Rtnl1 loss impacts synaptic transmission. (A) GCaMP fluorescence at rest (F), maximum fluorescence (Max F) in response to 1 Hz stimulation, and maximum change in fluorescence (Max ΔF) in examples of WT and Rtnl1¹⁸ at muscle 1, Type Is postsynaptic terminals. (B) Impact of Rtnl1 loss-of-function on peak evoked postsynaptic Ca²⁺. Plot shows the median responses to a burst of 2 Hz stimulation of larvae from each genotype. (C) Impact of Rtnl1 loss-of-function on peak evoked postsynaptic Ca²⁺ responses. Plot shows individual larval datapoints and mean ± SEM; datapoints represent the largest ΔF/F reached after either a 1 Hz or 2 Hz stimulation during the recording. Comparisons were analyzed with a mixed-effects two-way ANOVA. (D) Impact of Rtnl1 loss-of-function on postsynaptic resting miniature responses (minis). Plots show representative time traces (close to the mean stimulation frequency) over 5 s from the distal bouton during the recording collected. (E) Impact of Rtnl1 loss-of-function on minis frequency. Plot shows individual larval datapoints and mean ± SEM. Frequency datapoints represent the number of minis per second over a 5-s recording. Pairwise comparison was performed using Student’s t test. (F) Rtnl1 loss-of-function did not affect minis amplitude. Plot shows individual larval datapoints and median ± interquartile ranges. For each larva in E and F, minis from a 20-s recording from the distal bouton of one NMJ between segments A4-A6. Amplitude datapoints represent the largest ΔF/F over the recording. Pairwise comparison was performed using Mann–Whitney U-test (maximum mini amplitude). (B–F) Sample size (larvae) is indicated within each plot for each genotype. Each recording was from one muscle 1, Type Is NMJ between segments A4-A6. Genotypes are Is-GAL4, mhc-SynapGCaMP6f/UAS-tdTom::Sec61β, in either a WT or Rtnl1¹⁸ background.