We have been analyzing a set of 30 1500 r gamma-induced lethal mutations using the sDp2 lethal recovery system. sDp2 is a free duplication of the left third of LGI which we have been using as a 'balancer' for lethals in the region it covers. The recovered lethals have the genotype sDP2/ (let-x
unc-13/
dpy-5) the wild-type allele of
dpy-5 but not
unc-13, all lethal mutations that were recovered have an Unc-13 phenotype. The wild-type alleles carried by sDp2 will not recombine with the normal homologues. We have been mapping these lethals with respect to
dpy-5 and
unc-13 and complementing them with visibles and EMS-induced lethals. Of the 30, 13 are to the left and 8 to the right of
dpy-5 Of the 13 to the left, 9 have been complementation tested; one of these may be a deletion and another,
h330, is a viable allele of
unc-11 recovered as a synthetic lethal with
dpy-5 8 to the right, one
h168, fails to complement several loci including
let-78 and has been designated hDf2. Of the remaining 9 mutations, one,
h53 fails to complement two EMS- induced mutations to the right of
dpy-5 and is not as yet separable from
dpy-5. It is possible that other mutations which did not give recombinants with
dpy-5 are also deletions, perhaps even taking out
dpy-5. We are complementation testing these now. One of the strains which gave no recombinants appears to be carrying an X;I translocation. It was detected initially by a high frequency of males from the self-cross progeny of a heterozygote. There is evidence of pseudolinkage between
lon-2 (X) and
unc-87 (I). Other markers on the X are being tested. We have mapped 51 EMS-induced lethals, 30 to the left of
dpy-5 and 21 to the right. They define 21 complementation groups to the left and about 18 to the right. A note to all gene mappers out there -- If you are working with anything on LGI that might be under sDp2, please make a double of it with
dpy-5. We have found that it is a lot easier to do complementation tests if everything is linked to a common marker. We will be happy to test anything against our deletions if you send it to us or the Stock Center as a
dpy-5 double mutant.