Worm Breeder's Gazette 11(4): 68
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.
Unc-116 is a genetic locus identified by spontaneous mutation during a screen of TR679 for genes involved in axonal guidance. Unc-116( e2312) hermaphrodites display abnormal locomotion, primarily during backward movement. Anatomical abnormalities include the misplacement of axons which normally occupy a lateral position and abnormal hyp-7 nuclear migrations along the circumferential axis (Thierry-Mieg and Mancillas, in preparation). Unc-116 was cloned by a combination of transposon tagging and location in the physical map, and partial cDNAs were isolated from the Ahringer library using genomic probes. We have obtained sequence information from those cDNAs as well as genomic fragments. Comparison of sequences available in Genbank to sequence determined from the end of a 1.4 kb cDNA revealed a 63% identity to Drosophila melanogaster heavy chain kinesin (Yang et al, Cell (1989) 56: 879-889), over a stretch of 307 nucleotides. At the amino acid level, using the best open reading frame from the unc-116 sequence, unc-116 is 57% identical (71% similar) to amino acids 855-975 in the c-terminal end of Drosophila kinesin. The similarity to unc-116 is within the structural domain of kinesin which Yang et. al. propose to be involved in interactions with vesicles, organelles, or the light chain of kinesin and does not include any of the postulated ATP and microtubule binding domains. When the nucleotide sequence and predicted amino acid sequence of unc-116 were compared to Genbank and NBRF/Swissprotein data bases, respectively, no other significant matches were found. Sequence data (approximately 300 bp) of the other end of the 1.4 kb clone, 650 nucleotides away from the kinesin-like domain, showed no significant matches to Genbank or NBRF/Swissprotein data base entries. We suggest that unc-116 has a domain similar to the c-terminal 'tail' domain of Drosophila kinesin, and that this domain may play a role in 'recognition' events for both axonal guidance and intracellular transport. We are currently sequencing the remainder of the 1.4 kb cDNA and have used it as a probe to obtain longer, putative full-length clones from Stuart Kim's gt19 mixed stage hermaphrodite library. We obtained 150 positives after screening 100, 000 plaques, a frequency higher than anticipated (approx. 1/670). We plan to sequence our longer clones as well. We have also started to characterize the phenotype and mating efficiency of unc-116 males. From preliminary observations, unc-116 males display abnormal backward locomotion, adopting a U-shape when stimulated by a tap on the head. The posterior third of the animals appears abnormal: rigid, slightly swollen, and clear. Those morphological abnormalities are likely to be responsible for the low mating efficiency we have observed.