Fig. 6.

FM1-43 dye endocytosed at 32°C by BWSV stimulation can be released immediately at 32°C at cspmutant NMJs. At 32°C, exocytosis and subsequent endocytosis were induced with BWSV in the presence of external Ca²⁺. To label freshly endocytosed vesicles (FM1-43 staining), the preparation was pulsed with FM1-43 dye. After omitting the dye the BWSV stimulation was continued at 32°C (FM1-43 destaining). Using this protocol, neither wild-type (B) norcsp^E16 mutant (D) NMJs were stained with FM1-43 dye. However, control experiments, in which BWSV and neurotransmission were inactivated after the FM1-43 pulse, always showed FM1-43-stained synaptic boutons as exemplified for wild type (A) andcsp^E16 mutants (C). The images represent six independent trials using three larvae for each genotype per experiment (A–D).