Black DNA from earthworms

Joseph C. Bagshaw jbagshaw at wpi.WPI.EDU
Wed Jun 22 15:04:03 EST 1994

In article <weixCrt5HH.AJ8 at> weix at (Patrick Weix) writes:
><sjames at> writes:
>>I would like to know if anyone has encountered a similar phenomenon with 
>>other critters.  When we do any of several standard DNA preps, we get a 
>>very dark brown to black pellet that turns out to be DNA- it looks like 
>>DNA to UV, it does ok when we try to amplify various genes, etc.  Why the 
>>concern if it works?  It doesn't always work. Some worms yield darker DNA 
>>than others, and there have been problems getting PCR reactions to go.  
>>Magnesium manipulation sometimes helps, sometimes not.
>>   It would be nice to know 1) what is this dark stuff, 2) how to get rid 
>>of it, or 3) how to consistently work around it.  Yes, we have taken the 
>>dirt out of the worms first.  Thanks to all, and I hope this is not a FAQ.
>I doubt that this is a FAQ. I have encountered the co-purification of
>pigments with DNA in two different systems: yeast ADE mutants and
>melanocytes. Yeast ade1 and ade2 (I hope I am remembering this
>correctly) produce a red pigment.  The older the cell colonies are,
>the darker the pigment (likely just more of it).  
>   Also, in purifying DNA from melanoma cell lines, the pigment will
>co-purify with the DNA, giving me brown DNA preps.  So far, it has not
>been a problem with PCR, but I only use 60ng of this mouse melanoma
>DNA for a 20microl rxn. Perhaps you add too much DNA (more than is
>necessary) and thus get too much pigment in the rxn?  I do not know
>how you purify your DNA. Perhaps you could get it away from the
>pigment with Elutips or one of the glass powder systems?
>Good luck,
>                                             weix at

Colorfull colleagues,

I can produce DNA in a number of hues, depending on the choice
of starting material.  Brine shrimp DNA is a delicate muave.  
Marine shrimp DNA ranges from pale amber to deep purple, depending
on which part of the shrimp.  Terrestrial isopods produce DNA that 
is nearly black, and little fishies (whole) give violet DNA.
Colorless DNA comes from colorless critters, like rats and mice
and people.

********************  HAVE GENES, WILL TRAVEL  ********************
Joe Bagshaw, Worcester Polytechnic Institute
jbagshaw at
Roadkill on the information superhighway.

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