Figure 2.

Electrophysiological responses of campaniform mechanoreceptors in wild-type and mutant flies. (A) An image of a fly haltere. The mechanical probe (red) was positioned in the middle of the receptor field in the pedicel (green bracket). The cuticular structures that overlay the campaniform receptors are visible in the pedicel. This image of the haltere is used to indicate the position of the stimulation probe; the actual recording was performed on intact living flies immobilized on the stage. (B) Representative recording traces from a wild-type fly in response to different mechanical stimuli (uppermost curves). Typical response traces to five cycles of stimulation are shown at left. At right, the responses to 50 cycles are aligned with the stimulation cycles and overlaid (gray). The average trace is also shown (red). Note that the individual responses to 15-μm stimuli lose synchronicity with the stimulation (the gray lines do not overlap with each other as they do for 3- to 9-μm stimuli). (C) The distribution of the peak response amplitudes to 150 6-μm stimuli. An example of a response to 50 stimuli is shown above. The broad distribution of response amplitudes can be fit with a multipeaked distribution. (D) Representative recording traces from a mutant fly in response to different mechanical stimuli (note that the scale of the response traces differs from that in B). Typical recording traces of five cycles are shown at left. At right, the responses to 50 cycles are overlaid (gray) and the average trace is shown (red). (E) The distribution of the amplitudes of responses to 15-μm stimuli in a mutant receptor was similar to that to 3-μm stimuli in a wild-type receptor. The histograms have single peaks at P_f02655 = 0.060 mV and P_WT = 0.057 mV. The representative recording traces for 100 ms (10 cycles) are shown above the histograms. Note that wild-type receptors showed multiple spikes, whereas mutant receptors showed only a single spike. (F) The average peak response amplitudes from campaniform receptors in f02655 mutant flies (triangles) were significantly smaller than those in wild-type flies (circles). Data are represented as the mean ± SE (n = 4–6 flies/data point).