Evolution on a Petri Dish

Hall, Barry G.

doi:10.1007/978-1-4615-6968-8_2

Cited by 27 publications

(5 citation statements)

References 94 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nevertheless, it should be pointed out that the activation of cryptic genes in E. coli occurs at high frequencies, even though some of them require more than one mutation in order to be activated (3,11). Further ilation of carbon and nitrogen sources by C. albicans is well established, this phenomenon has not been investigated from a genetic or mechanistic point of view.…”

Section: Discussionmentioning

confidence: 99%

Chromosomal alterations of Candida albicans are associated with the gain and loss of assimilating functions

1994

View full text Add to dashboard Cite

We have demonstrated that a normal laboratory strain of Candida albicans spontaneously produces mutants which acquire the ability to assimilate certain carbon sources that are not utilized by the parental strain. The examination of mutants acquiring the ability to utilize either sorbose or D-arabinose revealed a few additional phenotypic changes, including the gain and loss of the capacity to assimilate other carbon sources. The change of assimilation patterns resembled the polymorphic variation of assimilation patterns found among different wild-type strains of C. albicans. Most importantly, these sorbose-and D-arabinose-positive mutants were associated with chromosomal rearrangements, with each class of positive mutants having alterations of specific chromosomes. These findings demonstrated for the first time that chromosomal alterations in C. albicans are involved in genetic variation of fundamental functions of this asexual microorganism.We previously reported that standard laboratory strains of Candida albicans spontaneously gave rise to various types of single and multiple chromosomal rearrangements at a frequency of about 1.4% (40), and we suggested that this high frequency of chromosomal aberrations provides a means for genetic variation in this asexual microorganism (38,40). Although the chromosomal aberrations were associated with alterations of colonial and cellular morphologies, rates of growth, pseudohyphae, chlamydospore production, germ tube formation, growth at extreme temperatures, and color differences on BiGGY and phloxine B media (38-40), we were unable to discern any specific relationships between the various types of chromosomal rearrangements and phenotypic variability.Recently, Wickes et al. (48) reported that certain Candida stellatoidea strains spontaneously gave rise to sucrose-positive (Suc+) colonies that exhibited chromosomal rearrangements.In addition, we observed that all of a large number of spontaneously derived colony morphology mutants having chromosomal alterations were also associated with different patterns of carbon and nitrogen assimilation (37).Because of the obvious selective importance of carbon and nitrogen sources, these findings prompted us to investigate possible relationships between the assimilation patterns, chromosomal rearrangements, and other phenotypic traits. Furthermore, changes in assimilation provide an opportunity to investigate discrete and easily assayable phenotypes.In this paper, we describe the isolation and characterization of positive mutants, i.e., mutants that have gained the ability to assimilate substrates. In particular, independently derived spontaneous mutants that have acquired the ability to utilize either sorbose or D-arabinose were isolated from the normal strain 3153A. Of considerable importance, and in contrast to the previous report (39), these positive mutants contained altered electrophoretic karyotypes, with each class of positive mutants having alterations of specific chromosomes. This is the

show abstract

Section: Discussionmentioning

confidence: 99%

Chromosomal alterations of Candida albicans are associated with the gain and loss of assimilating functions

1994

View full text Add to dashboard Cite

show abstract

“…We now know that E. coli and other bacteria contain cryptic genes that can be mutationally activated (44). In some cases, more than one mutation is required (17,42). Because the apparent frequency at which such multiple mutants arise vastly exceeds the frequency predicted if the mutations are independent, Hall (42) suggested that the mutations occur by some concerted mechanism.…”

Section: Evidence Contradictory To the Mutation Paradigmmentioning

confidence: 99%

“…In some cases, more than one mutation is required (17,42). Because the apparent frequency at which such multiple mutants arise vastly exceeds the frequency predicted if the mutations are independent, Hall (42) suggested that the mutations occur by some concerted mechanism. 4 Cairns et al (16) drew upon these discordant results and their own experiments to argue for "a non-random, possibly product-oriented form of mutation" (p. 142).…”

Section: Evidence Contradictory To the Mutation Paradigmmentioning

confidence: 99%

ADAPTIVE MUTATION: The Uses of Adversity

Foster¹

1993

Annu. Rev. Microbiol.

237

View full text Add to dashboard Cite

When populations of microorganisms are subjected to certain nonlethal selections, useful mutants arise among the nongrowing cells whereas useless mutants do not. This phenomenon, known as adaptive, directed, or selection-induced mutation, challenges the long-held belief that mutations only arise at random and without regard for utility. In recent years a growing number of studies have examined adaptive mutation in both bacteria and yeast. Although conflicts and controversies remain, the weight of the evidence indicates that adaptive mutation cannot be explained by trivial artifacts and that nondividing cells accumulate mutations in the absence of genomic replication. Because this process tends to produce only useful mutations, the cells appear to have a mechanism for preventing useless genetic changes from occurring or for eliminating them after they occur. The model that most readily explains the evidence is that cells under stress produce genetic variants continuously and at random, but these variants are immortalized as mutations only if they allow the cell to grow.

show abstract

Section: Evidence Contradictory To the Mutation Paradigmmentioning

confidence: 99%

Adaptive Mutation: The Uses of Adversity

Foster¹

1993

Annual Review of Microbiology

View full text Add to dashboard Cite

When populations of microorganisms are subjected to certain nonlethal selections, useful mutants arise among the nongrowing cells whereas useless mutants do not. This phenomenon, known as adaptive, directed, or selection-induced mutation, challenges the long-held belief that mutations only arise at random and without regard for utility. In recent years a growing number of studies have examined adaptive mutation in both bacteria and yeast. Although conflicts and controversies remain, the weight of the evidence indicates that adaptive mutation cannot be explained by trivial artifacts and that nondividing cells accumulate mutations in the absence of genomic replication. Because this process tends to produce only useful mutations, the cells appear to have a mech-anism for preventing useless genetic changes from occurring or for eliminating them after they occur. The model that most readily explains the evidence is that cells under stress produce genetic variants continuously and at random, but these variants are immortalized as mutations only if they allow the cell to grow.

show abstract

Evolution on a Petri Dish

Cited by 27 publications

References 94 publications

Chromosomal alterations of Candida albicans are associated with the gain and loss of assimilating functions

Chromosomal alterations of Candida albicans are associated with the gain and loss of assimilating functions

ADAPTIVE MUTATION: The Uses of Adversity

Adaptive Mutation: The Uses of Adversity

Contact Info

Product

Resources

About