Worm Breeder's Gazette 9(3): 44
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The ama-1 gene, which is located 0.05 map units to the right of dpy-
13 on LG IV, encodes the amanitin-binding subunit of RNA polymerase II.
The gene was originally defined by the dominant mutation, m118, which
conveys resistance to -amanitin (Sanford, Golomb, and Riddle, 1983, J.
Biol. Chem. 258, 12804-12809). Twenty amanitin-sensitive mutants that
carry recessive-lethal alleles of ama-1 were isolated following EMS
mutagenesis of resistant parents (Rogalski et al. WBG: Vol. 8, No. 3,
and Vol. 9, No.l).
We are working on a fine-structure analysis of ama-1 and have mapped
14 of these lethal mutations in five-factor crosses with respect to
m118, dpy-13, e of genotype f dpy-
13(e184) 8 mX) +/unc-17(e245) + + unc-S(e53) are
put into I ml liquid cultures with 3% OP50 and 20 g/ml -amanitin.
Only worms in which recombination between the resistance mutation (
m118) and the lethal mutation (mX) has occurred will grow in the
amanitin. If the lethal mutation is to the right of the resistance
mutation, then the resistance-bearing chromosome is + dpy-13(e184)
8) ), and recombinants carrying
this chromosome will be either Dpy or Unc-5. If the lethal mutation is
to the left of m118, then the recombinant chromosome is unc-17(e245) +
ama-1(m118) +, and animals carrying this chromosome will be either Unc-
17 or semi-Dumpy. There is an average of 500,000 worms in each
experiment.
A different strategy is being employed to order lethal mutations
with respect to each other. This requires the construction of
heteroallelic lethal strains, so mDp1 red for
viability (see Rogalski et al., this issue). For example, amanitin-
resistant progeny are to be selected among progeny of mDp1
45) 45)
84) 8 m328) +/ + dpy-13(e184)
8 m329) unc-S(e53) heterozygotes.
The figure shows the ama-1 fine-structure map. Allele names are
given along with phenotypes exhibited at 20 C (em1=embryonic lethal,
ell=early larval lethal, m11=mid-larval lethal, sa=sterile adult). The
map is 0.018 map units long, and the m118 mutation is near the dpy-13
end. The lethals have not yet been ordered with respect to each other,
so positions are based on recombination frequencies with m118. We are
unable to separate 4 of the adult sterile mutations from m118. So far,
all of the early larval lethal mutations map to the right of the m118
mutation, and only the mid-larval and embryonic lethal mutations map
to the left of m118. This represents the first fine-structure map of
an essential gene in C. ope that this will be
useful to guide the DNA sequence analysis of selected mutant ama-1
alleles.
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