Characterization of a tandemly repeated subtelomeric sequence with inverted telomere repeats in maize
Characterization of a tandemly repeated subtelomeric sequence with inverted telomere repeats in maize
复制标题
玉米中具有反向端粒重复的串联重复亚端粒序列的表征
作者：
Li, Jun;Yang, Fei;Li, Lijia
在这项研究中，两个互补的端粒引物应用于单引物PCR。其中一条引物扩增出清晰的条带，另一条引物扩增出模糊的条带。从该特异性扩增带分离的克隆的序列分析显示，命名为MTAS 1的412 bp克隆与已报道的玉米（Zea mays L.）的亚端粒序列（382 bp）具有高度同源性，这表明该克隆可能存在于亚端粒区域。克隆MTAS1展示了一种新的结构特征，两侧是正向和反向端粒重复序列。Southern杂交显示了一个梯形的杂交带，表明MTAS 1是一个串联重复序列。荧光原位杂交结果表明，在几条长染色体的短臂末端都有较强的MTAS1信号，证实了MTAS1是一个亚端粒序列，而高亮度的信号进一步表明该克隆序列是玉米中的一个高度串联重复序列。以端粒DNA和MTAS 1为探针，在中期染色体和延伸的基因组DNA纤维上进行荧光原位杂交，结果表明，该克隆的杂交信号与端粒串联重复序列的信号相邻或重叠，在多条染色体的亚端粒区域分布不均匀，甚至在同一条染色体的两个亚端粒区域也存在差异。
In this study, two complementary telomere primers were applied to a single-primer PCR. A clear amplification band was obtained with one primer, while a smear pattern was seen with the other primer. Sequence analysis of the isolated clones from this specific amplification band revealed that a 412 bp clone designated as MTAS1 shared high homology with a reported subtelomeric sequence (382 bp) from maize (Zea mays L.), which indicated that this clone was possibly present at subtelomeric regions. The clone MTAS1 displayed a novel structural feature flanked by the forward and inverted telomere repeats. Southern hybridization revealed a ladder of hybridization bands, suggesting that MTAS1 was a tandemly repeated sequence. Fluorescence in situ hybridization results showed that the strong MTAS1 signals were present at the ends of short arms of several long chromosomes, confirming that MTAS1 was a subtelomeric sequence and the high brightness of signals further indicated this cloned sequence was a highly and tandemly repetitive sequence in maize. Fluorescence in situ hybridization with telomeric DNA and MTAS1 as probes on metaphase chromosomes and extended genomic DNA fibers showed that hybridization signals of this clone located adjacent to or overlapped with signals of telomere tandem repeats distributed heterogeneously in subtelomeric regions of several chromosomes and even exhibited differences in two subtelomeres of a single chromosome.