Silnutzer J, Jargiello P
Somatic Cell Genet. 1981 Mar;7(2):119-31. doi: 10.1007/BF01567652.
Expression of the ribose-positive phenotype was examined in hybrids obtained from the fusion of parental pentose-negative Novikoff hepatoma cells and ribose-positive variants. The two ribose-positive variants used differed phenotypically in their ability to use pentoses other than ribose for growth. One variant used D-ribose, D-xylose, and L-arabinose for growth, while the other variant used only D-ribose. Each variant was fused to pentose-negative parental hepatoma cells, and resultant hybrids were tested for the ability to use ribose. In both instances extinction of ribose utilization was the primary event, suggesting the existence of a trans-acting negative control element in the parental cells. In addition, hybrids from both fusion experiments eventually reexpressed the ribose phenotype. The rate of reexpression, however, was different for the two fusion experiments. Reexpression of ribose utilization in hybrids derived from the nonspecific variant occurred at approximately 10(-3) segregants/cell/day. Reexpressing segregants arose from the specific-derived hybrids at a rate of 0.5 segregants/cell/day. Possible reasons for this difference include a differential rate in chromosomal segregation or a difference in the regulation of ribose metabolism.
在由亲本戊糖阴性的诺维科夫肝癌细胞与核糖阳性变体融合获得的杂种细胞中，检测了核糖阳性表型的表达。所使用的两种核糖阳性变体在利用除核糖以外的戊糖进行生长的能力上存在表型差异。一种变体利用D-核糖、D-木糖和L-阿拉伯糖进行生长，而另一种变体仅利用D-核糖。将每种变体与戊糖阴性的亲本肝癌细胞融合，并检测所得杂种细胞利用核糖的能力。在这两种情况下，核糖利用的消失都是主要事件，这表明亲本细胞中存在一种反式作用的负调控元件。此外，两个融合实验产生的杂种细胞最终都重新表达了核糖表型。然而，两个融合实验中重新表达的速率不同。源自非特异性变体的杂种细胞中核糖利用的重新表达速率约为每天10(-3)个分离株/细胞。源自特异性变体的杂种细胞中重新表达的分离株出现的速率为每天0.5个分离株/细胞。这种差异的可能原因包括染色体分离速率的差异或核糖代谢调控的差异。
