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.

A Convenient Phenotype for DNase - Mutant

P. Babu

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 
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.