Sister chromatids are often incompletely aligned in meristematic and endopolyploid interphase nuclei of Arabidopsis thaliana
Sister chromatids are often incompletely aligned in meristematic and endopolyploid interphase nuclei of Arabidopsis thaliana
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DOI：
10.1534/genetics.105.048363
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发表时间：
2006-01-01
期刊：
影响因子：
3.3
通讯作者：
Schubert, I
中科院分区：
文献类型：
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作者：
Schubert, V;Klatte, M;Schubert, I
我们通过研究不同染色体位置的姐妹染色单体排列来分析姐妹染色单体在分生组织和内多倍体拟南芥间期核中是否连续排列。使用单个 BAC 对流式分选的 4C 根和叶核进行 FISH 经常产生两个以上的杂交信号，表明姐妹染色单体比对不完整或不存在。高达 100% 的 8C、16C 和 32C 核在指定位置处未显示姐妹染色单体排列。使用来自不同染色体位置的 BAC 同时进行 FISH 显示末端比中臂位置更频繁地出现姐妹染色单体排列。着丝粒位置主要对齐到 16C 的倍性水平，但在 32C 核中变得分离或分散。 DNA 低甲基化（整个基因组）和转录活性（FWA 基因位置）不会损害姐妹染色单体的排列。只有 6.1% 的 4C 叶核显示整个 I 号上臂区域的姐妹染色单体分离。纯合转基因串联重复序列（lac算子）阵列比平均常染色质位点更频繁地显示体细胞同源配对，但不会促进姐妹染色单体比对频率的增加。 >= 4C 细胞核中分离的姐妹染色单体臂位置的高频率表明姐妹染色单体内聚力是可变的、动态的，并且在分生和分化的拟南芥细胞核中沿着整个染色体臂不是强制性的。
We analyzed whether sister chromatids are continuously aligned in meristematic and endopolyploid Arabidopsis interphase nuclei by studying sister-chromatid alignment at various chromosomal positions. FISH with individual BACs to flow-sorted 4C root and leaf nuclei frequently yielded more than two hybridization signals, indicating incomplete or absent sister-chromatid alignment. Up to 100% of 8C, 16C, and 32C nuclei showed no sister-chromatid alignment at defined positions. Simultaneous FISH with BACs from different chromosomal positions revealed more frequent sister-chromatid alignment in terminal than in midarm positions. Centromeric positions were mainly aligned up to a ploidy level of 16C but became separated or dispersed in 32C nuclei. DNA hypomethylation (of the whole genome) and transcriptional activity (at FWA gene position) did not impair sister-chromatid alignment. Only 6.1% of 4C leaf nuclei showed sister-chromatid separation of the entire chromosome I top arm territories. Homozygous transgenic tandem repeat (lac operator) arrays showing somatic homologous pairing more often than average euchromatic loci did not promote an increased frequency of sister-chromatid alignment. The high frequency of separated sister-chromatid arm positions in >= 4C nuclei suggests that sister-chromatid cohesion is variable, dynamic, and not obligatory along the entire chromosome arm in meristematic and differentiated Arabidopsis nuclei.