ANALYSIS OF ZEIN GENE EXPRESSION IN MAIZE

玉米的玉米醇溶蛋白基因编码种子贮藏蛋白。上一首 分析表明，玉米醇溶蛋白由三种不同的蛋白质类型组成 指定为阿尔法、贝塔和伽马。阿尔法玉米醇溶蛋白解释了 约占总存储蛋白的70%，由一种 多基因家族。贝塔和伽马玉米醇溶蛋白，这解释了 大约10%和20%的玉米醇溶蛋白分别是 仅由一两个基因编码的。玉米醇溶蛋白基因在 正常胚乳的发育，但它们的表达是定量的 并在几个突变的基因型质上被抑制。我们的预赛 研究表明，在相对表达上存在差异 玉米醇溶蛋白基因家族中与基因差异相关的基因 胞质信使核糖核酸含量。要定义规范 玉米醇溶蛋白基因在胚乳形成过程中的表达 描述控制其转录和转录的DNA序列 发育调控。~(32)P标记的核RNA与Well的杂交 特征化的基因组克隆将建立转录位点、计时 转录，以及转录或转录后 加工在玉米醇溶蛋白基因的调控中起着重要作用 表情。这一分析还将确定在多大程度上 反应受突变基因类型的影响。定义DNA序列 调控转录，基因侧翼序列将连接到一个 氯霉素乙酰转移酶(CAT)基因转化植物 通过电穿孔获得原生质体。转录所需的序列将 通过检测原生质体提取物中的CAT活性来进行监测。我们还将 分析转化后的转录调控序列 将玉米醇溶蛋白基因导入烟草和矮牵牛植株。在……里面 在这个案例中，我们将监测种子中的mRNA和蛋白质合成 用于描述控制发育的DNA序列的再生植株 表情。通过胚乳蛋白质的标记和鉴别 文库的筛选我们将尝试鉴定其基因产物 在降低玉米醇溶蛋白基因水平的突变体中表达被修改 表情。

The zein genes of maize encode the seed storage proteins. Previous analyses have shown that zeins consist of three distinct protein types designated alpha, beta, and gamma. The alpha zeins account for approximately 70% of the total storage protein and are encoded by a multigene family. The beta and gamma zeins, which account for approximately 10% and 20% of the zein fraction, respectively, are each encoded by only one or two genes. Zein genes are actively expressed during development of normal endosperms, but their expression is quantitatively and qualitatively inhibited in several mutant genotypes. Our preliminary studies indicate that there are differences in the relative expression of genes among zein gene families that correlate with differences in the amount of cytoplasmic mRNA. To define the mechanisms regulating the expression of zein genes during endosperm formation, we propose to characterize the DNA sequences controlling their transcription and developmental regulation. Hybridization of 32P-labeled nuclear RNA to well characterized genomic clones will establish sites of transcription, timing of transcription, and whether transcription or post-transcriptional processing play a major role in the regulation of the zein gene expression. This analysis will also determine the extent to which these reactions are affected by the mutant genotypes. To define DNA sequences regulating transcription, gene flanking sequences will be ligated to a chloramphenicol acetyltransferase (CAT) gene and transferred to plant protoplasts by electroporation. Sequences required for transcription will be monitored by assaying CAT activity in protoplast extracts. We will also analyze transcriptional regulatory sequences following transformation of zein genes into tobacco and petunia plants with a Ti-plasmid vector. In this case we will monitor mRNA and protein synthesis in seeds from regenerated plants to delineate DNA sequences controlling developmental expression. Through labeling of endosperm proteins and differential screening of cDNA libraries we will attempt to identify gene products whose expression is modified in mutants that reduce the level of zein gene expression.