Hagemann S, Haring E, Pinsker W
Institut für Allgemeine Biologie, AG Genetik, Medizinische Fakultät, Universität Wien, Austria.
Genetica. 1996 Jul;98(1):43-51. doi: 10.1007/BF00120217.
Two distinct P element subfamilies, designated M-type and O-type, reside in the genome of D. bifasciata. PCR-screening of 65 Drosophila species revealed that only D. bifasciata and its closest relative D. imaii possess O-type elements. Outside the genus, O-type elements were detected in Scaptomyza pallida. Restriction analyses show that the general structure of the O-type elements from S. pallida and D. bifasciata is the same. Sequence divergence turned out to be extremely low (0.43%). These results suggest that the O-type subfamily of D. bifasciata has been received by horizontal transfer from an external source, most probably from the genus Scaptomyza, as has been previously suspected for the M-type family. Since the sequence divergence between M-type elements from S. pallida and D. bifasciata is eighteen-fold higher than that between O-type elements, two independent intergeneric transfer events have to be postulated. In order to re-examine the taxonomic status of S. pallida, a partial sequence (489 bp) of the Adh gene was analysed. The data clearly prove that S. pallida has to be placed far outside the D. obscura group.
两种不同的P因子亚家族，分别命名为M型和O型，存在于双带果蝇的基因组中。对65种果蝇进行PCR筛选后发现，只有双带果蝇及其最近的亲缘种今西果蝇拥有O型因子。在果蝇属之外，在苍白潜蝇中检测到了O型因子。限制性分析表明，苍白潜蝇和双带果蝇的O型因子的总体结构是相同的。结果发现序列差异极低（0.43%）。这些结果表明，双带果蝇的O型亚家族是通过水平转移从外部来源获得的，很可能是从潜蝇属获得的，就像之前对M型家族所怀疑的那样。由于苍白潜蝇和双带果蝇的M型因子之间的序列差异比O型因子之间的差异高18倍，因此必须假定有两个独立的属间转移事件。为了重新审视苍白潜蝇的分类地位，分析了Adh基因的部分序列（489 bp）。数据清楚地证明，苍白潜蝇必须被置于远在黑腹果蝇组之外的位置。
