Biostatistics Branch, National Institute of Environmental Health Sciences (NIH), Research Triangle Park, NC 27709, USA.
Mutat Res. 2013 Sep;749(1-2):16-20. doi: 10.1016/j.mrfmmm.2013.07.006. Epub 2013 Aug 2.
In a recent description of the rate and character of spontaneous mutation in the hyperthermophilic bacterium Thermus thermophilus, the mutation rate was observed to be substantially lower than seen in several mesophiles. Subsequently, a report appeared indicating that this bacterium maintains an average of about 4.5 genomes per cell. This number of genomes might result in a segregation lag for the expression of a recessive mutation and might therefore lead to an underestimate of the rate of mutation. Here we describe some kinds of problems that may arise when estimating mutation rates and outline ways to adjust the rates accordingly. The emphasis is mainly on differential rates of growth of mutants versus their parents and on various kinds of phenotypic lag. We then apply these methods to the T. thermophilus data and conclude that there is as yet no reliable impact on a previously described rate.
在最近对嗜热菌 Thermus thermophilus 中自发突变的速率和特征的描述中，观察到突变率明显低于几种中温菌。随后，有报道表明，这种细菌平均每个细胞维持约 4.5 个基因组。这种基因组数量可能会导致隐性突变表达的分离滞后，因此可能会导致对突变率的低估。在这里，我们描述了在估计突变率时可能出现的一些问题，并概述了相应调整速率的方法。重点主要是突变体相对于其亲本的生长差异率和各种表型滞后。然后，我们将这些方法应用于 Thermus thermophilus 的数据，并得出结论，到目前为止，这对之前描述的速率没有可靠的影响。
