Re: Hormesis - Theory and Observation

["willy valdivia-granda" <willy_valdivia@ndsu.nodak.edu>]

> As a provocative speculation, I suggest that this phenomenon may be due to

> an induction of stress proteins that respond to many different types of 
> stress - of which DNA damage could be one involved. 

Note that for this experiment we irradiate seeds with low germination rate.
I don't know if can be possible obtain animal or human tissue with reduced
"survival" ability. So far, our speculation is that neutrons altered or
destroyed compounds involved in seed germination inhibition. Therefore,
better survival due to a fast germination with less seed deterioration was
observed. However, we don't know why plants irradiated with low doses were
taller and flowered early. These characteristics were not observed in the
control or with other doses. 

> The growth induction itself would then not reflect better "health" of the
seed but rather "the 
> environment is now so tough that you have better produce a plant and 
> reproduce while you have the chance (regardless of any induced
mutations)". 
> The strategies for growth and producing seeds of flowering plants are very
different depending on the general stress and "danger" in the environment.

We think that external factors have a relative strong influence in the
"hormetic" effect/response. When we look for specific mutation, we found it
in the "hormetic" material. We assume that despite that there is a
stimulatory effect, DNA radiation damage still produced. May be other
organisms with high ploidy level may have the ability to buffer these
mutations. Therefore, only the stimulatory effect is observed (I am not sure
about "in other organims"). 

Despite that these results are in the range of the hormetic effect proposed
by Calabrese (1999) we were unable to test the experiment again. We are
looking for a facility that have a clean fast neutron flux that can be use
to test our hypothesis that low doses of fast neutrons can induce
stimulatory effects. 
  
I could develop this more but would then drift off-topic. I would not expect

> the phenomen to show up in the next generations as well.

Please send me an e-mail with your ideas.

Thank you,

Willy Valdivia
North Dakota State University
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html