Worm Breeder's Gazette 1(2): 10
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Dew and Sulston have reported (WBG-1) the discovery of nuc-1 mutant of C. elegans which lacks the principal endodeoxyribonuclease. They also find on Feulgen staining, stranded material in the lumen of the gut which is presumably undigested DNA of E. coli. This observation suggested a method of providing a fluorescent phenotype for nuc-1 mutant by feeding the worm a chemical which binds to DNA and has enhanced fluorescence on binding to double stranded DNA. Among the various chemicals tried for this purpose, ethidium bromide works quite well for this purpose. About 0.5 ml of 0.5% ethidium bromide in water is spread evenly over the agar of a petri dish containing well fed worms. After a few minutes, the plate is observed under the dissecting microscope using incident high intensity UV in the range of 300-400 nm (Babu M.G.G. 135 39-44). Nuc-1 worms have a distinct orange fluorescence of the lumen; nuc-1+ worms lack this fluorescence. On transferring these worms to a plate which does not have ethidium bromide, the orange fluorescence of nuc-1 fades in a few minutes. The fluorescence phenotype of nuc-1 is easily scorable and thus provides a convenient phenotype. After a few hours on the ethidium bromide plate, the orange fluorescence sometimes spreads to the gut cells of both nuc-1 and nuc- 1+ worms; this makes scoring of nuc-1 difficult. Hence observation of nuc-1 phenotype must be made fairly soon after adding ethidium bromide.