RIBOSOMAL DNA IN PHYSARUM POLYCEPHALUM

拟议研究的目的是加深对 无细胞粘菌多头绒泡菌中的核糖体DNA。这个 这些染色体外基因的特性使它们成为 研究真核基因的一些一般特征，也许 真核细胞的染色体。这项研究有四个主要目标：第一 是为了确定几个重要区域的核苷酸序列 RDNA，包括转录、复制和结合的起源 一种调节蛋白的位置。第二是更明确地界定 复制起源于rDNA中心附近的功能，以及 线性rDNA末端附近的有间隙的DNA序列在 复制过程。对起源的结构和对 RDNA末端可能提供对真核dna起始的洞察。 复制并进入染色体端粒的结构。第三个是 为了阐明单亲、非孟德尔式婚姻背后的机制 我们最近在遗传杂交中观察到的遗传或rDNA。它 从遗传结果看，数百个rDNA分子 在生命周期的某个阶段，所有这些都必须来自单一分子。 第四个目标是有助于理解 鸟氨酸脱羧酶对rdna转录的调控作用。这种酶有 被其他人发现变得磷酸化，与rDNA结合，并 以多胺敏感的方式刺激转录。

The intent of the proposed research is to further the understanding of ribosomal DNA in the acellular slime mold Physarum polycephalum. The properties of these extrachromosomal genes make them a model system for investigating some of the general features of eucaryotic genes, and perhaps of eucaryotic chromosomes. The research has four major goals: The first is to determine the nucleotide sequences of several important regions of the rDNA, including origins of transcription and replication and binding site for a regulatory protein. The second is to define more clearly the functions that the replication origins near the center of the rDNA, and the gapped DNA sequences near the ends of the linear rDNA have in the replication process. Knowledge of the structure of the origins and of the rDNA ends may provide insight into the initiation of eucaryotic DNA replication and into the structure of chromosomal telomers. The third is to clarify the mechanism underlying the uniparental, non-Mendelian inheritance or rDNA that we have observed recently in genetic crosses. It appears from the genetic results that the several hundred rDNA molecules all must derive from a single molecule at some stage of the life cycle. The fourth goal is to contribute to the understanding of the function of ornithine decarboxylase in regulating rDNA transcription. This enzyme has been found by others to become phosphorylated, to bind to rDNA, and to stimulate transcription in a polyamine-sensitive manner.