Avian RNA tumor viruses: mechanism of recombination and complexity of the genome.
Avian RNA tumor viruses: mechanism of recombination and complexity of the genome.
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禽 RNA 肿瘤病毒：重组机制和基因组复杂性。
DOI：
10.1101/sqb.1974.039.01.099
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发表时间：
1975
期刊：
影响因子：
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通讯作者：
M. Lai
中科院分区：
文献类型：
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作者：
P. Duesberg;P. Vogt;K. Beemon;M. Lai
禽RNA肿瘤病毒经历宿主范围、转化和逆转录酶标记的重组（沃格特1971; Kawai and Hanafusa 1972;韦斯et al. 1973;怀克1973; Mason et al. 1974）。在考虑这种重组的可能机制时，必须考虑两个因素：（1）重组体以高频率发生，以及（2）病毒基因组，60- 70 S单链RNA，由几个30- 40 S片段组成。这两个因素表明类似于流感病毒，其具有分段的基因组，并且还显示出由位于不同基因组区段上的标记物的重配引起的高频重组。类似地，禽类RNA肿瘤病毒可以通过用不同的遗传标记交换30- 40 S RNA片段来重组。然而，初步实验并不支持禽类肿瘤病毒之间重配重组的假设，并提示可能发生分子交换（Duesberg and沃格特1973 a;沃格特and Duesberg 1973）。在本通讯中，我们将证实这些初步结果，并增加新的证据，表明禽类肿瘤病毒之间的重组是通过交换而不是通过重配产生的。通过同源核酸片段之间的交换而产生的重组将与目前RNA肿瘤病毒基因组的两种竞争模型相容：（1）其中每个30- 40 S RNA包含相同遗传信息的多倍体结构，和（2）单倍体，分节结构，其中几个遗传上不同的30- 40 S片段在60- 70 S复合体中结合。这两种模型在它们预测的病毒基因组的遗传复杂性方面有所不同。如果60- 70 S复合体是单倍体，则基因组的复杂性将接近1 × 107道尔顿。在多倍体60- 70 S结构中，单个基因组的复杂性约为3 × 106道尔顿。我们已经从寡核苷酸分析中估计了60- 70 S RNA的复杂性，发现它约为3 × 106道尔顿，有利于pelyploid基因组模型。
Avian RNA tumor viruses undergo recombination for host range, transformation and reverse transcriptase markers (Vogt 1971; Kawai and Hanafusa 1972; Weiss et al. 1973; Wyke 1973; Mason et al. 1974). In considering possible mechanisms of this recombination, two factors must be taken into account:(1) recombinants occur at a high frequency, and (2) the viral genome, a 60-70S single-stranded RNA, consists of several 30-40S pieces. These two factors suggest an analogy to the influenza viruses, which have a segmented genome and also show high frequency recombination resulting from the reassortment of markers situated on different genome segments. Similarly, avian RNA tumor viruses could recombine by exchanging 30-40S RNA pieces with different genetic markers. However, preliminary experiments did not support the hypothesis of reassortment between avian tumor viruses for recombination and suggested that molecular crossingover might occur (Duesberg and Vogt 1973a; Vogt and Duesberg 1973). In the present communication we will confirm these preliminary results and add new lines of evidence suggesting that recombinants between avian tumor viruses arise by crossing-over and not by reassortment.Recombination by crossing-over between homologous pieces of nucleic acid would be compatible with both presently competing models of the RNA tumor virus genome:(1) a polyploid structure in which each 30-40S RNA contains the same genetic information, and (2) a haploid, segmented structure in which several genetically distinct 30-40S pieces are united in the 60-70S complex. These two models differ in the genetic complexity which they predict for the viral genome. If the 60-70S complex is haploid, the complexity of the genome would be close to 1 x 107 daltons. In a polyploid 60-70S structure, individual genomes would have a complexity of about 3 x 106 daltons. We have estimated the complexity of the 60-70S RNA from oligonucleotide analyses and find that it is about 3 x 106 daltons, favoring the pelyploid genome model.