著者

Yuki Hara Kenta Adachi Shunsuke Kagohashi Kazuo Yamagata Hideyuki Tanabe Shinji Kikuchi Sei-Ichi Okumura Akatsuki Kimura

出版者

THE SOCIETY OF CHROMOSOME RESEARCH

雑誌

Chromosome Science (ISSN:13441051)

巻号頁・発行日

vol.19, no.1-4, pp.43-49, 2016 (Released:2017-06-26)

参考文献数

22

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Across species, eukaryotic chromosomes share common features at the molecular level. However, common features at the cellular level are not well investigated. A correlation has been suggested between the linear packing ratio of mitotic chromosomes and the intra-nuclear DNA density, by comparing these values in the nematode Caenorhabditis elegans. In this study, these values were measured and compared among several metazoan and plant species. The obtained values corroborated the correlation proposed in the previous study, supporting the theory that intra-nuclear DNA density is a common regulator of chromosome condensation. Moreover, the comparison among different species suggested a correlation between the length of a mitotic chromosome and the nuclear volume to the power of 2/3. Given this observation, we speculate that: (i) a rate-limiting component defines the length of a mitotic chromosome that is proportional to the nuclear surface area, and (ii) such regulation of the mitotic chromosomal length may play a role in maintaining the ratio between the cell size and the metaphase plate.

著者

Kazuo YAMAGATA Rinako SUETSUGU Teruhiko WAKAYAMA

出版者

The Society for Reproduction and Development

雑誌

Journal of Reproduction and Development (ISSN:09168818)

巻号頁・発行日

vol.55, no.3, pp.343-350, 2009 (Released:2009-07-02)

参考文献数

33

被引用文献数

58 75

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Mammalian preimplantation embryonic development is achieved by tightly coordinated regulation of a great variety of temporal and spatial changes. Therefore, it would be valuable to analyze these events three-dimensionally and dynamically. We have previously developed a live-cell imaging method based on the expression of fluorescent proteins, using mRNA injection and time-lapse florescence microscopy. However, with conventional fluorescent microscopy, three-dimensional images could not be obtained due to the thickness of the embryos and the optical problem in which `out-of focus blur' cannot be eliminated. Moreover, as the repeated exposure of intense excitation light to the cell yields phototoxicity, long-term observation was detrimental to embryonic development. Here, we improved our imaging system to enable six-dimensional live-cell imaging of mouse preimplantation embryos (x, y and z axes, time-lapse, multicolor and multisample). Importantly, by improving the imaging devices and optimizing the conditions for imaging, such as intensity of excitation and time intervals for image acquisition, the procedure itself was not detrimental to full-term development, although it is a prolonged imaging process. For example, live pups were obtained from embryos to which two different wavelengths of excitation (488 and 561 nm) were applied at 7.5-min intervals for about 70 h, and 51 images were acquired in the z axis at each time point; thus, a total of 56,814 fluorescent images were taken. All the pups were healthy, reproductively normal and not transgenic. Thus, this live-cell imaging technology is safe for full-term mouse development. This offers a novel approach for developmental and reproductive research in that it enables both retrospective and prospective analyses of development. It might also be applicable to assessment of embryo quality in fields such as human reproductive technology and production animal research.

著者

Taiga YAMAZAKI Satoru KOBAYAKAWA Kazuo YAMAGATA Kuniya ABE Tadashi BABA

出版者

The Society for Reproduction and Development

雑誌

Journal of Reproduction and Development (ISSN:09168818)

巻号頁・発行日

vol.53, no.5, pp.1035-1041, 2007 (Released:2007-10-31)

参考文献数

24

被引用文献数

11 13

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To elucidate the molecular dynamics of HP1β in mouse preimplantation embryos, we examined the localization, dynamics, and mobility of HP1β in the (pro)nucleus by live cell imaging. Time-lapse observation revealed that the chromatin association of HP1β is regulated in a cell cycle-dependent manner. HP1β was localized in the interphase nucleus and was dynamically dissociated from the nucleus during the metaphase stage. The HP1β assembly and clustered heterochromatin structure were both found in the nuclei of 2-cell and later-stage embryos. Moreover, fluorescent recovery after photobleaching analysis implied that HP1β is more freely mobile in the pronucleus of the 1-cell embryo than in the 4-cell nucleus. These results suggest that the chromatin configuration may be regulated by the stability and mobility of chromatin-associated proteins including HP1β during early embryonic stages.

著者

Misuzu YAMASHITA Kazuo YAMAGATA Keiko TSUMURA Tomoko NAKANISHI Tadashi BABA

出版者

日本繁殖生物学会

雑誌

Journal of Reproduction and Development (ISSN:09168818)

巻号頁・発行日

vol.53, no.2, pp.255-262, 2007 (Released:2007-05-12)

参考文献数

28

被引用文献数

9 15 14

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To improve assessment of the acrosome reaction of mouse epididymal sperm, we employed anti-Izumo1 antibody instead of antibodies against acrosomal proteins. The acrosomal states among acrosome-intact, spontaneously acrosome-reacted, truly acrosome-reacted, and probably dead and/or membrane-damaged sperm were clearly distinguished by combined application of anti-Izumo1 antibody, DNA dye Hoechst 33342, and monoclonal antibody MN7 to paraformaldehyde-fixed sperm. When the acrosome reaction of capacitated epididymal sperm on the oocyte zona pellucida was examined using anti-Izumo1 antibody, approximately 20% of sperm bound onto the zona pellucida were acrosome-reacted 30 min after insemination. We also observed the moment of the acrosome reaction of live sperm on the zona pellucida by time-lapse monitoring using fluorescein isothiocyanate-conjugated anti-Izumo1 antibody.