Worm Breeder's Gazette 9(2): 62
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.
Mutations in the gene mab-3 cause a variety of male-specific defects. mab-3 males lack most of their rays, possess a greatly diminished fan, and produce large quantities of yolk proteins (see 1985 CSH C. elegans Meeting Abstracts, p. 129), while mab-3 hermaphrodites appear wild-type. An examination of terminal phenotypes of mab-3 males suggested possible defects in the lateral hypodermal lineages (and perhaps in the B lineage), but probably not in the germline (WBG 9 #1: 87) or ventral hypodermis. All of these structures appear normal in mab-3 hermaphrodites. I have followed the lineages of the lateral hypodermal blast cells V5, V6, and T from mid-L2 to late L4 in mab-3(e1240) males. (e1240 is a candidate for a null mutation, as its terminal phenotype seems identical to that of e1240/Df, using deficiencies that span the mab-3 locus. The lineage alterations in the mab-3 male lateral hypodermis appear to be confined to the nine ray precursor (Rn) sublineages that generate nine ray cell groups (R1 descends from VS, R2-6 from V6, and R7-9 from T). The mutant lineage that mab-3 ray precursors can follow is depicted in the figure below, along with the wild-type ray precursor lineage. In mab-3(e1240) males, R1-4 generally adopt the mutant lineage, while R7-9 usually remain wild-type, and RS and R6 often follow an intermediate lineage. These results are consistent with the terminal phenotype. The anterior-posterior distribution of mutant lineages may reflect a gradation in the requirement for mab-3 gene product; this distribution is also observed in the terminal phenotypes of two weaker mab-3 alleles, e1921 and e2093. I have begun to examine the effect of mab-3(e1240) in combination with mutations that create ectopic ray cell groups. For example, males of lin-22(n372) (isolated by Bill Fixsen; see WBG 7 #2: 40) form an ectopic postdeirid and a pair of ectopic rays from each of V1-V4. mab-3;lin-22 males produce ectopic postdeirids, but instead of producing ectopic rays, they generate alae (based on inspection of late L4 animals). Thus, it appears that mab-3 mutations are capable of creating a transformation from ray to seam cell fates. This is reasonably consistent with the mab-3(e1240) terminal phenotype, in which patches of abnormal alae-like structures are seen in the tail region, where normally no alae are found. [See Figure 1]