Loreto E L, Valente V L, Zaha A, Silva J C, Kidwell M G
Departmento de Biologia, Universidade Federal de Santa Maria, CEP 97105-900, Santa Maria, RS, Brazil.
J Hered. 2001 Sep-Oct;92(5):375-81. doi: 10.1093/jhered/92.5.375.
Sequences homologous to the P element of Drosophila melanogaster were previously identified in Drosophila mediopunctata, a member of the tripunctata group, subgenus Drosophila. We report here that the P element is present in about three to five copies in the D. mediopunctata genome. While one of the insertion sites appears to be fixed, others may be polymorphic, indicating relatively recent P element activity. Phylogenetic analysis revealed that the D. mediopunctata element belongs to the canonical subfamily of P elements and that divergence of the D. mediopunctata element from other members of this subfamily ranges from 2% to 5% at the nucleotide level. This is the first report of a canonical P element outside the subgenus Sophophora. Based primarily on the striking incongruence between P element and host species phylogenies, the presence of a canonical P element in D. mediopunctata is most likely explained by horizontal transfer between species.
与黑腹果蝇的P因子同源的序列先前在果蝇亚属三斑果蝇组的成员——中斑果蝇中被鉴定出来。我们在此报告，P因子在中斑果蝇基因组中约有三到五个拷贝。虽然其中一个插入位点似乎是固定的，但其他位点可能是多态性的，这表明P因子的活性相对较新。系统发育分析表明，中斑果蝇的P因子属于P因子的典型亚家族，并且该P因子与该亚家族其他成员在核苷酸水平上的差异范围为2%至5%。这是关于Sophophora亚属之外典型P因子的首次报道。主要基于P因子与宿主物种系统发育之间的显著不一致，中斑果蝇中典型P因子的存在最有可能是由物种间的水平转移来解释的。
