Techniques for imaging human metaphase chromosomes in liquid conditions by atomic force microscopy

Area of Science:

• Biophysics
• Cell Biology
• Microscopy

Background:

• Understanding chromosome structure is crucial for cell biology.
• Traditional microscopy methods face limitations in imaging hydrated biological samples.

Purpose of the Study:

• To develop and apply atomic force microscopy (AFM) for high-resolution 3D imaging of wet human metaphase chromosomes in liquid.
• To optimize AFM parameters for imaging both chromosome spreads and isolated chromosomes.

Main Methods:

• Human metaphase chromosomes were prepared using chromosome spreads and isolation techniques.
• Atomic force microscopy (AFM) was employed in dynamic mode within a buffer solution.
• Optimized AFM parameters included soft triangular cantilevers (0.08-0.4 N/m) and high aspect ratio tips for isolated chromosomes.

Main Results:

• Clear 3D AFM images of chromosomes in spreads were obtained under optimized conditions.
• High-quality images of isolated chromosomes revealed surface structures approximately 50 nm thick.
• The Q-control and sampling intelligent scan (SIS) systems enhanced image quality for isolated chromosomes.

Conclusions:

• AFM is a viable technique for visualizing wet chromosomes in liquid, providing detailed structural information.
• Optimized AFM parameters and systems enable high-resolution imaging of chromosome surface topography.
• The study demonstrates AFM's potential for advancing research in chromosome structure and dynamics.