Scherthan H, Eils R, Trelles-Sticken E, Dietzel S, Cremer T, Walt H, Jauch A
Abt. Humanbiologie and Abt. Zellbiologie, der Universität, Postf. 3049, D-67653 Kaiserslautern, Germany.
J Cell Sci. 1998 Aug;111 ( Pt 16):2337-51. doi: 10.1242/jcs.111.16.2337.
The three-dimensional morphology and distribution of human chromosomes 3 were studied in nuclei of spermatogonia and spermatocytes I from formaldehyde-fixed human testis sections. Chromosome arms, pericentromeres and telomeric regions were painted by a three-color, five-probe fluorescence in situ hybridization protocol. Light optical serial sections of premeiotic and meiotic nuclei obtained by confocal laser scanning microscopy revealed that premeiotic chromosomes 3 are separate from each other and occupy variably shaped territories, which are sectored in distinct 3 p- and q-arm domains. Three-dimensional reconstructions of the painted chromosome domains by a Voronoi tessellation approach showed that mean chromosome volumes did not differ significantly among the premeiotic and meiotic stages investigated. A significant increase in surface area and reduction of dimensionless 'roundness factor' estimates of arm domains indicated that the restructuring of spatially separate chromosome territories initiates during preleptotene. Telomeric regions, which in meiotic stem cells located predominantly in arm-domain chromatin, showed a redistribution towards the domain surface during this stage. At leptotene homologues were generally misaligned and displayed intimate intermingling of non-homologous chromatin. Pairing initiated at the ends of bent zygotene chromosomes, which displayed a complex surface structure with discernible sister chromatids. The results indicate that, in mammals, homology search is executed during leptotene, after remodeling of chromosome territories.
利用三色五探针荧光原位杂交技术，对来自甲醛固定的人类睾丸切片中的精原细胞和初级精母细胞的细胞核进行研究，以观察人类3号染色体的三维形态和分布。通过共聚焦激光扫描显微镜获得的减数分裂前和减数分裂细胞核的光学连续切片显示，减数分裂前的3号染色体彼此分离，占据形状各异的区域，这些区域被划分成不同的3号染色体p臂和q臂结构域。通过Voronoi镶嵌法对染色的染色体结构域进行三维重建显示，在所研究的减数分裂前和减数分裂阶段，平均染色体体积没有显著差异。臂结构域的表面积显著增加，无量纲“圆度因子”估计值降低，这表明在细线前期开始了空间上分离的染色体区域的重组。端粒区域在减数分裂干细胞中主要位于臂结构域染色质中，在此阶段向结构域表面重新分布。在细线期，同源染色体通常未对齐，非同源染色质紧密交织。配对始于弯曲的偶线期染色体的末端，这些染色体呈现出具有可分辨姐妹染色单体的复杂表面结构。结果表明，在哺乳动物中，同源性搜索在染色体区域重塑后的细线期进行。
