From: Howard Shapiro (hms@shapirolab.com)
Date: Fri Oct 16 1998 - 16:59:30 EST
Derek Schulze asks: > >Does anyone know if chromomycin A3 will stain mitochondrial DNA. I am >trying to find a suitable DNA stain for yeast cells that does not stain RNA >or mitochondrial DNA. I am limited to an argon laser (488nm only). > >I was thinking that I could fix and stain the yeast with a chromomycin (or >mythramycin)/ ethanol mix. I guess my rational was that the short fixation >would not be adequate for permeabilizing the mitochondria thereby >preventing the stain from penetrating. > If mitochondrial DNA has G-C base pairs in it (and I'm sure it does), it will stain mitochondrial DNA. The idea of permeabiloizing the cells and not the mitochondria is cute, but I doubt you'll find anything which will make the cell wall permeable and leave the mitochondria intact. However, the biggest problem you will face is that neither chromomycin A3 nor its relatives (mithramycin and olivomycin) can be excited at 488 nm; 457 works, but shorter wavelengths (e.g., 436 nm from an arc lamp or 441 nm from a He-Cd laser) are better. You might have a shot with 7-aminoactinomycin D, which is a really big molecule, but which is at least DNA-specific. It won't stain the RNA, but it very likely would stain the mitochondrial DNA. -Howard
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