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RE: Radiation Hormesis -- or not
John;
Genetic effects are completely random and as you mention cannot be "willed."
We only see the positive genetic mutations such as opposable thumbs because
all of the negative mutations were selected against- in other words, they
died. Random effects are very unlikely to be positive and that is why
evolution takes so long. Most mutations change a protein structure such as
a hormone that may render it unusable to the organism.
My theory on the relative strength of the seedlings in the experiment in
question is that the radiation killed off various fungi and viruses that may
have lived on the seeds, and not a favorable mutation within the seed
itself. After all, a dormant seed is not made up of actively dividing
cells.
Cheers;
Catherine
-----Original Message-----
From: John Jacobus [mailto:crispy_bird@YAHOO.COM]
Sent: Monday, January 26, 2004 4:17 PM
To: Neil, David M; Carl Speer; radsafe@list.Vanderbilt.Edu
Subject: RE: Radiation Hormesis -- or not
Why would a genetic mutation favor a negative effect?
After all, evolution shows that genetic effects are
positive since they allow the organism to adapt.
Primates did not get opposed thumbs by willing it to
happen. It was genetics.
Again, my statement was that it should have been
checked to see if it was a genetic mutation by
following the growth pattern of the off-spring.
--- "Neil, David M" <neildm@id.doe.gov> wrote:
> If it were a genetic mutation, the odds favor
> (immensely) a negative effect. This would translate
> to lower germination ratios (live plants per seed
> planted) and a mixture of positive and negative
> effects. This is not what is observed.
>
> Dave Neil
>
> -----Original Message-----
> From: John Jacobus [mailto:crispy_bird@yahoo.com]
> Sent: Friday, January 23, 2004 7:09 AM
> To: Carl Speer; radsafe@list.vanderbilt.edu
> Subject: RE: Radiation Hormesis -- or not
>
>
> Carl,
> A thought came to me. How do you know this was a
> hormetic effect and not a genetic mutation? My
> understanding is the a hometic effect involves the
> addition of some simulus to an living organism to
> get
> a beneficial response. You irradite mice to low
> doses
> and you get a certain response, e.g., an increase in
> the immune system. When the agent is stopped, the
> hormetic effect is no longer evident after a time.
> Maybe this definition for hormesis is too limiting,
> but this is what I believe it is.
>
> Seeds are not actively growing or responding
> organisms. If you irradiated the growing plant, I
> would agree that would be be a way of demonstrating
> a
> hormetic effect. Did you try and grow new plants
> from
> the seeds produced from the mature, irradiated
> plants?
> I think that would have demonstrated the effect of
> genetic mutation.
>
> --- John Jacobus <crispy_bird@yahoo.com> wrote:
> > Interesting. What were the doses?
> >
> > --- Carl Speer <rtrs@cox.net> wrote:
> > > Karl (and others),
> > >
> > > We had and interesting laboratory experiment in
> > > Radiation Biology when I
> > > was in college where we irradiated bean seeds,
> > fruit
> > > flies, and onion
> > > root with low, med, and high doses from a Co-60
> > > source from a local
> > > hospital. To show the effects of hormesis, no
> > > effect, and ill effect
> > > the students all received seeds from each
> exposed
> > > group plus seeds that
> > > did not get any extra dose (controls). We
> planted
> > > the seeds in cups at
> > > our home, gave all plants the same amount of
> water
> > > and noted the
> > > differences. The seeds with the low doses had
> > more
> > > vigorous growth,
> > > smaller internodal lengths, and healthier leaves
> > > than the control. The
> > > higher dose plants had brown shriveled leaves,
> > > stunted growth, and other
> > > undesirable characteristics. We made a plot
> > showing
> > > that as the dose
> > > initially increased we saw a net positive effect
> > > (hormesis) but as the
> > > dose continued to increase, a negative effect
> > became
> > > apparent. This
> > > made a lasting impression and I have believed in
> > > hormesis ever since. I
> > > know people are not bean plants or fruit flies
> but
> > > this little
> > > experiment gave the hormesis theory more
> > > believability than the LNT in
> > > my mind.
> > >
> > > As for the fruit flies I don't remember the low
> > dose
> > > effects. What
> > > stands out in my memory were the horrific
> > mutations
> > > in the offspring of
> > > the high dose flies.
> > >
> > > The onion root tips were used so we could see
> the
> > > chromosome damage in
> > > the cells undergoing meiosis.
> > >
> > > See http://www.belleonline.com/n2v82.html
> > RADIATION
> > > HORMESIS: ITS
> > > HISTORICAL FOUNDATIONS AS A BIOLOGICAL
> HYPOTHESIS
> > by
> > > Edward J. Calabrese
> > > and Linda A. Baldwin for a good discussion on
> > > Hormesis.
> > >
> > > Carl Speer
> > > Real-Time Radiological Services, Inc.
> > > 2721 Losee Rd, Suite E
> > > North Las Vegas, NV 89030
> > > 702.639.0066
> > > www.RealtimeRad.com
> > > RTRS@cox.net
> > >
> > >
> > > -----Original Message-----
> > > From: owner-radsafe@list.vanderbilt.edu
> > > [mailto:owner-radsafe@list.vanderbilt.edu] On
> > Behalf
> > > Of
> > > RuthWeiner@AOL.COM
> > > Sent: Monday, January 19, 2004 7:28 AM
> > > To: "Karl Ellison";
> > > radsafe-digest@list.vanderbilt.edu
> > > Subject: Re: Radiation Hormesis
> > >
> > > I have always wondered how one could distinguish
> > > hormesis effects from
> > > ordinary good health. An example: small amounts
> > of
> > > ionizing radiation
> > > are supposed to stimulate bone knitting after a
> > > break (I read this
> > > somewhere). However, the rates of bone recovery
> > > vary. Has there beenn a
> > > controlled study of this phenomenon? After my
> > > latest hip surgery, my
> > > doctor predicted that incorporation of the bone
> > > graft would take two
> > > years. It took six months. I was taking a drug
> > > that enhances calcium
> > > metabolism and I had quite a few xrays and I get
> a
> > > lot of exercise, so
> > > was it the drug, the x-ray, the exercise, two of
> > > those, or all three?
> > > Are there definitive studies showing hormesis?
> > >
> > > I am perfectly ready to accept hormesis, but in
> > the
> > > current radiophobic
> > > climate, I believe we are better off just
> claiming
> > > no harm at less than
> > > a particular dose. Hormesis is one of those
> > > phenomena that even if it
> > > is real, doesn't SOUND real.
> > > --
> > > Ruth F. Weiner
> > > ruthweiner@aol.com
> > > 505-856-5011
> > > (o)505-284-8406
> > >
> > >
> >
>
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> >
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=== message truncated ===
=====
+++++++++++++++++++
"I have sworn upon the altar of God, eternal hostility against every form of
tyranny over the mind of man."
Thomas Jefferson
-- John
John Jacobus, MS
Certified Health Physicist
e-mail: crispy_bird@yahoo.com
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