Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 213/d, 41125 Modena, Italy.
J Hered. 2013 Jul-Aug;104(4):547-53. doi: 10.1093/jhered/est017. Epub 2013 Mar 25.
A non-LTR TRAS retrotransposon (identified as TRASAp1) has been amplified in the pea aphid Acyrthosiphon pisum and its presence has been assessed also in the peach potato aphid Myzus persicae. This TRAS element possesses 2 overlapping ORFs (a gag-ORF1 and a pol-ORF2 containing the reverse transcriptase and the endonuclease domains) that show a similarity ranging from 40% to 48% to proteins coded by other TRAS elements identified in insects (including the beetle Tribolium castaneum and the moth Bombyx mori). The study of the TRAS chromosomal insertion sites, performed by standard fluorescent in situ hybridization (FISH) and fiber FISH, showed that TRAS elements were located in a subtelomeric position, just before the telomeric (TTAGG) n repeats. In both the aphid species, TRAS elements were present at all termini of autosomes, but the 2 X chromosome telomeres show a clear-cut structural difference. Indeed, cromomycin A3 staining, together with FISH using a TRAS probe, revealed that TRAS signals only occur at the telomere opposite to the NOR-bearing one. Lastly, the analysis of the distribution of TRAS retrotransposons in a M. persicae strain possessing spontaneous fragmentations of the X chromosomes assessed that TRAS elements were not involved in the healing of de novo telomeres.
一个非长末端重复转座子（鉴定为 TRASAp1）在豌豆蚜 Acyrthosiphon pisum 中被扩增，并且在桃蚜 Myzus persicae 中也评估了其存在。这个 TRAS 元件具有 2 个重叠的 ORF（一个 gag-ORF1 和一个 pol-ORF2，包含逆转录酶和内切酶结构域），与昆虫中鉴定的其他 TRAS 元件（包括甲虫 Tribolium castaneum 和飞蛾 Bombyx mori）编码的蛋白质具有 40%到 48%的相似性。通过标准荧光原位杂交（FISH）和纤维 FISH 对 TRAS 染色体插入位点的研究表明，TRAS 元件位于端粒附近的亚端粒位置，就在端粒（TTAGG）n 重复之前。在这两种蚜虫中，TRAS 元件存在于所有染色体的末端，但 2 个 X 染色体的端粒显示出明显的结构差异。事实上，克菌霉素 A3 染色，结合使用 TRAS 探针的 FISH，表明 TRAS 信号仅出现在与含有 NOR 的端粒相对的端粒上。最后，对具有自发 X 染色体断裂的桃蚜品系中 TRAS 反转录转座子分布的分析表明，TRAS 元件未参与新端粒的修复。
