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The Effect of Magnesium Ions on Chromosome Structure as Observed by Helium Ion Microscopy

  • Astari Dwiranti (a1), Tohru Hamano (a1), Hideaki Takata (a1) (a2), Shoko Nagano (a3), Hongxuan Guo (a4), Keiko Onishi (a3), Toshiyuki Wako (a5), Susumu Uchiyama (a1) and Kiichi Fukui (a1)...


One of the few conclusions known about chromosome structure is that Mg2+ is required for the organization of chromosomes. Scanning electron microscopy is a powerful tool for studying chromosome morphology, but being nonconductive, chromosomes require metal/carbon coating that may conceal information about the detailed surface structure of the sample. Helium ion microscopy (HIM), which has recently been developed, does not require sample coating due to its charge compensation system. Here we investigated the structure of isolated human chromosomes under different Mg2+ concentrations by HIM. High-contrast and resolution images from uncoated samples obtained by HIM enabled investigation on the effects of Mg2+ on chromosome structure. Chromatin fiber information was obtained more clearly with uncoated than coated chromosomes. Our results suggest that both overall features and detailed structure of chromatin are significantly affected by different Mg2+ concentrations. Chromosomes were more condensed and a globular structure of chromatin with 30 nm diameter was visualized with 5 mM Mg2+ treatment, while 0 mM Mg2+ resulted in a less compact and more fibrous structure 11 nm in diameter. We conclude that HIM is a powerful tool for investigating chromosomes and other biological samples without requiring metal/carbon coating.


