TABLE 4

Weak ced-3 alleles did not prevent the sterility caused by the ced-9(n1950 n2077) allele

Parental genotype: ced-9(n1950 n2077)/+; ced-3/+ced-9 homozygotes: Fertile/total
ced-3 allele (avg. no. extra cells)
n2424 (0)0/30
n2923 (0)2/30*
n2446 (0.13)0/30
n2449 (0.2)0/30
n2425 (0.3)0/30
n2447 (0.8)3/30
n2443 (1.8)6/20
n717 (11.2)10/20
  • The ced-9(n1950 n2077) chromosome was marked with the unc-69(e587) mutation. Unc-69 animals were inferred to be homozygous for ced-9(n1950 n2077). ced-9 mutations result in sterility, which is dominantly rescued by strong ced-3 mutations (Hengartner et al. 1992). Thus, only ced-9; ced-3/+ or ced-9; ced-3 animals are fertile. Each ced-9 homozygote assayed contained zero, one, or two copies of a given ced-3 allele, because these animals were derived from the self-progeny of ced-9/+ ; ced-3/+ animals. For ced-3 mutations resulting in little ced-3 activity, 75% of ced-9 homozygotes scored should be fertile (one-third of these are ced-9; ced-3 and two-thirds are ced-9; ced-3/+). For weaker ced-3 mutations that retain significant ced-3 activity, <75% of ced-9 homozygotes scored should be fertile. Fertility was scored as the ability to lay >20 eggs with at least one embryo developing into a fertile adult. *, each of the two animals gave rise to one viable, sick, and infertile progeny.