Atomic force microscope tracking observation of Chinese hamster ovary cell mitosis

CHO cells possess easily identifiable karyotypes, and CHO cell chromosomes are large and few in number, making these cells ideal for mutational and drug toxicity studies and suitable for investigations of animal chromosome structure. Here, we used atomic force microscopy (AFM) in the tapping mode for detailed visualizations of Chinese hamster ovary (CHO) cell chromosomes during various mitotic phases, including typical prophase, prometaphase, metaphase, anaphase and telophase. Based on our detailed observations, we were able to divide metaphase and anaphase into sub-phases: metaphase I, II and III, and anaphase I and II. Furthermore, we used the AFM error-signal mode to visualize chromosomal ultrastructures and cytokinesis. While these visualizations were all successful, we found that the image quality was affected by cellular debris, contamination. Collectively, our results show that the AFM technique has great potential for the detailed study of chromosomes and chromosomal ultrastructures during all phases of the cell cycle, but that careful standards of sample preparation must be maintained.