On 28 Jan 1996, Ed Rybicki wrote:
> Bruce Phillips:
> > Given recent comments, mine and Ed. Rybicki's. could there by any
> > objection to called viroids (or perhaps certain satellite RNAs) RNA plasmids.
> > The natural objection, as I see it, is that plasmids are defined as DNA
> > molecules. But in all other attributes, viroids would seem to be the RNA
> > equivalent.
>> They would, wouldn't they...except that they are potentially
> pathogenic and offer no or no obvious survival advantage to their
> hosts, which means they are much more similar to viruses in thast
> respect.
I suppose a fundamental difference between plasmids and viroids is that
plasmids, as far as I know, always have at least one gene, encoding at
least one protein. Viroids do not encode any proteins. I'm not so familiar
with the hepatitis agent. But I agree that some plant satellite RNAs could
be considered similar to plasmids.
Murilo
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| Murilo Zerbini | Out of 3,000,000,000 DNA nucleotides, |
| Dep. of Plant Pathology | human beings and chimpanzees have |
| University of California, Davis | 2,999,400,000 in common. |
|fmzerbini at ucdavis.edu | |
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