Worm Breeder's Gazette 11(3): 53
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.
Sodium fluoride is sometimes used for prophylaxis of dental caries, but it is known to be toxic to most biological organisms, probably because it causes disorder in the metabolism of either calcium ion or phosphate. Although C. elegans may not be a good material for studies on the dental aspect (because it has no tooth), it is suited for studies on the mechanism of toxicity (because it is easily killed by NaF). Isolation and initial characterization of fluoride-resistant mutants of C. elegans have already been reported (Abstract of the 1989 Cold Spring Harbor Meeting on C. elegans). Here we report recent advances. There are now three genes that confer fluoride-resistance to C. elegans; flr-1 maps between unc-9 and unc-84 on the X chromosome (0.4 m.u. from unc-9 and 1.2 m.u. from unc-84), flr-2 maps between unc-76 and dpy-21 V (< 2 m.u. from unc-76), and flr-3 maps in the cluster of daf-1, a-1 and zyg-13 near the left end of chromosome IV. All the flr mutants produce active homozygous (or hemizygous, in the case of flr-1) males. Moreover, the flr-1 and flr- 3 mutants can be easily distinguished from N2 also by their slow growth rate. Accordingly, flr-1 and flr-3 are good genetic markers and may be useful in mapping other mutations. Putative Tc1-insertion mutants have been isolated for flr-1 and flr- 3 from mut-6 and mut-5 strains, respectively. One of them, flr-1(ut11) , has been outcrossed to N2 and to mutants in the flanking genes, unc- 9 and unc-3. Southern blotting of its DNA revealed an extra HindIII fragment of 2.8 kb that can hybridize to the Tc1 probe. We are now cloning this fragment and looking forward to seeing what kind of gene can confer fluoride-resistance to C. elegans by mutation. [See Figure 1]