Figure 6.

Rtnl1 loss decreases evoked ER Ca²⁺ uptake at Type Is termini. Evoked ER Ca²⁺ responses were measured at Type Is termini at muscle 1 in segment A4-A6. (A) Lumenal GCaMP fluorescence at Type Is NMJs, presented at rest (F), maximum fluorescence (Max F), and maximum change in fluorescence (Max ΔF) in representative examples of WT and Rtnl1¹⁸ presynaptic terminals. (B) Loss of Rtnl1 does not affect resting ER Ca²⁺. The graph shows larval datapoints as in Fig. 5 B, with median ± interquartile ranges, compared using a Mann–Whitney U-test. (C) ΔF/F timecourse of evoked lumenal GCaMP responses to 20 Hz stimulation (mean ± SEM). (D) Loss of Rtnl1 does not affect ER Ca²⁺ release immediately following stimulation. The graph shows the minimum ΔF/F value after stimulation. (E) Loss of Rtnl1 significantly decreases evoked ER Ca²⁺ uptake over a range of stimulation frequencies. The graph shows the maximum ΔF/F value reached after stimulation. In D and E, graphs and analyses are as for Fig. 5 D. Genotypes: Is-GAL4, UAS-ER-GCaMP6-210/UAS-tdTom::Sec61β in either a WT or Rtnl1¹⁸ mutant background.