A knob-associated tandem repeat in maize capable of forming fold-back DNA segments: Are chromosome knobs megatransposons?
A knob-associated tandem repeat in maize capable of forming fold-back DNA segments: Are chromosome knobs megatransposons?
复制标题
DOI：
10.1073/pnas.95.18.10785
复制
发表时间：
1998-09-01
影响因子：
11.1
通讯作者：
Rines, HW
中科院分区：
文献类型：
--
作者：
Ananiev, EV;Phillips, RL;Rines, HW
从玉米（Zea mays L.） 9号染色体旋钮DNA中分离出一类350 bp单位长度的串联重复DNA序列（TR-1）。比较荧光原位杂交发现，相对于先前描述的180 bp重复序列，TR-1元素也存在于其他玉米染色体的细胞学上可检测到的旋钮中，其比例不同。4号染色体上至少有一个旋钮主要由TR-1重复组成。此外，在不同的染色体上发现了一些TR-1和180-bp重复序列的小簇，其中一些不位于明显的球形异染色质上。限制性内切片段指纹图谱和TR-1元件拷贝数在玉米系间和玉米染色体间存在差异。长度达70千碱基的TR-1串联阵列可以穿插180 bp的串联重复阵列。DNA序列分析和对串联排列的TR-1单元的一个特定延伸的限制性映射表明，这些元件可能以折叠DNA片段的形式组织。TR-1重复序列与180 bp重复序列有两个短的同源片段。其中最长的片段（31 bp，同源性64%）对应于180 bp重复序列中的保守区。玉米旋钮DNA的多态性和复杂结构表明，玉米旋钮DNA可能与果蝇中含有巨型转座子的折叠DNA相似，具有转座因子的某些特性。
A class of tandemly repeated DNA sequences (TR-1) of 350-bp unit length was isolated from the knob DNA of chromosome 9 of Zea mays L. Comparative fluorescence in situ hybridization revealed that TR-1 elements are also present in cytologically detectable knobs on other maize chromosomes in different proportions relative to the previously described 180-bp repeats. At least one knob on chromosome 4 is composed predominantly of the TR-1 repeat. In addition, several small clusters of the TR-1 and 180-bp repeats have been found in different chromosomes, some not located in obvious knob heterochromatin. Variation in restriction fragment fingerprints and copy number of the TR-1 elements was found among maize lines and among maize chromosomes. TR-1 tandem arrays up to 70 kilobases in length can be interspersed with stretches of 180-bp tandem repeat arrays. DNA sequence analysis and restriction mapping of one particular stretch of tandemly arranged TR-1 units indicate that these elements may be organized in the form of fold-back DNA segments. The TR-1 repeat shares two short segments of homology with the 180-bp repeat. The longest of these segments (31 bp; 64% identity) corresponds to the conserved region among 180-bp repeats. The polymorphism and complex structure of knob DNA suggest that, similar to the fold-back DNA-containing giant transposons in Drosophila, maize knob DNA may have some properties of transposable elements.