Revertants of an ASV-transformed rat cell line have lost the complete provius or sustained mutations in src.
Revertants of an ASV-transformed rat cell line have lost the complete provius or sustained mutations in src.
复制标题
ASV 转化的大鼠细胞系的回复体已经失去了 src 中的完整 provius 或持续突变。
DOI：
10.1016/0042-6822(81)90525-0
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发表时间：
1981
期刊：
影响因子：
3.7
通讯作者：
Wyke,J
中科院分区：
文献类型：
--
作者：
Varmus,HE;Quintrell,N;Wyke,J
我们已经分离出12个突变体的克隆线（B31）的禽肉瘤病毒（ASV）转化的大鼠-1细胞。B31细胞含有单个正常ASV原病毒，显示病毒转化细胞的经典特征，并以低频率恢复正常表型。选择性杀死转化细胞后分离的回复突变体在形态上与未感染的大鼠-1细胞相似，不能在悬浮液中生长，并且致瘤性比B31细胞至少低100倍。在这些细胞中已经确定了两种逆转机制。(i)其中三个回复突变株丢失了整个前病毒，包括前病毒末端重复序列的两个拷贝;前病毒丢失的方式尚不清楚。(ii)其他9个回复体保留正常大小的前病毒和未改变的侧翼细胞DNA：含有与亲本系B31相同浓度的相同种类的病毒RNA;易受野生型ASV的再转化;并在与鸡细胞融合后产生转化缺陷型（td）病毒。在一种情况下，拯救的病毒转化鸡细胞，但产生梭形而不是正常的病灶，并且不会在形态上重新转化大鼠细胞。因此，这些回复突变体是病毒转化基因src中的非条件突变（碱基取代或小缺失）的结果。在一些情况下，回复突变细胞自发地再转化，或者转化病毒在通过鸡细胞后出现在拯救的td病毒储备中，表明回复突变为野生型。几种被拯救的td病毒也可以重组以恢复野生型表型。对src产物的结构和酶活性分析证实，回复突变细胞携带多种src突变。
We have isolated and characterized 12 revertants of a clonal line (B31) of avian sarcoma virus (ASV)-transformed rat-1 cells. The B31 cells contain a single normal ASV provirus, display the classical features of virally transformed cells, and revert to normal phenotype at low frequency. Revertants isolated after selective killing of transformed cells resemble uninfected rat-1 cells morphologically, fail to grow in suspension, and are at least 100-fold less tumorigenic than B31 cells. Two mechanisms of reversion have been identified in these cells. (i) Three of the revertant lines have lost the entire provirus, including both copies of the sequences repeated at the ends of the provirus; the manner in which the provirus is lost is not known. (ii) The other nine revertants retain a provirus of normal size and unaltered flanking cellular DNA: contain the same species of viral RNA at the same concentrations as in the parental line, B31; are susceptible to retransformation by wild-type ASV; and yield transformation-defective (td) virus after fusion with chicken cells. In one case, the rescued virus transforms chicken cells, but produces fusiform rather than normal foci and does not retransform rat cells morphologically. Hence these revertants arise as a consequence of nonconditional mutations (base substitutions or small deletions) in the viral transforming gene,src. In several cases, the revertant cells retransform spontaneously, or transforming virus appears in stocks of rescued td virus after passage through chicken cells, indicating back mutations to wild-type. Several of the rescued td viruses can also recombine to restore a wild-type phenotype. Analysis of the structure and enzymatic activity of products ofsrcconfirms that the revertant cells bear various mutations insrc.