>> This is probably a really dumb question but...
>> Does anyone out there know a good way to get DAPI into
> live embryos without removing the vitelline membrane?
>> Or do you know of any data referring to the toxicity of
> DAPI when injected into embryos and its dose dependence?
>> Any info much appreciated.
There are some methods out there for permeabilizing embryos with octane,
which pokes holes in the vitelline membrane and allows small molecules
to enter the embryo. DAPI is fairly bulky though; I do not know if it
would effectively move across the embryonic membrane (or across lipid
bilayers if you are working with cellular blastoderm or later), but
since it is used in flow cytometry (Cubria et al. Comp. Biochem.
Physiol. C 105: 251, 1994; Hotz et al. Cytometry 15: 237, 1994; Lee and
Garnett J. Biochem. Biophys. Methods 26: 249, 1993), and for working
with nuclei in apoptotic cells it should be reasonably cell-permeable.
Much of this info is from the CalBiochem catalog.
DAPI is supposed to be a carcinogen (not surprising given that it
intercalates between bases), but I would bet that toxicity is low at
least in the short term.
Hope that helps.
John Rinehart, Associate Professor
Eastern Oregon University
La Grande, OR USA