The role of macronuclear DNA sequences in the permanent rescue of a non-mendelian mutation in Paramecium tetraurelia.
The role of macronuclear DNA sequences in the permanent rescue of a non-mendelian mutation in Paramecium tetraurelia.
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大核 DNA 序列在永久拯救草履虫非孟德尔突变中的作用。
DOI：
10.1093/genetics/136.4.1319
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发表时间：
1994
期刊：
影响因子：
3.3
通讯作者：
Forney,J
中科院分区：
文献类型：
--
作者：
You,Y;Scott,J;Forney,J
四片草履虫突变体d48在其微核中具有a表面蛋白基因的完整拷贝，但在宏核中缺乏a基因。先前的实验表明，将含有整个a基因或大部分基因的质粒微注射到d48的大核中，可以在形成新的大核后挽救细胞系（自交配）。在这里，我们发现A基因的几个不同区域可以拯救d48，但100%的活性不能定位在一个单一的，确定的区域。a基因质粒中包含的序列倒置对救援效率没有可测量的影响，而两种不同质粒的共注射结果增强了救援活性，尽管DNA序列的形式不是连续的。这两个结果都表明，没有特定的产物（RNA或蛋白质）具有明确的终点是由挽救片段。在A基因中创建了一个独特的限制性内切位点，并用于证明注射的DNA不能作为合成新宏核DNA的直接模板。讨论了解释注射DNA作用的模型。
The paramecium tetraurelia mutant called d48 has a complete copy of the A surface protein gene in its micronuclei, but lacks the A gene in the macronucleus. Previous experiments have shown that microinjection of a plasmid containing the entire A gene or a large portion of the gene into the macronucleus of d48 rescued the cell line after formation of a new macronucleus (autogamy). Here we show that several different regions of the A gene can rescue d48, but 100% of the activity cannot be localized to a single, defined region. Inversion of a sequence contained within an A gene plasmid had no measurable effect on rescue efficiency and co-injection of two different plasmids results in enhancement of rescue activity despite the non-contiguous form of the DNA sequences. Both these results suggest that no specific product (RNA or protein) with defined end points is made from the rescuing fragment. A unique restriction site was created in the A gene and used to demonstrate that the injected DNA does not serve as a direct template for the synthesis of the new macronuclear DNA. Models to explain the action of the injected DNA are discussed.