Cloning, Identification and Characterization of a Repetitive Sequence Flanking Telomere and Homologous to canrep in Brassica napus

衛星DNA是由重複序列串聯形成，它是高等真核生物染色體的著絲粒有時也包括亞端粒區域的主要結構。端粒和著絲粒對於染色體的結構和功能至關重要。端粒DNA幾乎在所有植物中都是保守的。可是目前在很多植物中選殖的著絲粒序列幾乎沒有發現保守性。我們利用連接接頭進行巢式PCR的方法，通過選殖端粒旁側序列獲得了甘藍型油菜亞端粒序列。NCBI的BLAST比對結果顯示其中選殖的一個序列與以前報導的甘藍型油菜著絲粒衛星DNA高度同源。通過螢光原位雜交，這一衛星DNA主要位於染色體的著絲粒區域，另外也出現在一些染色體的末端。這一亞端粒衛星DNA在芸苔屬的染色體進化中較為活躍。系統發生數的分析表明了它序列的保守性。最後，我們討論了這一著絲粒衛星DNA出現在亞端粒區域的原因。

關鍵字

甘藍型油菜；亞端粒；端粒重複；著絲粒；衛星DNA

並列摘要

Satellite DNAs consist of long tandem arrays of short or large repeated sequences that form the centromeric and sometimes also subtelomeric regions of all higher eukaryote chromosomes. Telomeres and centromeres are the most important elements involved in the structure and function of chromosome. Telomeric DNA sequences are conserved among nearly all plant species. Although centromere-specific DNA sequences have been isolated in a wide range of plant species, almost no conservation was found in their DNA sequences. Here, we utilized the cassette-ligation-mediated PCR approach for cloning the sequence near the telomeric repeats of Brassica napus. Sequences analysis showed that one sequence was highly homologous to the centromeric satellite DNA sequence reported. FISH revealed that this satellite was located primarily at centromeric regions of most chromosomes, and also at some chromosome ends. The sequence was a subtelomeric satellite DNA which possessed variability in the evolution of chromosomes of Brassica species. The phylogenetic tree analysis of the satellite showed its sequence was conservative in Brassica. We discussed why the centromeric satellites appeared in the subtelomeric region.

並列關鍵字

Brassica napus ； Centromere ； Satellite DNA ； Subtelomere ； Telomeric repeat

國際替代計量

Cloning, Identification and Characterization of a Repetitive Sequence Flanking Telomere and Homologous to canrep in Brassica napus

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