Worm Breeder's Gazette 2(1): 19b

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.

Inhibition of Chemotaxis with HgCl2

M.S. Zwass, C. Johnson, D. Russell

While screening chemicals for effects on chemotaxis, it was found 
that treatment of young adult nematodes for 30 min with 10+E-4 M HgCl2 
produced a reversible loss of chemotactic responses to normally 
attractive ions, without markedly affecting motility.  Higher 
concentrations of HgCl2 (10+E-3 M) were lethal.  At sublethal 
concentrations, other sulfhydryl reagents (N-ethyl-maleimide, p-
chloromercuribenzene sulfate, methylmercuric hydroxide, and cysteine) 
were without effect on chemotaxis, but 10+E-4 M CdCl2 did give a 
similar effect.  The response deficit produced by HgCl2 was quite 
specific; responses to thermal and mechanical stimuli were not 
affected, and osmotic responses were only slightly affected.  The site 
of HgCl2 action is unclear, HgCl2 did not affect cooled worms or dauer 
larvae, both of which fail to show pharyngeal pumping, suggesting an 
internal site of action.  Attempts are now being made to determine the 
site of HgCl2 action more accurately and Dave Dusenbery is comparing 
the HgCl2-induced defect with that produced by sensory-defective 
mutations.  
Preliminary experiments with the radioactive isotope 203Hg suggest 
that it may be possible to identify the molecules with which Hg++ 
interacts to produce its effect.