SELECTIVE MECHANISMS IN BACTERIA
SELECTIVE MECHANISMS IN BACTERIA
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DOI：
10.1101/sqb.1951.016.01.026
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发表时间：
1951-01-01
期刊：
影响因子：
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通讯作者：
RYAN, FJ
中科院分区：
文献类型：
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作者：
ATWOOD, KC;SCHNEIDER, LK;RYAN, FJ
群体遗传学的目标是根据突变和选择相互作用产生的变化来重建生物体进化中可能的事件顺序，或更罕见的是实际的事件顺序。当然，完全成功的可能性取决于对所涉及的遗传系统的属性进行有效和完整的评估。如果做不到这一点，我们可以在为观察到的变异性指定任何精确的基础之前，凭经验检查种群的遗传构成。无性细菌在这些方面提供了良好的机会，因为遗传变异的直接来源在于现有基因型突变的能力，而不是重组类型的出现。换句话说，变异的储存库不是被隐藏的，而是直接由异质群体的组成部分所代表。通过选择，我们将了解除了突变之外的那些影响群体中突变频率的因素。可以想象许多形式的选择往往会改变突变体的比例。为了方便起见，可以将它们分为两类，即特定的和非特定的。在特定选择的情况下，突变体和亲本类型之间的选择性差异是突变本身的直接结果，无论是主要的还是作为某些多效性复合体的一部分。 Braun (1947)、Braun、Goodlow 和 Kraft (1950) 以及 Guthrie (1949) 已经提供了一些解释，主要是在生化水平上。另一方面，非特异性选择由那些同时改变各种不相关突变体频率的因素组成。在考虑选择作为决定细菌种群构成的因素的作用时，这项工作部分得到了美国癌症协会的资助，该资助由美国国家研究委员会增长委员会推荐，也得到了美国公共卫生服务部国立卫生研究院研究资助和奖学金部门的研究资助。作者感谢 Amos Norman 博士在制定方程时提供的帮助。
The objective in population genetics is to reconstruct the possible, or more rarely the actual, sequence of events in the evolution of organisms in terms of changes resulting from the interplay of mutation and selection. The possibility of entirely succeeding in this is of course dependent on a valid and complete assessment of the attributes of the genetic systems involved. Failing in this, we may empirically examine the genetic constitution of populations before specifying any precise basis for the variability observed. The non-sexual bacteria offer good opportunities along these lines, because the immediate source of genetic variability resides in the capacity of the existing genotype to mutate, and not in the emergence of recombinant types. In other words, the reservoir of variability is not concealed, but is directly represented by the components of heterogeneous populations.By selection we shall understand those factors other than mutation which influence the frequencies of mutants in populations. Many forms of selection can be imagined which would tend to alter the proportions of mutants. These, for convenience, can be divided into two categories which we can call specific and non-specific. In the case of specific selection, the selective differential between mutant and parental type is a direct consequence of the mutation itself, whether primarily or as part of some pleiotropic complex. The mechanisms involved in imposed or specific selection must be separately considered for individual cases and some explanations, mostly on a biochemical level, have been offered by Braun (1947), Braun, Goodlow and Kraft (1950) and Guthrie (1949). Non-specific selection, on the other hand, consists of those factors which operate to alter the frequencies of a variety of unrelated mutants simultaneously. In considering the role of selection as a factor determining the constitution of bacterial popula-1This work was supported in part by an American Cancer Society grant recommended by the Committee on Growth of the National Research Council and by a research grant from the Division of Research Grants and Fellowships of the National Institutes of Health, US Public Health Service. The authors are grateful to Dr. Amos Norman for his help in formulating the equations.