Cytokinesis in Aspergillus nidulans is controlled by cell size, nuclear positioning and mitosis

Tom D. Wolkow, Steven D. Harris, John E. Hamer

Research output: Contribution to journalArticle

93 Scopus citations

Abstract

The mycelium of Aspergillus nidulans is composed of multinucleate cellular compartments delimited by crosswalls called septa. Septum formation is dependent on mitosis and requires the recruitment of actin to the site of septum formation. Employing a collection of temperature sensitive nuclear distribution (nudA2, nudC3 and nudF7), nuclear division (nimA5, hfaB3), and septation (sepD5, sepG1) mutants, we have investigated the interdependency among nuclear positioning, mitosis, and cell growth in structuring the cellular compartments of A. nidulans. The cellular compartments of nud+ strains were highly uniform with regard to nuclear distribution and averaged 38 μm in length. Incubation of nud mutants at semi-restrictive temperature resulted in aberrant nuclear distribution that appeared to direct the formation of variable-sized cellular compartments, ranging from 5 μm to greater than 81 μm. In germinating spores, the first septum forms at the basal end of the germ tube following the third round of nuclear division. Germlings must undergo mitosis in order to form a septum. Temperature-sensitive mitotic mutants were used to show that a single nuclear division is sufficient to activate septum formation, provided a critical cell size has been attained. In mitotic mutants and wild-type cells, delays in nuclear division resulted in the misplacement of the first septum. These results strongly support the role of mitotic nuclei in determining septal placement, and suggest that cell size control is post-mitotic in A. nidulans.

Original languageEnglish (US)
Pages (from-to)2179-2188
Number of pages10
JournalJournal of cell science
Volume109
Issue number8
StatePublished - Aug 1996

Keywords

  • Aspergillus nidulans
  • Cell size
  • Nuclear positioning
  • Septation

ASJC Scopus subject areas

  • Cell Biology

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