Haynes S R, Dawid I B
Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, MD 20892.
Mol Gen Genet. 1987 Aug;209(1):203-5. doi: 10.1007/BF00329861.
Many cloned regions of the Drosophila genome show minimal variation between strains in overall sequence arrangement. While restriction site polymorphisms occur and the location of transposable elements may vary from one strain to another, such changes appear to be relatively minor variations superimposed on overall genome stability. In contrast to this general situation, we describe here a segment of the X chromosome that is highly polymorphic in four strains of D. melanogaster and in D. simulans. The strains differ in the presence and extent of a short duplication and the presence of repetitive DNA. These results suggest that different regions of the genome may be subject to different evolutionary constraints, with some regions being particularly prone to extensive changes, even within a single species.
果蝇基因组的许多克隆区域在不同品系间的整体序列排列上显示出极小的差异。虽然存在限制性酶切位点多态性，并且转座元件的位置可能因品系而异，但这些变化似乎是叠加在整体基因组稳定性之上的相对较小的变异。与这种一般情况形成对比的是，我们在此描述X染色体上的一个片段，它在黑腹果蝇的四个品系以及拟果蝇中具有高度多态性。这些品系在一个短重复序列的存在与否及长度以及重复DNA的存在情况上存在差异。这些结果表明，基因组的不同区域可能受到不同的进化限制，某些区域甚至在单个物种内就特别容易发生广泛的变化。
