Cancer Research Campaign, Eukaryotic Molecular Genetics Research Group, Department of Biochemistry, Imperial College of Science and Technology, London SW7 2AZ, UK.
EMBO J. 1983;2(5):721-6. doi: 10.1002/j.1460-2075.1983.tb01491.x.
We have examined the distribution of sequences homologous to the type I and type II rDNA insertions of Drosophila melanogaster in its sibling species. Each of the six species we have examined has sequences homologous to the type I insertion, which have undergone extensive divergence by the criterion of their EcoRI, BstI and HindIII restriction patterns. We have isolated cosmid clones containing type I sequences from D. simulans and D. mauritiana, the two species most closely related to D. melanogaster. Southern hybridisation analysis of these clones indicates that, as in D. melanogaster, the type I sequences can exist independently of rDNA and can also dissociate to give sub-components homologous to the right hand segment of the D. melanogaster type I insertion. The type II sequences, on the other hand are present in five out of the six species, but their restriction endonuclease cleavage profile is highly conserved. The differences in the degree of conservation of the two types of insertion sequence are discussed.
我们已经研究了与其近缘种果蝇的 I 型和 II 型 rDNA 插入序列同源的序列分布。在我们研究的六个物种中，每个物种都有与 I 型插入序列同源的序列，根据它们的 EcoRI、BstI 和 HindIII 限制图谱，这些序列已经发生了广泛的分歧。我们已经从与果蝇关系最密切的两个物种，即模拟果蝇和毛里求斯果蝇中分离出含有 I 型序列的 cosmid 克隆。对这些克隆的 Southern 杂交分析表明，与果蝇一样，I 型序列可以独立于 rDNA 存在，也可以解离形成与果蝇 I 型插入的右手片段同源的亚成分。另一方面，II 型序列存在于六个物种中的五个中，但它们的内切酶酶切图谱高度保守。讨论了两种插入序列的保守程度的差异。
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