Worm Breeder's Gazette 11(2): 115
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.
We have isolated a new T-ray defective mutation, bx59, in a screen for male-specific Uncs. bx59 is a recessive mutation that results in loss of rays 7-9 and ray 5. The mutant phenotype is fully penetrant, but has variable expressivity. Thus, every homozygous male exhibits some ray loss. Other rays are missing a low percentage of the time. An Unc phenotype (male-specific coiling, starting from the tail) has segregated with the Mab defect. bx59 has been localized to the left of dpy-17 on LGIII. We are currently investigating the nature of this mutation (i.e. lineage defect, ray attachment defect, etc.), but we have no data on this at the present time. The male-specific Unc screen was suggested to us by the observation that, in addition to loss of T rays, mab-19(bx38) males coiled transiently at a higher frequency and for a longer duration than him-5( e1490) males (for a description of mab-19(bx38), see the accompanying article). We observed what may be anomalous mating behavior: mab-19( bx38) males are unable to efficiently flip around the ends of moving hermaphrodites during the backward search for the vulva and end up coiling upon themselves, starting from the tail. mab-19(bx38) males are almost infertile, possibly due to a mating defect. We wanted to correlate the infertility and coiling phenotype with the loss of the T- derived rays. We tried ablating T.a in him-5(e1490) males, but found no difference in the frequency with which wild-type or surgically altered males coiled on mating plates. Surgically altered males produced cross progeny (but fewer than wild-type males), whereas mab- 19(bx38) males did not. Therefore, loss of T-rays alone did not account for the infertility. We then attempted to isolate Mab mutants on the basis of male- specific coiling in clonal populations from mutagenized hermaphrodites. F1 hermaphrodite progeny of EMS-mutagenized animals [him-5(e1490)] were picked separately to 35mm seeded plates. F1 populations were scored at 12x for male-specific coiling. 15 plates out of approximately 750 contained males that were coiling more than control him-5(e1490) plates. Males from each of these plates were scored at 400x on agar pads. Of the 15, two plates contained severely Mab males (blunt, rounded tail phenotypes). Another plate contained males that had lumpy rays (Ram phenotype). A single plate contained males that were missing T-derived rays (bx59). The other 11 plates did not contain males with any obvious Mab phenotype. Since we were able to find only a few plates that seemed to contain male-specific coilers, and of these, almost 25% contained animals that exhibited an obvious Mab phenotype, it appears that the premise of the male-specific Unc screen may have been correct. Since one of the mutations isolated resulted in loss of the T-derived rays, it is possible that the T rays may be necessary for flipping around the end of the hermaphrodite during the search for the vulva. However, bx59 males are more fertile than mab-19(bx38) males, although we have not performed any mating efficiency tests to date.