  We present experimental and numerical data on the supercontinuum generation
in an optical fiber pumped in the normal dispersion range where the seeded dark
and the spontaneously generated bright solitons contribute to the spectral
broadening. We report the dispersive radiation arising from the interaction of
the bright and dark solitons. This radiation consists of the two weak
dispersing pulses that continuously shift their frequencies and shape the short
and long wavelength wings of the supercontinuum spectrum.
