Genetics of Microorganisms

Tatum, E. L.; Perkins, David

doi:10.1146/annurev.mi.04.100150.001021

Cited by 25 publications

(4 citation statements)

References 65 publications

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“…But one may wonder why, if a gene is a differentiated molecule (or part of a molecule), it has not been possible to cause it to react in a specific way and thereby mutate. Chemical mutagens are well known but they do not cause patterns of mutation different from those induced by irradiation (Tatum & Perkins, 1950).…”

Section: Discussionmentioning

confidence: 99%

Adaptation to use Lactose in Escherichia Coli

Ryan

1952

Journal of General Microbiology

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SUMMARY : The adaptation of a genetically deficient strain of Escherichia coli (Bacterium coli) to the utilization of lactose was shown to involve overgrowth of the population by a small number of mutants. The rate of mutation to lactose utilization is about 2 x lo-' per bacterium per generation. This rate is not influenced by lactose or a series of substances related to that sugar. The distribution of these mutants among different cultures is in agreement with that expected on the basis of random mutation. These results are discussed in connesion with the theories of Hinshelwood on bacterial adaptation, and in relation to the problem of specifically induced mutation.Bacteria are remarkably plastic in their ability to undergo satisfactory adjustments in new environments. These adjustments are adaptations in the original biological sense of the word whether they are inherited or not, and irrespective of the underlying mechanisms.The adaptation of a bacterium to grow in one environment may be transmitted to its progeny for a few generations in a different environment, but such an adaptation would be considered t o involve a genetic change only if the intracellular factors responsible for the adapted character could be shown t o have multiplied in the course of these generations. Thus, in the case of those adaptive enzymes that are simply diluted to the unadapted level during bacterial division in the absence of their peculiar substrates, the adaptation does not involve a genetic change. On the other hand, when the adaptation involves the selective overgrowth of a population by organisms possessing a mutation in a chromosomal or non-chromosomal gene, it may be inherited in another environment because of the multiplication of the mutated factor.Nevertheless, the criterion of stability alone does not allow a distinction between genetic and non-genetic adaptations because gene mutations are generally reversible. Xor need the distinction be as clear-cut as first indicated. Rather, it is preferable t o ask more specific questions about the nature of the adaptive mechanism. First, it is important to know whether a n adaptation occurring in a population of bacteria involves all members of the population or whether there is selective overgrowth by a few unusual members. Further, it is necessary to know whether the change has been induced by the new environment or whether it may occur in another, or whether both possibilities exist.For example, Escherichia coZi (Bacterium coli) strain lac' possessing t h e inherited ability t o grow on lactose is unable t o do so at a maximum rate until i t has been exposed t o the sugar for some time (Monod & Audureau, 1946).

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Section: Discussionmentioning

confidence: 99%

Adaptation to use Lactose in Escherichia Coli

Ryan

1952

Journal of General Microbiology

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“…Later experiments confirmed that the same mutational process explained resistance to penicillin in different species of bacteria (Demerec ) and that mutations in fact arise from random processes rather than selective induction (Miller and Bohnhoff ; Lederberg and Lederberg ). Early study of antibiotic resistance mutations also demonstrated that the number of mutations appearing at every generation (i.e., the mutation rate) and the differences in individual mutations’ effects on phenotype (i.e., the distribution of fitness effects) could influence the rate of resistance evolution and therefore the time for a population to evolve specific traits (Tatum and Perkins ; Demerec and Hanson ). These findings provided the first experimental support for the ‘random’ character of evolution first advanced by Darwin () and espoused as a fundamental principle of evolutionary biology in the Modern Synthesis (Merlin ).…”

Section: Drug Resistance As a Model System For The Study Of Evolutionmentioning

confidence: 99%

Fighting microbial drug resistance: a primer on the role of evolutionary biology in public health

Perron

Inglis

Pennings

et al. 2015

Evolutionary Applications

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Although microbes have been evolving resistance to antimicrobials for millennia, the spread of resistance in pathogen populations calls for the development of new drugs and treatment strategies. We propose that successful, long-term resistance management requires a better understanding of how resistance evolves in the first place. This is an opportunity for evolutionary biologists to engage in public health, a collaboration that has substantial precedent. Resistance evolution has been an important tool for developing and testing evolutionary theory, especially theory related to the genetic basis of new traits and constraints on adaptation. The present era is no exception. The articles in this issue highlight the breadth of current research on resistance evolution and also its challenges. In this introduction, we review the conceptual advances that have been achieved from studying resistance evolution and describe a path forward.

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“…Primary antigens R1, o Secondary antigens Fig. 6 Transformation of the special type of the trypanosomes carrying two different antigens R1 and 0 [R1>0] after exposure to the antiserum to secondary antigen [0] Recently, the theory that hereditary variations in viruses and bacteria (cordon, 1950;Miller and Bohnhoff, 1950;Tatum and Perkins, 1950) are the result of spontaneous mutation regardless of environment is becoming widely accepted, but numerous questions are yet unanswered.…”

Section: R1 R20mentioning

confidence: 99%