Molecular and General Genetics MGG

, Volume 264, Issue 5, pp 546–554

The Aspergillus nidulans bncA1 mutation causes defects in the cell division cycle, nuclear movement and developmental morphogenesis

  • R. Castiglioni Pascon
  • A. A. Pizzirani-Kleiner
  • B. L. Miller
Original Paper

DOI: 10.1007/s004380000360

Cite this article as:
Castiglioni Pascon, R., Pizzirani-Kleiner, A. & Miller, B. Mol Gen Genet (2001) 264: 546. doi:10.1007/s004380000360

Abstract.

Wild-type Aspergillus nidulans conidia are uninucleate. The mutation bncA1 (binucleated conidia) was first described as a single mutation located on chromosome IV that caused formation of approximately 25% binucleate and 1% trinucleate conidia. In this study, we show that bncA1 conidia exit G1 arrest earlier than the wild type. Germlings have hyphal elements with abnormal morphology, elevated numbers of randomly distributed nuclei and an irregular septation pattern. Older hyphal elements undergo mitotic catastrophe, suggesting the nuclear division cycle of internal (non-terminal) elements is not arrested. The bncA1 mutation also causes aberrant morphogenesis of the asexual reproductive structure, the conidiophore. Metulae and phialides are elongated and have incorrect numbers of nuclei. Phialides also have internal septation that appears to delineate hyphal-like elements. Heterokaryon analysis using strains with contrasting auxotrophic markers showed that the bncA1 mutation resulted in a higher frequency of diploid and multinucleated prototrophic conidia than control heterokaryons. These results suggest that in bncA1 strains multiple nuclei can move from the conidiophore vesicle to the metulae and/or from the phialide to the conidium. The bncA1 mutant also showed hypersensitivity to the anti-microtubule drugs thiabendazole and nocodazole, which is consistent with the defects in cell cycle regulation and nuclear movement. We propose that bncA has an important role in correctly regulating both the cell division cycle and nuclear movement.

Morphogenesis Nuclear movement Conidiation 

Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • R. Castiglioni Pascon
    • 1
  • A. A. Pizzirani-Kleiner
    • 2
  • B. L. Miller
    • 1
  1. 1.Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, ID 83844, USAUSA
  2. 2.Departamento de Genética e Melhoramento de Plantas, Escola Superior de Agricultura "Luiz de Queiróz", Universidade de São Paulo, Piracicaba, SP, BrazilBrazil

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