纤细裸藻中的核核糖体DNA：染色体单元数量稀少及染色体外单元的复制

Université Lyon I, Laboratoire de Biologie Cellulaire, UA CNRS 92, Villeurbanne, France.

Nucleic Acids Res. 1988 Jun 10;16(11):4801-10. doi: 10.1093/nar/16.11.4801.

Copy number of chromosomal rDNA units was investigated in two Euglena gracilis wild-type strains. It was established by dot blot analysis that these strains possess about four integrated units per haploid genome. This is the first example of a photosynthetic cell with only a few chromosomal ribosomal genes. In addition to these units, Euglena has 800 to 4000 extrachromosomal rDNA units. Electron microscopy revealed that these free rDNA circles bear a replication origin, and intermediates of replication show a D-loop structure.

在两个纤细裸藻野生型菌株中研究了染色体rDNA单位的拷贝数。通过斑点印迹分析确定，这些菌株每个单倍体基因组拥有约四个整合单位。这是光合细胞中仅含有少数染色体核糖体基因的首个例子。除了这些单位外，裸藻还有800至4000个染色体外rDNA单位。电子显微镜显示，这些游离的rDNA环带有一个复制起点，复制中间体呈现D环结构。