Ananiev E V, Phillips R L, Rines H W
Department of Agronomy and Plant Genetics and Plant Molecular Genetics Institute, University of Minnesota, 1991 Upper Buford Circle, St. Paul, MN 55108, USA.
Proc Natl Acad Sci U S A. 1998 Oct 27;95(22):13073-8. doi: 10.1073/pnas.95.22.13073.
A set of oat-maize chromosome addition lines with individual maize (Zea mays L.) chromosomes present in plants with a complete oat (Avena sativa L.) chromosome complement provides a unique opportunity to analyze the organization of centromeric regions of each maize chromosome. A DNA sequence, MCS1a, described previously as a maize centromere-associated sequence, was used as a probe to isolate cosmid clones from a genomic library made of DNA purified from a maize chromosome 9 addition line. Analysis of six cosmid clones containing centromeric DNA segments revealed a complex organization. The MCS1a sequence was found to comprise a portion of the long terminal repeats of a retrotransposon-like repeated element, termed CentA. Two of the six cosmid clones contained regions composed of a newly identified family of tandem repeats, termed CentC. Copies of CentA and tandem arrays of CentC are interspersed with other repetitive elements, including the previously identified maize retroelements Huck and Prem2. Fluorescence in situ hybridization revealed that CentC and CentA elements are limited to the centromeric region of each maize chromosome. The retroelements Huck and Prem2 are dispersed along all maize chromosomes, although Huck elements are present in an increased concentration around centromeric regions. Significant variation in the size of the blocks of CentC and in the copy number of CentA elements, as well as restriction fragment length variations were detected within the centromeric region of each maize chromosome studied. The different proportions and arrangements of these elements and likely others provide each centromeric region with a unique overall structure.
一组燕麦 - 玉米染色体附加系，其中单个玉米（Zea mays L.）染色体存在于具有完整燕麦（Avena sativa L.）染色体组的植物中，这为分析每个玉米染色体着丝粒区域的组织提供了独特的机会。一个先前被描述为与玉米着丝粒相关的DNA序列MCS1a，被用作探针从由从9号玉米染色体附加系中纯化的DNA构建的基因组文库中分离黏粒克隆。对六个包含着丝粒DNA片段的黏粒克隆的分析揭示了一个复杂的组织。发现MCS1a序列包含一种类似逆转座子的重复元件CentA的长末端重复序列的一部分。六个黏粒克隆中的两个包含由一个新鉴定的串联重复序列家族CentC组成的区域。CentA的拷贝和CentC的串联阵列与其他重复元件交错分布，包括先前鉴定的玉米逆转座子Huck和Prem2。荧光原位杂交显示CentC和CentA元件仅限于每个玉米染色体的着丝粒区域。逆转座子Huck和Prem2沿着所有玉米染色体分散分布，尽管Huck元件在着丝粒区域周围的浓度有所增加。在所研究的每个玉米染色体的着丝粒区域内检测到CentC块大小、CentA元件拷贝数的显著变化以及限制性片段长度变化。这些元件以及可能其他元件的不同比例和排列为每个着丝粒区域提供了独特的整体结构。
