Transposition mechanism of DNA-type transposable elements of the medaka fish

青鳉鱼DNA型转座元件的转座机制

基本信息

批准号：
09680672
负责人：
KOGA Akihiko
金额：
$ 1.54万
依托单位：
Nagaya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09680672/
关键词：
Medaka Fish Transposable element Transposon Tol2 Transposition Natural population Genetic variation 戻し交配突然変異

项目摘要

For the purpose of studying the transposition mechanisms of the medaka fish transposable element Tol2, we first established an experimental system to obtain the excision rate of the element, in which the bacterial lacZ gene on a plasmid vector was used as an indicator of excision. In this system, loss of the Tol2 element due to its excision results in blue bacterial colonies. Next, using this system, we identified an autonomous Tol2 copy, Tol2 is present in the genome of the medaka fish (O.latipes) but is not in the Luzon medaka fish (O.luzonensis) which is closely related to the medaka fish. Therefore, excision of a single element introduced into the Luzon medaka fish indicates that the element is autonomous. It was successful to detect excision, and, thus, the copy used was found to be an autonomous element.After these preparations, we started examining portions of the autonomous Tol2 copy for their importance on the transposition function. We made various clones that carry sequence alterations or deletions, and estimated the transposition rate of the clones. The following results were obtained : (1) The terminal inverted repeat of the Tol2 element are required for transposition. (2) A factor necessary for transposition is present in the central region of the element. (3) The length of the element is positively correlated with the transposition rate. The last two things are unique to Tol2, that is, other transposable elements so far examined do not have these characters.We also examined variation in the structure of Tol2 elements in a medaka fish natural population. Tol2 was found to be highly homogeneous in length and the structure. This is consistent with the results about the transposition mechanisms described above.

为了研究青鳉鱼转座因子Tol2的转座机制，我们首先建立了一个实验系统，以质粒载体上的细菌lacZ基因作为切除指标，获得该元件的切除率。在该系统中，由于 Tol2 元件的切除而导致的损失导致蓝色细菌菌落。接下来，使用该系统，我们鉴定了一个自主的 Tol2 副本，Tol2 存在于青鳉鱼 (O.latipes) 的基因组中，但不存在于与青鳉鱼密切相关的吕宋青鳉鱼 (O.luzonensis) 中。因此，切除吕宋青鳉鱼中引入的单一元素表明该元素是自主的。成功地检测到切除，因此，发现所使用的副本是一个自主元件。在这些准备工作之后，我们开始检查自主 Tol2 副本的各个部分，以确定它们对转座功能的重要性。我们制作了各种带有序列改变或缺失的克隆，并估计了克隆的转座率。得到以下结果： (1)转座需要Tol2元件的末端反向重复。 (2)转置所需的因子存在于元素的中心区域。 (3)元素的长度与转置率正相关。最后两件事是 Tol2 所独有的，也就是说，迄今为止检查的其他转座元件不具有这些特征。我们还检查了青鳉鱼自然群体中 Tol2 元件结构的变异。发现 Tol2 在长度和结构上高度均匀。这与上述转位机制的结果是一致的。