Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/21321
標題: Characterization of AFLP sequences from regions of maize B chromosome defined by 12 B-10L translocations
以十二組B-10L易位染色體分析玉米B染色體之AFLP序列
作者: Peng, Shu-Fen
彭淑芬
關鍵字: 玉米
Zea mays. L.
B染色體
B-A易位染色體
AFLP
B chromosome
B-A translocation
AFLP
出版社: 分子生物學研究所
摘要: Maize B chromosome sequences have been previously cloned by microdissection, and all are proven to be highly repetitive, homologous to the normal complement, and showing no similarity to any published gene other than mobile elements. In this study, we isolated sequences from defined B regions. The strategy involved identification and then mapping of AFLPs-derived B fragments before cloning. Of 14 B AFLPs, 13 were mapped by 12 B-10L translocations: three around the centromeric knob region, three in the proximal euchromatic, one around the border of proximal euchromatic and distal heterochromatic, and six in the distal heterochromatic region of the B long arm. The AFLP fragments were cloned and sequenced. Analogous to the microdissected sequences, all sequences were repetitive, and all but two were highly homologous to the A chromosomes. FISH signals of all but three clones appeared in pachytene B as well as somatic A and B chromosomes. None of these clones exhibits identity to any published gene. Six clones displayed homology to two centromeric BACs, four to sequences of chromosomes 3, 4, 7, and 10, four to retrotransposons, and three to no sequence deposited in GenBank. Furthermore, flanking regions of two highly B-specific clones were characterized, showing extension of B-exclusive nature. The possibility of presence of novel B repeat(s) is discussed.
前人利用microdissection的方式分離到的玉米B染色體序列為重複性序列,且與A染色體的跳躍基因有相似性。本實驗利用不同的方式,分離特定B染色體區域的序列。此策略先分離B染色體專一性的AFLP片段,並將之定位到B染色體上,接著再經過選殖、南方墨點分析及定序。本實驗共得到十四個B染色體的AFLP序列,利用B-A易位染色體成功地將其中十三個序列定位在B染色體長臂的不同區域:三個定位於中節染色體節區域、三個在中節近側常染色質區、一個在中節近側常染色質及異染色質區交接處和最後六個在中節遠側異染色質區。定位之後再經過選殖、南方墨點分析及定序,顯示本實驗所分離的序列與microdissection的序列具有類似的結果:十一個AFLP皆為重複性序列,且為A與B染色體共有的序列;另外二個雖也為重複性序列,但其南方墨點雜合的訊號只出現在含有B染色體的材料,此二個序列在此稱為B染色體專一性序列。在螢光原位雜交的分析,十個序列的訊號同時出現在A與B根尖細胞或是粗絲期染色體,另外三個則無法偵測到訊號。這些序列並未與已發表的任何基因序列一致,其中有六與玉米二個中節的BACs有相似性,四個與第三、四、七和十條染色體的序列有相似性,及四個與跳躍基因有相似性,另外三個並未比對到相似的序列。更進一步的分析其中二個具有B染色體專一性序列其相鄰區域的序列,顯示B染色體專一性的區域延伸至相鄰區域,可能成為新的B染色體專一性的重複性序列。
URI: http://hdl.handle.net/11455/21321
Appears in Collections:分子生物學研究所

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