Figure 2.
mab-23 is required for ray dopaminergic patterning and axon pathfinding. (A) Postembryonic cell lineages leading to the ray neurons (Sulston and Horvitz 1977). RnA, A-type neuron; RnB, B-type neuron; Rnst, structural cell; X , programmed cell death. Rn.p is a hypodermal cell. Dopaminergic A-type neurons (green; Sulston and Horvitz 1977), EGL-5-expressing cells (yellow; Ferreira et al. 1999), MAB-23::GFP-expressing cells (black). (B) Adult male tail (lateral view; anterior,left; dorsal, up) showing the location of dopaminergic ray neurons (green). PAG, preanal ganglion. (C)
mab-23 expression in wild-type adult male rays. Fluorescent micrograph of a transgenic adult male (dorsal view) expressing EM#308 reporter. MAB-23::GFP localizes predominantly to cell nuclei in the A-type neurons of rays 1-4 and 6 and the non sex-specific PHCL/R neurons. (D-I) Dopaminergic fate expression in wild-type and mutant males (lateral view; anterior, left; dorsal, up). The dopaminergic fate marker is CAT-2::GFP (Lints and Emmons 1999). Nomarski and fluorescent micrographs of the same animal are superimposed. (D) Wild type. CAT-2::GFP is visible in ray 5, 7, and 9 A-type neurons. CAT-2::GFP signal more anteriorly in the tail corresponds to male spicule socket cell (SpSo) expression. (E)
mab-23(
bx118). The ray 3 A-type neuron expresses CAT-2::GFP ectopically (*) and its axon projects abnormally (yellow arrowhead). The Morpho-Mab tail defect characteristic of
mab-23 males is also apparent in this animal. (F)
sma-6(
wk7);
mab-23(
bx118). Ray abnormalities typical of DBL-1 pathway single mutants are apparent: fusion of rays 4 and 5 (4/5) and rays 6 and 7 (6/7), and ray 9 has been transformed to ray 8 (9->8). CAT-2::GFP is ectopically expressed in rays 3 and 4/5. (G)
egl-5(
u202);
mab-23(
bx118). Fluorescent micrograph [the presence ofegl-5
(u202) disrupts male tail retraction and, therefore, rays and fan are embedded in the tail]; body outline (gray solid line); gut autofluorescence (white arrowhead). CAT-2::GFP is absent form the A-type neurons of
egl-5-dependent rays 3 and 5. CAT-2::GFP is present in the A-type neurons of non-
egl-5-dependent rays 7 and 9 (R7A and R9A, respectively) and ectopically in ray 1 (R1A*). (H)
mab-3 (
e1240). Only rays 3, 7, and 9 are generated in this animal. CAT-2::GFP expression is observed in ray 7, one of the rays that express this fate in wild type. No ectopic expression of CAT-2::GFP is observed in the ray 3 that is present. (I)
mab-3 (
e1240);
mab-23 (
bx118). Double mutant shows both
mab-3 and
mab-23 phenotypes: missing rays and ectopic expression of CAT-2::GFP in ray 3, respectively. Magnification, 1000x. Bar, 10 μm.