Figure 3.

Segregation of the 2 micron plasmid in the Ipl1-1 mutant. When the Ipl1 (aurora kinase) function is inactivated by a temperature sensitive mutation, chromosomes frequently missegregate (shown here by the unequal DAPI staining in the mother and daughter compartments). A. A multi-copy 2 micron reporter plasmid, fluorescence tagged by (GFP-LacI)-LacO interaction, also shows high missegregation under this condition (31). Furthermore, the plasmid tends to be retained most often in the cell compartment that contains the bulk of the chromosomes. B. The segregation of a plasmid lacking STB (an ARS plasmid) is not coupled to that of the chromosomes. However, such a plasmid missegregates frequently regardless of the Ipl1 status.