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. 2018 Mar 22;7:e32785. doi: 10.7554/eLife.32785

Figure 2. AST-1 acts as temporal switch for HSN maturation.

(A) Micrographs showing expression of the HSN TF combination at L4 larval stage and adult animals. (B) Analysis of HSN TF expression across all developmental stages in the HSN neuron. n > 30 cells for each developmental point. Error bars are SEP values. See Figure 2—figure supplement 1 for more detailed hlh-3 developmental expression. (C) Heat-shock-induced expression of hlh-3 at L4 larval stage is able to rescue tph-1::gfp expression defects in the HSN neuron. n > 100 cells per condition. See Source data 1 for primary data and Fisher's exact test p-values. *: p-value <0.05. (D) Precocious L1 onset of expression of ast-1, hlh-3 or both using an early active HSN-specific promoter (also expressed in NSM, ADF and VC4/5 neurons). Precocious ast-1 advances tph-1::gfp expression, while hlh-3 alone or in combination with ast-1 delays tph-1::gfp expression and produces expression defects. YA: young adult. n > 30 cells per time point and condition. See Source data 1 for primary data and Fisher's exact test p-values. *: p-value <0.05.

Figure 2.

Figure 2—figure supplement 1. Dynamic HLH-3 expression in the HSN.

Figure 2—figure supplement 1.

(A) Schema of the modified ast-1 and hlh-3 locus to produce the corresponding fluorescent fusion proteins. (B) HSN lineage representation. (C) HLH-3 expression reappears postembryonically at L3 stage, peaks at late L3 and quickly disappears at the end of L4 stage. N > 100 cells each stage. (D) Alignment of the bHLH domain of C. elegans HlH-3, D. melanogaster SCUTE and M. musculus ASCL1 (EMBOSS Needle alignment tool default parameters). HLH-3 shows 48.3% identity and 63.8% similarity with SCUTE and 56.9% identity and 65.5% similarity with ASCL1.