I couple of months ago there was a short communication in Nature that I
meant to pass on. A tetrapoid rat species seems to have been found. The
Red Viscacha rat has 102 chromosomes though only one X and Y. Other
related genera of rats have 2N=57 so a strict doubling of them would have
lead to 4N=114. It is postulated that some chromosomal material has been
subsequently lost (another possibility is some extinct rat had 2N=51 that
doubled). What boggles the mind is that polyploidy could even occur in
mammals when one thinks about all the obstacles that have to be overcome to
maintain some sence of normallacy for these animals. On top of that the
Red Viscacha appears to uneffected at this point by carrying around twice
the genetic material that most other mammals though its sperm heads are
twice the size of other related rats. This is really an amazing example of
something that seems virtually impossible but there it is.
The article "Discovery of tetraploidy in mammals" was in Nature 401:341
(Sept 23 issue)
Joel Duff
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R. Joel Duff, Assistant Professor
Dept. of Biology, ASEC 185
Campus Mail 3908
University of Akron
Akron OH, 44325-3908
Office: 330-972-6077
rjduff@uakron.edu
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