https://scholars.lib.ntu.edu.tw/handle/123456789/96212
標題: | 竹嵌紋病毒之分子生物學─子計畫三:竹嵌紋毒毒缺失RNA之研究(1/3) | 作者: | 張雅君 | 關鍵字: | 竹嵌紋病;竹嵌紋病毒;缺失性RNA;Bamboo Mosaic;BaMV;Defective RNA | 公開日期: | 1998 | 出版社: | 臺北市:國立臺灣大學植物病理與微生物學系暨研究所 | 摘要: | 為了探討竹嵌紋病毒(bamboo mosaic virus,簡稱BaMV)的缺失性RNA 之性質,我 們從含有缺失性RNA 之BaMV 病毒顆粒中,利用RT-PCR 與TA-cloning 的方法,選殖 出35 個含有0.7-1.3 kb DNA 片段的cDNA 株。目前完成9 個cDNA 株的核酸定序與序 列分析,証實皆為BaMV缺失性RNA。序列分析顯示這些自然產生的BaMV缺失性RNA 是由來自BaMV基因體之5'端約474-868 個核甘酸及3'端約252-382 核甘酸(不含poly(A) 尾端)所組成,其核酸序列主要差異在於3'端接合區的序列起始點不同;其中有3 株缺失 性RNA 合併了BaMV 複製酵素基因5’端與鞘蛋白基因3’端之轉譯架,形成一特殊之融 合轉譯架。為分析那一株缺失性RNA 具有生物活性(即能被BaMV RNA 所複製),將 BaMV 與缺失性RNA 之生體外轉錄體同時接種至菸草原生質體,經24 小時光照培養後 ,抽取RNA,以非放射性的BaMV 5'端cDNA 探針進行北方雜配反應,結果發現其中 至少有6 株缺失性RNA 具有被增殖的能力,但因其不具干擾BaMV 複製的能力,故稱 它們為缺失性RNA。同屬於potexvirus 的三葉草黃化嵌紋病毒(clover yellow mosaic virus ,簡稱ClYMV)之缺失性RNA,其基因體皆具有由複製酵素基因5’端與鞘蛋白基因3’ 端合併形成之融合轉譯架,若破壞其鞘蛋白基因原有之轉譯架,則該缺失性RNA 會喪 失增殖能力。相反地,目前我們所選殖到具有增殖能力的六種BaMV 缺失性RNA,只 有D52 具有此特殊之融合轉譯架;故鞘蛋白基因轉譯架之維持,對於BaMV 缺失性RNA 的增殖並非必要。由上述實驗結果可知,BaMV 和ClYMV 的缺失性RNA 的性質不同 ,因此融合轉譯架對BaMV 的缺失性RNA 之影響,仍有待進一步的研究。 In order to study the defective RNAs of bamboo mosaic virus (BaMV), we used RT-PCR and TA-cloning methods to clone the defective RNAs from BaMV virions and obtained 35 cDNA clones. Nine cDNA clones were sequenced completely and proved to be the defective RNAs of BaMV. According to sequence analysis, these defective RNAs were composed of two noncontiguous regions, corresponding to 5' (474-868 nt) and 3' (252-382 nt) termini of BaMV genome. Besides, three clones were found to contain a special fusion open reading - 2 - frame (ORF), which joined 5’ terminus of replicase gene with 3’ terminus of coat protein gene. When assaying the biological activity of cloned defective RNAs, the RNA transcripts of BaMV and defective RNAs were inoculated into tobacco protoplasts, incubated for 24 hours and then analyzed by Northern blotting. The results indicated that at least six clones were infectious and could be replicated by BaMV transcripts in protoplasts, but all lack of interfering ability. The defective RNAs of clover yellow mosaic potexvirus (ClYMV) were reported to contain a fusion ORF of replicase and coat protein genes, which was essential for their infectivity. On the contrary, only D52 among the infectious defective RNAs of BaMV maintained the similar fusion ORF. The maintenance of the reading frame of coat protein gene was not required for the replication of defective RNAs of BaMV. From the above results, the characters of defective RNAs of BaMV are different from those of ClYMV, and the influence of fusion ORF on the defective RNAs of BaMV needs further study. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/29747 | 其他識別: | 872311B002003B11 | Rights: | 國立臺灣大學植物病理與微生物學系暨研究所 |
顯示於: | 植物病理與微生物學系 |
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