Restoration of Profiles from Slit-Scan Flow Cytometry

Slit-scan flow cytometry has been used to measure the distribution of fluorescent dye along mammalian chromosomes. In this procedure, the chromosomes are forced to flow lengthwise and one at a time through a thin laser beam. The resulting fluorescence profile is an approximation of the distribution of stain along the chromosome showing a dip at the centromere region. In this paper we describe a procedure, based upon Fourier analysis, to restore high spatial frequency information to the measured chromosome profile so that the centromeric dip can be precisely located. To accomplish this we estimate both the flow velocity and the laser beam profile. The procedure is applied to the restoration of profiles of fluorescent microspheres and Chinese hamster M3-l chromosomes. Validation of the procedure is accomplished by comparing restored chromosome profiles to those obtained through high resolution fluorescence microscopy.