From owner-drosophila@net.bio.net Wed May 25 23:00:00 1994 Path: biosci!agate!lsa3mac35.berkeley.edu!user From: dobson@mendel.berkeley.edu (Steve Dobson) Newsgroups: bionet.drosophila Subject: DNA Staining LIVING Embryos Followup-To: bionet.drosophila Date: 26 May 1994 23:08:30 GMT Organization: U C Berkeley Lines: 23 Message-ID: NNTP-Posting-Host: lsa3mac35.berkeley.edu Greetings, I'm trying to characterize chromosomal behavior of very early embryos (1st-4th cleavage division) in an ant ("relatively" close to drosophila). I've been observing fixed embryos, but I would like to observe living embryos. By far, the most popular method of visualizing chromosomes in living drosophila embryos is incorporating fluorescently labelled histones. Unfortunately, this method seems work best with observations of later embryos (after 7th cleavage division) due to the time required to incorporate the labelled histones. If I am mistaken, please inform me (I've never actually done this myself). So....I would like to know if anyone has ever successfully used DAPI, YOYO-1, or other DNA stain to stain living embryos. I have been informed that free radicals liberated from these dyes upon UV exposure stops normal chromosomal maintainence. Is this true ? Has anyone actually tried this ? Any other suggestions of ways to visualize early chromosomes ? Answer via this newsgroup or e-mail (dobson@mendel.berkeley.edu). Thank you very much !! Steve Dobson .