van Keulen H, Loverde P T, Bobek L A, Rekosh D M
Mol Biochem Parasitol. 1985 May;15(2):215-30. doi: 10.1016/0166-6851(85)90121-5.
The organization of the rRNA genes of Schistosoma mansoni has been determined by Southern blot analysis of genomic DNA digested with restriction enzymes, by isolation of the entire repeat on a single fragment of about 11 kilobase pairs from a genomic DNA library constructed in bacteriophage lambda and by characterization of three cloned EcoRI fragments which span the entire repeat. The segments encoding both the large and small rRNA subunits have been identified using specific cloned yeast rDNA fragments as probes and EcoRI, HindIII and BamHI restriction enzyme maps of the rRNA genes were constructed. The ends of the RNAs have been precisely mapped on the genomic DNA by S1 protection experiments. Our data indicate that the rRNA genes are present as a tight cluster. The total length of the rDNA repeat is about 10 kilobase pairs. There appears to be no variation in the size of transcribed and non-transcribed spacer DNA. At the RNA level we have characterized and mapped a small gap in the 28S RNA molecule. The interruption causes the RNA to dissociate into two equal sized fragments when analyzed under denaturing conditions.
通过对用限制性酶消化的基因组DNA进行Southern印迹分析、从构建于噬菌体λ中的基因组DNA文库中分离出约11千碱基对的单个片段上的完整重复序列以及对跨越整个重复序列的三个克隆的EcoRI片段进行表征，确定了曼氏血吸虫rRNA基因的组织方式。使用特定的克隆酵母rDNA片段作为探针鉴定了编码大、小rRNA亚基的片段，并构建了rRNA基因的EcoRI、HindIII和BamHI限制性酶切图谱。通过S1保护实验将RNA的末端精确地定位在基因组DNA上。我们的数据表明rRNA基因以紧密簇的形式存在。rDNA重复序列的总长度约为10千碱基对。转录间隔区DNA和非转录间隔区DNA的大小似乎没有变化。在RNA水平上，我们对28S RNA分子中的一个小缺口进行了表征和定位。当在变性条件下分析时，该中断导致RNA解离成两个大小相等的片段。
