Re: irradiating pumpkin seeds

ANDERSEN.CHRISTIAN_D@Seattle.VA.GOV wrote:
> 
> Some time ago i posted about irradiating pumpkin seeds, and the possible
> effects.  ..... I can't wait to nuke these seeds!
> 

This should give you some insight into the processes involved. The
following message was sent to me by a relative of the author(someone who
works in this field), I hope you find it interesting.
____________________________________

About irradiation sources:  

" Many things have be used to try to mutate seed, pollen, buds and
vegetative parts of plants.  Electrical fields, microwaves, soundwaves
etc., have very little effect.  You need a strong ionization source such
as a gamma ray, x-ray, or neutrons to knock the electrons out of orbit
so that the genetic material will rearrange.

Neutrons are nasty and cause the samples to be radioactive so they are
not used much. X-rays are usually a mixture of soft and hard (low
penetration and high penetration) so are difficult to calibrate to get
the correct dose.  

Gamma rays are the irradiation of choice because, they do not produce
radioactive, they are very penetrating so dosage is easly calibrated,
and the sources can usually be found around Universities and Hospitals. 
The hospitals treat cancer patients with high dosages.  These would be
good sources.  Universities have some around their Physics department to
look through metal, and they are usually hot sources.  

I use a cobalt source that gives about 2500 rads per hour.  Typical
exposure time for the sample is from 4 to 5 hours.  This is on
vegetative buds.  Seeds take much more dosage than this.  They will
require 20000 to 30000 rads. Dental machines that take pictures give
only a fraction of a rad. (for safety) to take a picture, so it would
take a very long time to get to these dose levels.  

If you cannot find an irradiation source, you might consider chemical. 
There are some chemical mutagens which have the same effect, but with
less chromosome damage.  Ethyl Methane Sulfonate, Diethyl sulfate and
others.  Be careful with chemicals, they are very toxic and need to be
handled in a good fume hood.  I have not kept up with chemical
mutagens.  There may be some that are easily obtained and not so toxic."
_________________________________________________________
Brian

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