Wejksnora P J
Gene. 1985;33(3):285-92. doi: 10.1016/0378-1119(85)90236-7.
We have examined the ribosomal RNA (rRNA) genes of the Chinese hamster ovary (CHO) cell line. A partial EcoRI library of genomic CHO DNA was prepared using lambda Charon-4A. We isolated two recombinants containing the region transcribed as 45S pre-rRNA and 13 kb of external spacer flanking 5' and 3' to the transcribed region. These sequences show restriction site homology with the vast majority of the genomic sequences complementary to rRNA. In addition to this form of rDNA, Southern blot analysis of EcoRI-cut CHO genomic DNA reveals numerous minor fragments ranging from 2 to 19 kb which are complementary to 18S rRNA. We isolated one clone which contains the 18S rRNA gene and sequences 5' which appear to contain length heterogeneity within the non-transcribed spacer region. We have nine additional cloned EcoRI fragments in which the homology with 18S rRNA is limited to a 0.9-kb EcoRI-HindIII fragment. This EcoRI-HindIII fragment is present in each of the cloned EcoRI fragments, and is flanked on both sides by apparently nonribosomal sequences which bear little restriction site homology with each other or the major cloned rDNA repeat.
我们检测了中国仓鼠卵巢（CHO）细胞系的核糖体RNA（rRNA）基因。使用λ噬菌体Charon - 4A构建了基因组CHO DNA的部分EcoRI文库。我们分离出两个重组体，它们包含转录为45S前体rRNA的区域以及位于转录区域5'和3'侧翼的13 kb外部间隔区。这些序列与绝大多数与rRNA互补的基因组序列显示出限制性酶切位点同源性。除了这种形式的rDNA外，对经EcoRI酶切的CHO基因组DNA进行Southern印迹分析，发现有许多大小从2 kb到19 kb不等的小片段，它们与18S rRNA互补。我们分离出一个克隆，它包含18S rRNA基因以及5'端序列，这些序列在非转录间隔区内似乎存在长度异质性。我们还有另外九个克隆的EcoRI片段，它们与18S rRNA的同源性仅限于一个0.9 kb的EcoRI - HindIII片段。这个EcoRI - HindIII片段存在于每个克隆的EcoRI片段中，其两侧是明显的非核糖体序列，这些序列彼此之间或与主要克隆的rDNA重复序列几乎没有限制性酶切位点同源性。
