ISOLATION OF THE B GENE: A REGULATORY LOCUS MAIZE

了解基因如何在发育过程中进行差异调控 生物体的进化是生物学中的一个基本问题。遗传病的研究 玉米提供了许多基因表达程序化变化的例子 在开发过程中，并确定了监管现象，如 参数转换和控制元素的影响。从基因上来说就是这样 玉米特有的基因座是调控基因表达的B基因座 植物中的花青素色素。组织特异性的变异 花青素的合成是由B等位基因决定的。 在分子水平上检查不同的B等位基因应该会发现 核苷酸序列负责调节数量、时间和 色素产生的组织特异性。某些B等位基因会经历或 促进辅助突变：促进基因表达的一种可遗传改变 在同一植物中存在两个特定的等位基因。多款车型 已经被提议用来解释截肢，包括改变 染色质结构、基因转换或相互作用或转座 DNA元素。这种等位基因相互作用的分子描述 应揭示细胞可遗传调控基因的一般原理 在发育过程中出现的表达式。这些原则应该是 适用于基因和分子相结合的其他生物 这种方法目前还不可行。 这项提议的长期目标是研究分子 B基因在玉米中表达的调控机制。具体的 这项建议的目的是利用B基因组序列 转座元件罗伯逊的突变体，以标记该基因座。多重 已经分离出独立的插入突变，以增加 获得整个基因的概率。然后基因就会被恢复 通过利用插入到B的元件之间的同源性 基因和克隆的转座元件。突变体和克隆体 本研究中生成的序列将提供工具，用于开始 用分子分析方法研究了B。

Understanding how genes are differentially regulated during the development of an organism is a fundamental problem in biology. Genetic studies of maize have provided many examples of programmed changes in gene expression during development and have identified regulatory phenomena such as paramutation and the effects of controlling elements. One such genetically characterized locus in maize is the B locus which regulates the expression of anthocyanin pigments in the plant. Variation in the tissue-specific synthesis of anthocyanins is determined by which allele is present at B. Examining different B alleles at the molecular level should reveal nucleotide sequences responsible for regulating the quantity, timing and tissue-specificity of pigment production. Certain B alleles undergo or promote paramutation: a heritable alteration in gene expression promoted by the presence of two specific alleles in the same plant. Many models have been proposed to explain paramutation, including alteration in chromatin structure, gene conversion, or the interaction or transposition of DNA elements. A molecular description of this allelic interaction should reveal general principles on cell heritable regulation of gene expression as it occurs during development. These principles should be applicable to other organisms where a combined genetic and molecular approach is not yet feasible. The long term goals of this proposal are to examine the molecular mechanisms controlling the expression of the B gene in maize. The specific aim of this proposal is to clone the B genomic sequences using the transposable element Robertson's Mutator to mark the locus. Multiple independent insertion mutations have been isolated in order to increase the probability of obtaining the entire gene. The gene will then be recovered by taking advantage of the homology between the element inserted into the B gene and the cloned transposable element. The mutants and the cloned sequences generated in this study, will provide tools with which to begin a molecular analysis of paramutation and gene expression at B.