Fig. 5. sma-9 functions in early stages to regulate body size. (A) Growth curve of sma-9 (cross), sma-4 (triangle), dbl-1(square) and N2 (diamond). In L1 stage larvae (12 hours), all animals are the same length. In L1 through L3 stages (48 hours), sma-9, sma-4 and dbl-1 show reduced a growth rate compared with N2. After L3, sma-9 mutants grow rapidly, whereas dbl-1 and sma-4 mutants continue to display a reduced growth rate. Data for N2 and dbl-1 is from Savage-Dunn et al. (Savage-Dunn et al., 2000). (B) At L3 stage, sma-9 worm length, pharynx length and seam cell length is indistinguishable from that of dbl-1 and sma-4. Data for N2 and dbl-1 is from Wang et al. (Wang et al., 2002). (C) Model of sma-9 function in the DBL-1 pathway. In body size development, sma-9 functions in early larval stages and may be replaced by other transcriptional cofactors in late larval stages. In male tail development, sma-9 prevents fusions in rays 8-9 specifically, but regulates cat-2 activity, the rate-limiting step in dopamine expression, in all rays. Other cofactors may be involved in ray 4-5 and 6-7 fusions. For spicule development, both sma-9 and other cofactors are probably required.