METHYLATION OF MACRONUCLEAR DNA IN TETRAHYMENA

生殖细胞系维持着物种的遗传连续性 而索马则负责 个体有机体。 物理差异之间 生殖细胞系和索马的基因组对于它们的 各自的角色。 纤毛虫原生动物的体细胞大核， 四膜虫是由生殖细胞系的有丝分裂产物发育而来的 在有性生殖过程中的微核。 大核 DNA甲基化，DNA重排和 大核基因组的转录激活。 我们将探讨的生物作用和机制， 大核DNA甲基化的遗传 四膜虫 转录调控：转录调控模式的先前研究 结构基因附近的甲基化将扩展到额外的 基因. 核糖体RNA基因将在体外高甲基化 并显微注射到营养细胞中。 DNA重排：DNA甲基化的相对时间 在发育中的大核中发生重排， 确定。 甲基化的遗传：我们将确定是否 核小体定相发生在基因组的区域， 以及是否存在甲基化位点， 当它存在于体内的不同位置时， 基因组 我们将询问甲基化模式是否引入了 当DNA显微注射到宿主体内时， 细胞中是否存在半甲基化位点， 分裂细胞的复制DNA。

The germ line maintains the genetic continuity of the species while the soma is responsible for the growth and development of the individual organism. Physical differences between the genomes of the germ line and the soma are essential for their respective roles. The somatic macronucleus of the ciliated protozoan, Tetrahymena, develops from a mitotic product of the germ line micronucleus during sexual reproduction. Macronuclear development involves DNA methylation, DNA rearrangement and transcriptional activation of the macronuclear genome. We will investigate the biological role and mechanism of inheritance of DNA methylation in the macronuclear DNA of Tetrahymena. Transcriptional regulation: Previous studies on the pattern of methylation near structural genes will be extended to additional genes. Ribosomal RNA genes will be hypermethylated in vitro and microinjected into vegetative cells. DNA rearrangement: The relative timing of DNA methylation and rearrangement in the developing macronucleus will be ascertained. Inheritance of methylation: We will determine whether nucleosome phasing occurs in regions of the genome which are uniformly methylated and whether a site which is methylated in vivo is methylated when it is present at a different position in the genome. We will ask whether methylation patterns introduced in vitro are maintained when the DNA is microinjected into host cells and whether there are hemimethylated sites in newly replicated DNA of dividing cells.