Re: Non-DNA inheritance - RNA implicated???

From: Joe Felsenstein (joe_at_removethispart.gs.washington.edu)
Date: 03/24/05 

Date: Thu, 24 Mar 2005 13:41:45 -0500 (EST)

In article <d1tj88$3pp$1@darwin.ediacara.org>,
IRR <iotarhorho@REMOV3hotmail.com> wrote:
>I guess in trying to understand the various possible alternative
>explanations (mutant reversion to wild type, possible unknown paralogous
>gene copies -- each of which it seems the authors attempt to rule out), I'm
>wondering if this could turn out to be a transient effect? In other words,
>if there is some metastable double stranded RNA template carrying the
>original/nonmutant allele, won't this template eventually be degraded or
>otherwise not penetrate into subsequent progeny? Is this right, and if so
>would such a transient effect really be undermining Mendelian inheritance?

It would not undermine it -- there are genes known in organisms like
Drosophila where RNA from the parent causes large "maternal effects", and
these have long been studied. There are even mathematical models in
quantitative genetics such as this one:
   Falconer, D. S. 1965. Maternal effects and selection response.
     pp. 763-774 in Genetics Today, Proc. XI International Congress of
     Genetics, Vol. 3, ed. S. J. Geerts. Pergamon Press, Oxford.
although most of the maternal effects he had in mind are probably effects
of uterine environment or maternal case, as he was studying mammals.(*)

But it would be true that if an RNA inertia system was major and important
in lots of traits, we would need to modify our models.

>I don't suppose this could be the reason I inherited my grandfather's mutant
>hairline, whereas my uncles all turned out fine...?

Such "throwbacks" were seen as a major phenomenon of heredity ("atavism")
110 years ago. With the rediscovery of Mendel's work 105 years ago, it
was gradually realized that what people were seeing was just recessive
traits.

PS (*) This posting is dedicated to the memory of Douglas Falconer, a
fine researcher and a really nice guy, who was very kind to me during my
stays in Edinburgh. I learned theoretical population genetics first from
his newly-published "Introduction to Quantitative Genetics" in 1960. It
was such a good book that its fourth edition is still in print, 45 years
later.

---
Joe Felsenstein joe@removethispart.gs.washington.edu
 Department of Genome Sciences and Department of Biology,
 University of Washington, Box 357730, Seattle, WA 98195-7730 USA