Die Variabilität der Kerndomänen und der DNA-Proteinstruktur von Telomeren während der pflanzlichen Entwicklung Varibility of the nuclear domains and the DNA-protein structure of telomeres during plant development

端粒是在真核生物染色体末端发现的dna -蛋白质复合物，是一些重要的细胞功能所必需的。它们参与有丝分裂过程中染色体的分离，它们阻止染色体的降解和端到端融合，它们通过一种特定的核酶，端粒酶，使线性DNA完全复制。在酵母中，端粒对端粒附近基因的转录以及DNA复制的时间也有毒害作用。端粒在细胞核内不是随机分布的，而是定位于特定的核室，可能在细胞核内构成一个独立的功能域。对于拟南芥，我们能够在年轻的根细胞中显示核仁周围的大部分端粒的定位。随着细胞年龄的增长，核仁周围的这种特异定位丧失并分散。此外，我们可以证明，端粒DNA与特定蛋白（ATBP1）形成稳定的复合物。在这里，端粒dna -蛋白质复合物的组成再次显示出发育动态，在叶片衰老开始时，一个额外的蛋白质（ATBP2）通过蛋白质/蛋白质相互作用与该复合物结合。ATBP1和ATBP2现在应该得到更精确的纯化和表征。在植物发育的其他阶段，拟南芥端粒染色质结构和dna -蛋白质复合物组成的变化将被研究，我们的主要兴趣将集中在这种特定核定位的功能含义以及这种核定位变化与端粒dna -蛋白质相互作用动态之间的相关性。

Telomeres are the DNA-protein complexes found at the termini of eukaryotic chromosomes and are required for several important cellular functions. They are involved in the segregation of the chromosomes during mitosis, they prevent the chromosomes from degradation and end-to-end fusions, and they enable complete replication of linear DNA by a specific ribozyme, the telomerase. In yeast, telomeres also exhibit poistion effects on the transcription of genes located in close proximity to the telomeres as well as on the timing of DNA replication. Telomeres are not randomly distributed within the nucleus but localised to certain nuclear compartments probably constituting an independent functional domain within the nucleus. For Arabidopsis thaliana we were able to show the localisation of most of the telomeres around the nucleolus in young root cells. This specific localisation around the nucleolus was lost and became dispersed with increasing age of the cells. Furthermore, we could show, that telomeric DNA forms a stable complex with a specific protein (ATBP1). Here again, the composition of the telomeric DNA-protein complex exhibits a developmental dynamic, an additional protein (ATBP2) binds to this complex via protein/protein interaction during the onset of leaf senescence. ATBP1 and ATBP2 should now be purified and characterised more precisely. Changes in chromatin structure and composition of the DNA-protein complexes of the Arabidopsis thaliana telomeres during other stages of plant development will be investigated and our main interest wil focus on the functional implication of this specific nuclear localisation and on the correlation between changes in this nuclear localisation and the dynamic of the DNA-protein interaction at the telomeres.