Fig. 1. Expression of a
vab-3::gfp reporter transgene. (A, C, F, I) Nomarski DIC micrographs of males. In all photos, anterior is left. (D, G, J) Epi-fluorescent images of the same animals. (A) A diagram of the four post-embryonic blasts of the male hindgut and their progeny in early L2 and mid L3, and micrograph of the adult male tail. Cells of the B cell lineage (gray) generate the copulatory spicules (arrows). The Y cell progeny (black) also generate sensory structures (the post-cloacal sensilla) in adults. (B) A diagram of the genomic structure of the C. eleganspax-6 locus. Coding exons are black, with parentheses marking
mab-18-specific exons. The exons coding for the DNA-binding paired domain (PD) and homeodomain (HD) are noted. Dashed arrows denote
vab-3 and
mab-18 transcripts. Sequences contained in the
vab-3::gfp reporter transgene guEx356 are indicated as follows: solid line denotes the included
vab-3 genomic sequence, gray box denotes GFP coding sequence, and dotted line denotes
unc-54 3' UTR. (C and D) L2 larval
vab-3 expression in unidentified neuronal cells of the head. This expression begins in embryogenesis, persists throughout the animals' lifespan, and was used as an internal control for hindgut expression experiments. (E and H) Diagrams of the early L2 (E) and mid L3 (H) male hindgut. (E, F, G) The B and Y cells have undergone one asymmetric cell division. Nuclei are labeled.
vab-3 is expressed in the sensory organ precursors B.a and Y.p. (F and G) The dotted circle indicates the position of U, which lies out of the focal plane. (H, I, J) The B.a and Y.p precursors have generated eight progeny. Nuclei of B.a descendents are labeled with greek letters.
vab-3 expression is robust in all B.a cell types. (I and J) The epsilon and zeta lateral pairs are out of the plane of focus (dotted circles), as are the Y.p descendents, which have differentiated and have diminished
vab-3 expression.