GENETICS AND EVOLUTION OF TRANSPOSABLE ELEMENTS

本研究的长期主题是识别和理解 决定分布的遗传和进化因素， 物种间丰富的转座因子。 我们打算利用 果蝇转座因子mariner的新特征 确定控制转座和切除的遗传因子。 的 水手元素在体细胞中是活跃的，因此切除， 较小程度的转座，可以遵循表型。 的 最直接感兴趣的现象是遗传的躯体的 马赛克，其中水手的自主复制导致高 所有水手成员，包括一名报告员，被切除的频率 插入白桃等位基因的元件。 因此，水手系统是 这是果蝇中第一个提供了 在转座因子的分析中， 玉米。 拟议的遗传学研究包括四个具体目标：目标1。 引起遗传性的自主性Mos（镶嵌）因素分析 体细胞嵌合体，以确定的分子机制， 水手切除率高。 目标二。 克隆和分析两个 另外的，独立衍生的，遗传性体细胞嵌合体的病例， 并确定不同镶嵌表型的机制 "高"（早期切除事件，大片）与"低"（晚期事件， 小补丁）。 目标3。 插入特异性的表征 以及水手元素的切除性质。 目标4。 引入 白桃等位基因和Mos因子与D. 黑腹通过P-元素转换，以允许详细 该物种的遗传分析，并开发该系统用于 其它类型的遗传研究（例如，转座子标记，镶嵌 生产、转型的替代系统）。 水手元素也非常适合进化研究 因为有功能的复制品似乎集中在果蝇体内， 黑腹物种亚组，其中系统发育关系 物种之间的关系已经建立。 水手的进化 将在第五个具体目标：目标5中寻求发展。 到 确定果蝇中水手的DNA序列 物种支持随机损失或水平转移模型。

The long term theme of this research is to identify and understand the genetic and evolutionary factors that determine the distribution and abundance of transposable elements among species. We propose to exploit novel features of the Drosophila transposable element mariner in order to define genetic factors that control transposition and excision. The mariner element is active in somatic cells, so that excision, and to lesser extent transposition, can be followed phenotypically. The phenomenon of greatest immediate interest is inherited somatic mosaicism, in which an autonomous copy of mariner results in a high frequency of excision of all mariner elements, including a reporter element inserted in the white-peach allele. Thus, the mariner system is the first in Drosophila that provides the kinds of phenotypic indicators that have proven so powerful in the analysis of transposable elements in maize. The proposed genetic studies include four specific aims: Aim 1. Analysis of the autonomous Mos (mosaic) factor that causes inherited somatic mosaicism in order to identify the molecular mechanism of the high rates of mariner excision. Aim 2. Cloning and analysis of two additional, independently derived, cases of inherited somatic mosaicism, and determination of the mechanism of the distinct mosaic phenotypes "high" (early excision events, large patches) versus "low" (late events, small patches). Aim 3. Characterization of the insertional specificity and excision properties of the mariner element. Aim 4. Introduction of the white-peach allele and the Mos factor in to the genome of D. melanogaster by means of P-element transformation to allow detailed genetic analysis in this species and to develop the system for use in other types of genetic studies (e.g., transposon tagging, mosaic production, alternative system for transformation). The mariner element is also ideally suited for evolutionary studies because functional copies appear to be concentrated in the Drosophila melanogaster species subgroup, in which the phylogenetic relationships among species are well established. Evolutionary aspects of mariner evolution will be pursued in the fifth specific aim: Aim 5. To determine whether DNA sequences of mariner among related Drosophila species support the model of stochastic loss or horizontal transfer.