Organization of endoreduplicated chromosomes in the endosperm of Zea mays L
Organization of endoreduplicated chromosomes in the endosperm of Zea mays L
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DOI：
10.1007/s00412-006-0068-2
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发表时间：
2006-10-01
期刊：
影响因子：
1.6
通讯作者：
Birchler, James A.
中科院分区：
文献类型：
--
作者：
Bauer, Matthew J.;Birchler, James A.
玉米胚乳的染色体在发育后期经历内复制阶段。内复制是细胞周期继续DNA合成但不通过胞质分裂进行的过程。当这种情况发生时，在一些玉米品系中，正常的三倍体胚乳细胞可以达到200倍以上的倍性水平。在这项工作中，我们检查了内复制染色体的结构。以前的细胞学研究表明，虽然每个细胞的DNA含量增加，但核仁和结节的数量保持不变。利用荧光原位杂交和狭缝印迹技术，我们发现A和B染色体上的高度重复的异染色区以及几个活跃转录的基因被内复制。这一结果表明，整个基因组都遵循同样的趋势。进一步的证据表明，不同的染色质链在复制后在整个染色体长度上保持关联，着丝粒和结节区域的DNA比染色体的其他区域更紧密地关联。同一自交系的二倍体和四倍体衍生品之间的异倍体杂交表现出着丝粒和异染色结染色质组织的变化。
The chromosomes of the maize endosperm proceed through an endoreduplication phase in later stages of development. Endoreduplication is a process in which the cell cycle continues DNA synthesis but does not proceed through cytokinesis. When this occurs, the normally triploid endosperm cell can reach ploidy levels greater than 200x in some lines of maize. In this work, we examined the structure of the endoreduplicated chromosomes. Previous cytological work has indicated that, although the DNA content per cell increases, the number of nucleoli and knobs remains the same. Using fluorescence in situ hybridization and slot blot techniques, we show that the highly repetitive heterochromatic areas both on the A and B chromosomes, as well as several actively transcribed genes, are endoreduplicated. This result suggests that the entire genome follows that same trend. Further evidence shows that the various chromatin strands stay associated throughout the length of the chromosomes after they have been replicated, and that the DNA at the centromeric and knob regions is more tightly associated than the other regions of the chromosomes. Interploidy crosses between diploid and tetraploid derivatives of the same inbred exhibit changes in the chromatin organization of centromeres and heterochromatic knobs.