Fluorescence imaging and investigations of directly labelled chromosomes using scanning near-field optical microscopy.

Scanning near-field optical microscopy (SNOM) has been successfully employed to generate high resolution (<100nm) fluorescence images of directly tagged human chromosomes. Direct tagging, fluorescence in-situ hybridisation processes (with and without amplification) are investigated and their fluorescence response to near-field excitation are compared. Using the simultaneous topography mode of SNOM, chromosome morphology was seen to differ as a result of the two processes; with chromatin collapse more extensive when the amplified direct tagging procedure was used. The results are discussed in the context of developing locus specific direct tags together with high resolution SNOM imaging for the observation of chromosome aberrations.