dye for DNA

Paul N Hengen pnh at fcs260c2.ncifcrf.gov
Tue Aug 15 10:52:26 EST 1995

| A company called Molecular Probes Inc. located in Eugene Oregon sells a green
| dye which they claim is quite a bit more sensitive than ethidium bromide for
| detecting DNA.  I haven't used it, but I am planning to give it a try within
| the next couple of months.  So if you try it, let me know how it well it works
| for you.

This topic has been covered here quite extensively. See the FAQ list for more
information about SYBR Green I. I've used it alot and really like it, however,
there are some shortcomings compared to EtBr. First, if you stain your gel with
SYBR Green I (SGI), it is nearly impossible to remove the dye because you can't
extract it with an organic solvent like isopropanol or isoamyl alcohol. I found
out when I tried to extract DNA from a gel for a mobility shift expt. I was
forced to use EtBr which I could separate from the DNA for later shifts. Second,
it is very expensive and has a very short lifespand. Over a short time (less
than one year in DMSO at -20 C) it begins to lose it's effective staining
ability. I thought at first this might be in part due to freezing and thawing,
but even when I aliquoted it into small volumes of 20 ul and used one at a
time, the sensitivity dropped and I ended up adding more and more until I
finally gave up and went back to EtBr to avoid buyng more SGI. Anyone else
notice this? On the better end, when fresh it is much more sensitive than EtBr
and is less mutagenic according to the Ames test. I asked Molecular Probes
about this recently and I got a fax of the details. They wouldn't tell me who
did the Ames test but here are the results they supplied...SGI produced an
approximately 2-fold increase in histidine(+) revertants in S. typhimurium
strains TA98 and TA102. No mutagenic activity was observed in strains TA100,
TA1535, TA1537, TA1538, and TA97a. EtBr produced an approximate increase of
70-fold in strain TA98, 15-fold in TA1537, 4-fold in TA97a, 80-fold in TA 1538,
and 2-fold in TA102. No activity was observed in TA100 or TA1535.

* Paul N. Hengen, Ph.D.                           /--------------------------/*
* National Cancer Institute                       |Internet: pnh at ncifcrf.gov |*
* Laboratory of Mathematical Biology              |   Phone: (301) 846-5581  |*
* Frederick Cancer Research and Development Center|     FAX: (301) 846-5598  |*
* Frederick, Maryland 21702-1201 USA              /--------------------------/*
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