Many years back as a graduate student I used DAPI to image individual
chromosomes in dividing sea urchin embryos.  There was a concentration in
which the cell cycle timing was undistubed and you could see each
chromosome clearly for at least three cell divisions.  At higher
concentrations the chromosomes did not condense as well and tore themselves
apart during cell division.  As my thesis involved microtubules and the
spindle I never pusued the cause and effect of the problem.

-Neal Gliksman Ph.D.

At 10:58 PM 8/12/97 -0400, you wrote:
>I need some help from people who have experience in using DAPI as a vital
>staining!!
>
>I'm studying the nuclear cycle of some particular Zygomycetes. For this
>doing I incorporate a certain concentration of DAPI to the culture medium,
>and, after a certain period of fungal growth, I observe the features of
>nuclei along the fungal hyphae. I've observed that some nuclei stain more
>brightly than other, and I'm wondering about the reason of this.
>
>I have several questions I'd really appreciate to be answered...
>
>- Do some of you have any experience on possible interferences of DAPI with
>the nuclear cycle? It's generally considered as a "vital stain",
>semi-permeant (??) and used for cell-cycle studies (Molecular Probes'
>Handbook, 6th ed.); however, and although some authors have stated that it
>do not reduce the viability of cells (Toda et al., 1981) I still wonder if
>it could disturb/interfere:
>
>                                        - DNA replication
>                                        - Chromosome condensation
>                                        - Mitosis
>                                        - RNAs viability
>
>- Kulik and Dery (1995) stated that DAPI reacts only with LIVING nuclei
>(!!); Would that meant that it would not stain nuclear debris or DNA
>suspensions? What is the real meaning of "vital stain" (in this case,
>applied to DAPI)?
>
>- Do you guess any reason for the increased DAPI's fluorescence intensity
>in certain nuclei of my cultures compared to others? Could I expect an
>increase in fluorescence when the nucleus is endommaged (as in this
>situation the DNA would be in a more decondensated/degrading state,
>therefore more accesible to the dye)?
>
>- Barcellona et al. (1990) stated that DAPI interacts REVERSIBLY with DNA.
>Do any of you know/guess the nature of this reversibility?
>
>- Any hints about possible DAPI degradation/elimination once inside a
>living cell?
>
>Please, reply directly to my email address!
>
>Many thanks for your cooperation,
>
>Berta.
>
>Dr. Berta Bago
>Centre de Recherche en Biologie Forestiere
>Pavillon C.-E. Marchand
>Universite Laval, Quebec
>G1K 7P4,Canada
>
>