Key Laboratory of Freshwater Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, China.
FASEB J. 2012 Jul;26(7):2743-52. doi: 10.1096/fj.11-199273. Epub 2012 Mar 21.
Hobo/Activator/Tam3 (hAT) superfamily transposons occur in plants and animals and play a role in genomic evolution. Certain hAT transposons are active and have been developed as incisive genetic tools. Active vertebrate elements are rarely discovered; however, Tgf2 transposon was recently discovered in goldfish (Carassius auratus). Here, we found that the endogenous Tgf2 element can transpose in goldfish genome. Seven different goldfish mRNA transcripts, encoding three lengths of Tgf2 transposase, were identified. Tgf2 transposase mRNA was detected in goldfish embryos, mainly in epithelial cells; levels were high in ovaries and mature eggs and in all adult tissues tested. Endogenous Tgf2 transposase mRNA is active in mature eggs and can mediate high rates of transposition (>30%) when injected with donor plasmids harboring a Tgf2 cis-element. When donor plasmid was coinjected with capped Tgf2 transposase mRNA, the insertion rate reached >90% at 1 yr. Nonautonomous copies of the Tgf2 transposon with large-fragment deletions and low levels of point mutations were also detected in common goldfish. Phylogenetic analysis indicates the taxonomic distribution of Tgf2 in goldfish is not due to vertical inheritance. We propose that the goldfish Tgf2 transposon originated by recent horizontal transfer and maintains a highly native activity.
Hobo/Activator/Tam3 (hAT) 转座子存在于植物和动物中，在基因组进化中发挥作用。某些 hAT 转座子是活跃的，并已被开发为有效的遗传工具。活跃的脊椎动物元件很少被发现；然而，Tgf2 转座子最近在金鱼（Carassius auratus）中被发现。在这里，我们发现内源性 Tgf2 元件可以在金鱼基因组中转座。鉴定出七种不同的金鱼 mRNA 转录本，编码三种长度的 Tgf2 转座酶。在金鱼胚胎中检测到 Tgf2 转座酶 mRNA，主要在上皮细胞中；在卵巢和成熟卵子以及所有测试的成年组织中含量较高。内源性 Tgf2 转座酶 mRNA 在成熟卵子中具有活性，当用含有 Tgf2 顺式元件的供体质粒注射时，可以介导高转座率（>30%）。当供体质粒与加帽的 Tgf2 转座酶 mRNA 共注射时，在 1 年内插入率达到>90%。在普通金鱼中还检测到带有大片段缺失和低水平点突变的 Tgf2 转座子的非自主拷贝。系统发育分析表明，金鱼 Tgf2 的分类分布不是由于垂直遗传。我们提出金鱼 Tgf2 转座子是由最近的水平转移产生的，并保持高度的天然活性。
