We have cloned the
tra-2 gene by Tc1 tagging. The
tra-2 gene product is thought to regulate the fem genes (or their products) to allow female development in both soma and germ line of XX animals (Hodgkin et al.,1985,CSHSQB,50,585-593). To isolate Tc1 insertions into
tra-2, we selected for intragenic revertants of the
tra-2(gf) allele
q122. We backcrossed
q122 (a gain-of-function allele of
tra-2 that was induced by EMS on a Bristol chromosome) and a closely linked marker,
e120, into two strains in which Tc1 actively transposes (TR403 or EM1002). Because XX animals heterozygous for
q122 develop as females and XO animals develop as males, it is possible to construct male/female mating strains. Large populations of stable male/female strains (
q122 e120/ mnCl in TR403 or EM1002) were grown on Petri plates to permit mating. Five spontaneous recessive
tra-2 alleles located in cis to
q122 were isolated by shifting these animals to liquid culture to prevent mating and to select for self-fertility. Two of these alleles,
q149 and
q150, were backcrossed several times against N2. In addition, recombinants between each of these
tra-2 alleles and linked markers on both sides of
tra-2 were isolated to eliminate Tc1s which are not closely linked to
tra-2. A radioactively labelled Tc1 probe was used to hybridize N2 DNA,
q122 e120/mnCl (in Bristol) DNA, and DNAs isolated from a strain carrying the recombined
q149 or
q150 chromosome in Southern blots. A single novel 7.0kb BglII fragment was detected in
q150 DNA. The fragment carrying this novel Tc1 was cloned, and a unique sequence flanking the
q150 Tc1 insertion was subcloned to probe DNAs from other spontaneous
tra-2 alleles. Hybridization with the unique probe showed that
q149 contains a short deletion and that
sc146, a spontaneous
tra-2 allele isolated in TR679 and kindly sent to us by Corrine Basch and Bob Edgar, contains a rearrangement. Interestingly, this TR679 derived spontaneous allele is not a Tc1 insertion. The same probe was then used to isolate 30kb of DNA in the region of
tra-2 from a C. library provided by Claudia Cummins and Phil Anderson. We are currently mapping the
tra-2 gene more precisely within this 30kb region and attempting to identify the
tra-2 transcript.