Figure 6. Function and Expression of
lin-39 in the Central Body Region(A) Summary of P cell lineages and Q cell migrations in wild type (Sulston and Horvitz, 1977) and
lin-39 mutants. Diamonds and arrowheads denote cell fates dependent on HOMC genes. The closed diamonds denote
lin-39-dependent cell fates. The open arrowheads point to cell deaths(x) that require
mab-5 activity (Kenyon, 1966). The closed arrowhead points to an epidermal cell division dependent on
egl-5 activity (Chisholm, 1991). Lineages of overlapping subsets of P cells were followed in several
lin-39(
mu26) Ll hermaphrodites. The ventral hypodermis was disorganized in the vicinity of P(3-6). Our lineage data was consistent with previous analysis of the weaker allele
n709 (Ellis, 1965) except that in
lin-39(
mu26) animals, the Pn.p cells did not divide. The Q migrations on the left are indicated by a solid arrow, the Q migrations on the right by a dashed arrow. V, vulva1 precursor cell; N, VC neuron.(B and C) Expression of an integrated
lin-39-lacZfusion in an Ll larva. The two panels show the right (B) and left (C) sides of an Ll that is 4 hr old. At 4-6 hr after hatching, expression in Ll animals was seen in the juvenile ventral cord neurons (60%, n = 197; see unmarked cells in ventral cord of animal shown), in Q.a and Q.p (R, 51%, n=101;L,40%,n=90)inP(3/4)(R,10%, n=107;L,7%,n=90) in P(5/6) (R, 84%, n = 107; L, 73%, n=90), in P(7/8) (R, 96%, n= 107; L, 89%, n = 90) and in an unidentified cell near the pharynx (39%, n = 197; visible on left side of animal shown). Expression was also seen in Q itself (R, 19%, n = 59; L, 40%, n = 58). Expression was also occasionally seen in V3-V5 (under 5%). Staining was present in descendants of the P and Q cells; however, it is not clear whether this presence reflected continued transcription or perdurance of beta-galactosidase activity. Older larvae and adults consistently expressed the fusion in the central body region (in over 95%, n > 50). In adult hermaphrodites, the fusion was often expressed in the vulva1 muscles (data not shown).