Atomic force microscopy imaging of human metaphase chromosomes in liquid.

Methods for atomic force microscopy (AFM) imaging of human metaphase chromosomes were -introduced in the present study. Chromosomes from the lymphocytes were fixed and prepared onto glass slides as the chromosome spread, and observed in phosphate-buffered saline by dynamic mode AFM. On the contrary, chromosomes from the human cell line BALL-1 were isolated using the hexylene glycol method, absorbed onto a silane-coated glass slide, and observed in a hexylene glycol buffer solution by dynamic mode AFM. AFM provides three-dimensional topographic images of both fixed and unfixed human chromosomes with height information. The ultrastructural image of a pair of chromatids was also obtained by AFM in a liquid condition. The combined use of the AFM and light microscopy of cytochemically and/or immunocytochemically stained chromosomes is also expected to be useful for studies on the localization of chemical components in relation to the higher-order structure of the chromosomes.