TRANSPOSABLE GENETIC ELEMENTS OF MAIZE

这项研究的目的是了解如何插入一个 转座因子进入基因座可以影响基因表达。 一个 对这种现象的理解与人类健康有关，因为一些 已知逆转录病毒插入物会激活导致 诱发肿瘤。 转座因子的插入也可能 在发育过程中基因表达模式的改变， 与某些人类疾病有关 我们建议检查一种情况，其中基因被“关闭”， “on”取决于可转座的内部重排 元素 这项工作是在玉米中进行的， 遗传学在这个系统中可用，因为生物体容易允许 稀有表型事件的选择。 研究的原始突变是 由McClintock选择，是一个Ds插入到Shrunken基因中， 编码蔗糖合成酶。 重组DNA技术和 Southern印迹分析表明，原始突变等位基因含有 约20 kb的插入元件插入插入到插入的 顺序 在随后的回复和再突变过程中， 在同一地点和同一方向，但显然已经经历了 复杂的内部重组。 这些重新排列会产生后果 对于基因的转录：在原始突变中没有检测到 转录本;在二次突变中，只有基因的一部分 在回复突变体中，插入位点的5'端的完整片段被转录; 长度消息被制作。 这里看到的变化类似于“变化的 与其他转座元件控制的等位基因一起出现。 的 将通过限制分离和详细分析改变的元素 对有关区域进行分析和排序，以确定 他们经历的变化。 其他控制元件诱导的突变 还将检查其回复突变体的结构变化， 生理效应。

The objective of this research is to learn how the insertion of a transposable element into a locus can affect gene expression. An understanding of this phenomenon is relevant to human health because some retroviral insertions are known to activate genes that lead to the induction of tumors. Transposable element insertions might also account for the altered patterns of gene expression in development that is associated with some human disorders. We propose to examine a situation in which a gene is turned either "off" or "on" depending on the internal rearrangements within the transposable element. The work is being carried out in maize because of the excellent genetics available in this system and because the organism readily permits the selection of rare phenotypic events. The original mutation studied was selected by McClintock and is a Ds insertion into the Shrunken gene which encodes the enzyme sucrose synthetase. Recombinant DNA techniques and Southern blotting analyses showed that the original mutant allele contains an insertional element of about 20 kb inserted within an intervening sequence. During subsequent reversion and remutation the element remains in the same site and in the same orientation but apparently has undergone complex internal rearrangements. These rearrangements have consequences for transcription of the gene: in the original mutation no detectable transcript is made; in the secondary mutation only the portion of the gene 5' to the site of insertion is transcribed; and in a revertant the full length message is made. The changes seen here resemble the "changes of state" seen with other transposable element-controlled alleles. The altered elements will be isolated and analyzed in detail by restriction analyses and sequencing of pertinent regions to determine the nature of the changes they have undergone. Other controlling element-induced mutations and their revertants will also be examined for their structural changes and physiological effects.