Osmotic Stress-coupled Maintenance of Polar Growth in Aspergillus nidulans


Han K and Prade R 2002 Stress Coupled Maintenance of Polar Growth in Aspergillus nidulans Molecular Microbiology 43: 1065 -1077

Free-living cells monitor extracellular ‘osmotic strength’ and respond metabolically to offset unfavourable osmotic intracellular solute concentrations. Here, we report the reconstruction of the Aspergillus nidulans salt stress-controlling MAP kinase pathway, based on homology analysis with known yeast genes. In A. nidulans, salt stress HOG genes, such as pbsA, hogA, ptpA and msnA, are upregulated when exposed to high concentrations of salt and, in a hogA deletion mutant (SIK1), the accumulation of pbsA is strongly reduced, suggesting a salt-specific feedback induction mechanism. Growth of SIK1 appears to be unchanged in unstressed cells, but hyphal extension rates are reduced by as much as 60% in the presence of salt. Microscopic observation revealed abnormal hyperbranched hyphal tips, disproportionate accumulation of nuclei and absence of septa. Thus, the inability to maintain turgor pressure depresses cell expansion and results in slower volume increases. In addition, SIK1 fails to partition the apical cell; thus, nuclei are not likely to arrest mitosis in interphase as in normal cells, but continue to divide, accumulating to high levels. 

Pusztahelyi T, Klement E, Szajli E, Klem J, Miskei M, Karányi Z, Emri T, Kovács S, Orosz G, Kovács KL, Medzihradszky KF, Prade RA, Pócsi I (2011) Comparison of transcriptional and translational changes caused by long-term menadione exposure in Aspergillus nidulans. Fungal Genetics & Biology 48:92-103

Balázs A, Pócsi I, Hamari Z, Leiter E, Emri T, Miskei M, Oláh J, Tóth V, Hegedus N, Prade RA, Molnár M, Pócsi I. (2010) AtfA bZIP-type transcription factor regulates oxidative and osmotic stress responses in Aspergillus nidulans. Molecular Genetics & Genomics 283:289-303

Pócsi I, Miskei M, Emri T, Ayoubi P, Pustahelyi T, Balla G and Prade R 2005 Comparison of gene expression signatures of diamide, H2O2 and menadione exposed Aspergillus nidulans cultures - linking genome-wide transcriptional changes to cellular physiology. BMC Genomics 6:182 1-18

Prade R Ayoubi P Krishnan S Macwana S and Russell H 2001 Accumulation of Stress and Cell Wall Degrading Enzyme Associated Transcripts During Asexual Development in Aspergillus nidulans Genetics 157: 957-96



Cell & Molecular Biology
ONLINE  Cell & Molec. Biol.
Medical Mycology
Eukaryotic Genetics
Biomass Technology
Biomass Degradation
High Temp. Enzymes
Protein expression systems

Molecular Genetics
Gene Silencing
Stress Responses
Gene Regulation

DNA Bioinformatics
Structural Protein Modeling
Physical Mapping