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標題: | 絲瓜簇葉病植物菌質體rRNA操縱子基因之組成及分析 Gene Organization of a Ribosomal RNA Operon in Phytoplasma Associated with the Loofah Witches' Broom. |
作者: | 蔡祁樟 |
出版年 : | 1999 |
學位: | 碩士 |
摘要: | 本研究室鍾德磊曾利用含有黴漿菌(Mycoplasma genitalium) rRNA基因片段之clone 138作為探針,篩選絲瓜簇葉病植物菌質體(phytoplasma)之Hind Ⅲ基因庫,得到一選殖株(clone H1),含有一4.0 kb左右的植物菌質體DNA片段,定序後與M. genitalium rRNA基因比對,確定包含完整的16S rRNA基因及2/3的23S rRNA基因,且16S rRNA基因與23S rRNA基因間的序列含有一tRNAIle基因。 本實驗即藉此4.0 kb片段後端約1.0 kb之EcoR I-Hind Ⅲ片段為探針,改以對該菌質體之EcoR I基因庫進行篩選,得到一選殖株(clone D1),含有一6.0 kb左右的植物菌質體DNA片段,經分析後發現包含先前尚未完整的23S rRNA基因片段及完整的5S rRNA基因。由於尚未有植物菌質體rRNA操縱子(operon)的完整的序列發表。因此,將篩選出之二DNA片段(4.0 kb及6.0 kb)與親源性較近的Mollicutes綱及其它革蘭氏陽性菌(gram-positive)的rRNA操縱子序列進行進一步分析,結果發現此二片段結合而成的9.0 kb序列中,包含有此植物菌質體完整的rRNA操縱子,且此操縱子內之基因排列順序為5'-16S rRNA基因-23S rRNA基因-5S rRNA基因-3',其為原核生物rRNA操縱子內rRNAs基因典型的排列方式。此外,此rRNA操縱子內5S rRNA基因序列的後端緊接著二個tRNA基因,分別為tRNAVal及tRNAAsn。本研究同時對這兩片段中基因的二級結構進行分析並討論。 Previously, using insert DNA fragment of clone 138, which contained Mycoplasma genitalium rRNA gene, as probe to screen a Hind Ⅲ genonic library of loofah witches' broom (LfWB) phytoplasma, a clone (cloneH1) with a 4.0-kb insert was obtained in our lab. Comparing the nucleotide sequence of this 4.0-kb fragment with the nucleotide sequence of M. genitalium genomic databank revealed that it contained entire 16S and two-third 23S rRNA sequence of LfWB phytoplasma, with a tRNAIle gene in the spacer region between 16S and 23S rRNA genes. In order to clone the complete LfWB phytoplasma rRNA operon, an 1.0-kb EcoR I-Hind III fragment of the 4.0-kb insert was used as probe to screen a EcoR I genomic library of LfWB phytoplasma. A clone (clone D1) with a 6.0-kb insret was obtained. Aligment of this 6.0-kb sequence with M. genitulium genomic databank had shown it contained the other one-third 23S rRNA gene and entire 5S rRNA gene, and two tRNA genes (tRNAVal and tRNAAsn) downstream from few bases of 5S rRNA gene. The nucleotide sequence of these two fragments (4.0-kb, 6.0-kb) were compared with the rRNA operon sequence of Mollicutes and other gram-positive bacteria. The results indicated these two fragments contained the complete sequence of the LfWB phytoplasma rRNA operon with a context of 5'-16S-23S-5S-3', presenting a typical rRNA operon orginization of prokaryotes. This was the first rRNA operon of a phytoplasma published. The secondary structures of the genes in the operon were also analyzed. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/75035 |
全文授權: | 未授權 |
顯示於系所單位: | 植物科學研究所 |
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