Collett M S, Faras A J
J Virol. 1975 Nov;16(5):1220-8. doi: 10.1128/JVI.16.5.1220-1228.1975.
DNA transcripts, ranging from 1,500 to 4,500 nucleotides in length, can be identified in the DNA product synthesized in vitro by the Rous sarcoma virus-associated RNA-directed DNA polymerase. Although these DNA transcripts are considerably larger than the size classes of the DNA product previously reported, they only represent a minor proportion (less than 5%) of the total DNA synthesized in standard reaction mixtures containing rate-limiting concentration of one of the four deoxynucleoside triphosphates. However, the proportion of these larger transcripts relative to the total DNA product increases substantially when the enzymatic synthesis of DNA is performed in the presence of equimolar concentrations of deoxynucleoside triphosphate precursors. Both rate-zonal sedimentation in alkaline sucrose and nucleic acid hybridization techniques have confirmed the length and genetic complexity of these larger DNA transcripts. The identification of large DNA chains in the DNA product synthesized in vitro by the avian oncornavirus RNA-directed DNA polymerase provides an explanation for the paradox that exists between the limited number of primer sites per 70S RNA genome, the small size of the bulk of the DNA product, and the extent of the Rous sarcoma virus genome represented by the DNA product.
在由劳氏肉瘤病毒相关的RNA指导的DNA聚合酶体外合成的DNA产物中，可以鉴定出长度在1500至4500个核苷酸之间的DNA转录本。尽管这些DNA转录本比先前报道的DNA产物的大小类别要大得多，但它们仅占在含有四种脱氧核苷三磷酸之一的限速浓度的标准反应混合物中合成的总DNA的一小部分（不到5%）。然而，当在等摩尔浓度的脱氧核苷三磷酸前体存在下进行DNA的酶促合成时，这些较大转录本相对于总DNA产物的比例会大幅增加。碱性蔗糖中的速率区带沉降和核酸杂交技术都证实了这些较大DNA转录本的长度和遗传复杂性。禽肿瘤病毒RNA指导的DNA聚合酶体外合成的DNA产物中存在大DNA链，这为每70S RNA基因组中引物位点数量有限、大部分DNA产物尺寸小以及DNA产物所代表的劳氏肉瘤病毒基因组范围之间存在的矛盾提供了解释。
