We have begun to clone and characterize a newly identified gene, unc-(
ev505ts) II. The
ev505 mutation causes worms to be slightly uncoordinated, semi-dumpy and have ventral clear patches characteristic of mutations affecting circumferential guidance of the Distal Tip Cells as in unc -5, -6 and -40. The penetrance of the gonad defect in
ev505 is temperature-sensitive and, interestingly, shows a strong bias for the posterior arm. The
ev505 mutation does not affect the expression pattern of an
unc-5-lacZ reporter construct, indicating that the gene is not required for
unc-5 expression.
ev505 does, however, appear to affect guidance functions mediated by
unc-5, as preliminary results show that it partially suppresses the ability of the
mec-7-
unc-5 transgene to mediate the ectopic dorsalward guidance of the touch cell axons (see Colavita & Culotti abst., this Meeting).
ev505/mnDf77 is more penetrant than
ev505, and two more alleles found in a non-complementation screen both have less penetrant gonad defects than
ev505 itself. The gene lies on LGII between
unc-53 and
sqt-1. We have rescued the mutant phenotype of unc-(
ev505) worms by transformation with a single cosmid, C47G2, which lies just left of
sqt-1 and are currently attempting to minimise the rescuing region using subclones of the cosmid.