Handler Alfred M, Furlong Richard B
Center for Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, U.S. Department of Agriculture, Gainesville, Florida, USA.
Insect Mol Biol. 2024 Jun;33(3):185-194. doi: 10.1111/imb.12891. Epub 2024 Jan 22.
The hAT family transposable element, hopper, was originally discovered as a defective 3120-bp full-length element in a wild-type strain of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), and subsequently a functional 3131-bp element, hopper, was isolated from a white eye mutant strain. The latter study showed that closely related elements exist in melonfly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae), a closely related subgenus, suggesting that hopper could have a widespread presence in the Bactrocera genus. To further understand the distribution of hopper within and beyond the B. dorsalis species complex, primer pairs from hopper and its adjacent genomic insertion site were used to survey the presence and relatedness of hopper in five species within the complex and four species beyond the complex. Based on sequence identity of a 1.94 kb internal nucleotide sequence, the closest relationships were with mutated elements from B. dorsalis s.s. and species synonymized with B. dorsalis including B. papayae, B. philippinensis and B. invadens, ranging in identity between 88.4% and 99.5%. Notably, Bactrocera carambolae (Drew & Hancock) (Diptera: Tephritidae), which is most closely related to B. dorsalis beyond the synonymized species, shared hopper identities of 97.3%-99.5%. Beyond the B. dorsalis complex, Z. cucurbitae, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) and Bactrocera zonata (Saunders) (Diptera: Tephritidae) shared identities of 83.1%-97.1%, while hopper was absent from the Bactrocera oleae (Gmelin) (Diptera: Tephritidae) strain tested. While the functional autonomous hopper element was not detected in these species, another closely related hopper element isolated from a B. dorsalis genetic sexing strain has an uninterrupted transposase open reading frame. The discontinuous presence of hopper in the Bactrocera genus has implications for its use for genomic manipulation and understanding the phylogenetic relationship of these species.
hAT家族转座元件hopper最初是在东方果实蝇（Bactrocera dorsalis (Hendel)，双翅目：实蝇科）的野生型菌株中作为一个有缺陷的3120 bp全长元件被发现的，随后从一个白眼突变菌株中分离出一个功能性的3131 bp元件hopper。后一项研究表明，在瓜实蝇（Zeugodacus cucurbitae (Coquillett)，双翅目：实蝇科）中存在密切相关的元件，瓜实蝇是一个密切相关的亚属，这表明hopper可能在果实蝇属中广泛存在。为了进一步了解hopper在桔小实蝇物种复合体内部及之外的分布情况，使用来自hopper及其相邻基因组插入位点的引物对来调查该复合体中的五个物种以及复合体之外的四个物种中hopper的存在情况和相关性。基于1.94 kb内部核苷酸序列的序列同一性，最密切的关系是与桔小实蝇指名亚种和与桔小实蝇同义的物种（包括番木瓜实蝇、菲律宾实蝇和入侵实蝇）中的突变元件，同一性范围在88.4%至99.5%之间。值得注意的是，杨桃实蝇（Bactrocera carambolae (Drew & Hancock)，双翅目：实蝇科）与同义物种之外与桔小实蝇关系最密切，其hopper同一性为97.3% - 99.5%。在桔小实蝇复合体之外，瓜实蝇、昆士兰实蝇（Bactrocera tryoni (Froggatt)，双翅目：实蝇科）和具条实蝇（Bactrocera zonata (Saunders)，双翅目：实蝇科）的同一性为83.1% - 97.1%，而在测试的油橄榄实蝇（Bactrocera oleae (Gmelin)，双翅目：实蝇科）菌株中未发现hopper。虽然在这些物种中未检测到功能性自主hopper元件，但从桔小实蝇遗传性别品系中分离出的另一个密切相关的hopper元件具有不间断的转座酶开放阅读框。hopper在果实蝇属中的间断存在对其用于基因组操作以及理解这些物种的系统发育关系具有重要意义。
