Construction of gene tagging system by means of the medaka fish transposable element Tol-2

已经在脊椎动物基因组中描述了几种末端倒置重复序列的转座元件。其中一些被认为是有活性的，因为插入的元件存在于基因区域或多态情况。然而，检测从头切除或插入的元素尚未成功完成。我们已经确定了一种新的末端倒置重复类转座元件在米达卡鱼。该元素被指定为tol2。在胚胎发生过程中，通过PCR分析含有tol2拷贝的基因组区域来检测tol2的切除。tol2的长度为4681 bp。tol2含有4个与玉米Ac、果蝇hobo和金鱼鱼Tam3氨基酸序列相似的orf，均为活性转座元件。因此，tol2是建立鱼类基因标记系统的独特材料。

Several transposable elements of the terminal-inverted-repeat class have been described in vertebrate genomes. Some of them are considered to be active because of the presence in genic regions or polymorphic situations of inserted elements. However, detection of de novo excision or insertion of the elements has not been successfully done. We have identified a novel terminal-inverted-repeat class transposable element in the medaka fish Oryzias latipes. The element was designated Tol-2. Excision of Tol-2 during embryogenesis was detected by a PCR analysis of a genomic region containing a Tol-2 copy. Tol-2 is 4681 bp in length. Tol-2 contains 4 ORFs which have amino acid sequence similarity with Ac of maize, hobo of Drosophila and Tam3 of snapdragon, which are all active transposable elements. Tol-2 is thus a unique material for establishing a gene tagging system in fish.