Delgado M, Frescatada M, Ribeiro-Varandas E, Viegas W, Jones R N
Centro de Botânica Aplicada à Agricultura, Instituto Superior de Agronomia, Technical University of Lisbon, Tapada da Ajuda, Portugal.
Cytogenet Genome Res. 2010 Jul;129(1-3):64-71. doi: 10.1159/000311607. Epub 2010 May 26.
Biologists have been fascinated for more than 2 centuries about how the nucleus in eukaryotes is organised. Certain of the component parts are well known, but the overall picture is blurred and often confusing. Small genome species have chromosomes in their interphase nuclei disposed in diffuse chromosome territories, without any Rabl arrangement, while in large genomes the chromosomes run string-like through the nucleus with a Rabl orientation following through the cell cycle. What happens in genomes of intermediate size is either a bit of both, depending on the tissue being studied, or still remains to be determined. The centromeres are the most dynamic and least well understood part of the nucleus, subject to rapid evolutionary change and with an epigenetic mark based on a special form of histone CENH3. Nonetheless, the centromere epigenetic mark has been inherited for millions of years by a process that is a complete mystery. Centromeres are involved with the dynamic interactions between chromosomes and other parts of the nuclear environment, such as the nuclear matrix and inner nuclear membrane, and they also engage with the spindle when the order within the nucleus changes during its division. The nucleolus organizer regions have likewise posed tantalising problems about their massive amplification of rDNA sequences, and how they are regulated and expressed. Some of these issues are now becoming clearer with advances in the science and the ongoing development of new molecular tools. These developments are discussed in this contribution, with particular reference to the centromere and the nucleolus organizer.
两个多世纪以来，生物学家一直对真核生物细胞核的组织方式着迷。某些组成部分是众所周知的，但整体情况却模糊不清，常常令人困惑。小基因组物种的间期核中的染色体分布在弥散的染色体区域，没有任何拉布尔排列，而在大基因组中，染色体呈线状贯穿细胞核，并在整个细胞周期中保持拉布尔方向。中等大小基因组中的情况则介于两者之间，具体取决于所研究的组织，或者仍有待确定。着丝粒是细胞核中最具动态且了解最少的部分，它经历快速的进化变化，并且具有基于特殊形式的组蛋白CENH3的表观遗传标记。尽管如此，着丝粒表观遗传标记已经通过一个完全神秘的过程遗传了数百万年。着丝粒参与染色体与核环境其他部分（如核基质和内核膜）之间的动态相互作用，并且在细胞核在分裂过程中其内部秩序发生变化时，它们也与纺锤体相互作用。核仁组织区同样在其rDNA序列的大量扩增以及它们如何被调控和表达方面提出了诱人的问题。随着科学的进步和新分子工具的不断发展，其中一些问题现在正变得更加清晰。本论文将讨论这些进展，特别提及着丝粒和核仁组织区。
