Molecular and General Genetics MGG

, Volume 204, Issue 1, pp 98–102

Spontaneous amplification of yeast CEN ARS plasmids

  • R. Bitoun
  • A. Zamir

DOI: 10.1007/BF00330194

Cite this article as:
Bitoun, R. & Zamir, A. Molec Gen Genet (1986) 204: 98. doi:10.1007/BF00330194


Transformation of Saccharomyces cerevisiae with several yeast CEN4 ARS1 plasmids containing the his3-Δ4 allele (as well as the URA3 and TRP1 markers) yielded His+ transformants at 0.1%–50% the frequency of Ura+ Trp+ transformants. Additional His+ derivatives arose on continuous growth of transformants originally scored as His- Ura+ Trp+. In all cases, the His+ phenotype was not due to plasmid or host mutations but invariably correlated with an up to 12-fold increase in plasmid copy number. On removal of selective pressure, the His+ phenotype was lost more readily than the Ura+ Trp+ markers, with a corresponding decrease in plasmid copy number. Also, the amplification did not decrease the mitotic loss rate of the Ura+ Trp+ markers. These results indicate that CEN ARS plasmids can be spontaneously amplified to higher levels than previously observed. However, when amplified, apparently not all copies exhibit the characteristic stability of CEN ARS plasmids.

Key words

Saccharomyces cerevisiae Minichromosomes Centromere Copy number Mitotic stability 

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • R. Bitoun
    • 1
  • A. Zamir
    • 1
  1. 1.Biochemistry DepartmentWeizmann Institute of ScienceRehovotIsrael
  2. 2.Centre National de la Recherche AgronomiqueVersaillesFrance

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