原始真核生物DNA中(dA.dT)20 - 25序列的存在。
The presence of (dA.dT)20-25 tracts in the DNA of primitive eukaryotes.
作者信息
Mol J N, Flavell R A, Borst P
出版信息
Nucleic Acids Res. 1976 Sep;3(9):2367-77. doi: 10.1093/nar/3.9.2367.
Previous work by Jacobson et al. (1) has shown that the number and distribution of (dA.dT)25 tracts in the nuclear DNA of the slime mold Dictyostelium discoideum reflects the number and the distribution of transcriptional units. To investigate whether this is a general phenomenon we compared the nuclear DNAs of other primitive eukaryotes with respect to their content of large (dA.dT)n tracts via the thermal stability of their hybrids with poly(rA). The results of our analysis indicate that all nuclear DNAs tested have (dA.dT)20-25 tracts, but the frequency of such tracts varies from one per 5.4 X 10(6) daltons in Dictyostelium nuclear DNA to one per 2.8 X 10(8) daltons in Crithidia luciliae nuclear DNA. We conclude that the presence of (dA.dT)20-25 tracts is not an obligatory characteristic of the transcriptional unit in primitive eukaryotes. Chromatography of native DNAs on poly(rU) Sephadex columns shows that the large (dA.dT)n tracts occurring in the genomes of both primitive and higher eukaryotes are widely distributed throught these genomes.
雅各布森等人此前的研究（1）表明，黏菌盘基网柄菌核DNA中（dA.dT）25片段的数量和分布反映了转录单位的数量和分布。为了研究这是否是一种普遍现象，我们通过与聚（rA）杂交体的热稳定性，比较了其他原始真核生物核DNA中大型（dA.dT）n片段的含量。我们的分析结果表明，所有测试的核DNA都有（dA.dT）20 - 25片段，但此类片段的频率有所不同，在盘基网柄菌核DNA中每5.4×10⁶道尔顿有一个，而在鲁氏锥虫核DNA中每2.8×10⁸道尔顿有一个。我们得出结论，（dA.dT）20 - 25片段的存在并非原始真核生物转录单位的必然特征。天然DNA在聚（rU）葡聚糖凝胶柱上的色谱分析表明，原始和高等真核生物基因组中出现的大型（dA.dT）n片段在这些基因组中广泛分布。
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