Abstract
Many fungi are capable of growing by polarized cellular extension to form hyphae or by isotropic expansion to form buds. Aspergillus nidulans anucleate primary sterigmata (apsA) mutants are defective in nuclear distribution in both hyphae and in specialized, multicellular reproductive structures, called conidiophores. apsA mutations have a negligible effect on hyphal growth, unlike another class of nuclear distribution (nud) mutants. By contrast, they almost completely block entry of nuclei into primary buds, or sterigmata (bud nucleation), produced during development of conidiophores. Failure of the primary sterigmata to become nucleated results in developmental arrest and a failure to activate the transcriptional program associated with downstream developmental steps. However, occasionally in mutants a nucleus enters a primary bud and this event relieves the developmental blockage. Thus, there is a stringent developmental requirement for apsA function, but only at the stage of primary bud formation. apsA encodes a 183-kD coiled-coil protein with similarity to Saccharomyces cerevisiae NUM1p, required for nuclear migration in the budding process.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Actins / isolation & purification
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Amino Acid Sequence
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Aspergillus nidulans / cytology*
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Aspergillus nidulans / genetics*
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Aspergillus nidulans / growth & development
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Aspergillus nidulans / ultrastructure
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Base Sequence
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Calcium-Binding Proteins / genetics
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Cell Division / genetics
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Cell Nucleus / physiology
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Cell Nucleus / ultrastructure*
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Cloning, Molecular
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Cytoskeletal Proteins
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Fluorescent Antibody Technique
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Fungal Proteins / chemistry
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Fungal Proteins / genetics*
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Genes, Fungal / genetics*
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Microscopy, Electron, Scanning
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Microtubules / ultrastructure
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Molecular Sequence Data
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Morphogenesis / genetics
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Movement
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Nuclear Proteins / chemistry
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Nuclear Proteins / genetics*
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Protein Structure, Tertiary
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Restriction Mapping
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae Proteins*
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Sequence Homology, Amino Acid
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Spores, Fungal / cytology
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Spores, Fungal / genetics
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Spores, Fungal / growth & development
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Spores, Fungal / ultrastructure
Substances
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Actins
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Calcium-Binding Proteins
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Cytoskeletal Proteins
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Fungal Proteins
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NUM1 protein, S cerevisiae
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Nuclear Proteins
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Saccharomyces cerevisiae Proteins
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apsA protein, Aspergillus nidulans