Ethidium Bromide

John Nash nash at
Thu Jun 10 20:41:22 EST 1993

In article <C8F77F.MzA at> horton at (Robert Horton) writes:
>From: horton at (Robert Horton)
>Subject: Ethidium Bromide
>Date: Thu, 10 Jun 1993 19:18:57 GMT

>Subject: Re: Ethidium Bromide mutagenesis
>Newsgroups: bionet.molbio.methds-reagnts
>References: <1993May6.145845.42883 at>
>X-Newsreader: Tin 1.1 PL5

>bickle at wrote:
>: Since this (very thin) thread started, I've done a little reading in the
>: subject. It turns out that EtBr is not mutagenic in the Ames test unless
>: it is S100 activated, when it scores just above background.

>So why all of the paranoia about EtBr? In our lab, we've ended up collecting
>the stuff in jugs until the "to bleach or not to bleach" question is finally
>settled. Is it really that dangerous? The Merck index lists its therapeutic
>cat (vet) as an antihelminthic in sheep ("Mary had a little lamb/ Whose fleece
>was orange and glowed...") but the way people treat it, you'd think it was
>(gasp!) radioactive or somethin'. If they've been feeding it to sheep for
>years in quantities large enough to kill worms, you'd think somebody would
>actually KNOW if it causes leukemia or not by now. I haven't been able to find
>much in the biomed literature (ok, I didn't look REAL hard); any NetWisdom
>would be appreciated.

I always figured ethidium bromide was over-rated as a hazard, but being the 
cautious type, and _not-an-expert_, always erred on the side of not 
splashing it on my colleagues.

What I do remember was an experiment we did in 2nd year biochem, wa-a-ay 
back in 197-umph!.  We looked at the ability of ethidium bromide to: a) 
cause petite mutations in yeast, and b) revert a tyr mutation to wild type
(also in yeast).  It did the former very well, but not the latter at all.  
On the other hand, EMS did b) very well indeed.  So, if your DNA is not 
naked, maybe you don't have to worry as much????

  cheers, John

  John Nash                           | Email: Nash at
  Institute for Biological Sciences   |
  National Research Council of Canada | Email to my other NRC accounts
  Ottawa, Ontario, Canada.            | is usually forwarded here.
	  *** Disclaimer:  All opinions are mine, not NRC's! ***

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