Worm Breeder's Gazette 13(3): 58 (June 1, 1994)
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.
The semidominant mutations e1597 and n500 in unc-103 m between unc-79 and dpy- l7 result in paralyzed movement and defective egg-laying. Some spontaneous intragenic suppressors were shown to be null alleles of unc-103 (1), and thus both e1597 and n500 were considered to be gain-of-novel-function alleles. We have begun to clone and sequence this gene by the conventional transposon tagging method, assuming that disruption of the unc-103 semidominant alleles by transposon insertion must result in wild-type phenotype.
We first constructed a strain that carries the semidominant e1597 mutation in the mut-6 background by introducing e1597 into RW7097 and then from this strain isolated spontaneously arising apparently wild-type revertants. All of the three revertants so obtained ( e1597 k103 , e1597 k104 , e1597 k105 )were tightly linked to e1597 ,and one spontaneous Unc revertant from e1597 k104 showed a phenotype similar to that of e1597 .
New Tc1s were detected on LGIII in all of the three revertants. A Tc1 -tagged1.7-kb SalI fragment, which was genetically mapped between unc-79 ( e1068 )and dpy-17 ( e164 ),was cloned from e1597 k104 and sequenced. The 1.7-kb fragment consisted of a 976-bp Tc1 fragment and a 0.7-kb genomic sequence. The 0.7-kb fragment, which expectedly hybridized to the 1.7-kb SalI fragment from e1597 k104 ,hybridized to a fragment of more than 20 kb in e1597 and in the Unc revertant. The results together indicate that a new Tc1 was inserted into a terminal region of the large SalI genomic fragment in e1597 k104 and that it was excised from the region in the Unc revertant. The "large to small to Large" band shift is consistent with the corresponding phenotypic change "Unc to Wild to Unc," suggesting that the 0.7-kb fragment is a portion of unc-103 .We are trying to sequence genomic and complementary DNA clones that hybridize to the 0.7-kb fragment.