Figure S1 - A Developmental Timing Switch Promotes Axon Outgrowth Independent of Known Guidance Receptors

lin-4 and its targets, lin-14 and lin-28, temporally regulate tph-1 expression. (A,B) Percentage of wild-type or mutant animals which expressed the integrated tph-1::GFP transgene in at least one HSN during L4 and adult stages. (A) At the restrictive temperature (23°C), lin-14(lf) mutant animals initiated precocious GFP expression at the L4 stage, and lin-14(lf) was sufficient to suppress the lin-4(lf) retarded phenotype in double lin-4(lf); lin-14(lf) mutants. (B) lin-28(lf) animals displayed precocious tph-1::GFP expression, and lin-28(lf) suppressed the lin-4(lf) retarded phenotype. For (A), n≥50, and for (B), n≥100 for all conditions, and error bars represent standard error of proportion. (C) Representative images of L4- and adult-stage HSNs using DIC or fluorescence microscopy. At the L4 stage, GFP was not detectable in wild-type HSNs, and was precociously expressed in lin-14(lf) or lin-28(lf) HSNs. In the adult, GFP was present in the HSNs of wild-type animals but not in lin-4(lf) mutants. Arrowhead: HSN cell body. Scale bars represent 5 µm, and anterior is to the left and ventral is down.
(2.00 MB EPS)

lin-4及其靶基因lin-14与lin-28时序调控tph-1的表达。(A,B) 野生型或突变体动物在L4期与成虫期，至少1个HSN（雌雄特异性运动神经元，hermaphrodite-specific motor neuron）中表达整合型tph-1::GFP转基因的百分比。(A) 在限制性温度（23℃）下，lin-14功能缺失（loss-of-function, lf）突变体在L4期即提前启动GFP表达，且在双突变体lin-4(lf); lin-14(lf)中，lin-14(lf)足以抑制lin-4(lf)的发育延迟表型。(B) lin-28功能缺失（loss-of-function, lf）突变体表现出tph-1::GFP的提前表达，且lin-28(lf)可抑制lin-4(lf)的发育延迟表型。对于(A)组，所有实验条件下样本量n≥50；(B)组所有实验条件下样本量n≥100，误差棒代表比例的标准误。(C) 为采用微分干涉差（DIC, Differential Interference Contrast）显微镜或荧光显微镜拍摄的L4期与成虫期HSN的代表性图像。L4期时，野生型HSN中未检测到GFP信号，而lin-14(lf)或lin-28(lf)的HSN中GFP出现提前表达。成虫期时，野生型动物的HSN中可检测到GFP，但lin-4(lf)突变体中则无GFP表达。箭头指示HSN细胞体。比例尺为5 μm，图像前部朝左，腹侧朝下。(2.00 MB EPS)