SCANNING NEAR-FIELD OPTICAL MICROSCOPE - A METHOD FOR INVESTIGATING CHROMOSOMES

Karyotypes of human metaphase chromosomes are used to detect genetic d efects like deletions or translocations. For these investigations the chromosomes are treated by the trypsin-Giemsa protocol, resulting in a typical banding pattern. These patterns are investigated using conven tional light microscopy. Because of the diffraction limit, even the sm allest visible band contains similar to 1 million base pairs. We want to improve resolution by using bright-field scanning near-field optica l microscopy (SNOM). Images of trypsin-Giemsa-treated chromosomes are presented and compared with conventional light microscopic, scanning f orce and scanning fluorescence near-field optical microscopic data. Fo r fluorescence investigations, the chromosomes were stained using prop idium iodide. To our knowledge, it is the first attempt to investigate G-banded chromosomes by SNOM. (C) 1997 by John Wiley & Sons, Ltd.