Four viruses were irreversibly photosensitized by 4 × 10 -ethidium chloride but not by more dilute solutions. Photosensitization was greatest with vaccinia, pseudorabies, herpes tamarinus and reoviruses, intermediate with western equine encephalitis virus, and least with fowl plague and Newcastle disease viruses. Pseudorabies virus was also inactivated by ethidium chloride at 37° in the dark. The order of susceptibility of the viruses to other dyes varied according to the concentration of dye. Native thymus DNA, but not heated DNA, inhibited the action of ethidium chloride on viruses. Toluidine blue and neutral red were more strongly inhibited by heated DNA than by native DNA, and both DNAs inhibited the action of proflavine to the same extent.

Toluidine blue and proflavine catalysed the degradation of guanine by light in both native and heated thymus DNA. The action of neutral red differed in two respects: at a low ratio of dye to nucleotide molecules, the cytosine of native DNA was also degraded; at a higher ratio, only the guanine of heated DNA was destroyed. There was no effect of ethidium chloride on any of the four bases of DNA.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error