DNA Extraction from odd sources...

David Hinds dhinds at leland.Stanford.EDU
Tue Mar 10 16:30:15 EST 1992


In article <1992Mar01.210559.16145 at yuma.acns.colostate.edu> rbereson at lamar.ColoState.EDU (Rachel Bereson) writes:
>In article <1992Feb26.182351.16337 at news.nd.edu> bpollak1 at frumpy.helios.nd.edu (brian pollak) writes:
>>
>>     I'm not 100% certain, but I though that feathers were made of proteins
>>(specifically keratin - like hair).  In which case, there is no DNA in feathers.
>>Please let me know if I'm way off here.
>>
>>                                              -Bri at n
>I believe you are off here.  Feather pulp contains dermal material and
>therefore does have DNA.  When a feather forms it is supplied with nutrients
>and blood through the pulp.  However, when the feather is molted, the pulp
>withdraws and is used to develop the next replacement feather.  Therefore,
>I would think that one could get DNA from a living feather (before molting)
>by pulling the feather out of the bird.  But, one couldn't get DNA from
>a feather that is found  on the ground.

Actually, you can probably get DNA from either, the same way you can
get DNA from hair.  It seems that occasionally, white blood cells or
other bits of stuff get into the hair/feather at the growth point, and
get incorporated into the final product.  These contaminants contain
detectable amounts of DNA.  With modern methods (Polymerase Chain
Reaction), you can detect and amplify a single DNA molecule.  If a
growing feather contains living tissue, then I'm sure some cells get
left behind after molting.  All you need is one!

There was a joke in our lab that if you want to get a piece of cloned
DNA from someone else's lab without asking, just get them to mail you
something, and make a library of clones from the traces of DNA in the
fingerprints on the envelope.  Any sequence that has been cloned in
the lab is bound to be on there somewhere.  It is extremely difficult
to clean all the DNA off of anything - it is a perfect contaminant,
because it is very stable, and a single molecule is all you need.

	- David Hinds
	  dhinds at allegro.stanford.edu



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