Worm Breeder's Gazette 7(2): 24
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.
l) An almost invisible tra-2 mutant In the course of mapping a dominant mutation, dpy-25(e8) I found that the original isolate CB817 carried a weak tra-2 allele, e1875, which was easily separated from e817. The phenotype of heterozygotes with strong tra-2 alleles, e.g. e1875/e1425 is similar to that of tra- 2 (f70) ( = tri of Beguet and Gibert, 1978), i.e. a self-fertile hermaphrodite with a variably masculinized tail. However, the homozygote e1875/e1875 is anatomically indistinguishable from a wild- type hermaphrodite, thus it is a 'subliminal' allele. The interesting difference from wild type is that the self-progeny broods of e1875 hermaphrodites are more variable in size and on average larger than wild type (N2) : [See Figure 1] This may indicate that one of the wild type functions of tra-2 is to control the number of sperm made by the hermaphrodite. The larger brood size does not mean that e1875 is a 'better' strain than N2 and in fact N2 grows faster, as judged by its consistent victories in eating races between the two strains. 2) Male chauvinist piggies Two mutants abducted from MIT, n198 and n199, prove to be alleles of a new dumpy gene, dpy-26 IV. These mutants have strange properties: homozygotes derived from a heterozygous dpy-26/+ parent are fully viable and only slightly dumpy, but their self progeny consist of many dead eggs and larvae, a few severely dumpy hermaphrodites which are usually infertile, and a few (0 to 15) non-dumpy males. Homozygous stocks are almost impossible to maintain. As with dpy-21 V,it is the number of X chromosomes that determines the phenotype: tra; dpy-26 XX males are dumpy, and her; dpy-26 XO hermaphrodites are non-dumpy. Therefore, dpy-26 appears to be a maternal effect XX lethal. However, the mutation has some effect on XO animals: both dpy-26 XO males and dpy-26; phrodites are less fertile than the equivalent wild-type or dpy-21 strains. The similarities between dpy 26 and the Drosophila mutant daughterless (see Genetics 96: 903-926 and other T. Cline papers) are distinctly intriguing. There are also similarities between dpy-26, animals, both in dumpy phenotype and in partially suppressing Tra phenotypes. The dpy-21 XXX combination appears to be lethal, but dpy-26,dpy-21 XX is viable (for the first generation). It is curious that dpy-26 should have a Him phenotype (both alleles and the heterozygote n198/n199). One possibility that can be excluded is that the Him-ness is a consequence of pre-meiotic selection for XO germ cells: if this were the case, then a dpy-26, aphrodite should tend to give jackpots of all wild or all Unc males, and this was not observed.