Morelli Meisha A, Werling Uwe, Edelmann Winfried, Roberson Mark S, Cohen Paula E
Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, College of Veterinary Medicine, Ithaca, NY 14853, USA.
Chromosome Res. 2008;16(5):743-60. doi: 10.1007/s10577-008-1224-8. Epub 2008 Jun 2.
Events occurring during meiotic prophase I are critical for the successful production of haploid gametes. Many prophase I events are mediated by a meiosis-specific structure called the synaptonemal complex. To date, the limited knowledge we have about the dynamics of these prophase I events in mice comes from fixed, two-dimensional preparations of meiotic cells making it impossible to study the three-dimensional (3D) arrangement of meiotic chromosomes. The current study involves the development of an imaging system to view prophase I events in live mammalian spermatocytes by generating a transgenic mouse, Sycp3-Eyfp ( 21HC ), expressing a fluorescently tagged synaptonemal complex protein, SYCP3. Using this live imaging system, the 3D structural arrangement of chromosomes in the different prophase I substages has been characterized in live spermatocytes, and aspects of the 3D architecture of spermatocytes have been observed that would not be possible with existing techniques. Additionally, chromosome movement in prophase I spermatocytes and meiotic progression from pachynema to diplonema were observed following treatment with the phosphatase inhibitor, okadaic acid (OA), which accelerates the progression of cells through late prophase I. These studies demonstrate that the Sycp3-Eyfp ( 21HC ) live imaging system is a useful tool for the study of mammalian prophase I dynamics.
减数分裂前期I期间发生的事件对于单倍体配子的成功产生至关重要。许多前期I事件是由一种称为联会复合体的减数分裂特异性结构介导的。迄今为止，我们对小鼠这些前期I事件动态的了解有限，这源于减数分裂细胞的固定二维标本，使得研究减数分裂染色体的三维（3D）排列成为不可能。当前的研究涉及开发一种成像系统，通过生成一种表达荧光标记联会复合体蛋白SYCP3的转基因小鼠Sycp3-Eyfp（21HC），来观察活的哺乳动物精母细胞中的前期I事件。利用这种实时成像系统，已在活的精母细胞中对不同前期I亚阶段染色体的3D结构排列进行了表征，并且观察到了精母细胞3D结构的一些方面，而这些方面用现有技术是不可能观察到的。此外，在用磷酸酶抑制剂冈田酸（OA）处理后，观察到了前期I精母细胞中的染色体运动以及从粗线期到双线期的减数分裂进程，OA可加速细胞通过前期I后期的进程。这些研究表明，Sycp3-Eyfp（21HC）实时成像系统是研究哺乳动物前期I动态的有用工具。
