Figure 4
Removal of Eve increases IKfast and sensitivity to ACh. (A) Supression of Eve function, using the temperature-sensitive allele eve1D 19, results in an increase in IKfast but no change in IKslow (78.5 ± 6.1 versus 96.8 ± 4.6 pA, p < 0.05; see Materials and methods for details). (B) Removal of Eve function, through development at 30°C, is also sufficient to increase the amplitude of AP-independent quantal synaptic currents. Cumulative probability plots show that mini currents recorded in aCC/RP2 at 30°C (restrictive temperature, gray line) are greater in amplitude than at 20°C (wild-type Eve level, black line). Inset shows averaged mini current amplitudes (6.6 ± 0.19 versus 9.4 ± 0.26 pA, p < 0.001). Note that the current amplitude in controls (20°C) is smaller in second instars than in first instars (compare Figure 3b), even though the aCC/RP2 neurons are greater in size. This is undoubtedly because the dendritic regions, where these synaptic inputs occur, are further away from the cell body in second instars and, as such, the increased axonal resistance results in smaller quantal currents. All values are mean ± SE, n ≥ 8 cells.