Crow J F
Department of Genetics, University of Wisconsin, Madison 53706, USA.
Exp Clin Immunogenet. 1995;12(3):121-8. doi: 10.1159/000424865.
From various estimates of the mutation rate per nucleotide per generation, centering around 1-2 x 10(-8) and the number of nucleotide pairs, 3 x 10(9) per genome, the number of new mutations in a human zygote is very large, in the order of 100. The mutation rate is an order of magnitude higher in males than females, due presumably to the greater number of cell divisions in the male germ line, and increases more than linearly with paternal age. It is likely that a large fraction of these mutations are in unimportant 'junk' DNA, but if even 2% of the mutations are selected, this means two new deleterious mutations per generation. It is suggested that quasi-truncation selection is the most likely way in which this large number of mutations can be eliminated from the population without an excessive burden of reduced viability and fertility.
根据对每代每个核苷酸突变率的各种估计，集中在1 - 2×10⁻⁸左右，以及每个基因组3×10⁹个核苷酸对，人类受精卵中的新突变数量非常大，约为100个。男性的突变率比女性高一个数量级，这可能是由于雄性生殖系中的细胞分裂次数更多，并且随父亲年龄增长的增加幅度超过线性关系。很可能这些突变中的很大一部分存在于不重要的“垃圾”DNA中，但即使只有2%的突变被选择，这意味着每代有两个新的有害突变。有人提出，准截断选择是最有可能的方式，通过这种方式可以在不对生存能力和生育能力降低造成过度负担的情况下，从种群中消除大量这种突变。
