Kinetochore detection in micronuclei: an alternative method for measuring chromosome loss

Area of Science:

• Cytogenetics
• Molecular Biology
• Cell Biology

Background:

• Micronuclei (MN) formation is a biomarker for chromosomal instability.
• Detecting whole chromosome loss within MN is crucial for understanding genotoxicity.
• Current methods may not precisely differentiate chromosome breakage from whole chromosome loss.

Purpose of the Study:

• To develop and validate a method for detecting whole chromosomes within micronuclei.
• To quantify kinetochore-positive micronuclei in human lymphocytes under various conditions.
• To assess the utility of kinetochore detection in identifying aneuploidy-inducing agents.

Main Methods:

• Utilized anti-kinetochore antibodies from scleroderma patient serum for detection.
• Employed a peroxidase-labelled secondary antibody and nickel chloride-modified DAB reaction for permanent slides.
• Analyzed micronuclei in cytokinesis-blocked human lymphocytes after colchicine treatment, spontaneous occurrence, and X-ray exposure.

Main Results:

• 82-92% of colchicine-induced MN were kinetochore-positive, indicating whole chromosome inclusion.
• Spontaneously occurring MN showed 42% (young) and 50% (elderly) kinetochore-positivity.
• Approximately 12% of X-ray-induced MN were kinetochore-positive, suggesting whole chromosome loss events.

Conclusions:

• Kinetochore detection in micronuclei offers a novel approach to quantify chromosome loss.
• This technique can distinguish whole chromosome loss from chromosome breakage events.
• The method holds significance for identifying agents that induce aneuploidy and assessing chromosomal damage.