Intragenic mutations in tba-1 and a novel tbb-2 mutation suppress synapse remodeling defects in tba-1(gf) dlk-1(0).
(A) Schematic of remodeling of DD neuron synapses. In young larvae, pre-synaptic terminals are visualized along the ventral nerve cord (VNC) using GFP- tagged synaptobrevin (SNB-1::GFP). These synapses are completely eliminated in wild type animals, to form new synapses along the dorsal nerve cord (DNC).(B) Schematic of an adult DD neuron, with the red box representing the region of interest. Representative images of DD synapses in the adult DNC of various genotypes, visualized using Punc-25-SNB-1::GFP (juIs1). Scale bar: 10 μm. (C) Bright field images of a tba-1(gf) dlk-1(0) animal and an animal isolated following EMS mutagenesis of tba-1(gf) dlk-1(0). Suppressors were isolated based on improved behavior, with a total of 8 intragenic tba-1 mutants and 8 suppressors with mutations in genes besides tba-1 and dlk-1. (D) Representative images of DD synapses in the adult DNC of various genotypes, visualized using Punc-25-SNB-1::GFP (juIs1). Scale bar: 10 μm. (E) Quantification of synaptic puncta in the DNC of adult animals. Data are mean ± SEM; n>10 animals per genotype. Statistics: One-Way ANOVA followed by Tukey’s posttest; ***p<0.001, ns- not significant. (F) DNC synapses in tba-1(gf) dlk-1(0); tbb-2(ju1535); juIs1 animals that either lack or contain a rescuing transgene expressing wild type TBB-2 (Ex-TBB-2(+)).