In article <DJ4Iro.G4G at gpu.utcc.utoronto.ca> lamoran at gpu.utcc.utoronto.ca (L.A. Moran) writes:
>In article <30c3689c at d4.niaid.pc.niaid.nih.gov>,
>Graham Clark <Graham_Clark at d4.niaid.pc.niaid.nih.gov> wrote:
>>Jonathan A. Eisen wrote:
>>>>-So I ask Mark and others out there, are there examples of significant
>>-differences between rRNA genes within a single organism in eukaryotes?
>>-Or, in other words, how rapid is the homogenization process, and how
>>-complete is it (do all of the 1000s of rRNA genes evolve in concert?).
>>>>There are certainly differences within genomes and within species but
>>whether one considers them 'significant' is another question. Where
>>multiple rRNA gene sequences from the same organism are available there
>>are almost always differences - is it real or is it artifact? Probably
>>a bit of both.
>> Clayton, R.A., Sutton, G., Hinkle Jr., P.S., Bult, C. and
> Fields, C. (1995) Intraspecific Variation in Small-Subunit
> rRNA Sequences in GenBank: Why Single Sequences May Not
> Adequately Represent Prokaryotic Taxa.
> Int. J. Syst. Bacteriol. 45, 595-599.
I agree. In fact, on southerns a friend has found multiple "alleles" if you
will of actin that are of equal length (i.e., one band from pcr) but
yet have more than a base here or there different.
Most of us figure that some of these genes evolve so slowly that we
needn't worry too much about sequencing multiple clones (which will still
miss rarer ones anyway) and yet we may be missing out on a lot of
information about paralogy even if this is so.
Mark E. Siddall "I don't mind a parasite...
mes at vims.edu I object to a cut-rate one"
Virginia Inst. Marine Sci. - Rick
Gloucester Point, VA, 23062