Lansman R A, Shade R O, Grigliatti T A, Brock H W
Proc Natl Acad Sci U S A. 1987 Sep;84(18):6491-5. doi: 10.1073/pnas.84.18.6491.
P elements have been cloned and sequenced from Drosophila nebulosa. Their sequences have diverged less than 6% from P elements of Drosophila melanogaster. However D. nebulosa P elements have nucleotide changes that close all four open reading frames found in the D. melanogaster P element. Microinjection experiments show that D. nebulosa P elements cannot provide transposase function for D. melanogaster P elements, nor are D. nebulosa P elements mobilized by the transposase provided by a D. melanogaster P factor. Three D. nebulosa P elements appear to have integrated into the same position of a complex, centromeric repeated sequence. Comparison of nucleotide sequences suggests that D. nebulosa P elements have diverged upon different pathways from a common ancestor that was 99% homologous to the P elements of D. melanogaster.
P 元件已从星云果蝇（Drosophila nebulosa）中克隆并测序。它们的序列与黑腹果蝇（Drosophila melanogaster）的 P 元件相比，差异不到 6%。然而，星云果蝇的 P 元件存在核苷酸变化，这些变化使黑腹果蝇 P 元件中发现的所有四个开放阅读框都关闭了。显微注射实验表明，星云果蝇的 P 元件不能为黑腹果蝇的 P 元件提供转座酶功能，星云果蝇的 P 元件也不会被黑腹果蝇 P 因子提供的转座酶所激活。三个星云果蝇的 P 元件似乎整合到了一个复杂的着丝粒重复序列的同一位置。核苷酸序列比较表明，星云果蝇的 P 元件从一个与黑腹果蝇的 P 元件有 99%同源性的共同祖先开始，沿着不同的途径发生了分化。
