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DNA Question

Mary K. Kuhner mkkuhner at kingman.genetics.washington.edu
Wed Dec 9 17:52:09 EST 1998

In article <74mr7j$58h at net.bio.net>, Guy Hoelzer  <hoelzer at med.unr.edu> wrote:

>environmentally induced phenotypic changes are generally not considered
>evolutionary, in part because they are easily reversed.  For example, body
>size can often be influenced by temperature (or feeding rate) during

There are at least a few examples of more strictly heritable changes,
however.  If you peel a strip of cell surface off a ciliated paramecium
and put it on backwards, so that the cilia are pointing the other way,
they will stay backwards, and the offspring of the cell will have
strips which are backwards--indefinately, at least until you go at them
with another razor blade.  The basal bodies of the existing cilia are
apparently used as templates for constructing the new ones.  Thus,
cilium direction is heritable without reference to the DNA.

We don't really know how common this kind of non-DNA inheritance is.  

It's conceivable that you could have some trait maintained by mother/
child interaction in a very strict, fixed fashion, but with no DNA
involvement, so that it could be drastically changed without DNA

Mary Kuhner mkkuhner at genetics.washington.edu

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