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標題: | 線狀噬菌體cf在柑橘潰瘍病原菌中基因轉錄之研究 Transcription in Bacteriophage cf-Infected Xanthomonas campestris pv. Citri |
作者: | 王惠貞 |
出版年 : | 1995 |
學位: | 碩士 |
摘要: | 線狀噬菌體cf的DNA序列已定序完成,整個基因組(genome)共有7308個核?酸,以電腦分析及推論得知其至少含10個基因。目前基因II、III、V、VIII的蛋白質已得到,然而對整個基因組的轉錄方式和遺傳圖譜(genetic map),瞭解的仍不多。 本研究利用北方轉印雜合法(Northern blotting hybridization),將cf的複製型(replicative form)DNA切成不同片段,做成探針(probe)偵測cf感染寄主後RNA的種類,以及RNA在不同時期表現的差異。由結果得知線狀噬菌體cf至少轉錄出5個RNA片段,大小約在400-2300個核?酸,比較不同探針雜合的結果可定出cf轉錄(transcription)方向,也可推測出起動子(promoter)的可能位置及終止碼(terminator),並由此構築一個cf的轉錄圖譜;進而配合DNA序列推測的開放讀框(open reading frame),和參考線狀噬菌體fl的遺傳圖譜(genetic map),推測線狀噬菌體cf其他基因的位置,完成一個較完整的cf遺傳圖譜。 Filamentous phage isolated from Xanthomonas campestris pv. citri (X. c. c.) normally forms turbid plaques and undergoes the integration life cycle. The nucleotide sequence of the filamentous single-strand DNA phage cf has been determined. The genome size of cf is 7308bp. According to the open reading frame analysis, there are at least ten putative genes in the genome. Four of the gene products, encoded by gene II, III, V, VIII have been identified. However, the genomic map of the phage cf is still poorly defined. In this study, the transcription pattern of the phage cf in X. c. c. was analyzed by Northern blotting hybridization using different restriction fragments of cf replicative form DNA (RF DNA) as probes. During the infection cycle at least five cf-specific RNAs are transcribed with sizes ranging from 400 to 2300 nucleotides. Characterization of these RNA species with respect to their genetic origins, codogenic properties and nucleotide sequence has indicated that the transcription of the five RNA initiated at five different sites and terminated at two different sites. From these information we can construct the cf transcription map. Two different domains of transcription can be distinguished on the cf DNA. One is actively transcribed and the other is low level of transcription. The region with the higher transcription activity coincides with the region coding for the polypeptides which are needed most abundantly during the infection cycle. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76122 |
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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