We have been trying to clone
age-1 gene.
age-1 was mapped to the left of
unc-4 on chromosome II. The predicted genetic distance between
age-1 and
daf-23 is about 2 c.m. Recently, it has been proposed that
age-1 and
daf-23 may be allelic, because they do not complement for the Daf-c phenotype at 27oC (Inoue, T. and Thomas, J., 10th international C.elegans meeting). To test this possibility, we performed genetical mapping between
age-1 and
daf-23 by taking advantage of the Daf-c phenotype. We crossed TJ1052 [
age-1(
hx546)] males and
daf-23 homozygotes from DR846 {
unc-4(
e120);
daf-23(
m333)/mnC1[
dpy-10(
e128);
unc-52(
e444)] }(DR846 is from Don Riddle). The cross produced two F2 recombinants out of 1,261 tested. The genotype of these recombinants indicates that the genetical distance between
age-1 and
daf-23 is 0.3 c.m. This result is consistent with the data that the Daf-c phenotype ofage-1 maps between
bli-1 and
rol-1 (Thomas, J., personal communication). This suggests two possibilities: 1)
age-1 and
daf-23 are allelic and 0.3 c.m. reflects intragenic recombination, or 2)
age-1 and
daf-23 are not allelic but genetically close to each other. More precise mapping, such as physical mapping of the two genes, would be necessary to test these possibilities. Since partial non-complementation between different genes has been observed in yeast (e.g., Murakami, S. and Niwa, O., in press), it might be possible that mutations in different genes fail to complement. We have also tried to map
age-1 by using chromosome deficiencies (Dfs). Interestingly, many, but not all, strains carrying deficiencies around
unc-4 or
sqt-1 (close to
daf-23) produce dauers at 27oC. This finding suggests that they are haplo-insufficient. Although these Dfs are not very useful for mapping the Daf-c phenotype of
age-1, they may be a good tool for mapping new Daf-c mutations. A single copy of one or more genes in these deficiency regions causes dauer formation at this temperature. We are now mapping these Daf-c responsible regions. Preliminary results suggest three possible regions: to the left of
unc-4, to the right of
unc-4 (this does not include
daf-19), and at
daf-23.