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.
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.