Roberts N Y, Osman K, Armstrong S J
School of Biosciences, University of Birmingham, Birmingham, UK.
Cytogenet Genome Res. 2009;124(3-4):193-201. doi: 10.1159/000218125. Epub 2009 Jun 25.
The ends of linear eukaryotic chromosomes are protected by the telomere, a specialised nucleoprotein complex. The primary role of the telomere is to protect the chromosome ends from being degraded or recognised and processed as double strand breaks. Additionally, the telomeres are involved in interphase chromosome organisation and also in chromosome pairing, synapsis and movement during meiotic prophase. The main emphasis of this review is concerned with the distribution and dynamics of the telomeres in the somatic cell and meiocytes of plants, focusing on the model plant Arabidopsis thaliana. In Arabidopsis the telomeres are organised around the nucleolus in both the somatic and meiotic interphase. One of the outstanding questions in meiosis is how homologous chromosomes pair (align) and synapse during meiotic prophase. Recent attention has been paid to the bouquet formation, a nearly universal event, during which the telomeres cluster on the nuclear membrane in early prophase. It has been suggested that because the telomeres are in close proximity this would enhance their pairing and subsequent synapsis of the homologues. In Arabidopsis we observe that the telomeres are paired homologously in early meiosis whilst still arranged around the nucleolus. They are moved to the nuclear membrane preceding synapsis and reveal only a loose clustering, which may represent a transient bouquet. On completion of synapsis the paired telomeres are dispersed and remain attached to the nuclear membrane until diplotene when they dissociate from the nuclear membrane. We also discuss the prospects for live imaging of the telomeres in Arabidopsis.
线性真核染色体的末端由端粒保护，端粒是一种特殊的核蛋白复合体。端粒的主要作用是保护染色体末端不被降解，或不被识别和处理成双链断裂。此外，端粒还参与间期染色体的组织，以及减数分裂前期染色体的配对、联会和移动。本综述的主要重点是植物体细胞和减数分裂细胞中端粒的分布和动态，重点关注模式植物拟南芥。在拟南芥中，端粒在体细胞和减数分裂间期围绕核仁组织。减数分裂中一个突出的问题是同源染色体在减数分裂前期如何配对（对齐）和联会。最近人们关注到花束形成这一几乎普遍存在的现象，在此过程中，端粒在前期早期聚集在核膜上。有人提出，由于端粒靠得很近，这将增强它们的配对以及随后同源染色体的联会。在拟南芥中，我们观察到端粒在减数分裂早期同源配对，同时仍围绕核仁排列。它们在联会之前移至核膜，仅显示松散的聚集，这可能代表一个短暂的花束。联会完成后，配对的端粒分散，并一直附着在核膜上，直到双线期它们从核膜上解离。我们还讨论了拟南芥端粒实时成像的前景。
