Department of Genetics, Osaka University Medical School, Kita-ku, Osaka 530, Japan.
Proc Natl Acad Sci U S A. 1985 Sep;82(18):6236-9. doi: 10.1073/pnas.82.18.6236.
Several DNA sequences with homology to the complete 2.9-kilobase (kb) P element from a P strain in the United States were isolated and characterized from two Drosophila melanogaster strains collected on Chichi Jima, an island 1000 km south of Tokyo. Except for a missing central region and trivial unsequenced regions of 38 base pairs, the 2.1-kb element isolated from a Q strain had the same DNA sequence as that of the complete P element. Seven other elements cloned from genomic DNAs of the Q strain and a Q-derived M strain all possessed the same restriction sites as those of the 2.9-kb P element except for one deleted region in each element. The finding of sequence conservation in P elements have had a common ancestor relatively recently. Thus, it is suggested that the P element family was a recent invader of the species. By contrast, no complete P element was found in these Japanese strains so far as surveyed, indicating the possibility that P elements in the Chichi Jima population are almost all defective. The implication of this possibility is discussed in relation to the uniqueness of the population on Chichi Jima where Q strains predominate and no P strains have yet been found.
从在东京以南 1000 公里的 Chichi Jima 采集的两个 Drosophila melanogaster 品系中分离并鉴定了几个与来自美国 P 品系的完整 2.9kb P 元件同源的 DNA 序列。除了缺失中央区域和无关紧要的未测序的 38 个碱基对之外，从 Q 品系中分离出的 2.1kb 元件与完整的 P 元件具有相同的 DNA 序列。从 Q 品系和源自 Q 品系的 M 品系的基因组 DNA 中克隆的另外七个元件都具有与 2.9kb P 元件相同的限制位点，除了每个元件中缺失的一个区域。P 元件序列保守性的发现表明它们具有相对较近的共同祖先。因此，这表明 P 元件家族是该物种的近期入侵物。相比之下，到目前为止，在这些日本品系中尚未发现完整的 P 元件，这表明 Chichi Jima 种群中的 P 元件几乎都是有缺陷的。这种可能性的含义与 Chichi Jima 种群的独特性有关，该种群以 Q 品系为主，尚未发现 P 品系。
