Figure 2. Mab-5 protein distribution in larvae. (A-B) Early L1 male. On the right side (B), P9/10 and P11/12 stain, as do their bilaterally symmetric homologs on the left (not shown). The more anterior P1/2, P3/4, P5/6, and P7/8 cells are unstained. The epidermal cell V6, M myoblast, and several posterior body wall rnuscles also stain. In the ventral nerve cord (A), seven embryonically produced juvenile motoneurons, DB6-DA8, stain. This pattern is reproducible (n = 61 sides, -25 male, >-17 hermaphrodite, n = 17 ventral, 10 male, 7 hermaphrodite). Nonspecific germ-line staining is indicated (^) (see Materials and methods). (C) Older L1 male (--12 hr after hatching). P1-P10 have divided; P11- P12 have not. Mab-5 is detected in P7-P12 or descendants but not in P1-P6 descendants. Juvenile motoneurons continue to stain (n = 14 male, 3 hermaphrodite). (D) Early L2 male (n = 38). Pn.p nuclei are indicated. Other P descendants are mixed with juvenile motoneurons and cannot be distinguished unequivocally on the basis of morphology or staining. P12 descendants do not stain at this stage. (E) Early L2 hermaphrodite. P(9- 11).p cells have fused with the epidermal syncytium and no longer express
mab-5 ( T ). P(9-11).aap cells have undergone programmed cell death. Aside from these differences, expression is identical' to that in the male (n = 18). (F)
lin-39(
n1760) early L1 male. As in wild type, P7/8 does not stain at this stage (n = 16). Expression first appears when P7-8 cells enter the ventral cord (n = 6) and after they divide (n = 3). The pattern is indistinguishable from wild type, although fainter. (G)
mab-5(
e1751gf) L1 male --12 hr post hatching. All P descendants stain (n = 10). (H)
egl-5(-) early L2 male. Mab-5 is not only detected in P9-P1 l descendants, as in wild type (D), but also in P12.p and in four additional cells that appear to be the P12.a descendants (n 6). In hermaphrodites, only three additional cells stain, presumably because of the death of P12.aap in this background (n = 13). Precursors of these cells can be identified unambiguously and consistently exhibit Mab-5 labeling (n = 8).