Hagemann S, Haring E, Pinsker W
Institut für Medizinische Biologie, AG Allgemeine Genetik, Universität Wien, Austria.
Genome. 1996 Oct;39(5):978-85. doi: 10.1139/g96-122.
A new P element subfamily, designated T-type, was found in the genomes of the three closely related species Drosophila ambigua, Drosophila obscura, and Drosophila tristis. The subfamily comprises both full-sized and internally deleted P elements. The T-type element of D. ambigua is longer than the canonical P elements owing to a 300-bp insertion in the 3' noncoding region. Tandemly arranged T-type elements were detected in D. ambigua and D. tristis. The overall structure of T-type elements resembles that of the Drosophila melanogaster P element and the termini are formed by perfect inverted repeats of 33 bp. However, none of the elements studied so far have intact reading frames. Sequence comparisons with other P element subfamilies from the obscura group indicate that the T-type elements are most closely related to the terminally truncated P homologues of Drosophila guanche and Drosophila subobscura. Therefore they can be considered as the lineage-specific P transposons of the obscura group. Furthermore, this finding indicates that the clustered P homologues of D. guanche and D. subobscura must be derived from transpositionally active P elements rather than from an immobile genomic sequence.
在近缘的三个物种——模糊果蝇（Drosophila ambigua）、 obscura果蝇（Drosophila obscura）和三刺果蝇（Drosophila tristis）的基因组中发现了一个新的P因子亚家族，命名为T型。该亚家族包含全长和内部缺失的P因子。由于在3'非编码区插入了300个碱基对，模糊果蝇的T型因子比典型的P因子更长。在模糊果蝇和三刺果蝇中检测到串联排列的T型因子。T型因子的整体结构类似于黑腹果蝇（Drosophila melanogaster）的P因子，其末端由33个碱基对的完美反向重复序列形成。然而，到目前为止所研究的所有因子都没有完整的阅读框。与obscura组中其他P因子亚家族的序列比较表明，T型因子与关氏果蝇（Drosophila guanche）和次暗果蝇（Drosophila subobscura）末端截短的P同源物关系最为密切。因此，它们可被视为obscura组中谱系特异性的P转座子。此外，这一发现表明，关氏果蝇和次暗果蝇中成簇的P同源物必定来源于具有转座活性的P因子，而非来自固定的基因组序列。
