Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

Directed mutation: paradigm postponed

D G MacPhee1

  • 1Department of Microbiology, LaTrobe University, Bundoora, Vic., Australia.

Mutation Research
|January 1, 1993
PubMed
Summary
This summary is machine-generated.

Spontaneous mutations are not directed. Glucose repression, a known phenomenon, explains the apparent directedness of mutations observed in selective media, particularly for Lac+ and Trp+ mutants.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Catabolite repression of SOS-dependent and SOS-independent spontaneous mutagenesis in stationary-phase Escherichia coli.

Mutation research·2010
Same author

Radiation dose-dependent increases in inflammatory response markers in A-bomb survivors.

International journal of radiation biology·2003
Same author

Characterization of mutant clones lacking T-cell receptor alleles in a cell line from an adult T-cell leukaemia patient.

British journal of haematology·2001
Same author

Possible role of natural killer cells in negative selection of mutant lymphocytes that fail to express the human leukocyte antigen-A2 allele.

Mutation research·2001
Same author

Chromosomal instability in BRCA1- or BRCA2-defective human cancer cells detected by spontaneous micronucleus assay.

Mutation research·2001
Same author

Reflections in mutation research. Reflections of Zhores Medvedev.

Mutation research·2000

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Previous hypotheses suggested spontaneous mutations could be directed by specific environmental conditions.
  • Selective media with unutilizable carbon sources (e.g., lactose) or absent essential amino acids (e.g., tryptophan) were implicated.

Purpose of the Study:

  • To investigate the hypothesis of a "directed" origin for spontaneous mutants.
  • To determine the role of specific environmental factors, like glucose, in the observed mutation rates.

Main Methods:

  • Selection for valine-resistant (Valr) mutants on plates with varying carbon sources.
  • Comparison of Valr mutant recovery rates with and without glucose in overlay media.
  • Analysis of mutation recovery in the presence of "directed" Lac+ or Trp+ mutants.

Related Experiment Videos

Main Results:

  • Valine-resistant mutants (Valr) occurred in significantly higher numbers when a carbon source other than glucose was present.
  • Even low concentrations of glucose (< 0.02%) in overlay media prevented the recovery of Valr mutants.
  • The recovery of Valr mutants was hindered when large numbers of "directed" Lac+ or Trp+ mutants were present.

Conclusions:

  • The apparent "directed" nature of spontaneous mutation is a misinterpretation.
  • This phenomenon is explained by glucose repression, a well-established biological process.
  • Environmental factors, specifically glucose, significantly influence the observable rates of spontaneous mutations.