Author(s):  
Thomas M. Durant ◽  
Charles R. Shuman

1963 ◽  
Vol 02 (02) ◽  
pp. 49-51 ◽  
Author(s):  
K. Knapp ◽  
W. Lenz

SummaryIn 1961 an increase in certain congenital malformations was noticed in various parts of the Federal Republic of Germany. From the outset, it seemed very probable that a single cause was responsible, since, although these malformations varied, they appeared to belong to one and the same syndrome. For general reasons, such causes as radioactivity, contraceptives, attempted abortions or virus diseases did not provide an acceptable explanation. The epidemiology was, however, suggestive of some chemical substance taken orally.After thalidomide had been indicated in several histories, suspicion of that drug was aroused and, within one week, intake of it could be proved or was found to be very likely in 17 out of 20 cases, while in the remaining cases it could not be excluded. Though this first result was highly significant, we were at first reluctant to incriminate thalidomide definitely, because there was still some doubt about the reliability of the histories. But within a few weeks, the thalidomide aetiology received support from many sources. Specific studies on limited material are sometimes superior to extensive, broadly planned investigations.


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