Scherthan H, Bähler J, Kohli J
Institute of General Microbiology, University of Bern, Switzerland.
J Cell Biol. 1994 Oct;127(2):273-85. doi: 10.1083/jcb.127.2.273.
Interactions between homologous chromosomes (pairing, recombination) are of central importance for meiosis. We studied entire chromosomes and defined chromosomal subregions in synchronous meiotic cultures of Schizosaccharomyces pombe by fluorescence in situ hybridization. Probes of different complexity were applied to spread nuclei, to delineate whole chromosomes, to visualize repeated sequences of centromeres, telomeres, and ribosomal DNA, and to study unique sequences of different chromosomal regions. In diploid nuclei, homologous chromosomes share a joint territory even before entry into meiosis. The centromeres of all chromosomes are clustered in vegetative and meiotic prophase cells, whereas the telomeres cluster near the nucleolus early in meiosis and maintain this configuration throughout meiotic prophase. Telomeres and centromeres appear to play crucial roles for chromosome organization and pairing, both in vegetative cells and during meiosis. Homologous pairing of unique sequences shows regional differences and is most frequent near centromeres and telomeres. Multiple homologous interactions are formed independently of each other. Pairing increases during meiosis, but not all chromosomal regions become closely paired in every meiosis. There is no detectable axial compaction of chromosomes in meiotic prophase. S. pombe does not form mature synaptonemal complexes, but axial element-like structures (linear elements), which were analyzed in parallel. Their appearance coincides with pairing of interstitial chromosomal regions. Axial elements may define minimal structures required for efficient pairing and recombination of meiotic chromosomes.
同源染色体之间的相互作用（配对、重组）对减数分裂至关重要。我们通过荧光原位杂交技术，在粟酒裂殖酵母的同步减数分裂培养物中研究了整条染色体并定义了染色体亚区域。将不同复杂度的探针应用于铺展的细胞核，以描绘整条染色体，可视化着丝粒、端粒和核糖体DNA的重复序列，并研究不同染色体区域的独特序列。在二倍体细胞核中，同源染色体甚至在进入减数分裂之前就共享一个共同的区域。所有染色体的着丝粒在营养细胞和减数分裂前期细胞中聚集在一起，而端粒在减数分裂早期聚集在核仁附近，并在整个减数分裂前期保持这种构型。端粒和着丝粒似乎在营养细胞和减数分裂过程中对染色体组织和配对起着关键作用。独特序列的同源配对表现出区域差异，在着丝粒和端粒附近最为频繁。多个同源相互作用彼此独立形成。配对在减数分裂过程中增加，但并非所有染色体区域在每次减数分裂中都紧密配对。在减数分裂前期没有可检测到的染色体轴向压缩。粟酒裂殖酵母不形成成熟的联会复合体，但形成了轴向元件样结构（线性元件），并对其进行了平行分析。它们的出现与染色体间质区域的配对同时发生。轴向元件可能定义了减数分裂染色体有效配对和重组所需的最小结构。
