acridine orange and M phase detection

JOHN F. BOYLAN (boylanjf@a1.lldmpc.umc.dupont.com)
Thu, 21 Mar 96 11:46:27 -0500

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I have a question about the mechansim by which acridine orange
can discriminate between the G2 and M phases of the cell cycle.
As described by Dr. Darzynkiewicz, we have been able to use
acridine orange to separate G2 from M. As I understand the
procedure acridine orange fluoresces red when bound to denatured
DNA and green when bound to double stranded DNA. Under mild
denaturization conditions, G2 DNA exist in the double stranded
state. M phase DNA exists in a more denatured state because it
is condensed.

Questions:

Why is condensed DNA more sensitive to mild denaturation?

What determines whether acridine orange fluoresces red or green
once bound to the different types of DNA? Does AO take on a
different configuration once bound emitting at different
wavelenghts??????

thanks
john

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