TRANSPOSABLE GENETIC ELEMENTS OF MAIZE

这项研究的目的是了解如何插入一个 转座元件进入基因座可以影响基因的表达。一个 对这种现象的理解与人类健康有关，因为有些人 众所周知，逆转录病毒的插入可以激活基因，导致 诱发肿瘤。可转置的元素插入也可以解释 对于发育过程中基因表达模式的改变，即 与某些人类疾病有关。 我们建议研究一种情况，在这种情况下，一个基因要么被关闭，要么 “on”取决于可转座基因的内部重排 元素。这项工作正在玉米上进行，因为 在这个系统中可用的遗传学，因为有机体很容易 稀有表型事件的选择。最初研究的突变是 由McClintock选择，是缩水基因的DS插入 编码蔗糖合成酶。重组DNA技术和 Southern blotting分析表明，原始突变等位基因含有 大约20kb的插入元件，插入在中间的 序列。在随后的回复和再突变过程中，元素保持不变 在相同的地点和相同的方向，但显然经历了 复杂的内部重组。这些重新安排会产生后果 对于基因转录：在原始突变中没有检测到 转录本被生成；在第二次突变中，只有基因的一部分 5‘到插入位置被转录；在回复突变体中，完整的 制作了长度为的消息。这里所看到的变化类似于 状态与其他可转座的元素控制的等位基因一起出现。 更改的元素将通过限制进行详细的分离和分析 对相关区域进行分析和排序，以确定 他们所经历的变化。其他控制元素诱导的突变 它们的返回体也将被检查它们的结构变化和 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.