Spindle formation and chromatin condensation in cells blocked at interphase by mutation of a negative cell cycle control gene.
In Aspergillus nidulans the temperature-sensitive cell cycle mutation bimE7 causes chromosome condensation and pre-anaphase spindle formation to occur at restrictive temperature. By constructing double mutants between bimE7 and S phase or G2 phase mutants and blocking DNA replication with hydroxyurea, we demonstrate that bimE7 can cause chromatin condensation and spindle formation in cells held in S or G2. Thus bimE7 overrides normal control systems that prevent mitosis from prematurely occurring during S or G2. We show that bimE7 is a loss of function mutation and propose that bimE normally functions to negatively control a positive mitotic inducing factor, possibly the cell cycle gene nimA.
Osmani
S A
SA
Department of Pharmacology, Robert Wood Johnson Medical School, UMDNJ, Piscataway 08854.
Engle
D B
DB
Doonan
J H
JH
Morris
N R
NR
D001233:Aspergillus nidulans / Q000235:genetics* / Q000648:ultrastructure; D002453:Cell Cycle; D002843:Chromatin / Q000648:ultrastructure*; D004247:DNA / Q000235:genetics; D004261:DNA Replication / Q000187:drug effects; D004274:DNA, Recombinant; D005455:Fluorescent Antibody Technique; D005800:Genes, Fungal; D006918:Hydroxyurea / Q000494:pharmacology; D007399:Interphase; D008870:Microtubules / Q000648:ultrastructure; D008940:Mitotic Index; D009154:Mutation; D010957:Plasmids; D008941:Spindle Apparatus / Q000648:ultrastructure*; D013696:Temperature; D014170:Transformation, Genetic; D014404:Tubulin / Q000032:analysis
D002843:Chromatin; D004274:DNA, Recombinant; D014404:Tubulin; D004247:DNA; D006918:Hydroxyurea