Worm Breeder's Gazette 10(1): 114
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We have isolated several gain-of-function (gf) alleles of tra-1 as suppressors of fem-3(q96gf). One of these, q183, is temperature sensitive for its XX (but apparently not for its XO) mutant phenotype. q183 was identified as tra-1 by mapping and reversion to tra-1(lf). At 25 C, both q183/q183 and q183/+ XX animals are female (n>200); at 15 C, q183/q183 XX animals are still always female (n>200), but q183/+ XX animals are sometimes hermaphrodite. XO animals homozygous or heterozygous for q183 are intersexual at both 15 C and 25 C. A maternal effect of q183 can be observed when q183/+ XX progeny derived from homozygous or heterozygous mothers are compared. At 15 C, a homozygous q183 XX female crossed with N2 males produces q183/+ XX offspring that are 97% female and 3% hermaphrodite (n=181). (In this experiment, XX progeny were distinguished from XO progeny solely on the basis of phenotypic sex. Since hermaphrodites plus females ( presumed XX) were about half and intersexual animals with masculinized tails (presumably XO) were about half the progeny, use of phenotypic sex to distinguish XX and XO animals is reasonable.) A heterozygous XX parent selfing at 15 C produces XX heterozygous progeny that are 50% female and 50% hermaphrodite. The maternal effect of q183 suggests that wild-type tra-1 product, too, may be contributed to the embryo by the heterozygous mother. The temperature sensitive period of tra-1(gf) for hermaphrodite spermatogenesis has been examined in q183/+ XX animals. Animals shifted from 15 C to 25 C prior to the end of the L2 stage are all female, but are 50% hermaphrodite and 50% female if shifted up at the end of L2. The percentage of XX animals that can make some sperm decreases as they are shifted from 25 C to 15 C during L1, L2, and L3. These shifts suggest that the time of tra-1(gf) synthesis and/or function is during L2 and/or L3. The tra-1(gf) TSP is prior to that of fem-3(lf) (Hodkgin, 1986) and fog-1 (Barton and Kimble, Abstracts for C. elegans meeting, 1987, p. 173). This data is consistent with a role of tra-1 in the regulation of the fem genes and fog-1 in the hermaphrodite germ line. [Although the results of double mutant experiments (e.g. tra-1(lf); fem(lf) doubles) suggest that the fem genes regulate tra-1 in somatic tissues, they also suggest that tra-1 regulates the fem genes and fog-1 in the germ line. ] We are currently extending our maternal effect experiments with strains marked to distinguish XX and XO animals and we are seeking extragenic suppressors of tra-1(gf).