Recently we have been moving to the University of Colorado at Boulder and have not accomplished much. Before that, however, we had proceeded with isolation and characterization of recessive lethals linked to the markers
dpy-10 II and
unc-4 II. These mutants were isolated following EMS mutagenesis of the heterozygote
dpy-10/unc-4 and are maintained in this background as heterozygotes by passing worms of wild phenotype (WBG, Confabulation Issue, April 1977). A total of 34 lethals now has been isolated from a screening of 1504 F1 clones. The following table summarizes their lethal phenotypes: [See Figure 1] The distribution of phenotypes is similar to that found among the ts lethals of Hirsh and Vanderslice (1976), except for the large percentage of larval arrest mutants in our sample. All the mutants mapped so far lie within 5% of either
unc-4 or dpy- 10. All possible pairwise complementation tests have been carried out between the class (3) mutants,and each of these mutants has been tested against B244, a maternal ts zyg mutant from the Hirsh collection. Only one case of allelic lethals has been found so far:
ct10 fails to complement
b244ts. Clearly this method is effective for obtaining closely linked lethals in a particular region of the map, and can be expected to yield more allelic lethals as more mutants are isolated.