Bunn C L, Wallace D C, Eisenstadt J M
Proc Natl Acad Sci U S A. 1974 May;71(5):1681-5. doi: 10.1073/pnas.71.5.1681.
A chloramphenicol-resistant mutant, isolated from mouse A9 cells, was enucleated and fused with a nucleated chloramphenicol-sensitive mouse cell line. Resultant fusion products, cytoplasmic hybrids (or "cybrids"), were selected as resistant to chloramphenicol, and had the nuclear markers and chromosome complement of the chloramphenicol-sensitive parent. These cybrids appeared at the high frequency of 2-8 per 10(4) cells plated. Neither parent produced any colonies when plated under identical selective conditions. Fusion between enucleated chloramphenicol-sensitive cell fragments and the chloramphenicol-sensitive cell produced no resistant colonies, suggesting that chloramphenicol resistance is not due to an increase in the ratio of cytoplasm to nucleus. Furthermore, fusions between resistant and sensitive nucleated cells produced resistant hybrids at a frequency 100 times less than that of resistant cybrids. Thus, these stable chloramphenicol-resistant cybrids result from the fusion of a chloramphenicol-resistant cytoplasm with a chloramphenicol-sensitive cell. It is proposed, therefore, that chloramphenicol resistance is a cytoplasmically inherited characteristic in this mouse cell line.
从小鼠A9细胞中分离出的一株耐氯霉素突变体，去核后与一株有核的对氯霉素敏感的小鼠细胞系融合。将所得的融合产物，即细胞质杂种（或“胞质杂种”），筛选为对氯霉素有抗性的细胞，它们具有对氯霉素敏感亲本的核标记和染色体组型。这些胞质杂种以每10⁴个接种细胞2 - 8个的高频率出现。在相同的选择条件下接种时，两个亲本均未产生任何菌落。去核的对氯霉素敏感的细胞片段与对氯霉素敏感的细胞之间的融合未产生抗性菌落，这表明氯霉素抗性并非由于细胞质与细胞核比例的增加所致。此外，抗性有核细胞与敏感有核细胞之间的融合产生抗性杂种的频率比抗性胞质杂种低100倍。因此，这些稳定的耐氯霉素胞质杂种是由耐氯霉素的细胞质与对氯霉素敏感的细胞融合产生的。所以，有人提出，在这个小鼠细胞系中，氯霉素抗性是一种细胞质遗传特征。
