THE PERIOD GENE CONTROLS COURTSHIP SONG CYCLES IN DROSOPHILA-MELANOGASTER

We developed a technique that assists in objective identification of p ulse and sine components in the Drosophila,melanogaster courtship song . The song was recorded digitally and subjected to wavelet analysis, w hich decomposed the signal into a series of bands of decreasing freque ncy in which acoustic power appeared as a function of time. This time- frequency analysis expresses characteristic 'fingerprints' of the puls es, which appear in all frequency bands, and characteristic 'fingerpri nts' of the sine song, which appear only in the band containing its fr equency. Means of the interpulse intervals (IPIs) for each second of 1 0-min recordings of song in which pulse singing occurred constituted a n irregularly sampled time series, intractable to common spectral anal ysis techniques. Therefore, we took the discrete Fourier transform of this series, which retained all the spectral information in the Fourie r coefficients, and used the inverse Fourier transform of these coeffi cients to yield a new series that was regularly spaced, with an estima te of IPI for each second in the interval. We observed an IPI period o f 67.9 s in wild type, 31.1 s in per(O), 45.9 s in per(s), and 72.0 s in per(L). (C) 1998 The Association for the Study of Animal Behaviour.