Gene conversion as a focusing mechanism for correlated mutations: A hypothesis
Gene conversion as a focusing mechanism for correlated mutations: A hypothesis
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DOI：
10.1007/bf02173638
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发表时间：
1996-07-19
期刊：
影响因子：
--
通讯作者：
Ninio, J
中科院分区：
文献类型：
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作者：
Ninio, J
探索了在不大幅提高原发突变率的情况下产生复杂突变事件的方法。如果通过错配DNA修复系统的作用而重新合成的少量DNA不需要进一步修复，则双突变的发生率可以增加100倍，而单突变的发生率仅增加30%。这种双突变发生率的增加似乎不足以满足高等生物的需要。对他们来说，另一种策略是通过在几个有性世代中以相关方式发生的一系列单一突变来产生复杂事件。有人提出基因转换可能完成了这一作用。假设在基因转换过程中发生的DNA再合成在转换区产生突变，我们可以预测，在转换过程中，两条同源染色体中相应序列的密切突变倾向于促进其附近的进一步突变。半定量计算表明，如果一对染色体之间的差异在10（-4）左右或更少，这种机制可能相当有效。这种机制可能构成在种群水平上起作用的适应性突变策略。
Ways of producing complex mutational events without substantially raising the primary mutation rate are explored. If the small amount of DNA that is resynthesised through the action of the mismatch DNA repair system is not subject to further repair, the incidence of double mutations can increase by a factor of 100, while single mutations would increase by only 30%. Such a boost in the incidence of double mutations seems insufficient to meet the needs of higher organisms. For them, an alternative strategy would be to produce complex events by a succession of single mutations occurring in a correlated manner over several sexual generations. It is proposed that gene conversion may fulfill this role. Assuming that the resynthesis of DNA that occurs during gene conversion produces mutations in the conversion tract, one predicts a tendency for close mutations in corresponding sequences in the two homologous chromosomes, to promote, during conversion, further mutations in their vicinity. Semiquantitative calculations suggest that such a mechanism can be quite effective, provided the divergence between two paired chromosomes is around 10(-4) or less. Such a mechanism might constitute an adaptive mutation strategy acting at the population level.