- 作者: 楊素娥; 吳方盛
- 作者服務機構: 中央研究院植物研究所
- 中文摘要: Bacteriophage Xp12, active on X. oryzae, contains 5-methylcytosine instead ofcytosine in its DNA composition. The presence of that unusual pyrimidine in viralDNA and its absence in host DNA arise a question as to how is the cytosine ex-cluded from viral DNA. It is probable that the degradation of host DNA results from the action of aDNase system, although the phage induced DNase may not play a major role in thephenomenon in certain phage bacterial systems. However, Wiberg reported thatphage T4 induces the synthesis of a deoxyribonuclease which specifically attackscytosine-containing DNA. When DNases of Xp12 infected and uninfected X. oryzae were detected withdifferent kinds of DNA substrates, it was found that‘DNases of Xp12 infected cellextract is specific to its host DNA; its activity increases with infection period, andit is more active on native DNA than heat-denatured DNA. As to the activity of DNase to heat-denatured DNA, phage may cause the arisingof inhibitor of DNase which is specific to heat-denaturee DNA, so that its activitydecreases with infection period.
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