Hozumi N, Tonegawa S
Proc Natl Acad Sci U S A. 1976 Oct;73(10):3628-32. doi: 10.1073/pnas.73.10.3628.
A high-molecular-weight DNA from Balb/c mouse early embryo or from MOPC 321 plasmacytoma (a k-chain producer) was digested to completion with Bacillus amyloliquefaciens strain H restriction enzyme (BamH I). The resulting DNA fragments were fractionated according to size in preparative agarose gel electrophoresis. DNA fragments carrying gene sequences coding for the variable or constant region of k chains were detected by hybridization with purified, 125I-labeled, whole MOPC 321 K MRNA and with its 3'-end half. The pattern of hybridization was completely different in the genomes of embryo cells and of the plasmacytoma. The pattern of embryo DNA showed two components, one of which (molecular weight=6.0 million) hybridized with C-gene sequences and the other (molecular weight=3.9 million) with V-gene sequences. The pattern of the tumor DNA showed a single component that hybridized with both V-gene and C-gene sequences and that is smaller (molecular weight=2.4 million) than either of the components in embryo DNA. The results were interpreted to mean that the Vk and Ck genes, which are some distance away from each other in the embryo cells, are joined to form a contiguous polynucleotide stretch during differentiation of lymphocytes. Such joining occurs in both of the homologous chromosomes. Relevance of these findings with respect to models for V-C gene joining, activation of a specific V k gene, and allelic exclusion in immunoglobulin gene loci is discussed.
来自Balb/c小鼠早期胚胎或MOPC 321浆细胞瘤（一种κ链产生者）的高分子量DNA用解淀粉芽孢杆菌H株限制酶（BamH I）完全消化。所得DNA片段在制备性琼脂糖凝胶电泳中按大小分级分离。通过与纯化的、125I标记的完整MOPC 321 K mRNA及其3'-末端一半进行杂交，检测携带编码κ链可变区或恒定区基因序列的DNA片段。胚胎细胞和浆细胞瘤基因组中的杂交模式完全不同。胚胎DNA的杂交模式显示出两个组分，其中一个（分子量 = 600万）与C基因序列杂交，另一个（分子量 = 390万）与V基因序列杂交。肿瘤DNA的杂交模式显示出一个单一的组分，它与V基因和C基因序列都杂交，并且比胚胎DNA中的任何一个组分都小（分子量 = 240万）。这些结果被解释为意味着在胚胎细胞中彼此相距一定距离的Vk和Ck基因在淋巴细胞分化过程中连接形成一个连续的多核苷酸片段。这种连接发生在两条同源染色体上。讨论了这些发现与V-C基因连接模型、特定Vk基因的激活以及免疫球蛋白基因位点中的等位基因排斥的相关性。
