The maternal-effect nob mutation
ct344 is an allele of
unc-62.(1) Heterozygous
ct344/+ hermaphrodites produce 12% F1 Nob embryos; their viable
ct344/ct344 siblings produce 42% Nob embryos and 57% dead eggs.
ct344 fails to complement the two other known
unc-62 mutations,
s472 (L1 lethal) and
e644 (viable, Unc.(2) Surprisingly, however, the
e644 and
s472 mutations recombine with a frequency of 0.75%, suggesting that
unc-62 might be a large gene or a complex locus. Using molecular markers, we have mapped these mutations to a small region of the physical map containing two cosmids and two gaps. Luckily, injection of these two cosmids together into heterozygous
ct344/+ hermaphrodites gives rise to stable, viable, homozygous
ct344 mutant strains. The majority of these rescued animals display body morphology defects remeniscent of those seen in
e644 homozygous mutant animals and most die as fertile, but severely Egl adults. Further molecular characterization and analysis of the
ct344 Nob phenotype are in progress.