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Abramoff, M.D., Magalhaes, P.J. & Ram, S.J. (2004). Image processing with ImageJ. Biophoton Intern 11, 3642.
Adolph, K.W., Kreisman, L.R. & Kuehn, R.L. (1986). Assembly of chromatin fibers into metaphase chromosomes analyzed by transmission electron microscopy and scanning electron microscopy. Biophys J 49, 221231.
Bazou, D., Behan, G., Reid, C., Boland, J.J. & Zhang, H.Z. (2011). Imaging of human colon cancer cells using He-ion scanning microscopy. J Microsc 242, 290294.
Bell, D.C. (2009). Contrast mechanisms and image formation in helium ion microscopy. Microsc Microanal 15, 147153.
Bian, Q. & Belmont, A.S. (2012). Revisiting higher-order and large-scale chromatin organization. Curr Opin Cell Biol 24, 359366.
Caravaca, J.M., Caño, S., Gállego, I. & Daban, J. (2005). Structural elements of bulk chromatin within metaphase chromosomes. Chromosome Res 13, 725743.
Cole, A. (1967). Chromosome structure. In Theoretical and Experimental Biophysics: A Series of Advances, Cole, A. (Ed.), vol. 1, pp. 305375. New York: Marcel Dekker.
Dwiranti, A., Lin, L., Mochizuki, E., Kuwabata, S., Takaoka, A., Uchiyama, S. & Fukui, K. (2012). Chromosome observation by scanning electron microscopy using ionic liquid. Microsc Res Tech 75, 11131118.
Eltsov, M., Maclellan, K.M., Maeshima, K., Frangakis, A.S. & Dubochet, J. (2008). Analysis of cryo-electron microscopy images does not support the existence of 30-nm chromatin fibers in mitotic chromosomes in situ . Proc Natl Acad Sci 105, 1973219737.
Fukui, K. (2009). Structural analyses of chromosomes and their constituent proteins. Cytogenet Genome Res 124, 34.
Fukui, K. & Uchiyama, S. (2007). Chromosome protein framework from proteome analysis of isolated human metaphase chromosomes. Chem Rec 7, 230237.
Grigoryev, S.A. & Woodcock, C.L. (2012). Chromatin organization—The 30 nm fiber. Exp Cell Res 318, 14481455.
Hayashihara, K., Uchiyama, S., Kobayashi, S., Yanagisawa, M., Matsunaga, S. & Fukui, K. (2008). Isolation method for human metaphase chromosomes. Protoc Exchange doi:10.1038/nprot.2008.166.
Morgan, J., Notte, J., Hill, R. & Ward, B. (2006). An introduction to the helium ion microscope. Microsc Today 14, 2431.
Nishino, Y., Eltsov, M., Joti, Y., Ito, K., Takata, H., Takahashi, Y., Hihara, S., Frangakis, A.S., Imamoto, N., Ishikawa, T. & Maeshima, K. (2012). Human mitotic chromosomes consist predominantly of irregularly folded nucleosome fibres without a 30-nm chromatin structure. EMBO J 31, 16441653.
Osawa, T. & Nozaka, Y. (1998). Scanning electron microscopic observation of the epidermal basement membrane with osmium conductive metal coating. J Electron Microsc 47, 273276.
Pretorius, E. (2010). Traditional coating techniques in scanning electron microscopy compared to uncoated charge compensator technology: Looking at human blood fibrin networks with the Zeiss ultra plus FEG-SEM. Microsc Res Techniq 74, 343346.
Rice, W.L., van Hoek, A.N., Păunescu, T.G., Huynh, C., Goetze, B., Singh, B., Scipioni, L., Stern, L.A. & Brown, D. (2013). High resolution helium ion scanning microscopy of the rat kidney. PLoS One 8, e57051.
Shinaoka, A., Momota, R., Shiratsuchi, E., Kosaka, M., Kumagishi, K., Nakahara, R., Naito, I. & Ohtsuka, A. (2013). Architecture of the subendothelial elastic fibers of small blood vessels and variations in vascular type and size. Microsc Microanal 19, 406414.
Sone, T., Iwano, M., Kobayashi, S., Ishihara, T., Hori, N., Takata, H., Ushiki, T., Uchiyama, S. & Fukui, K. (2002). Changes in chromosomal surface structure by different isolation conditions. Arch Histol Cytol 65, 445455.
Strick, R., Strissel, P.L., Gavrilov, K. & Levi-Setti, R. (2001). Cation-chromatin binding as shown by ion microscopy is essential for the structural integrity of chromosomes. J Cell Biol 155, 899910.
Suzuki, E. (2002). High-resolution scanning electron microscopy of immunogold-labelled cells by the use of thin plasma coating of osmium. J Electron Microsc 208, 153157.
Uchiyama, S., Doi, T. & Fukui, K. (2008). Isolation of human and plant chromosomes as nanomaterials. In Chromosome Nanoscience and Technology, Fukui, K. & Ushiki, T. (Eds.), pp. 155166. UK: CRC Press.
Uchiyama, S., Kobayashi, S., Takata, H., Ishihara, T., Hori, N., Higashi, T., Hayashihara, K., Sone, T., Higo, D., Nirasawa, T., Takao, T., Matsunaga, S. & Fukui, K. (2005). Proteome analysis of human metaphase chromosomes. J Biol Chem 280, 1699417004.
Uchiyama, S., Kobayashi, S., Takata, H., Ishihara, T., Sone, T., Matsunaga, S. & Fukui, K. (2004). Protein composition of human metaphase chromosomes analyzed by two-dimensional electrophoreses. Cytogenet Genome Res 107, 4954.
Ura, K. (1998). Contrast mechanism of negatively charged insulators in scanning electron microscope. J Electron Microsc 47, 143147.
Ward, B.W., Notte, J.A. & Economou, N.P. (2006). Helium ion microscope: A new tool for nanoscale microscopy and metrology. J Vac Sci Technol 24, 28712874.


The Effect of Magnesium Ions on Chromosome Structure as Observed by Helium Ion Microscopy

  • Astari Dwiranti (a1), Tohru Hamano (a1), Hideaki Takata (a1) (a2), Shoko Nagano (a3), Hongxuan Guo (a4), Keiko Onishi (a3), Toshiyuki Wako (a5), Susumu Uchiyama (a1) and Kiichi Fukui (a1)...


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