We are characterizing the
mut-2 gene in C. elegans. We want to understand its role in regulating transposons in the worm genome. These studies should augment transposon-based reverse genetic approaches in this organism and may reveal features of a novel process for regulating transposon activity in eukaryotic genomes. How the host genome regulates transposon activity is not well understood. The
mut-2 gene was identified in a screen for EMS-induced mutations that elevated reversion frequency of an
unc54::Tc1 mutant. Subsequent studies showed that this mutation,
mut-2 (
r459), also increased transposition of Tcl and activated transposition and excision of at least three other families of transposons in the C. elegans genome, Tc3, Tc4 and Tc5. For these reasons, this mutant allele of
mut-2 has been termed the
mut-2 mutator. We would like to know the function of the wild type
mut-2 gene and its role in transposon control and genome integrity in C. elegans, and how these are altered by the
mut-2 mutator. To this end we want to map and clone
mut-2. Early studies mapped the
mut-2 mutator activity to the
unc-13/unc-15 region of LG1 (Finney and Horvitz, pers comm). We have refined this map position, using the high incidence of males (Him) phenotype conferred by
mut-2(
r459) as our genetic assay. We crossed a
dpy-5;
mut-2 strain by a
sem-4;
unc-13 strain, picked Dpy,Sem,Unc and Dpy,non-Sem,Unc recombinants and scored each for spontaneous male offspring to determine
mut-2 mutator status for each. Results place
mut-2 in the 1.65 map unit interval between
dpy-5 and
sem-4 and suggest it is near
sem-4. This corresponds to a physical distance of approximately 200-300 kb, which is covered by a single YAC. Experiments are underway to clone
mut-2. We will attempt to rescue the
mut-2 mutator phenotype with cosmids from the region. We are also making a genomic library from a
mut-2 mutant strain. We will use the existing cosmids and YAC from this region to identify candidate clones from the
mut-2 mutant library and test them by microinjection for ability to donate
mut-2 mutator activity.