Table III.
Comparison of characteristics of spontaneous response, quantal content, and evoked responses from w1118 control and the double-mutant larval NMJs
| Parameter | w1118 | Double mutant | P{Scramb 1}; Double mutant |
|---|---|---|---|
| Quantal content (m) | 0.35 ± 0.07 (9) | 0.74 ± 0.14 (6) | 0.32 ± 0.07 (5) |
| Release probability (pr) | 0.29 ± 0.05 (9) | 0.51 ± 0.06 (6) | 0.27 ± 0.05 (5) |
| Frequency of spontaneous currents (Hz) | 2.76 ± 0.51 (14) | 5.61 ± 0.97 (20) | 2.82 ± 0.44 (5) |
| Integral of current evoked by release of a single quanta (pC) |
16.00 ± 0.41 (3) | 16.46 ± 0.36 (3) | 16.16 ± 0.28 (3) |
| Ca2+ cooperativity coefficient of nerve-evoked currents | 3.40 ± 0.07 (5) | 3.36 ± 0.12 (5) | 3.47 ± 0.19 (4) |
| Amplitude of current evoked at 0.5 Hz (nA) | 25.90 ± 3.66 (12) | 41.64 ± 3.66 (11) | 24.35 ± 3.93 (11) |
| Paired-pulse facilitation | 1.41 ± 0.09 (27) | 1.25 ± 0.14 (20) | 1.45 ± 0.28 (8) |
| Tetanic facilitation | 1.94 ± 0.19 (12) | 1.68 ± 0.07 (12) | 1.91 ± 0.23 (8) |
Quantal content, probability of releasing at least one quanta, and frequency of spontaneous postsynaptic currents were monitored and estimated as described previously (Acharya et al., 1998) in a standard working solution containing 75 μM, under conditions at which release probability is low. Also, quantal and charge transferred by release of a single quanta were studied as described previously (Acharya et al., 1998; Delgado et al., 2000). Paired-pulse facilitation was defined as the ratio of the amplitude of the postsynaptic currents evoked by two consecutive stimulating episodes separated by 100 ms. Tetanic facilitation was taken as the ratio of amplitudes of last and first currents evoked by a 50-s tetanic stimulation at 10 Hz.